Southern Marin Service Review and Sphere of Influence Update - Almonte Sanitary - October 2011 (pdf)

SOUTHERN MARIN SEWER AGENCIES SERVICE REVIEW AND SPHERE OF INFLUENCE UPDATE Appendices to Correspondence from Bonner Beuhler, Almonte Sanitary District October 2011 ] J J J RICHARDSON BAY SANITARY DISTRICT MARIN COUNTY, CALIFORNIA J-- "-.----------~-- ] J ] ] REPORT ON ] .INTERIM IMPROVEMENTS ] ] ] JUNE, 1. '171 J ] ] ] J. WARREN NUTE, INC. J CIVIL AND SANITARY ENGINEERS ,-, J j J. WARREN NUTE. INC. CIVIL AND SAN1TAftY ENGINEERS 411 FOURTH STREET J. WARREN NUTE, P. E. SAN RAFAEL, CALIFORNIA 94901· WARREN E. NUTE. P. E. TELEPHONE (415) 453·4-i80 June 18, 1971 To the Honorable Board of Directors RICHARDSON BAY SANITARY DISTRICT 618 Town & Country Village Mill Valley, CA 94941 Letter of Transmittal ' ..:1 ...1 11'.- Gentlemen and Madam: In accordance with your request, we have analyzed the requirements of the Regional Water Quality Control Board Order No. 71-14 and have investigated possible interim improvements to allow growth of the District over the next few years while still holding waste loadings to the bay within present levels. As summarized herein, the interim improvements at the (1) Trestle Glen Plant consist of a chlorine contact chamber already under contract for construction and (2) la~d disposal of a portion of the effluent at the plant site. Within the Salt Works and Ricardo Road Watersheds, the interim improve ments consist of corrections and repairs to the sewer system as a means of preventing significant amounts of storm water from entering the sewer system and thereby reducing the level of bypassing. It is hoped that this report will provide a basis on which the District can meet the interim improvements required by the Regional Water Quality Control Board until such time as the studies being conducted by Improvement District A are completed. Very truly yours, J. WARREN NUTE, INC. ByA. .... ] ~J4, 4 ", ..... • Warren Nute BY~\.U~·~ ""~~ .c ~.~ ~.~ ~~JII.~b.. .. Warren E. Nute '] J TABLE OF CONTENTS CHAPTER I - INTRODUCTION General - - - - - - - - - - - - - - - - - 1-1 Water Quality Control Board Orders - - - 1-1 Scope of Report on Interim Improvements - - - 1-2 CHAPTER 2 - DISTRICT BACKGROUND General - - - - - - - - - - - 2-1 Historical Background - - - - - - - - - 2-1 Present District Activities - - - - - - 2-5 Summary - - - - - - - - - - 2-5 CHAPTER 3 - INTERIM NEEDS General - - - - - - - - - - - - - 3-1 Area Served by the District - - - - - - - - - - - 3-1 Service Characte~istics - - - - - - - - - 3-2 Projected Interim Growth Rates 3-5 Alto Strip Detachment - - - - - 3-6 Summary - - - - - - - - - - - - 3-6 CHAPTER 4 - INTERIM IMPROVEMENTS General - - - - - - - - - - - - - - 4-1 J 4;..1 Waste "A" - - - - - - - - - - - - -' - - - Chlorine Contact Chamber Enlargements - - - - - - 4-2 Interim Effluent Disposal - - - - - - - - - - 4-2 Waste "B" - - - - - - - - - - - - - - - - - - - - 4-5 Sausalito-Marin City Sanitary District - - - 4-7 Bypassing Correction Program 4-9 ] . Future Permanent Improvements 4-14 Summary - - - - - - - - - - - - - - - - - 4-15 ] CHAPTER 5 - CONCLUSIONS AND RECOMMENDATIONS General - - - - 5-1 ] Conclusions - - 5-1 Recommendations 5-2 ORDER. NO. 71-14 - - - - - - - - - - - - - - - - - Appendix A ] J ] CHAPTER 1 INTRODUCTION General The Richardson Bay Sanitary District has a commendable history of productive effort t.oward providing efficient and effective water pollution control and water quality enhance ment, with the added objective of a minimum financial burden ] upon the citizens served by the District. Consistent with the District's past ,history of meeting ] i ts obligations, the present interim efforts described hereirt have been undertaken for the purp'oses of allowing growth of the Dis tric t .' to continue while still holding was te loadings to the bay within present levels. These interim efforts must continue until such 'time as a permanent sewage disposal solu tion can be implemented to serve~he District as well as other communities in the Bay area. Richard~on Accordingly, the purpose of this report is to review the District's ,past. efforts of pollution control, project needs J for the immediate future, describe the interim improvements' which have already been undertaken and present a program of continuing improvements to the. system so that the District can continue to accommodate the e;xpected,growth over the next J few years. until a permanent sewage disposal solution is im- plemented. . ] Water Quality Control Board Orders ] On April 22, 1971, the Regional Water Quality Control Board, San Francisco Bay Region, adopted Order No. 71-14 which set new waste discharge requirements for the Richardson Bay Sanitary District. Order No. 71-14 resc'inded Resolution No. ] 228 which previously regulated waste. discharge from the Richard son Bay Sanitary District an,d is reproduced in Appendix A. ] In essence, to comply with Order No. 71-14, the District must install an extreme level of tertiary treatment at its Trestle Glen Treatment Plant (waste "A") and eliminate all ] wet weather bypassing throughout its system (waste "B"). In asmuch as the District cannot ,immediately comply with either of the new discharge requirement,s, a cease and desist hearing has been set by the Regional Water Quality Control Board to J consider issuance of such an order and also to consider re stricting additional connections to the District system. J 1-1 J [ INTRODUCTION [ To avoid a restriction on additional connections, the District must demonstrate that interim improvements which have been instituted will hold waste loadings to the bay within present levels when additional connections are made. Such interim improvements will be necessary until a permanent solution is implemented which will comply with all present and future waste discharge orders. Scope of Report on Interim Improvements In compliance with Water Quality Control Board Policy, this report provides background information about the District and describes the interim improvements which have been in stituted by the District. Further, this report demonstrates that the interim improvements already accomplished, along with a continuing program of sUch improvements, will serve to en hance water quality of the bay and thereby make the issuance of a restriction of future connections to the District system unnecessary. Specifically, this report covers the following basic subject areas: (a) DISTRICT BACKGROUND Review of the history of the District and review of efforts now being made by the District itself and on a regional basis in cooperation with other agencies around Richardson Bay to enhance r- water quality of the bay by providing adequate sewage collection and disposal. (b) FUTURE NEEDS -_ A description of the District service areas, development of present and anticipated future [ growth of the District and projection of service r- needs for the immediate future. (c) INTERIM IMPROVEMENTS -- Description of interim im provements already instituted and development of a program of interim improvements which will allow additional connections to the system while still enhancing water quality by holding waste loadings to .r - the bay within present levels. (d) CONCLUSIONS AND RECOMMENDATIONS Presentation of conclusions and recommendations as to a program of interim improvements. 1-2 CHAPTER 2 DlSTRICT BACKGROUND Gene.ral To establish a general understanding of past District activities, this chapter presentsi brief historical descrip tion of the District's past activities. Further, in recogni tion of the necessity to plan future sewage disposal improve ments, a review of the present District activities toward achieving permanent solutions for enhancement of water quality in the bay is presented. Historical Background Since its formation. in 1949, the Richardson Bay Sanitary District has a commendable history in meeting its obligations of providing sewerage service and meeting the demands of con tinued growth within the District. The first sewer system in the Strawberry area was installed about 1945 to serve the Bay view Terrace subdivision after septic tanks throughout the tract had failed. A collecting system was constructed in the ".•l.• J rear of the houses to intercept septic tank effluent and an ~ outfall line was run to the Salt Works Canal which discharged without further treatment into the bay. In 1947 sewers from Bayview Heights were copnected to this outfall line. In 1946 d.evelopment of the Strawberry Point properties was started with the construct'ionof homes along Belvedere Drive. Two community septic tanks were installed by the de veloper to serve this tract with approval of the County Health Department. One septic tank and leaching field was installed ] on the west side between Reed Boulevard and the State Highway and the second on the east slope between Ricardo Road and Strawberry Drive. Subsequently, in 1948, a third community septic tank was installed on the west slope to serve the Strawberry Manor tract. This tank was located south of Ricardo Road with an outfall to the bay on the east side of DeSilva Island. Ap proval of these facilities by the County Health authorities was with the understanding that they were temporary in nature and that they would have to be replaced with better treatment and disposal facilities in the near future. It became evident to the new residents of these tracts that the facilities pro vided by the developer would soon become entirely inadequate and, since the proposed Southern Marin Sanitation District had ] 2-1 [ I DISTRICT BACKGROUND I been rejected by the voters, the residents of the Strawberry area formed the Richardson Bay Sanitary District in February, 1949. Upon its formation, the District became the owner of I the three community sewage disposal systems. To solve the problem of the east side of Strawberry, a I Biofilter, Jr. package-type sewage treatment plant was con structed in 1950 on the Tiburon Highway adjacent to Salt Works Canal. At the same time, the Belveron Gardens area was I under development and was subsequently annexed to the District. A second Biofilter, Jr. treatment plant was constructed by the developer of Belveron Gardens at the location of the present Trestle Glen plant. Each plant was designed to provide com I plete treatment for a population of 800. Rapid growth of the Strawberry Point area had, by 1953, I made the Salt Works Canal plant and the two community septic tanks on the west side entirely inadequate. After studies to seek the most economical soiution,the District contracted [ with the City Sanitary District for treatment Sausalito~Marin of sewage at their new plaI)t near Fort Baker rather than at tempt to enlarge the Salt Works Canal plant or to construct another package-type plant to serve the west side of Strawberry [ Point. To. connect the system to the Sausalito-Marin City Sanitary [ District plant, a new force main and trunk sewer was laid from the Salt Works Canal plant along Belvedere Drive and Highway 101 to the west end of Ricardo Road together with a force main [ across the Richardson Bay bridge and connecting with the Sausa lito system at Manzanita. The treatment plant at Salt Works Canal was converted to a pumping station and a new pumping plant was built at the western end of Ricardo Road. As part I of the widening project for the Tiburon Highway, a new pumping station was constructed for the District in 1962 by the State Highway Department on the north side of the highway and the old I Salt Works plant was dismantled. The original force main across Richardson Bay Bridge was I installed on the old redwood highway bridge which had a lift span. Every time the span was raised, it was necessary to disconnect the pipe. When the present high level concrete bridge was built in 1956, a new force main was installed as I part of the construction. Connection to the Sausalito system was made into an 8-inch I force main with limited capacity which connected with a larger I 2-2 I ] ] DISTRICT BACKGROUND main at Marin City. This line was replaced by the Sausalito Marin City District in 1959 with a l6-inch pipe line to serve both the Richardson Bay and Tamalpais Valley systems. It had been expected that the connection to the Sausalito system would provide adequate service for the future needs of the areas served by the Ricardo Road and Salt Works pumping' stations. However, the Sausalito system is of limited capacity to handle peak flows, and operating experience has indicated that the present system will be inadequate to serve the ulti mate needs of the District. That portion of the District served by the original. Bio filter, Jr. plant at Trestle Glen was growing rapidly, and by 1956 it became evident that the plant should be enlarged. "1 About 1,200 persons were being served by the plant which £1 amounted to about 50 per cent overload, and the degree of treatment was rapidly deteriorating. In view of the high degree of treatment necessary at the Trestle Glen ;Location, the design for the enlarged plant incor porated a modified activated sludge process known as Spiro Vortex system. The plant was designed to serve a population i"..•.1••I•.. ' . of 4,000 to be constructed in two stages. The first stage was constructed in 1958. By making u'se of the existing set tling tanks of the Biofilter, Jr. plant, the construction of the secondary clarifier was delayed until 196J. Over the years, the Richardson Bay Sanitary District has brought about the consolidation of a number of separate and community disposal systems and the elimination of several sewage discharges to the bay as itemized in Table 2-1. The consolidation of facilities represents the results of con siderable planning and progress on the part of the District toward enhancing water quality in the bay and providing for protection of the health of the community through adequate sewage collection and treatment. At the present time, the District operates the Trestle Glen Sewage Treatment facility which discharges disinfected secondary effluent to Richardson Bay. Sewage from the Salt Works and Ricardo Road Watersheds is pumped to the Sausalito Marin City Sanitary District for treatment and disposal. J ] 2-J [ [ DISTRICT BACKGROUND [ TABLE 2-1 [ CONSOLIDATION OF SEPARATE AND COMMUNITY SEWAGE DISPOSAL SYSTEMS BY THE RICHARDSON BAY SANITARY DISTRICT [ Connected Type of Effluent to Dist. Community System Watershed Treatment Disposal System East Strawberry Salt Works Community Leaching 1950 Septic Tank Field [ West Strawberry Ricardo Rd. Community Leaching 1954 Septic Tank Field Strawberry Manor Ricardo Rd. Community Outfall 1958 [ Septic Tank to bay Bayview Terrace Salt Works Indiv. Septic Outfall 1955 Sewer Maint. Tanks to bay District West of Highway Ricardo Rd. Indiv. Septic Leaching 1957 Tanks Field South Knoll Road Ricardo Rd. Indiv. Septic Leaching 1957 Tanks Field Richardson Bay Salt Works Biofilter Jr. butfall 1962 I Sanitary Dist. Sec. Trea t. to bay Del Mar Trestle Gl. Community Leaching Septic Tank Field Hawthorne Terrace Trestle Gl. Community Outfall Sewer Main t . Septic Tank to bay District Bay Vista Dr. - Salt Works Indiv. Septic Leaching Sky Rd. Tanks Field ( I···' 2-4 [ ] DISTRICT BACKGROUND Present District Activities 1....:. 1.· ~ In a 1963 report to the District, it was recommended that the sewage originating in the Salt Works Watershed which is 1- pumped to Sausalito be diverted to the Trestle Glen plant for treatment and thus relieve the load on the Sausalito-Marin City system. This plan was never implemented, basically because the growth of the District slowed down and there was a renewed interest in finding a regional solution to the sewage disposal problems of the Richardson Bay area. Recognizing the need to further enhance water quality on a regional basis, the Richardson Bay Sanitary District is co operating with the other sewerage agencies in the Southern Marin area and participating in a subregional study to develop I a wastewater management program. The subregional study is now being conducted by the Marin Municipal Water District under Improvement District A, and the results of the study should be known by mid-l972. Since the feasibility of a regional sewerage plan depends on reduction of peak flows in so far as possible, the Dis_ trict, on an individual basis, has undertaken an intensive program of infiltration detection and leak correction. This I program is intended both as a permanent solution toward reduc tion of wet weather flows and as an interim solution toward enhancing water quality by holding waste loadings to the bay I within present levels until a permanent sewerage plan can be implemented. Summary The Richardson Bay Sanitary District has a commendable I history of providing adequate sewage disposal as well as meet ing the demands of growth. Since its foundation in 1949, the District eliminated four separate outfalls to the bay and I various individual and community septic tank systems. Recognizing the need to further enhance water quality, I the District is now participating in a subregional wastewater management study for Southern Marin now being conducted by the Marin Municipal Water District. Further, in anticipation of the need to reduce peak flows, the District itself has under I taken a program of infiltration detection and leak correction in its sewer system. I 2-5 I ] CHAPTER 3 INTERIM NEEDS General In development of the interim needs of the District, it , is necessary to have a general understanding of the physical area served by the District and the existing service charac teristics as determined by the measured flows and population estimates. ;] Estimates of growth rates are then determined on the basis of past service and growth characteristics. Once esti mates of the interim. needs are made, the nature and magnitude of interim improvements can be determined so that the waste loading to the bay can be held within present levels .while still allowing for growth over the next few years. Area Served by the District The Richardson Bay Sanitary District generally serves the southwest slope of the Tiburon peninsula and is physically divided into three distinct watersheds as shown in Figure 3-1. Each watershed, along with its general physical sewage dis posal facilities, is described below. TRESTLE GLEN WATERSHED - Encompasses the Reedlands, Belveron Gardens, Little Reed Heights, Del Mar and Hawthorne Terrace areas of the Tiburon peninsula. Development in the service area is entirely residential, and there is almost no prospect for future commercial or multiple dwelling develop ment. Sewage disposal in the Trestle Glen Watershed is provided by the Trestle Glen sewage treatment plant,with disposal of the disinfected effluent to the shallow water of Richardson Bay. The existing treatment plant provides complete activated sludge secondary treatment with separate sludge incineration. The trea tment plan t is now oper.a ting at approx:ima tely two-thirds of its design capacity. ] SALT WORKS WATERSHED - Encompasses the Bel Air Estates, Reedland Woods, East Strawberry and Harbor Point areas of the Tiburon peninsula. With the exception of one small shopping center, development in this area is residential in nature, with both single family and multiple residences. Future de:" velopment potential will probably consist of both single family and multiple development. ) 3-1 I INTERIM NEEDS Sewage originating in the Salt Works Watershed is pumped by the Salt Works Pumping Station west to the Ricardo Road Watershed, where it is pumped again by the Ricardo Road Pump I" ing Station to the Sausalito-Marin City Sanitary District for treatment and disposal. Since sewerage service to the Salt Works Watershed and Ricardo Road Watersheds are physically combined, the two watersheds will be hereinafter discussed together. RICARDO ROAD WATERSHED - Encompasses the Eagle Rock, West Strawberry, Seminary, and Highway 101 frontage road de velopments. The service area contains commercial, multiple and single family developments and has a large future poten tial for commercial and multiple dwelling developments. As described above, the sewage from both the Salt Works and Ricardo Road Watersheds is pumped by means of the Ricardo Road Pumping Station to the Sausalito-Marin City Sanitary Dis trict for treatment and disposal. Service Characteristics The service characteristics of each watershed are tabu lated in Table J-l. Since the Salt Works and Ricardo Road j Watersheds are physically served together, their flow and I population estimates have been combined. The average dry weather flow and the peak wet weather I flows shown are actual measured flows. The population served has been estimated on the basis that the average sewage con tribution is 75 gallons per capita per day. In so far as interim facilities are concerned, the problem in the Trestle Glen Watershed is completely different from the problem in the Salt Works and Ricardo Road Watersheds. Sewage generated within the Trestle Glen Watershed receives complete secondary treatment, and no bypassing has been experienced in , recent years. I Sewage disposal from the Salt Works and Ricardo Road Watersheds is by contract with the Sausalito-Marin City Sani tary District. The Ricardo Road Pumping Station pumps the sewage across the Richardson Bay Bridge to the Sausalito-Marin City Sanitary District system. During storms, considerable bypassing of untreated sewage occurs since neither the Richard son Bay Sanitary District system nor the Sausalito-Marin City Sanitary District system can handle extreme wet weather flows. J-2 , , .~ (~ 'L..J LJ (~ L.J LJ U LJ .L-.I W W W 1.$ [,j {c',,1! b :\. " " 'A ,'" t . . ......A 1·,1 .. II e •• e •• _ •.• •o • • .. ............... .. • • • o • • • III .. " .. e' """ ... WATERSHED BOUNDARY .- \ \' • o · " •, DISTRICT BOUNDARY . . : •• eo ..... e •.:• . . . :' eo e. e 1000 1600 ~-- --- ~ - . """'\" I • : ·• • • . • o .TO STRIP DETACHMENT RICHARDSON BAY SANITARY DISTRICT MARIN COUNTY, CALIFORNIA FIGURE 3-1 ( [ INTERIM NEEDS [ TABLE 3-1 [ RICHARDSON BAY SANITARY DISTRICT WATERSHED SERVICE CHARACTERISTICS [ Trestle Glen Salt Works Ricardo Rd. Service Area Watershed Watershed Watershed* Total watershed L area, acres 704 714 700 Total developed [ area, acres 368 383 227 [ 1970 Average Dry Weather Flow, mgd 0.188 0.486 [ 1970 Estimated Population @ 75 gpcd 2510 6480 1970 Peak Wet Weather Flow, mgd 1.129 1.130 (12/3/70) (12/4/70) 1970 Wet Weather Bypassing, mgd 0 Unknown Existing Sewerage Complete Pumped to Sausalito- Facilities Secondary Marin City Sanitary Dis- Treatment trict for treatment and Disposal to disposal Richardson Bay r- *Includes Alto Strip Detachment. r f 3-4 f 'J INTERIM NEEDS Projected Interim Growth Rates The growth rates in each watershed for the past three ye'ars and a proj ec ted 1971 growth rate is tabula ted in Table 3-2. The rates of growth for succeeding years will probably be similar to the 1971 projected growth rates. Projections of population and waste flows have been made on the basis of the following design criteria: People per single family living unit 3.5 = People per apartment unit = 2.5 Per capita ,waste flow, gallons per day = 75 ""'~ TABLE 3-2 ~ RICHARDSON BAY SANITARY DISTRICT .. PAST GROWTH RATES AND PROJECTED INTERIM GROWTH RATES BY WATERSHED Trestle Glen Salt Works Ricardo Rd. Service Area Watershed Watershed Watershed , Living Units Connected 1968 27 20 10 1969 28 42 1 1970 16 27 2 Projected Annual Single Family Living Units 30 30 0 Projected Annual Apart- ment Living Units 0 12 170 Projected Annual Population Increase 105 135 425 Projected Annual Flow Increase, gal/day 7,875 10,125 31 ,875 3-5 INTERIM NEEDS I Alto Strip Detachment On May 12, 1971, the Local Agency Formation Commission approved detachment of approximately 60 acres from the Richard son Bay Sanitary District. Once detached, this area will be served through the City of Mill Valley sewer system. The Alto Strip detachment lies within the Ricardo Road Watershed and, although now within the city limits of Mill Valley, at the present time the Richardson Bay Sanitary District provides the sewerage service. To avoid double taxation and to serve the Alto Strip area through its system, it will be necessary for the City of Mill Valley to construct new collection facilities and cut off connections to the Richardson Bay Sanitary District. The number of existing connected living units and services in the Alto Strip detachment is given in Table 3-3. Once this area is physically disconnected from the Richardson Bay Sani tary District system and served through the City of Mill Valley system, it is proposed that the Richardson Bay Sanitary Dis trict receive credit for the equivalent number of new connec I tions elsewhere in the Salt Works and Ricardo Road Watersheds. TABLE 3-3 ALTO STRIP DETACHMENT Area, ac. 60 o Single Family Living Units Apartment Units 107 Motel Units 65 Commercial Establishments 5 Water Consumption (per Marin Municipal Water District records) avo gal/day 51,665 Equiva~ent Population Credit @ 75 gpcd 689 Summary The purpose of this chapter is to develop the interim needs of the District in terms of population and waste flow for each watershed service area. Based on the foregoing, the interim needs in terms of the projected annual population increase for each watershed are given below: Projected Annual Population Increase Trestle Glen Watershed 105 Salt Works'Watershed 135 Ricardo Road Watershed 425 Alto Strip Detachment - Equivalent Population Credit 732 3-6 CHAPTER 4 INTERIM IMPROVEMENTS General. In previous. chapters of this report, the District's past arid present effo~ts. to meet i.ts obl.igations toward pol.l.ution control. have beep summarized, and the present and anticipated future service characteristics of·the District have been de vel.oped, The purpose of this chapter is toeval.uate the capabil.ity ~ 01 of the existing facil.ities to meet the new requirements and describe the program of interim improvements a1.ready under taken by the District. The interim improvements are intended to enhance water qual.ity by hol.ding waste l.oadings to the bay wi thin present l.evel.s whil.e stiLL accomJlloda ting the anticipated interim growth of the District. Further, this chapter wil.l. present recommendations for a continuing program of interim improvements to continue to.al.l.ow future connections to the District system until. a permanent sewage disposal. sol.ution is impl.emented. Waste "A" ' ~ lJ ......•. Waste "A" as defined by Order No. 7l.-l.4 is the discharge of the District's Trestl.e Gl.en Sewage Treatment .Pl.ant. The Trestl..e Gl.en Sewage .Treatment Pl.ant handl.es onl.y sewage gen erated within the Trestl.e Gl.en Watershed and discharges the chl.orinated effl.uent to the shal.l.ow water of Richardson Bay. The requirements for discharge of Wast.e "A" as set forth in Order No. 7l.-l.4 are extremel.y restrictive, requiring in stal.l.ation of highly advanced, possibly experimental. tertiary I processes, which in essence is tantamount to a prohibition of discharge of Waste "A". The existing tre.atment pl.ant al.ready provides complete secpndary treatment with separate sl.udge incineration, which is equival.ent to the degree of treatment provided by the best and most modern sewage treatment pl.ants now existing in the Bay Area. Inasmuch as the District cannot compl.y with the require ments of Order 7l.-l.4 for Waste "A", the interim improvements described bel.ow wil.l. enhance the water quality in the bay I whil.e hol.ding waste l.oading within existing l.evels. 4-1 [ [ INTERIM IMPROVEMENTS [ Chlorine Contact Chamber Enlargements [ Under the previous Regional Water Quality Control Board orders, Resolution 228, disinfecti.on was considered adequate if the chlorine residual was 0.5 ppm in the effluent for at ( least 20 minutes prior to discharge or if the coliform or ganisms in Richardson Bay within 500 feet, but not more than l50 feet distant from the discharge point, did not exceed lO per milliliter in at least 80 per cent of the samples analyzed, ( nor in more than three (3) consecutive daily samples. The District elected to test the bay waters rather than the efflu ent to demonstrate compliance with this requirement with good ( success except during months with generally high rainfall and storm water runoff to the bay. Furthermore, the existence of numerous septic tanks in the vicinity of Greenwood Beach, ( adjacent to the plant, undoubtedly contributed to some water quality degredation in the vicinity of the plant outfall. The Regional Water Quality Control Board Order No. 71-14 now requires that the effluent be filtered and have a moving median of seven daily samples of coliform organisms of 2.2 MPN/100 m1. Although this requirement cannot be met without L tertiary treatment faci1it,ies, the District on June l5, 1971, awarded a construction contract for enlargement of the chlorine contact chamber (see Figure 4-1) as an interim improvement so ( that better effluent disinfection can be aChieved. At 300,000 gallons per day, the contact time will be increased from 17 minutes to 61 minutes, thereby affording an improvement in disinfection capability and significantly reducing the number [ of coliform organisms entering the bay. Interim Effluent Disposal Regarding the amount of waste loading in terms of BOD and r suspended solids now going to the bay from this plant, at the present time it is extremely smalL The average daily BOD loading to the bay is 52 pounds and suspended solids 43 pounds. Under Regional Water Quality Control Board Policy, how ever, interim improvements must further reduce this already small waste loading. Accordingly, to enhance the water quality [ of the bay on an interim basis by reducing the existing waste loading below present levels, it is proposed that a portion of the effluent be held out of the bay by means of land disposal r on the treatment plant property. Further, it is proposed that new connections within the Trestle Glen Watershed be allowed [ 4-2 5..'J{~ \'i""'!> ~~ ";".,,,; I:;";":" ';Cier¥" "';'" !'i'3"~ F""" i:,":"~' '·;~'f{,';~:ij' L·;;\;:;.ikl 1,::':", I';,., I ~ ; ... L<'·., i'"!::''' ~ ~, ! l ' --------- "Q( I . + ~~- ----~.'::!-~.!:.!...~--------­ -----~ \ \~ TIBuR.ON B.L VD. \~ ~----- \'" ---~- \ It CITY O.c TIBURON i~ (ABANDONED N.IA/,P R.R R/W) ~, '-l > " CONTACT ENLARGEMENTS NT DISPOSAL AR /J/ 'Y " ,,'Y --- - - --~- -II - - - .~.~ ~~=;:=;::~-==-------- - : - :. - ; .- ' - ; - _ c " . ' - ~ ~ O- _-_-_. -~:: :::- _ _. ____<5 1 I 1. __ :------. ..- . e- - -- - .:: - ;:- - -.:= - -: ;;:-~ - -' --" - --- - - . - RICHARDSON BAY SANITARY DISTRICT • LEGEND MARIN COUNTY, CALIFORNIA IMMEDIATE INTERIM IMPROVEMENTS TRESTLE GLEN SEWAGE TREATMENT PLANT FUTURE INTERIM ~ IMPROVEMENTS INTE RIM IMPROVEMENTS o 50 100 150 SCALE IN FEET FIGURE 4-1 [ [ INTERIM IMPROVEMENTS [ equivalent to the flow withheld from the bay by means of land disposal at the treatment plant site. [ In April, 1971, realizing that interim improvements might be necessary under the new Order 71-14, the Richardson Bay [ Sanitary District installed a land disposal facility for a portion of the plant effluent. This facility consists of a pump equipped with a water meter which pumps disinfected ef fluent through water sprinklers over an existing sludge bed whi.ch has been cleaned and sealed (see Figure 4-1). The sprinklers are turned on at 8 p.m. every evening and turned off at 8 a.m. in the morning. No discharge to the bay is pos I sible from the sludge bed, and in the event excess water ac cumulates, it can be measured as it is returned to the plant influent. I In 49 consecutive days since interim effluent disposal began on April 12, 1971, approximately 308,520 gallons of effluent have been disposed of on land and thus have not reached the bay. This rate of disposal amounts to 6,300 gallons per day on a 1,800 square foot area. The rate of disposal is thus 5.6 inches per day. On this basis, 153.000 I gallons per day could be disposed of on one acre. Table 4-1 .shows the present disposal area and and loading and future disposal area immediately available. All disposal areas would I be fenced and inaccessible to the public. TABLE 4-1 TRESTLE GLEN SEWAGE TREATMENT PLANT INTERIM EFFLUENT DISPOSAL Annual Disposal Application Application Population Area Rate Rate * Equivalent I sq.ft. gal/day gal/day @ 75 fipcd Present spray [ field 1,800 6,300 5,440 72 Projected Future spray fields 19,000 66,500 57.400 Total Potential spray fields 20,800 72,800 62,840 837 *Based on 315 days of application per year. [ 4-4 ] INTERIM IMPROVEMENTS To date, the weather has been relatively dry, and it is expected that the effluent disposal will have to be som·ewhat curtailed on very wet and rainy days. Thus, assuming there are 50 wet days out of the year and that effluent can be dis posed of at the rate of 6,300 gallons per day, for the remain ing 315 days of the .year,approximately 1,984,500 gallons of effluent can be disposed of over the entire year at the Trestle Glen Plant. Assuming 75 gallons per capita per day, the 1,984,500 gallons of effluent disposed of per year isequiva lent to about 72 people or 21 new single family connections to the plant. Based on the foregoing, it is proposed that on an interim basis to enhance the water quality in the bay by holding the waste loading to the bay within present levels, new connections to the system be justified against the amount of effluent withheld from the bay on an annual basis. With the present interim effluent disposal program, it is proposed that 21 new connections be allowed in the Trestle Glen Watershed if a cease and desist order is adopted. It is recommended that as the demand for new connections increases, the District will have to expand its effluent disposal facilities on additional land around the plant site to allow the increased flow to be withheld from the bay. Waste "B" Waste "B" as defined by Order 71-14 is the wet w·eather untreated sewage bypasses to Richardson Bay or its tributaries from Hawthorne Terrace and Salt Works Pumping Stations and a manhole in Frontage Road at Belvedere Drive. Under Order 71,..14, the bypassing of untreated sewage, Waste "B", is prohibited. Although not specifically prohibited under previous Water Quality Control Board Orders (Resolution 228), the bypassing of untreated sewage during wet weather is an intolerable situ ation. Basically, it is caused by excess storm water entering / the sanitary sewers through broken and defective pipe joints as well as through patio drains, open cleanouts, or roof leaders illegally connected to the sewers. Within the Richardson Bay Sanitary District, consider able bypassing of untreated sewage occurs during wet weather. A general description of the bypassing locations in each watershed and frequency of bypassing for Waste "Bit are given in Table 4-2 and generally described below. 4-5 [ [ TABLE 4-2 [ RICHARDSON BAY SANITARY DISTRICT INVENTORY OF EXISTING BYPASSES [ Bypass Frequency No. Description Pipe Size of Use [ TRESTLE GLEN WATERSHED [ 1. Hawthorne Terrace 10" flap gate During power Pumping Station failure only L 2. Trestle Glen Sewage Treatment Plant A. Raw Sewage Bypass 8" flap gate During power [ failure only B. Primary Effluent 12" slide gate During extreme Bypass (manual) wet weather [ SALT WORKS WATERSHED L 3. Salt Works Pumping Station A. High water bypass 10" flap gate During extreme [ high water B; Force Main bypass 6" (auto During extreme matic control) wet weather 4. Strawberry Circle 6" flap gate During extreme high water protective high water bypass 5. Harbor Point 6" flap gate During power l high water protective failure RICARDO ROAD WATERSHED 6. Frontage Road at 12" flap gate During extreme Belvedere Drive wet weather [ 4-6 ,- INTERIM IMPROVEMENTS TRESTLE GLEN WATERSHED - Although there are three physical .~.·.•.. ·..f l bypass locations within the Trestle Glen Watershed, they oper ,i{j ate only during a power failure or during an extreme wet weather situation. Sincy bypassing is so infrequent, it is generally not considered to be a problem in this watershed. To improve the system and enhance the water quality in the bay, bypasses #1 and #2A have been closed off. Conse quently, during extreme wet weather or a power failure, the sewer system will be required to provide more storage of the rather than discharging through the bypass before all sewag~ the possible storage is utilized. Further, some connections to this sewer system have been made to reduce infiltration as described hereinafter. SALT WORKS AND RICARDO ROAD WATERSHEDS - Bypassing within the Salt Works and Ricardo Road Watersheds is generally re garded as a problem. There are five separate bypasses, two of : ~ ...:• ' •.S. ..•. ' •'. .! which (#3B and #6) operate r'elatively .<:!!.eln during wet weather. Bypass #3B operated for approximately 43 hours during 1970. In 1969, the District installed an automatic gate on the bypass which was controlled by water level. Prior to in stallation o.f the automatically controlled bypass, the District personnel would simply open the bypass during every heavy rain just in case the level became high. With the automatically controlled bypass, the number of hours of bypassing has been significantly reduced. Bypass #6 relieves the Ricardo Road system when the pumps at the Ricardo Road Pumping Station cannot handle all the water. There is no estimate on how often this bypass is open. Bypasses #3A, #4 and #5 are relatively minor bypasses and only operated during extreme high water. Bypass #4 is needed as a protection to low-level houses which are subject to inun dation if there is a major malfunction of the Salt Works Pumping Station. Bypasses #3A and #5 have been closed off in an effort to enhance the water qual.ity in the bay by utilizing additional storage in the sewer system. 7'1.• · .~ Sausalito-Marin City Sanitary District Contract The Richardson Bay Sanitary District contracts with the Sausalito-Marin City Sanitary District for treatment and dis posal of all the wastes generated in the Salt Works and Ricardo ·.8~..·• .·. 1. .·• . ... · 4-7 ..J .... ;...f ' iW I INTERIM IMPROVEMENTS '[ Road Watersheds. The sewage flow pumped to Sausalito is metered at the Ricardo Road Pumping Station. ··1··· ... The annual flows pumped to the Sausalito-Marin City Sani tary District for the last five years are given below. I ANNUAL FLOWS PUMPED TO SAUSALITO-MARIN CITY SANITARY DISTRICT FROM THE SALT WORKS & RICARDO ROAD WATERSHEDS Gallons I ~ 1965-66 146,576,000 1966-67 177,761,200 I 1967-68 180,698,000 1968-69 205,836,000 I 1969-70 204,733,000 I On September 8, 1970, the Sausalito-Marin City Sanitary District informed the Richardson Bay Sanitary District that their system was almost up to capacity and requested that the I District take measures as necessary to maintain a gallonage not to exceed the 1968-69 flow of 205,836,000 gallons. The Sausalito-Marin City Sanitary District further stated that they cannot make firm plans for future expansion of their I facilities until a Master Plan for sewage disposal has been developed and approved by all Districts and Agencies in the Richardson Bay Watershed area. I In response to this request, the Richardson Bay Sanitary District undertook a program of collection system improve r ments to restrict storm water inflow and ground water infil tration. Further, the District is reviewing all requests for as commercial and multiple apartment unit connections it pertains to available system capacity. Appropriately, this I program of collection system improvements which commenced September, 1970, coincides with the need under Order 71-14 to eliminate infiltration to the system and, further, to justify I new connections to the District against enhancement of bay water quality by reducing bypasses below present levels. ( ( 4-8 , INTERIM IMPROVEMENTS ,'',:.'.,:• .] • ••.•' ,;" Bypassing Correction Program Bypassing of the untreated sewage can be prevented by one or more of the following methods: (1) provide storage for the excess storm flows so they can be treated after the storm --ends-, (2) provide additional sewer line and pumping capacity, (3) correction of leaks and defective or illegal connections to the sanitary sewer system. Storage of excess flows for treatment later would be a good interim method of leveling out peak flows if suitable land and storage ponds are available. Unfortunately, in the case of the Richardson Bay Sanitary District, no such land is available. Additional sewer line and pumping capacity is also an 'adequate way of handling peak flows, provided the problem is not just transferred elsewhere. In consideration of the re ~:... ..: :.i.; "0,1 quest by the Sausalito-Marin City Sanitary District to limit -~' I the sewage flows to 1968-69 levels, installation of additional pumping capacity at this time is not considered to be an ap propriate solution to eliminating bypassing in the District system as it would only transfer the problem to the Sausalito Marin City system. Accordingly, the District has elected to undertake an aggressive program of leak correction and elimination of il legal storm water connections. Leak correction is a permanent solution to eliminating excess infiltration to the sewers and thereby eliminate bypassing of raw sewage. Furthermore, a leak correction program will be an essential part of any long-range 11 sewage disposal solution in the Richardson Bay area. Ulti mately, however, in the long-range solution a bypass elimina tion program must include both increased system capacity and correction of leaks and illegal storm drainage connections. Table 4-3 summarizes the sewer correction program under taken by the District since September, 1970. Estimates have been made of the amount of infiltration eliminated by each repair or improvement. Since it is usually impossible to make measurements of the amount of water leaking into a sewer pipe, in the estimates given in Table 4-3 have been made from typical -~I measurements of infiltration. ) -1 Specifically, estimates for leakage into a manhole have -; been based on an average of actual measurements of some typical '.'. leaks. In a typical leaky manhole, one half a gallon a minute of inf.il tra tion is considered a reasonable volume. 4-9 TABLE 4-3 RICHARDSON BAY SANITARY DISTRICT SEWER LINE CORRECTION PROGRAM Est. Amount of Report Basis of Infiltration Infiltration Date Location & Description Watershed Estimate Eliminated - gpd SEWER MAIN CORRECTIONS 9-9-70 Belvedere Drive 430 LF 12" sewer @ Replaced 12" Sewer Main Ricardo Rd. 50,000 gal/day/in/mile 49,000 1-19-71 108 Richardson Drive 20 LF 4" sewer @ Plugged leaking 4" sewer stub Ricardo Rd. 50,000 g",l/day/in/mile 760 2-16-71 Sutter Court - Repaired break 40 LF 6" sewer @. & 5-20-71 .. and relaid main Trestle Gl. 50,000 gal/daY/in/mile 2,280 +- 2-16-71· 240 E. Strawberry Drive 20 LF 6" sewer @ .I. .. Repaired large hole in main Sal t 1,orks 50,000 gal/day/in/mile 1,140 o 3-16-71 82 S. Knoll Road 40 LF 6" sewer @ Repaired 2 breaks Ricardo Rd. 50,000 gal/day/in/mile 2,280 3-16-71 Tiburon Blvd. at Reedlands 20 LF 6" sewer @ Repaired break Trestle Gl. 50,000 gal/daY/in/mile 1,140 4-20-71 Bayview Terrace 180 LF 6" sewer @ Repaired 9 breaks Ricardo Rd. 50,000 gal/day/in/mile 10,250 4-20-71 Tiburon Blvd. @ Palmer Ave. 40 LF 6" sewer @ Repaired 2 breaks Trestle Gl. 50,000 gal/daY/in/mile 2,280 5-1-71 Belvedere Drive 190 LF 12" sewer @ Replaced 12" sewer main Ricardo Rd. 50,000 gal/daY/in/mile 21,600 5-20-71 Reed Blvd. 80 LF 6" sewer @ Repaired 4 breaks Ricardo Rd. 50,000 gal/day/in/mile 4,560 5-20-71 South Knoll Road 40 LF 6" sewer @ Repaired 2 breaks Ricardo Rd. 50,000 gal/day/in/mile 2,280 6-15-71 Richardson Drive 52 LF 6" sewer @ Abandoned 52' of leaky sewer Ricardo Rd. 50,000 gal/day/in/mile 2,960 .- :....., I" r >~ ~ ~ l""""', JIIIIIIIIII\ JIIIIIIIIq JIIIIIIIIIII JIIIIIIIIIII ""'""'I ""'""'I ""'""'I ""'""'I ~ ~ ~ ~ ~ (i"';'''lL'''''c! ,it;;:I'r""';;" I'ii'"'' "'I'U ~I ;;""" j,," !l"1 i..;;..J L.;.;l '1-..1 .......& MANHOLE REPAIRS 1-19-71 112 Richardson Drive Ricardo Rd. 1/2 gpm 720 2-16-71 Clotilda Ct. & Carlotta Cir. Ricardo Rd. 1/2 gpm 720 2-16-71 Cecilia Way Salt Works 1/2 gpm 720 2-16-71 )01 E. Strawberry Drive Salt Works 1/2 gpm 720 5-20-71 Carlotta Circle Ricardo Rd. 1/2 gpm 720 SMOKE TESTING REPAIRS 2-4-71 18 Clair~ Way, Bel Air Salt Works 50 LF 4" sewer @ 1,900 50,000 gal/day/in/mile )-4-71 26 Claire Way, Bel Air Salt Works 50 LF 4" sewer @' 1,900 50,000 gal/day/in/mile ..,. 2-5-71 146 Blackfield Dr., Bel Air Salt Works 50 LF 4" sewer @ 1,900 I 50,000 gal/day/in/mile I-' I-' TOTALS 109,8)0 [ [ [ [ TABLE 4-4 RICHARDSON BAY SANITARY DISTRICT L SEWER LINE CORRECTION PROGRAM SUMMARY OF ESTIMATED AMOUNT OF INFILTRATION ELIMINATED September 1970 to May 1971 [ Trestle Gl. Salt Works Ricardo Rd. [ Watershed* Watershed Watershed Sewer Main Corrections [ Wet Weather flow eliminated, gpd 5,700 l,l40 93,690 Manhole Repairs [ Wet Weather flow eliminated, gpd o l,440 2,l60 __ 'I [ Smoke Testing Repairs Wet Weather flow eliminated, gpd o 5,700 o [ TOTAL WET WEATHER FLOW ELIMINATED, gpd 5,700 8,280 95,850 [ Equivalent Raw Sewage [ Flow, gpd 2,850 4,l40 47,925 [ .. Equivalent Additional Population @ 75 gpcd 38 55 639 [ *Bypassing within the Trestle Glen Watershed is not a problem. However, the basic data is included in this table for com r- pleteness. r· 4-l2 INTERIM IMPROVEMENTS Estimates for infiltration into typical leaky sewer lines have been based on data presented in the following report: County of Sonoma, Sanitation Department UEvaluation of External Sealing Method to Reduce Storm Flow Effects in Sewerage Systems" Final Progress Report,F.W.P.C.A. Demonstration Grant WPD 111-01-66. Accordingly, in a typical leaky sewer line, 50,000 gallons per day per inch of diameter per mile of pipe is considered a reasonable volume and is used in Table 4-3. Under District testing requirements, a new sewer must have an infiltration rate of less than 630 gallons per day per inch of diameter per mile of pipe. ~j' - •...-.•..: .."...,.. •... Inasmuch as the Salt Works and Ricardo Road system ade quately handles the dry weather flows, new connections will only be a problem during th,e wet weather when bypassing is a problem. Thus, during a severe storm, each new connection will add.to the amount of untreated sewC\ge bypassed unless the storm water entering the system is decreased accordingly • . Consequently. to ,enhance water quality by holding waste loadings to the bay within present levels, additional connec tions must be justified against estimates of the waste loadings withheld from the bay during wet weather. Since the mixture of sewage and storm water which bypasses from the sewer system '.~ is 'approxima tely half the strength of raw sewage in terms of BOD and suspended solids, it is suggested that infiltration eliminated from the system in gallons per day be equated to the daily flow contribution from new connections on a 2 to 1 basis. Accordingly, Table 4-4 summarizes the results of the Dis trict's sewer line correction program to date for each water shed and estimates the equivalent additional population which can be allowed to connect to the District's system while still holding waste loading to the bay from wet weather bypasses within present levels. It is recommended that this program of sewer system im provements be continued so that excess infiltration flows can be reduced as much as possible. Infiltration reduction has both the short-term benefit of allowing additional connections -\ to the system and the long-term benefit in terms of reduced ] ......•. pumping and treatment costs during wet weather. 4-13 r [ INTERIM IMPROVEMENTS [ Future Permanent Improvements [ Although the present chapter discusses primarily interim improvements, it is appropriate at this time to look ahead at possible directions which will lead to more permanent improve ments. Permanent improvements to the District system must [ have the direction of the subregional study for Southern Marin now being conducted by the Marin Municipal Water District, the results of which should be known by mid-1972. [ In so far as the Trestle Glen Treatment Plant is con cerned, the nature of future permanent improvements will depend very heavily upon the conclusions of the subregional [ study. Basically, two alternatives exist: (1) the plant can be phased out in favor of a regional treatment plant in which case the plant would be converted to a major pumping station [ or (2) the plant can be converted to a water reclamation plant. Water reclamation is appropriate at this location since [ the reclaimed water would be used to irrigate the considerable amount of landscaping for parks and parkways now being planned along the shore of Richardson Bay north and south of the treat [ ment plant site. The District has long proposed to make use of the effluent for landscape irrigation and recreational lakes and ponds at such time as the City of Tiburon is ready to pro Geed with park improvements. [ In this regard, the District has initiated a pilot pro gram to test the reclaimability of the effluent for possible [ reuse and for compliance with discharge requirements under Order 71-14. The pilot program consists of the testing of a small sand fi'l ter which treats a portion of plant effluent. [ Test results are being analyzed, and it is hoped they will become basic information for analysis of alternatives in the subregional plan. [ Regarding corrections and repairs to the District sewer system which eliminate water infiltration, almost any work that is done can be considered a permanent improvement. Ba [ sically, any alternative project which may be recommended in the subregional plan must handle all sewage flows, including the peak wet weather flows. ,Reduction in wet weather flows will be essential to the functional adequacy of a 'regional [ system and, furthermore, will put the District in a favorable position if it is necessary to negotiate contracts for sewage treatment and disposal. [ [ 4-14 [ ] ] INTERIM IMPROVEMENTS " ·······1 bi Summary This chapter outlines the program of interim improvements which the Richardson Bay Sanitary District has undertaken intended to enhance water quality in the bay. Furthermore, the interim improvements described herein should accommodate the anticipated interim growth of the District while holding waste loadings to the bay within present levels. At the Trestle Glen Plant, the District has awarded a contract to enlarge the existing chlorine contact chamber to better comply with disinfection requirements. In addition, the District has started a program of land disposal of a por tion of the plant effluent and thus decrease the volume dis charged to the bay. Disposing of effluent on land will make it possible to permit additional connections to the system without increasing waste loadings to the bay. Within the Salt Works and Ricardo Road Watersheds, the District has undertaken an aggressive program of sewer system corrections which will significantly reduce the bypassing of sewage during wet weather. The sewer system corrections are intended to serve both as interim and as permanent improve ments toward enhancement of water quality in the bay. Esti mates of the amount of infiltration eliminated by each system repair have been equated to the additional population which can be accommodated on an interim basis while still holding waste loadings to the bay within present levels. Future permanent improvements to the District system depend heavily on the recommendations of the Southern Marin jj .;ubregional plan now being conducted by the Marin Municipal water District. The possibility of making use of a major por tion of the effluent from the Trestle Glen Plant for landscape irrigation and recreational lakes and ponds has long been pro posed by the District in its planning and is only dependent upon definitive plans being considered by the City of Tiburon for parkway and recreational improvements in the vicinity of the plant. Improvements which will be permanent and most essential to the functional adequacy of any regional or local plan is the elimination of excess storm water infiltration to the sanitary sewer system. 4-15 3) CHAPTERS CONCLUSIONS AND RECOMMENDATIONS General The general objective of the present study has been to develop a program of interim improvements to the District system which will enhance water quality in the bay by holding waste loadings within present levels and thus allow the Dis trict to continue to accommodate the expected growth over the next few years until a permanent sewage disposal solution is implemented. Conclusions Based on the general objective outlined above and con siderations previously summarized, the following conclusions are made: 1. It:is concluded that the District has a commendable history of meeting its obligations of providing sewerage service and meeting the demands of con tinued growth. 2. It is concluded that the District has recognized the need to further enhance water quality in the bay and is participating in the Southern Marin subregional study now being conducted by the Marin Municipal Water District. 3. It is concluded that over the next few years there 'j will be need to accommodate additional growth in the I District . . -,iii 4. It is concluded that the District cannot immediately comply with the requirements of Water Quality Control Board Order 71-14. 5. It is concluded that at the Trestle Glen Plant en largement of the chlorine contact chamber and land disposal of a portion of the plant effluent will l,. enhance water quality in the bay and allow additional connections to the system while holding waste loadings to the bay within present levels. 6. It is concluded that sewer system corrections and re pairs within the Salt Works and Ricardo Road Watersheds 5-1 J [ [ CONCLUSIONS AND RECOMMENDATIONS [ will enhance water quality in the bay and allow addi [ tional connections to the system while holding waste loadings to the bay within present levels. [ Recommendations Based on the foregoing conclusions and considerations pre [ viously summarized, the following recommendations are presented: 1. It is recommended that the District expand its land [ disposal facilities at the Trestle Glen Plant as necessary to accommodate the interim growth by holding waste loadings to the bay within present levels. [ 2. It is recommended that the District continue its ag gressive program of sewer system corrections and repairs, both to accommodate interim growth by holding waste loadings to the bay within present levels and also as permanent improvements for enhancement of water quality. [ J. It is recommended that the District continue to evaluate the water reclamation potential at the Trestle Glen Plant as necessary input to the sub [ regional study. [ [ 5-2 , __ .JIlI APPENDIX A CALIFORi'HA REGIONAL WATER .QUALITY CONTROL BOARD SAN FRANCISCO BAY REGION ORDER NO. 71-14 WASTE DISCHARGE REQUIREHEHTS FOR J RICHARDSON BAY SANITARY DISTRICT TIBURON, MARIN COUNTY The California Regional Water Quality Control Board, San Francisco Bay Region, finds that: 1. This Board prescribed requirements for the Richardson Bay Sanitary District, called the discharger belo,;, in Resolution No. 228 on November 15, 1956. 2. The discharges include: Waste "A" is 0.2 mgd of sewage only, in dry weather, from 2800 people, and discharges through rocks at the shoreline of Richardson Bay. Design capacity of the plant is 0.3 mgd to serve a population of 4200 people. Wastes "B" are ,,,et ,,,eather untreated sewage bypasses to Richardson Bay or its tributaries from Hawthorne Terrace and Salt Works pumping stations and a manhole in Frontage Road at Belvedere Drive. 3. The Board adopted a water quality control plan fortiual waters inland from the Golden Gate and within the San Francisco Bay Region on Harch 26, 1970. 4. The beneficial uses of Richardson Bay are: Swimming, water-skiing, ,.,ading, pleasure boating, marinas, fishing and shellfishing Fish, shellfish, and wildlife propagation and sustenance, and waterfowl and migratory birds habitat and resting Navigation channels Esthetic appeal. 5. Land within 1000 feet of the point of discharge for Waste "A" is used for transportation, business, residence and recreation. Mt. Tamalpais Game Refuge encompasses this area and along the sh.ore of Strawberry peninsula, just opposite the discharge, is an area designated by Fish and Game as suitable for protecting as a shellfish bed. ~ 1 - r [ [ 6. The Board has notified the discharger and interested agencies and persons of its intent to prescribe waste discharge requirements for the discharge. [ 7. The Board in a public meeting February 25, 1971 heard and considered all comments pertaining to the discharge. IT IS HEREBY ORDERED, the discharger shall comply with the following: [ A. Haste Discharge Requirements [. 1. The treatment or disposal of waste shall not create a nuisance as defined in Section 13050 (m) of the California Code. ~later [ 2. Waste "A" shall not cause: a. Floating, suspended, or deposited macroscopic particulate matter or foam, in waters of the State at any place; [ b. Bottom deposits or aquatic growths at any place; c. Alteration of temperature, or apparent color beyond present natural background levels in waters of the State at any place; [ d. Visible, floating, suspended or deposited oil or other products of petroleum origin in waters of the State at any place; r e. Waters of the State to exceed the following limits of quality at any point: Dissolved oxygen 5.0 mg/l minimum When natural factors cause lesser concentrations then this discharge shall not cause further reduction in the concentration of dissolved oxygen. r Dissolved sulfide O. 1 mg/l ma:dmum Nutrients 50 ug chlorophyll ;( /1 When background levels exceed this requirement then this discharge shall not add further nutrients. Other substances Anyone or more substances in concen trations that impair any of the protected beneficial water uses or make aquatic life or wildlife unfit or unpalatable for consumption. - 2 - 3. Waste "A" as discharged or at some point in the treatment process shall meet the following quality limits at all times: a. The waste sha11 meet quality requirements equivalent to those which would result from conformance with Section 8047 of Title 17, California Administrative Code. b. Coliform organisms 2.2 MPN/lOO ml, moving median of seven consecutive daily samples, maximum. 4. Haste "A'.' as discharged to waters of the State shall meet these quality limits at all times: a. In any grab sample: pH 7.0 minimum 8.5 maximum b. In any representative 24-hour composite sample: (1) Turbidity 10 units, maximum (2) 5-day BOD 5 mg/l, median for any 30-day period 10 mg/I, maximum c. In any representative set of samples: Toxicity: survival of test fishes in 96-hour bioassays of the waste as discharged Any determination 70% minimum Average of any three or more consecutive deter minations made during any 21 or more days 90% minimum 5. The mean daily flow of Waste "A" for any month shall not exceed 0.3 mgd. 6. The bypassing of untreated sewage, Wastes "B", is prohibited. E] B. Provisions ·~ 1. This Order, includes itemD numbered 1, 2,'3, 4, 6 and 7 of the attached t..•,.. ..· . 7.....•.1 "Reporting Requirements" dated"August 28, 1970. ¥;. d 2. This Order rescinds Resolutions Nos. 228, 42, 41 and 26. - 3 - [ [ [ 3. This Order includes items numbered 1, 2, 3, 4, 5, 6 and 7 of the attached "Notifications" dated January 6, 1970. [ 4. This Order notifies the discharger that more restrictive requirements than the above may be imposed for the protection of shellfishing when information on the dispersion characteristics of the District's waste discharge has been analyzed. [ 1'1 1: [ I, Fred H. Dierker, Executive Officer, do hereby certify the foregoing is a i full, true, and correct copy of an order adopted by the California Regional 'W-' Water Quality Control Board, San FranCisco Bay Region, on February 25, 1971. [ :I ! Executive Officer [ :,J [ :l . 'j [ ;1 [ ~l - 4 - I I HOMESTEAD VALLEY SANITARY DISTRICT I MARIN COUNTY, CALIFORNIA I , :3" "-1' 1---- I I I SANITARY SEWER SYSTEM ANALYSIS AND EVALUATION I I NOVEMBER 1970 J. WARREN NUTE. INC. CIVIL AND SANITARY ENGINEERS J. WARREN NUTE, INC. CIVIL AND SANITA.RY ENGINEERS 4! I FOURTH STREET J, WARREN NUTE, P. E. SAN RAFAEL, CALIFORNIA 94901 WARREN E. NUTE, P. E. I TELEPHONE {"IS} <453·+48(1 I November 23, 1970 I To the Honorable Board of Directors HOMESTEAD VALLEY SANITARY DISTRICT P.O. Box 149 Mill Valley, California 94941 I Letter of Transmittal Gentlemen: In accordance with your request, we have investigated the condition of the District's sewer system, particularly with respect to wet weather flow conditions, and herewith submit our findings. Basically, we have measured the peak wet weather flows in the District system and find that they are unnecessarily high. Not only do these excessive flows overtax the District's sewer system,' but they also contribute to Mill Valley's wet weather flow problem. Furthermore, unless such peak flows are attenu ated in all sewerage agencies around Richardson Bay, the ability of any area-wide sewage disposal project to intercept and treat all flows is questionable. As a first step to mitigate the storm water infiltration problem we have recommended that the District undertake a program of smoke testing the sewers. To be effective, however, the smoke testing program or any leak detection program must be followed by corrective measures. It is hoped that this report will provide a basis on which the Board can proceed with a program to upgrade the Dis trict sewer system. Very truly yours, J. WARREN NUTE, INC. ~~.~ By Warren E. Nute I I TABLE OF CONTENTS I CHAPTER 1 - INTRODUCTION I General - - - - - - - - - - - - - - - - - - - 1-1 Historical Background - - - - - - - - - - - - - - 1-2 I Scope of the Present Studies - - - - - - 1-3 CHAPTER 2 - SEWERAGE SYSTEM STUDIES AND ANALYSIS I General - - - - - - - - - - 2-1 Area Served - 2-1 I Land Use 2-3 Population Projections 2-5 Waste Volumes - - - - - 2-5 I Peak Dry Weather Flows 2-6 Storm Water Infiltration 2-6 Peak Flow 'Measurements - - - - 2-8 Sewer System Evaluation - - - - - 2-10 I Infiltration Mitigation - - - - - - 2-11 Summary - - - - - - - - - - - - - - - 2-13 I CHAPTER 3 - CONCLUSIONS AND RECOMMENDATIONS I General - - - - - - - - - 3-1 Conclusions - - - - - - 3-1 Recommendations - - - - 3-1 Acknowledgments - - - - - - - - 3-2 I I I I I I I I I I I CHAPTER l. INTRODUCTION I General. 1- Homestead Val.l.ey Sanitary District is one of four sepa rate--sewerage agencies which contract with the City of Mil.l. Val.l.ey for sewage treatment and disposal.. The City of Mil.l Val.ley provides secondary treatment for the sewage received I and discharges the effl.uent to the upper end of Richardson Bay. The Mil.l. Val.ley sewer system, like many sewer systems in Marin County, contains many miles of ol.der sewers which con tribute large vol.umes of storm water into the system during wet weather. In real.ization of this problem, the City of Mill Vall.ey, in 1968, undertook preparation of a study of the sanitary sewer system to determine the sources of storm water infil.tration and to recommend a program of general upgrading to meet present and future needs. Recognizing that the contracting sewerage agencies in cluding the Homestead Val.ley Sanitary District al.so experience high wet weather fl.ows which ultimately must be handled by the Mill Vall.ey treatment plant, the l.968 Master Plan recommended as foll.ows: "That the various Sanitary Districts which use the Mill Valley treatment pl.ant eliminate excessive storm water intake and upgrade their sewage collection systems to at l.east the same degree as Mil.l Val.ley," More recently, in March and April. of l.970, the Regional Water Qual.ity Control. Board held hearings regarding the ad visabil.ity of prohibiting all. discharge of sewage bearing waste to Richardson Bay under the assumption that certain areas of .the Bay should be protected for the taking of shel.l fish for human consumption. To date the discharge prohibi tion has not been adopted. However, the sewerage agencies around Richardson Bay have requested the Marin Municipal. Water District to undertake studies to develop an area-wide sewerage program that will adequately protect Richardson Bay for all. beneficial uses. Whatever sol.ution is developed for the Richardson Bay area. it will be necessary to eliminate or minimize al.l wet l.-l IJ l!fI Itl INTRODUCTION weather sewage overflows. In addition, the ability of any regional project to intercept and carry off all of these flows will be very questionable unless all sewerage agencies upgrade their sewer. system so as to mitigate, in so far as possible, storm water infiltration to the sewers. Accordingly, in anticipation of the need to upgrade the sewer system, the Homestead Valley Sanitary District author ized the present study to document the amount of storm water infiltration experienced and provide a basis of comparison with conditions within the Mill Valley system. Historical Background The Homestead Sanitary District was established by the Board of Supervisors on July 7, 1931 under the Sanitary Dis trict Act of 1919 after an election which favored its forma tion. This election was precipitated by a controversy between residents in the area and the Board of Supervisors in which the Supervisors attempted to construct sewers in the Homestead Valley area. The Board of Supervisors finally abandoned the proceedings on assurance that the Sanitary District would diligently proceed with construction of sewers. In 1932 the District was reorganized under the Sanitary District Act of 1923 as the Homestead Valley Sanitary District. Some sewers were constructed in the lower part of the District which connected to Mill Valley's outfall line on Miller Avenue. However. this arrangement was unsatisfactory since the tide would occasionally back the sewage into houses. Plans for the sewers in the rest of the District were prepared by 1933. The Sanitary Board, however, did not proceed because it was de termined that the people would be better off with septic tanks in view of the problem of tidal backups in the Mill Valley outfall. Between 1933 and the end of World War II, the District concerned itself with inspection of septic tank installations. With increasing development following the war, the Sanitary Board undertook the installation of sewers in the District, In 1948 the District sold bonds and, with the assistance of a State grant, a contract was awarded to construct sewers which now form the major part of the present sewer system. Simi larly, the City of Mill Valley constructed a new trunk line and outfall system in 1946, a pumping station in 1948 and the initial stage of the present sewage treatment plant in 1952. 1-2 I INTRODUCTION In order to dispose of the sewage from Homestead Va~~ey. the Sanitary District negotiated a contract with Mi~~ Va~~ey which granted the District a to use the City's system. ~icense The and operating costs of the treatment capita~ Mi~~ Va~~ey are on the basis of the respective assessed p~ant a~~ocated of the two agencies. In the va~uations ~958 Mi~~ Va~l.ey treatment was expanded to its present capacity which p~ant now provides secondary treatment for ~.6 mi~~ion ga~~ons per day discharging the to the upper end of Richardson eff~uent Bay. Scope of the Present Studies The basic purpose of the present study is to document the existing condition of the Homestead sewer system, Va~ley particularly under wet weather conditions. This documentation is to provide a basis on which to evaluate the Homestead sewer system in relation to the Mill Valley sewer sys Val~ey tem and to provide a reference on which to plan system im provements. the present study has been directed to the Specificall~ basic subject areas: fol~owing 1. Collection and of basic data with ana~ysis availab~e respect to the sewer system layout, topography and present development within the District. 2. Development of expected waste under both dry vo~umes weather and wet weather conditions for various sew erage service areas within the District. 3. Measurement and observation of flow experi actua~ enced during maximum wet weather flow conditions. 4. Comparison of f~ow measurements within the District system with and flows actually recorded rainfa~~ at the Mill Valley treatment plant. 5. Presentation of a report summarizing our findings and conclusions. It was originally contemplated that smoke testing of the sewers in a few selected areas would be included as part of this report. However, considering the size of the sma~l total District, a complete smoke testing program can be 1-3 INTRODUCTION performed at rather low cost and will be recommended as a first stage of the system upgrading. In anticipation of this program, the District has already adopted ordinances which permit the District to require property owners to correct deficiencies in individual laterals which may be found during a testing program, smo~e 1-4 I I I I CHAPTER 2 SEWERAGE SYSTEM STUDIES AND ANALYSIS I General To analyze and evaluate the District's sewer system, a 1- comparison must be made between the calculated flow based on accepted design criteria and the flow actually measured during wet weather. The relation of measured wet weather flows to I similar data developed for other systems provides a good indi cation of the relative condition of-the District's sewers. A basic consideration of this study has been the estab lishment of design criteria on which to evaluate the Dis trict's sewer system. Design criteria have been developed taking into consideration the size and topography of the area served, present and future land use, estimates of population and waste volumes to be expected. Actual measurements were made of flows experienced during several storms in early 1970. These flows represent the peak wet weather flows experienced within the District and contain storm waters which have infiltrated to the sewers through de fective pipelines or through direct storm drainage connec tions 0 The following two studies have been used in developing and evaluating the data for the District's sewer system and are referred to in the text: 1. Bala and Strandgaard, "Mill Valley Master Plan for Sanitary Sewers," 1968. 2. Brown and Caldwell, "Sewerage Study, County of Marin," 1967. Area Served The Homestead Valley Sanitary District serves the water shed generally known as Homestead Valley located south and west of the City of Mill Valley. The entire watershed com prises about 620 acres, of which 450 acres are included within the Sanitary District boundaries (See Figure 1). Undeveloped lands suitable for future service by the Dis trict generally lie on the ridges to the south and west of the valley mostly within the area known as the Dias Ranch. 2-1 TABLE 1 HOMESTEAD VALLEY SANITARY DISTRICT ASSESSED VALUATION AND CONNECTED LIVING UNITS FISCAL ASSESSED CONNECTED YEAR VALUATION LIVING UNITS (approx.) 1956-57 1,441,680 535 1957-58 1,525.968 558 1958-59 1,876,590 580 1959-60 1,953,500 595 1960-61 2,340,900 627 1961-62 2,423,440 651 1962-63 2,576,790 673 1963-64 2,729,410 718 1964-65 3,832,160 756 I 1965-66 4,052,740 779 I 1966-67 4,182,190 795 1967-68 5,046,048 805 I 1968-69 5,111,130 849 1969-70 5,176,073 856 II , II II I I 2-2 SEWERAGE SYSTEM STUDIES AND ANALYSIS I The assessed valuation of the District and estimated con nected living units for the last fourteen years are tabulated in Table 1. I Land Use I Prior to preparation of population estimates, available data regarding zoning and land use was compiled in order to make a projection of anticipated population density at the I time of ultimate development of the service areas. Generally, the Homestead Valley area is zoned for single family residential development and it is not expected to de I velop in any other manner except perhaps on the Dias Ranch. The Dias Ranch, on the other hand, is zoned for Planned Com munity which does not specify allowable density. For the I purposes of this report, it is assumed that the population density would not exceed twelve persons per acre. I Curiously, the portion of the Dias Ranch lying within the Homestead Valley drainage area has now been annexed to the Tamalpais Valley Community Services District which only provides sewer service within the adjacent watershed to the I south. Such a situation ind.icates a failure on the part of the Local Agencies Formation Commission to recognize the principles of sound sewer system planning and will very I likely lead to serious complications when the area is finally developed. In attempting to project populations from land use cri I teria it should be noted that Planning Commissions often re zone areas for multiple or higher densities without consult ing the agencies involved with providing basic services. The I possibility of higher densities makes it necessary to periodi cally re-evaluate the adequacy of District facilities to handle additional flows. I In developing population projections, it should be em phasized that, whereas population and/or density projections contained in this report may vary somewhat from planning pro I jections, it is not the intention to promote or encourage higher population densities but rather to try to anticipate such forseeable occurrences in order that the District is more I fully prepared to meet the demands of the future. I 2-J I I TABLE 2 I PROJECTED POPULATION AND WASTE FLOWS FROM SEWERAGE I SERVICE AREAS I Service Area Area in Projected ADWF Peak Excess PWWF Desig. Acres Population mgd Factor Infi1. mgd I HV-1 55 550 0.044 0.24 I HV-2 20 200 0.016 0.09 HV-3 26 310 0.025 0.11 I HV-4 49 390 0.031 0.21 I HV-5 161 1610 0.129 0.46 HV-6 84 840 0.067 0.25 I HV-7 134 1340 0.107 0.34 HV-8 20 200 0.013 0.09 I HV-9 37 300 0.024 0.16 I HV-10 33 260 0.021 0.14 J TOTALS 619 6000 0.477 1.9 2.09 3.00 Design Criteria: I Daily Per Capita Flow 80 gpcd People per Single Family Unit = 3·5 I Infiltration Rate Existing System = 4300 gad Future Systems = 1000 gad I ADWF = Average Dry Weather Flow PWWF = Peak Wet Weather Flow mgd = million gallons per day I gpcd = gallons per capita per day gad = gallons per acre per day I 2-4 SEWERAGE SYSTEM STUDIES AND ANALYSIS Population Projections Based on the estimated number of connections in the Dis trict as given in Table 1, the present population is estimated to be about 3,000 assuming 3.5 person~ per living unit connec tion. From an analysis of the planned and anticipated land development, the projected ultimate population of the overall service area of the District is estimated to be about 6,000 people. In arriving at this projection, the Homestead Valley watershed was divided into sub-areas. The sub-areas are de lineated on the map of the "Sewer System and Sewerage Service Areas" (Figure 1) and a detailed tabulation of the servic e areas, population projections and associated waste volumes is given in Table 2. It is difficult to estimate when the District will ap proach its ultimate population. However, the single most significant contribution to a population increase will be the development of the Dias Ranch. Waste Volumes To establish a basis on which to compare the average dry weather flows to peak wet weather flows, an estimate must be made of the per capita waste contribution. In developing the average dry weather per capita waste flow to be used as basic design criteria for the Homestead Valley system, a flow contribution of 80 gallons per capita per day (gpcd) was arrived at by comparing Mill Valley's present average dry weather flow of 1.42 million gallons per day (mgd) to the estimated population served of 18,000. This flow rate is consistent with flow projections for other areas of Marin County which averages 70 to 80 per cent of the esti mated 103 gpcd water consumption rate. It should be noted that in the 1968 "Mill Valley Master Plan for Sanitary Sewers" the present flow rate was estimated to be 60 gpcd and proposed a rate of 80 gpcd .vi th ul tima te de velopment. The 1967 Marin County Study tabulated all the flows for the County and found the present usage averages 79 gpcd but used the value of 100 gpcd for system design. 2-5 SEWERAGE SYSTEM STUDIES AND ANALYSIS Since the Homestead Valley is very similar in nature to other residential areas of Marin County, the per capita flow contribution of 80 gpcd was considered a reasonable estimate of average dry weather flows to be expected within the system. Peak Dry Weather Flows Peak flows are experienced daily during dry weather and are caused by varying hourly rates of flow in the sewers as a result of water usage and by changes in pipe storage with changes in flow. In this regard a sewer system should be con sidered an underground watershed. Accordingly, a smaller watershed will have quick response to peak demands on the system and a larger system will have a slower response. Thus, the ratio of maximum to average flows is greater for small populations served and decreases as the tributary areas and number of persons increase. The ratio of peak dry weather flow to average flow has been projected in the 1968 "Mill Valley Master Plan for Sani tary Sewers" and is shown in Figure 2. Although other slightly different curves have been developed elsewhere, it is recommended that Figure 2 be accepted in order to analyze the Homestead Valley District system on the same basis as the Mill Valley system. Using this curve, with about 856 single family residences in the District, the dry peak factor wea~her is 2.1. Thus, with about ),000 people in the District at 80 gpcd and a peak factor of 2.1, the peak dry weather flow is projected to be 0.50 mgd. This peak flow will usually be ex perienced between 8 and 10 in the morning. Storm Water Infiltration I Storm water infiltration is of major importance in the hydraulic design of sewers, pumping stations and treatment facilities since this must provide for the maximum or extreme peak flows to be expected in the system. Storm water infil I tration to the sewers usually comes from two sources, ground water infiltration and direct inflow. Ground water infil trates to the sewers through broken or defective pipe joints I in the older sewers and broken and defective house laterals. The direct inflow is storm water which enters the sewers through patio drains, open c1eanouts, roof leaders illegally I connected to the sewers and through manholes or rod holes in poorly drained and unimproved street areas that become I 2-6 I I I SEWERAGE SYSTEM STUDIES AND ANALYSIS I FIGURE 2 I RATIO OF PEAK FLOW TO AVERAGE DAILY FLOW 4 I······ ~ ~ ~-.: ......... - '" "" I .~ I'- II I"-r-. 1) " 3 lI\ ~ I Q ~ ~ ~ l"- 0 t--. --- I ~ " .... r- Z -I( C ~ ~ l- i-- I , \, I ~ I I .,. ., I I People per Bingle Family Unit = 3.5 I inundated. During heavy storms, water also enters directly through defective sewer pipe and particularly house laterals I which are relatively shallow. For the purposes of analysis and design, the storm water I infiltration component of flow is measured in gallons per acre per day (gad). Accordingly, the peak wet weather flow (PWWF) is the combination of the peak dry weather flow and the storm water infiltration factor applied to the tributary I area. As a general rule, the storm water infiltration component I of flow usually averages about 1000 gad for new systems and up to 5000 gad for older systems. The infiltration rates of I 2-7 I SEWERAGE SYSTEM .STUDIES AND ANALYSIS J soma very deteriorated sewer systems mostly in bay mud areas such as Kay Park and Gallinas Village are reported to be as high as 9500 gad. • The 1968 "Mill Valley Master Plan for Sanitary Sewers" reports the storm inflow for Mill Valley as 700 gallons per capita per day (gpcd) which with 12,000 people amounts to about 2800 gallons per acre per day over the entire 3044 acres • of the Mill Valley watershed. This is low, however, since about 1800 acres in the watershed are developed. Using 700 gpcd for the Mill Valley area, this storm water inflow amounts • to about 4700 gad. Obviously, certain areas of the City will have higher inflow rates and the 4700 gad should be considered an average value. The 1967 "Sewerage Study, County of Marin" gives the storm water infiltration rate in Mill Valley as about 5000 gad, which is typical of high infiltration rates of older sewer systems. Peak Flow Measurements The main purpose of the present study was to make a de 11 termination as to the magnitude of the peak flows experienced in the District sewer system. Measurements were made of the sewage flow in the 10" sewer line in Evergreen Avenue. This sewer line serves about 83 per cent of the District, and flows should be fairly representative of conditions in the entire District sewer system. I In January of 1970 a flow meter was installed in the man hole at Evergreen and Lillian Lane. However, the flow meter had to be removed to avoid damage prior to the severe storms of January 15 and January 21, 1970 which surcharged the sewer line almost to the top of the manholes. Even though the flow meter could not be used during these particular storms, the surcharged sewers provided an excellent method of measuring peak flows. By measuring elevations of the surcharge level in the manholes along Evergreen Avenue, the flow was calculated from tables of flow rates in a 10" pipe under pressure. Accordingly, the highest surcharge levels occurred about 8 A.M. on January 21, 1970, during the most severe storm of the season, which caused extensive flooding along Miller Avenue. Although the water level in the surcharged sewers nearly reached the top of the manholes, the only two manholes 2-8 I I SEWERAGE SYSTEM STUDIES AND ANALYSIS I in the District which overflowed were on Ethel Avenue one I block from Miller Avenue. The main reason for these two over flows and the extreme height of the water in the District's line was the fact that the City of Mill Valley's sewer was full and most of the manholes on Miller Avenue were overflow ing. Measurements of the surcharge levels taken on January 21, I 1970 along Evergreen Avenue showed that the highest level, as indicated by the grease on the side of the manhole, showed the District's sewer was carrying a peak flow of 1400 gallons per I minute (gpm) or 2.00 million gallons per day (mgd). Later measurements showed that the maximum flow rate was of rela tively short duration dropping less than 1200 gpm one hour after the rain stopped. The short duration of the peak flow in the District's relatively small watershed indicates that most of the water comes from direct storm water connections and from broken pipes or open joints which are relatively I shallow. Both of these types of deficiencies are easily de tected with a smoke testing program. I Assuming that the peak flow rate of 2.00 mgd coincided with the morning peak usage of the sewers,the per acre in filtration contribution was calculated from the criteria out lined previously. Accordingly, with approximately 2,500 [ people in the tributary area of 370 acres, 80 gpcd flow and a 2.1 peak factor, the theoretical peak dry weather flow should be 0.42 mgd. The difference between this flow and the I peak wet weather flow of 2.00 mgd of 1.58 mgd represents an infiltration rate of 4300 gad. [ The rainfall during the January 21 storm was 3.85 inches during the preceding 24-hour period. There was no way to measure the amount of flow the Mill Valley sewer system had received during this storm because control gates at the plant had been throttled to pass a maximum of 3.8 mgd through the plant, and most of the manholes in the lower part of the City's sewer system were overflowing. The infiltration rate 1 of 4700 gad previously calculated for the City's system from data given in the 1968 "Mill Valley Master Plan for Sanitary Sewers" is the only guide available. [ Although the District infiltration rate is not quite as high as that estimated for Mill Valley, it is unnecessarily high and should be mitigated through a systematic program of leak detection and correction. l 2-9 [ SEWERAGE SYSTEM STUDIES AND ANALYSIS Sewer System Evaluation Besides computing the storm water inflow rates for the .Homestead Valley sewer system, it is important to consider the system itself in order to appraise its condition as it relates to storm water infiltration. The District's sewer system connects to the Mill Valley I sewer system in three places: at Miller Avenue and Evergreen Avenue; at Miller Avenue and Reed Street; and at Miller Avenue . I east of Reed Street (See Figure 1). The sewer connecting at I Evergreen and Miller is a 10" line which serves about 8J per cent of the present District. The other two connections are . - ! 6" lines serving the remainder of the District designated as HV-l and HV-Z on Figure 1. ~ .- In so far a·s infiltration is concerned, it should be ex pected that the District's sewers will be in better condition than Mill Valley's sewers simply because they are not as old. Some sewers in Mill Valley, reportedly still in use, were con structed before 1900. In Homestead Valley almost all sewers were constructed as a part of the initial sewerage project in 1948. The type of sewer pipe used in this initial project was vitrified clay with cement joints. Although the vitrified clay is a long lasting material, it is generally brittle and subject to damage from backfill loads and earth movement. Furthermore, cement pipe joints are subject to deterioration from corrosive action of the sewage. As the joints deterior ate, ground water and roots are allowed to enter the pipe. Roots not only plug the pipe and cause sewer stoppages but will also break the pipe as they grow. In this regard, an annual preventative maintenance program to clean sewers and cut the roots will help keep the sewers in good condition. It was not until the mid-1950's that better joint materials were developed for vitrified clay pipe and made possible the construction of relatively watertight sewers. Since the District is hilly and many sewer lines are constructed in easements, roots entering the sewers have un doubtedly broken many pipes. House laterals are probably in similar condition and provide a major source of infiltration to the sewer system. Direct connections of roof leaders and patio drains is not anticipated to be a major problem. The District staff has 2-10 I I I I SEWERAGE SYSTEM STUDIES AND ANALYSIS in the past surveyed roof leaders and reported very few con I nected to the sewers, Since topography of the area served by the District provides good drainage, there should be little temptation for people to connect patio drains to the sanitary sewers. No information is available on possible street storm drains which may be connected to the sewers. A smoke testing program is well advised as it would reveal almost all direct storm drain connections as well as broken and defective sewers and house laterals. Based on an infiltration rate of 4300 gad derived from the above analysis, the total peak flow expected from the fully developed District, providing nothing is done to miti gate the infiltration, is estimated to be 3.00 mgd (See 2). Table Infiltration from Servi)e Zones HV-5, HV-6 and HV-7 was calculated using a factor of 4300 gad for the sew ered a'reas and 1000 gad for undeveloped areas. In general, if no infil tra tio.1 mi tiga tion measures are undertaken, the existing District 3ewer system will not be capable of handling the peak wet weather flows from the fully developed District. Peak flows from the existing development would probably be totally contained, even though the sewers are surcharged, providing the City's sewer on Miller Avenue does not surcharge. Infiltration Mitigation Since the District's sewer system evidences a high infil tration rate it is advisable that the storm water inflow be reduced. Not only would this decrease the District's peak wet weather flow contribution to Mill Valley's already overtaxed sewers, but it would also reduce the likelihood of stoppages, overflowing manholes, and bypassing wi thin' the Dis tric t' sown system. Furthermore, the functional adequacy of any area-wide scheme for intercepting, pumping and treating sewage from the Richardson Bay watershed depends on a substantial reduction in excess storm water infiltration in all the contributing sewer systems. One of the simplest methods of locating direct storm drain connections, leaks and broken sewer pipe is through a thorough smoke testing program. An innocuous white smoke is blown into a sewer manhole and will appear from illegal drain age connections and broken sewer pipe. Breaks in shallow sewers such as house laterals are readily found. Once 2-11 SEWERAGE SYSTEM STUDIES AND ANALYSIS obvious leaks are found, efforts should be made to correct the deficiencies, otherwise the leak detection is only of academic interest. When severe leaks are located in the District mains, the lines should be televised and sealed or replaced where neces sary. Leaks in manholes are easily repaired and can be readily located when ground water levels are high. Leaks in sewer mains are, of course, the District's responsibility to repair. However, leaks in private laterals must be corrected by the property owner. Line sealing programs for sewer mains are difficult and expensive. Furthermore, the results with present sealing methods are questionable. If the backfill around the sewer pipes is granular, it. is possible to seal the joints with a bituminous compound injected from the surface. In most cases, however, pipes must be sealed from the inside with a cement grout or a two component plastic compound applied under pres sure. A line sealing program is recommended only as a last resort if the infiltration rate remains high after a thorough smoke testing and repair program has been completed. Although replacement of large portions of the sewer sys tem would be exorbitantly costly, it is recommended that sewer lines in very poor condition be replaced with better pipe material. The District should insist that all new sewer mains and house laterals be constructed with the best pipe and joint materials available and be watertight. In addition, preventa tive measures such as inspection and hydrostatic or air tests for leakage should become routine for new sewer lines and new house lateral construction so that future infiltration rates can be kept to a minimum. With a knowledge of the present infiltration rate, the overall effectiveness of an infiltration mitigation program can be measured during severe storms by the same method as used in these studies. It should be pointed out, however, that even after smoke testing and possibly line sealing, the infiltration rate may still be well above the 1000 gallons per acre per day (gad) rate which can be expected for new systems. Of perplexing interest, it should be noted that the 1968 "Mill Valley Mas ter Plan for Sanitary Sewers" concluded that it would be realistic to expect to reduce storm water intake 2-12 I I I SEWERAGE SYSTEM STUDIES AND ANALYSIS I to the sewers to 100 per cent of the projected domestic flow. I With a density of 10 people per acre this amounts to less than the 1000 gad rate found in new systems. We do not expect that such a low infiltration rate is obtainable with the present I methods of infiltration mitigation and without rebuilding the entire sewer and house lateral system. I Summary Essentially, the purpose of the studies summarized herein I has been to investigate and analyze the Homestead Valley sewer system, to document the magnitude of the peak wet weather flows experienced and to provide a basis for comparing the I conditions existing in the system with that of the Mill Valley sewer system. Accordingly, the analysis of the District's sewer system I has yielded the following flow criteria: Per capita sewage contribution 80 gpcd I Per acre storm water infiltration rate 4JoO gad Peak Factor Per Figure 2 The following are estimates of population and flow con I ditions for the existing District system and the fully de veloped District service area using the above flow criteria: I Present Ultimate Population 3000 6000 I Average Dry Weather Flow mgd 0.24 0.48 Peak Dry Weather Flow mgd 0.50 0.90 Peak Wet Weather Flow mgd 2.43 3.00 I If an infiltration mitigation program is undertaken, it is possible to obtain a sUbstantial reduction in the storm water infiltration rate and the peak wet weather flows which I presently cause surcharging of the system. 2-13 I I I CHAPTER J CONCLUSIONS AND RECOMMENDATIONS I General I The general objective of the present study has been to analyze and evaluate the District's sewer system, particu larly with respect to the amount of storm water infiltration I entering the system. Documentation of the wet weather flows experienced provides a basis on which to evaluate the condi tion of the District's sewer system and provide a reference on which to plan system improvements. I Conclusions I Based on the general objectives outlined above and con siderations previously summarized, the following conclusions I are made: 1. It is concluded that the per capita flow contribution is approximately 80 gallons per day. 2. It is concluded that the storm water infiltration rate to the existing sewer system is approximately 4300 gallons per acre per day. J. It is concluded that a preventative maintenance pro gram and a smoke testing program would substantially reduce this infiltration rate. 4. It is concluded that the functional adequacy of any sewage treatment and disposal system depends on the reduction of storm water inflow to the sewer systems. Reconunenda tions Based on the foregoing conclusions and considerations previously sununarized, the following reconunendations are pre sen ted: 1. It is reconunended that the District establish an annual preventative maintenance program of line cleaning and root removal. 2. It is reconunended that as a first stage of sewer system improvements the District undertake a program J-1 CONCLUSIONS AND RECOMMENDATIONS of smoke testing, the repairing of faulty sewers and the elimination of sources of direct storm water in flow to the system. 3. It is recommended that after the smoke testing and sewer correction program is completed, the peak wet weather flows be again measured to determine the ef fectiveness of the corrective work performed and the necessity for further system improvements. Acknowledgments For their interest and helpful cooperation, we wish to express our appreciation to the District Board, including Gus Wolfe and Jim MacNichols; and to Mr. Philip B. Lygren, now deceased. u ~ J-2 I L .. ( PRE l 1M I N A R Y D R AFT ,,~"., ;:;UU! l!:~:\~i NORTH MARIN - SOUTH SONOMA CENTRAL MARIN SOUTH MARIN WASTEWATER MANAGEMENT PROGRAMS OVERVIEW REPORT INCLUDING ENVIRONMENTAL IMPACT EVALUATION OF REGIONAL , AREA-WIDE ALTERNATIVES NOVEMBER 1973 J. WARREN NUTE, INC. / JENKS 8 ADAMSON YODER - TROTTER - ORlOB 8 ASSOCIATES PRE F ACE This document has been prepared for the purpose of assisting the responsible local sewering agencies and affected public within North Marin/South Sonoma, Central Marin and South Marin County areas, in reaching final decisions as to the Alternative Water Quality Management Program best suited to meeting of combined, regional needs. OVERVIEW REPORT Including ENVIRONMENTAL IMPACT EVALUATION of REGIONAL, AREA-WIDE ALTERNATIVES SUMMARY PREPARED FOR Wastewater Planning Coordinating Committee -PARTICIPATING AGENCIES North Marin/South Sonoma Subregion Novato Sanitary District County of Sonoma Sonoma Valley County Sanitation District City of Petaluma Hamilton Air Force Base Las Gallinas Valley Sanitary District San Rafael Sanitation District Central Marin Subregion San Rafael Sanitation District Sanitary District No. I of Marin County California State Prison at San Quentin South Marin Subregion City of Mill V"lley Richardson Bay Sanitary District Sanitary District No. 5 of Marin County City of Belvedere Sausalito-Marin City Sanitary District Homestead Valley Sanitary District Almonte Sanitary District Alto Sanitary District Tampalpais County Sanitary District PREPARED BY Jenks &A damson; J. Warren Nute, Inc.; and Yoder-Trotter-Orlob &A ssociates Introduction @ Three subregional Water Quality Management Program studies and reports have been completed on behalf of 25 local sewering agencies within, (1) North Marin/South 'Sonoma Counties, (2) Central Marin County, and (3) South Marin County. The separate subregional studies were performed pursuant to and in accordance ~ with requirements of the State Regional Water Quality Control Board, San Francisco Bay Region. o The separate subregional studies were performed by two consortiums of the same engineering firms who provided the important coordination between the studies. -i- The separate subregional studies all considered essentially the same altern @ atives for regional consolidations and are in common agreement as to the best apparent regional program. @ The best apparent regional program, covering the entire three subregional areas, Alternative Program A, involves reducing the number of treatment plants from 15 to 4 and the number of points for discharges from 15 to 2. @ In order to provide a summarl of the separate subregional study results in respect to alternatives and to establish a fuller evaluation of regional alter __ natives, an Overview Report has been prepared. 4iI Further, the Overview Report ,was mandated by the San Francisco Bay Regional Water Quality Control Board as a condition of State and Federal grant applica tion approval. Background The three separate subregional studies were performed and reported upon by the engineering firms of J. Warren Nute, Inc., Jenks & Adamson and Yoder-Trotter Orlob & Associates. The three separate subregions cover essentially the entire Marin and South Sonoma County lands which normally drain to the waters of San Francisco and San Pablo Bays. The subregions are separated by natural topographic boundaries. lVi thin the separate subregions there are a combined total of 25 sewering agencies serving a total population of about 157,000, contributing 20 million gallons per day combined sewage flow to 15 treatment plants l"ith 15 separate points of near shore disposal. Wit~ ~he possible exception of the San Rafael Sanitation District Marin Bay fac~l~ty, none of the wastewater dischargers within the subrecrional areas are meeting all requirements and objectives of the State. 0 Projections e Proj ections have been established based on a "Low," "Median" and High level of development with the median projections utilized for present planning purposes. @iMedian projections for the combined three subregional service areas sugrrest a , future year 2000 population of 589,410, with associated wastewater volU:;;e of 5?8 million gallon: per. day .. The lo~ projections indicate a year 2000 popula hon of 42?, 0,00, wh~ch f~gure lS conslstent l"i th the controlled groth projections by the varlOUS responsible planning agencies . ., It is noted that the Alternative Programs were later tested in respect to ftmda mental changes in assumed population and. wastewater volume projections and were found to be insensitive to those changes. . Objectives Program obj ecti ves were established and uti lized based upon State and Federal water quality objectives. -ii- Program objectives are essentially the same for each of the three subregional 6) studies. In respect to treatment and disposal, Program objectives call for at least (I full secondary treatment, together with central Bay discharge. Mathematical modelling established that objectives could be met through dis ~ charge of treated wastewater offshore from either or both Point San Quentin and Point San Pedro. In respect to reclamation, it was established that this common objective will (I be realized to best advantage through developing a program of large-scale recla mation in the South Sonoma County area, phased to include elements for a recrea tion lake, agriculture irrigation, landscape irrigation and ultimately, direct potable water supply supplement. ® Uncertainties in respect to the economics of large-scale reclamation at present result in questions relating to the time this objective can be fully achieved. Regional Alternatives Of the some S4 regional and subregional alternatives considered as part of the (I combined SUbregional studies, 4 regional final candidate alternatives have been identified as Al ternativ e Programs "Alt, "B", "C" and "D" for evaluation. Alternative A would involve consolidations resulting in four treatment plants and two points of disposal. Alternative B would involve consolidations resulting in three treatment plants and one point of disposal. Alternative C would involve consolidations resulting in four treatment plants and one point of disposal. Alternative D would involve consolidations reSUlting in one treatment plant and one point of disposal (Pacific Ocean). ® Alternative Programs A, B and C would accommodate the same long-range program for large-scale reclamation. Alternative Program B would limit possibilities of local reclamation in the (I Central and South Marin areas and Alternative D would essentially eliminate possibilities for reclamation. The evaluation of Alternatives provided as part of the three separate subregion (I al studies indicated that on the combined basis of economic and non-economic factors utilized for comparison, Alternative Program A is the best apparent means of meeting objectives. -iii- i',,",_' ,; __ "." ,7 ""'':,r -''~'./../- ; \'--\_.a '.::~.~ ,; =r~~IN -> ---~"~/ , n~' ,t'i ,J ' •• "~M""')-r-_V_/'- REGIONAL ALTERNATIVE PROGRAMS Additional Evaluation <::I Al ternati ve D, the total consolidation for ocean disposal Al ternativ e, was eliminated ·as a candidate Alternative because ·of, (1) excessive costs, (2) lack of reclamation potential, and (3) negative environmental impact. @ Alternative Progr~~s were subjected to further evaluation on the basis of economics and effectiveness within the framework of different potential Program sequencing,. or staging . . It was found that sequencing changes did not basically alter the economic ranking of Alternative Programs. It was found that in consideration of numerous factors related to, (1) en vironmental, (2) resource utilization, (3) flexibility, (4) reliability, (5) planning objectives, and (6) implementation, Alternative Programs A and C are preferred over Alternative B. e Alternative Programs were subjected to sensitivity analysis in respect to costs, including cost impact of, (1) reducing "excessive" infiltration/inflow, (2) 0 and M versus Capital cost refinement, and (3) plant site relocation. It was found that potential cost sensitivity factors do not basically alter the ranking of Alternative Programs. o The Alternative Programs were subjected to sensitivity analysis in respect to effectiveness factors, including relative impacts .on, (1) ove.rall environmental impact, (2) resource utilization, (3) flexibility in respect to reclamation and changed reqUirements, and (4) reliability. It was found that sensitivity factors in respect to effectiveness do not basic ally alter the ranking of Alternative Programs. & Alternative Programs were subjected to sensitivity analysis in respect to meeting of the reclamation objectives, including, (1) timing of large-scale reuse market, (2) recreation lake possibilities, and (3) '.'zero" discharge. It was found that Alternative Programs A and C offer the greatest amount of flexibility in respect to providing means of meeting combined, limited local reuse market, while Alternative Programs B and C could enhance the early possibilities of large-scale wastewater reuse. Alternative Programs were subjected to sensitivity evaluation in respect to ~ other fact9rs, specifically public acceptance. It was found that additional evaluation of the factor of public acceptance does not basically alter the ranking of Alternative Programs. A re-evaluation of the economics related to Alternative Programs was undertaken ~ on the basis of utilizing most recently prescribed Federal cost/effectiveness analysis criteria. The re-evaluation of economics indicated a somewhat \;ider spread between Alternati ves with Alternative Program A being the least costly, followed by Alternatives C and B in that order, with Alternative B being 20% more costly and Alternative C being 10% more costly than A on a Present Worth basis. -iv- Environmental Impact e A detailed environmental impact report has been prepared as part of a separate study. That portion of the environmental impact report dealing with the impacts of @ Alternative Programs has been excerpted and included verbatim in the Overview Report. 9 The environmental impact report identifies both construction and long-term impacts related to each Alternative Program. Secondary impact of Alternative Programs, including growth inducing potential _.-_._--- - @ - are also considered. o The environmental and economic impacts associated with different Alternative Program sequencing has also been evaluated. III It was found that changing the implementation sequencing did not basically alter the ranking of Alternative Programs. 9 It was found that the most significant differences in negative impacts related to construction of a Point San Pedro outfall line and the larger interconnect ing line of Alternatives B and C. (II It was sugges_ted by State Fish & Game and State Department of Public Health Staff that as a matter of principle, concentrating the larger volume of wastewater discharge closer to the Golden Gate, offshore from Point San Quen tin, as under Alterna!ive Program C, was more-desirable. <!II It \;as suggested that meeting of most stringent water quality objectives re lated to shellfish beds could be met to greater advanatage by a single Point San Quentin discharge. \\) It was agreed that from the overall standpoint of achieving water quality Objectives, no Alternative Program is clearly more advantageous. While the differences on a combined, overall basis do not appear to be major, @ the evaluation of combined environmental impacts indicate a preference for Alternative Programs C and A over B. Combined Evaluation ~ Combining the results of the separate economic, effectiveness and enviror~ental impact evaluations of Alternative Programs set forth in the Overview Report re sults in the ?ummary found in Table 13. e Assuming that the economic advantage of Alternative Progra~ A outweighs in im portance the less tangible, somewhat more advantageous environmental and "effectiveness" advantages of Alternative Program C, then Alternative Program A remains the best apparent Alternative. -v- • Table of Contents Introduction - 1 ] Background - - - - - - - - - - - 3 Projections 7 1 j Objectives - 9 ''t! Regional Alternatives 16 J Additional Evaluation 22 Environmental Impact 48 Combined Evaluation 65 • D R AFT Marin/Sonoma Overview Report I N T ROD U C T ION Because of the evident needs to do so, coupled specific requirements of \~ith the San Francisco Bay Regional Water Quality Control Board, three separate subregional Water Quality Management Programs have been developed during the past three years, covering the entire South Marin, Central Marin and North Marin/South Sonoma County areas, which naturally drain to the waters of San Francisco Bay. _1_ _ ~, ____ _ The three separate subregional Study efforts were undertaken through coopera tion of 25 separate sewering agencies served by 15 separate existing waste water treatment plants. The three separate Studies were performed by two different consortiums of the same engineering firms, thus affording excellent opportunity of coordinated study efforts between the contiguous subregional areas and, in particular, in respect to consideration of Alternative Programs on an entire, area-wide, regional basis. A total of 54 Alternatives within the combined study areas were evaluated, including 4 Alternatives involving consolidations covering all three subregional areas. The three separate engineering Studies are consistent with each other in ]' respect to final Water Quality Management Program recommendations, recommenda tions which call for major physical facility consolidations, both within each subregional area and, in the case of the South Marin subregion, consolidation for joint treatment and disposal with the Central Marin. subregion. The recommended combined Program would result in reducing the total number of ex isting treatment plants, 15 to 4 and points of discharge from 15 to 2. Coordinating Committee While each of the three separate Studies did include an independent evaluation of the conSOlidation Alternatives involving combined facilities serving the three subregional areas, it has been agreed that a need exists to summarize this area of evaluation in a single, "overview" document. To work towards fulfilling this objective, the Wastewater Planning Coordinating Committee - Marin/South Sonoma Counties was established during December of 1972, with representatives from each of the subregional areas, plus representatives from the two major water districts serving the combined area, and County representatives. The Coordinating Committee has met since January 1973 and during this time has undertaken a systematic review of the basic factors relating to Water Quality Management Program needs of the combined subregional areas. In particular, the Coordinating Committee has studied the four basic Alternative Programs, including the recommended Program, all involving various degrees of consolida tion and coordination wi thin and between the three subregions. Regional Water Quality Control Board Resolution No. 73-12 On June 26, 1973, the San Francisco Bay Regional Water Quality Control Board passed their Resolution No. 73-12, "Regarding Marin/Sonoma Subregional Studies Coordination," a copy of which ReSOlution is appended hereto. -1- I The action of the Regional Water Quality Control Board established the follow ing points of special significance: XIII. THEREFORE, BE IT RESOLVED, that this Regional Board commends the efforts of the Wastewater Planning Coordinating Committee. XIV. BE IT FURTHER RESOLVED, that this Regional Board finds that full evaluation of alternatives involving consolidation of subregional facilities will be necessary prior to any grant certification by the Regional Board. xv. BE IT FURTHER RESOLVED, that this Regional Board finds that, in order to assure this evaluation, any project report submitted by the three subregions for facilities for the subregional programs must be accompanied by an "overview" report and environmental impact state ment which fully evaluates the consolidation alternatives. PUrpose of Present Study Essentially, the purpose of the study summarized hereinafter has been to fulfill the need for an "overview" report as further required by the Regional Water Quality Control Board in addition to the established Project Reports as a con di tion for grant approvals. To assist in achieving the present study purpose, as reported upon hereinafter, the following basic areas of previous specific study have been summarized. BACKGROUND information describing the combined, three subregional ~. study areas geographically and existing conditions. summari~ing III PROJECTIONS of wastewater volume and other characteristics for the combined, three subregional study areas, on the basis of which anticipated future facility needs are assumed. • OBJECTIVES in respect to meeting of receiving water quality object ives as well as consideration of reclamation for purposes of beneficial reuse. • REGIONAL ALTERNATIVES for meeting of Objectives are defined and evaluated, centering on the basic Alternatives for conSOlidations covering the combined, three subregional study areas. Following the foregoing summary of previous study results, subsequent studies pro vided to the Coordinating Committee have been summarized, also centering on: ENVIRONMENTAL IMPACT of the Alternative Programs from recently com ~ pleted draft of final EIR. • ADDITIONAL EVALUATION of regional Alternative Programs to provide more thorough basis upon which final decisions can be made in respect to best Program Alternative implementation. • COMBINED EVALUATION of Alternative Programs summarizing the result of evaluations of the economics, effectiveness and environmental impacts of Alternatives. It is important to note that the studies hereinafter are not meant to sum~arized take the place of the prior three separate subregional studies, nor to develop new information beyond that already prOVided. Nor is the present report meant to obviate the need for the required Project Reportes). Thus, with the exception of that section concerning the Additional Evaluation, the information provided herein is primarily a concise, limited sYnopsis of the information previously developed and set forth comprehensively in the three separated subregional studies, which are incorporated herein and herewith by reference. -2- B A C K G R 0 U N D BACKGROUND Subregional Studies The pertinent three separate subregional Water Quality Management Program studes are referenced as follows: Regional Water Quality Management Program North Marin-South Sonoma Dated: December 1, 1972 J. Warren Nute, Inc./Jenks &A damson/Yoder-Trotter-Orlob &A ssociates J A Water Quality Management Program for ) Central Marin County Dated: July 1972 Jenks & Adamson/J. Warren Nute, Inc. ] Southern Marin Subregional Wastewater Management Plan Dated: October 8, 1973 J. Warren Nute, Inc./Jenks &A damson/Yoder-Trotter-Orlob &A ssociates The foregoing· studies contain a detailed and comprehensive summary of all background information leading to study recommendations and should be referred J to as basic foundational resources, along with the "overview" presented herein. . Subregional Planning Area Characteristics l The three subregional study areas are shown geographically in Fig. 1. The specific wastewater dischargers within each subregion and related contract ing sewering agencies are summarized in Table 1. 1 J J 1 1 RICHMOND SAN FRANCISCO MARIN - SONOMA SUBREGIONS TABLE 1 Participants in Coordinated Marin/South Sonoma Counties - Subregional Water Quality Management Program Studies 1972/1973 Subregional Area Dischargers Cqntracting Agencies SOUTHERN MARIN Sausalito·Marin City Sanitary Tamalpais Valley Community Services District District Ri charn<on Bay Sani1:arv District City of Mill Valley Fromesteaa Valley ::sanitary Dlstr1ct Almonte Sanitary District Kay Park Sewer Maintenance District Alto Sanitary District Richardson Bay Sanitary District Sanitary District No.5 City of Belvedere CENTRAL MARIN Sanitary District No.1 Corte Madera (S.D. No.2) City of Larkspur Murray Park Sewer Maintenance District San Rafael Sanitation District (Main Plant) San Quentin San Quentin Village Sewer Maintenance District NORTH MARIN/SOUTH SONOMA Novato Sanitary District Hamilton AFB (portion) (Novato, Ignacio, Bahia Plants) Las Gallinas Valley Sanitary District San Rafael Sanitation District (Marin Bay Plant) Hamilton AFB City of Petaluma Sonoma Valley Sanitation District -4- An additional summary of exi;ting conditions within the subregional areas is presented in Table 2. TABLE 2 EXisting Conditions -, - -- -, - -- - Present Present Wastewater Plain Number of Number of Sub·Region Population Avg .. dry~weather, mgd Sewering Agencies Treatment Plants SOUTHERN MARIN 47,000 3.5 10 4 CENTRAL MARIN 92,000 7.8 7 3 NORTH MARINI SOUTH SONOMA 118,000 8.6 8 8 Totals 157,000 19.9 25 15 Present Wastewater Treatment & Disposal Practices Wastewater treatment and disposal practices related to each of the wastewater dischargers within the three subregional study areas are summarized in Table 3. ~compliance with Existing Requirements It is noted that all of the fifteen dischargers except two in the combined study areas provide a degree of wastewater treatment which is beyond "primary, tI and the two "primary" plant dischargers, Sausalito-Marin City S. D. and S. D. No.5 of Marin County, dispose of treated effluent to deep water. However, with the advent of most recent waste discharge requirements based upon higher water quality objectives of the Interim Basin Plan, particularly in respect to limitations upon and prohibitions against shallow water discharge, none of the fifteen dischargers in the combined subregional study areas, with the possible excepti'on of San Rafael S. D. Marin Bay are currently meeting dis charge requirements and objectives. This condition of non-compliance with ex-. isting waste discharge requirements and objectives is, of course, by no means unique to the San Francisco Bay area or elsewhere. The determination of how best to correct the conditions of non-compliance and to meet anticipated still more stringent requirements and objectives in the future has constituted the primary motivation for the three subregional studies referenced herein . . J , -5- . .,I ;: 'ABLE 3 Existing Wastewater Treatment & Disposal Fuilities lithin Marin/Sonoma Subregional Study Areas I Subregional Area Discharger Degree of Treatment Location of Disposal SOUTHERN ~~IN Sanitary District Primary Deep Water No. 5 (Tiburon Racoon Straights and Belvedere) Richardson Bay S.D. Secondary Shallow Water Richardson Bay Mill Valley Intennediate Shallow Water Richardson Bay Sausali to-Marin Primary Deep Water City S.D. S. F. Bay CENTRAL ~~IN San Rafael S. D. Intermediate Shallow Water Main Plant San Rafael Bay Sanitary District Secondary Shallow Water No. 1 (Ross Valley, Corte Madera Corte Madera, Creek Larkspur) San Quentin Intermediate Shallow Water Corte Madera Creek NORTH MA..Q,IN/ San Rafael S.D. Secondary Submerged Discharge SOUTH SONOMA Marin Bay Plant San Paolo Bay Novato S. D. Novato Plant Secondary Shallow Water San Pablo Bay Ignacio Plant Secondary Shallow Water San Pablo Bay Bahia Plant Secondary Submerged Discharge Petaluma River Los Gallinas Intermediate Slough to San Valley S. D. Pablo Bay Hamilton AFB Intermediate Shallow Water San Pablo Bay Petaluma Secondary Submerged Discharge Petaluma River Sonoma S. D. Secondary Schell Slough to San Pablo Bay -6- PRO J E C T ION S PRO J E C T ION S Population & Wastewater Characteristics ,-a j It should be noted that during the intervening period of time, now totaling more than two years, during which the three subregional studies were being performed, a considerable amount of change has taken place in respect to basic land use planning and population projections. Basic planning policy Objectives have 'been undergoing re-evaluation wi thin all three subregional areas and are, at the time of this writing, still in a general state of flux. Nevertheless, for purposes of present study and evaluation, the population projections developed, utilizing all planning data available and as specifi cally referenced in each of the subregional Water Quality Management Program studies, are considered sufficiently valid for purposes of Alternate Program evaluation, the fundamental purpose of the "overview" reported upon herein. In any case, as further noted, as part of the evaluation of Alternatives, the Alternates were tested in respect to sensitivity to fundamental changes in assumed population and wastewater volume projections. It is considered that this process adequately accounts for possible major changes in projections -~::ij J in respect to potential impact from such changes upon the evaluation of Alternatives. The projections derived, as discussed above, covering a range of possible future populations and wastewater volumes, are summarized in Table 4 • .m TABLE 4 Wastewater Flow {)o "' Projections- J Population Projections- Year 2000 Year 2000 Avg. dry-weather, mgd ~:;] Low Median High Low Median High ~ SOUTHERN MARIN 63,000 87,000 125, 000 5.4 7.5 10.7 em, CENTRAL MARIN 110,000 127,000 140,000 11.7 13.2 14.8 , .J NORTH MARINI SOUTH SONOMA 253,200 375,410 425,000 23.6 36.1 42.5 -\:l Totals 426,200 589,410 690,000 40.7 56.8 68.0 .. A summary of the cowbined subregional median value projections, utilized for pur poses of predicting long-range needs within each major service area subdivision, and as utilized in the evaluation of Alternatives, are summarized in Table 5. Local Planning Objectives In developing the above proj ections, considerable effort was made to' take into. • account local planning objectives. Specifically, many of the responsible plan ning agencies in Marin and Southern Sonoma County are considering the adoption of positive growth controls, thus reducing the historic rate of growth. In this regard, it should be noted that the low projections as given in Table 4 are gen erally slightly lower than the projected year 2000 populations if it is assumed that growth controls are implemented. Although the projected wastewater management facilities were planned around the median population, they were found to be insensitive to the low population pro jections, primarily because of the need to provide large enough facilities to handlethe higher' sewage flowsElxperienc~d. .~ l!ringwet weather. -7- -8- 1 1 ] 1 1 o B J E C T I V E S J 1 J o B J E C T I V E S ] Each of the three separate subregional studies utilized Water Quality Manage ment Program objectives \;hich are essentially the same. These objectives were ] derived through careful consideration of, (1) State and Federal receiving water" objectives and requirements, (2) mathematical model studies to ascertain impact on the receiving waters of alternative points of disposal, and (3) waste J water reclamation for potential reuse and/or meeting of the "zero discharge of pollutants" objective. State and Federal Objectives and Requirements J The subregional studies uniformly assumed that mlnlmum objectives and require ments would be those associated with the "Interim Water Quality Control Plan J for San Francisco Bay" combined with specific requirements of the Regional Water Quality Control Board, particularly in respect to biostimulants. Of the receiving water objectives, it was uniformly judged that the most critical "] needs would be those associated with: Toxicity (both acute and "relative") l Dissolved Oxygen Bacterial Contamination Biostimulants Prohibi tions While specific significance was attached to the prohibitions of discharge con tained in the Interim Basin Plan objectives and specifically that prohibition against discharge to, "any embayment, Slough, creek, or other confined shallow water area," nevertheless, for study purposes it was assumed that such dis charge to the Petaluma River or San Pablo Bay could be evaluated on the basis of substantially removing all "biostimulants" and "toxicants" as well as sub i stantial removal of suspended solids and biochemical oxygen demand through use j of higher forms of tertiary treatment. A more detailed summary of the basis upon which Study objectives and require ments were assumed are to be found in each of the subregional reports. Essentially, the common conclusion of each subregional study has been that to meet State and Federal objectives and requirements, both current and antici pated, at least the following would be necessary: Treatment For San Francisco Bay discharge, a minimum of full secondary affording 90% reduction of both 5-day biochemical oxygen demand and resulting in an effluent in which 90 percent of test fishes survive after 4 days (activated Sludge treatment was assumed as necessary to meet this study obj ective with possible inclusion of a nitrification stage and/or filtration (or fine screening)). Similar treatment, but limited to a minimum of 85% reductions for ocean discharge. Disposal Central Bay discharge to deep water at sufficient depth and at a location where a 100:1 initial dilution could be achieved (discharge to the deep -9- " Imter channel of San Francisco Bay offshore from Point San Pedro or Point San Quentin was assumed as necessary to meet this study object 1 ive, ?S well as discharge to the offshore \~aters of the Pacific Ocean at Tennessee Cove), agaiP; with a minimum 100:1 initial dilution. ] As further noted above, in spite of the current prohibitions against shallow water disposal, for study purposes it has also been assumed ,that such discharge could be evaluated on the basis of assuming prior treatment ] to a level such as afforded by secondary fOllowed by nitrogen removal, filtration and carbon adsorption. 1 Mathematical Modelling A detailed evaluation of the impacts resulting from disposal of treated waste water at alternative locations was common to all three subregional studies ] through use of a single mathematical model developed by Water Resources Engineering Co. of Walnut Creek. This model was used to evaluate, (1) back- ground conditions resulting from discharges to the system other than } those in the combined study areas, (2) assumed disposal of combined, three subregional treated wastewaters offshore from Point San Pedro, (3) assumed disposal of combined, three subregional treated wastewaters offshore from ] Point San Quentin, and (4) assumed disposal of separate treated wastewaters at present local points of discharge, (except for South Marin dischargers). The modelling was done on the basis of assumed "high" proj ections of popula tions and associated loadings from the combined study areas and corresponding peak loading conditions resulting from Contra Costa County and Vallejo discharges. High projections were used to establish the most conservative basis 1 of comparison. The mathematical model was run to determine the resultant impact on the receiving water for the alternative conditions of disposal in respect to: Relative Toxicity Nitrogen Chlorophyl "a" The modelling studies confirmed the fact that for combined discharge at either the offshore, deep water areas from Point San Quentin or Point San Pedro, all existing and anticipated water quality objectives and requirements can be met. A qualification to this conclusion would be in respect to pOSSible need for nitrogen removal at some future date applicable to any discharge to the upper Bay system by reason of potential exceeding of Chlorophyl "a" limitations. On the other hand, the modelling showed that for local discharge, objectives in respect to "relative toxicity" as currently defined, cannot be met. The details of the foregoing studies are summarized to best adVantage in the North Marin-South Sonoma subregional report, Chapter 8, beginning at page 8-16. It is noted again, however, that the modelling studies and results therefrom were utilized uniformly and applied to the evaluations of each of the three subregional studies. -10- 'l J J Reclamation and "Zero Discharge" Throughout all three of the subregional studies, it was clearly established J that ultimate Program objectives would include a maximum amount of wastewater reclamation for beneficial reuse. Also, each of the studies has recognized the possibilities of a "zero discharge" of pollutants requirement being imposed at some time in the future. As part of the evaluation of these ultimate Study object- J ives, an unusually thorough investigation of reclamation and beneficial reuse alternatives was iniated and made applicable uniformly to each of the three subregional studies. A slli~ary of the separate and combined studies relating to wastewater reclama tion and beneficial reuse wi thin the subregional areas is presented as follows: Southern Marin -- The potential reuse market for landscape irrigation, industrial reuse, recreation lakes and direct municipal recycle was evaluated. This study and evaluation led to the conclusion that, J "--the potential for reclamation of wastewater within Southern Marin is very small. Furthermore, the present highly mineralized quality of J Southern Marin wastewater makes it practically unsuited for many uses without expensive demineralization. '1 Aside from the development of an effluent impoundment in Southern Marin, j which apparently is unacceptable to environmental groups, there is no potential for total reuse of reclaimed Southern Marin effluents. There J may be a justification, however, to develop local small-scale landscape irrigation projects as demonstration projects to educate the public with regard to the feasibility of water reclamation and enhance the possibility for public acceptance of future direct reuse." The foregOing conClusions led to a further study of potential for large-scale reclamation and reuse in the south Sonoma County area, combined \'iith the Central and North Marin-South Sonoma subregional areas. These further studies led to the following conclusions: "--It appears that the most viable large-scale potential exists in the North Marin-South Sonoma area in the form of recreational lakes, and in the North Bay and Delta areas in the form of agricultural irrigation. Once a recreational lake is developed utilizing reclaimed wastewater, the chances of receiving Health Department approval for direct municipal re cycle appear to be greatly enhanced. There is the possibility, of course, that it may be preferable to use the overflow from the recreational lakes for agricultural irrigation rather than for domestic reuse." The studies from which the conclusions noted above were derived are to be found in Chapter 8 of the South Marin subregional report. Central Marin -- As was the case with South Marin; the Central Marin sub regional study included an evaluation of the potential w'astewater reuse market for landscape irrigation, recreation lakes and direct municipal reuse ~Ii th essentially the same conclusions. However, a wider, but still limi ted market for landscape irrigation wi thin the lower Ross Valley does appear to be prac tical and is offered as a potential near-term, economically feasible possibility. -11- In respect to large-scale wastewater reclamation for beneficial reuse, the con clusions in respect to the Central Marin subregional study area were precisely the same as for Southern Marin, that is, the market is to the North in the form of recreational lakes, and in the North Bay and Delta areas in the form of agricultural irrigation. The studies from which the conclusions noted above were derived are to be found in Chapter VI of the Central Marin subregional report. North Marin-South Sonoma -- Having concluded concurrently that the potential wastewater reuse market on a large-scale basis exists uniquely with in the North Marin-South Sonoma Counties study area, the most comprehensive studies in this regard are to be found summarized in the North Marin-South Sonoma subregional report. In addition to the potentials for local and large-scale wastewater reuse, the North Marin-South Sonoma subregional study included a thorough review of basic municipal water requirements and alternatives for meeting these requirements within the context of a water resources development program. Separate additional studies were made in respect to ground water recharge, wetlands development and stream flow augmentation, wetlands enhancement with runoff to the bay, wetlands development with disposal by evaporation with final emphasis upon the potential for recreation lake and water supply agri culture irrigation. Recognizing that the possibilities for large-seale wastewater reclamation for beneficial reuse related primarily to recreation lake water supply and agri culture irrigation within the foresseable future, this conclusion being con sistent with those arrived at as part of both the Southern Marin and Central Marin subregional studies, a more detailed evaluation was provided in this regard with specific alternatives identified for recreation lakes. Also, the agriculture irrigation potential l~as defined on the basis of actual survey of irrigation interests amongst farmers in the area. The study conclusions were essentially: "Basically, the greatest potential for utilizing reclaimed wastewater appears to lie in developing an agricultural irrigation demand or (and) creating a recreational lake." The studies from which the conclusion noted above was derived are to be found in Chapter 9 of the North Marin-South Sonoma subregional report. SynthesiS -- All three subregional studies were in common agreement that large-scaie wastewater reclamation for beneficial reuse is limited to the South Sonoma County area where large volumes of reclaimed wastewater could be utilized for, (1) a recreation lake, and/or (2) agriculture irrigation. The foregoing conclusion was not meant to imply that wastewater reclamation for beneficial reuse for limited purposes in South and Central Marin should not be encouraged, but merely did serve to establish that ultimate Program object ives for maximum reuse most likely will be realized through transport of 11aste lvater for reuse to the north. -12- ] Need Versus Supply -- An important factor which speaks to the question of potential for large-scale wastewater reuse of course is in respect to actual reuse potential in relationship to potential supply. In this regard, Tables No. 6 and 7 are of interest. Of particular significance, the foregoing referenc ] ed Tables reveal that the potential volume of wastewater from the combined three subregional areas exceeds the currently identified potential large-scale reuse market. In fact, most of the ultimate reuse potential could be supplied by ] North Marin-South Sonoma wastewater dischargers alone. Thus, it appears that if total reclamation and beneficial reuse, or a "zero" discharge objective is to be realized ultimately, then it may be necessary to develop additional markets l and/or areas for ground disposal beyond those already identified. j Economics -- While the conclusion is that a recreation la.'<e and/or large scale agriculture irrigation in South Sonoma County through use of reclaimed ] wastewater represents the most viable reclamation alternative for the combined subregional areas, it is recognized that the time at which this potential might be realized will rest significantly upon the economics related thereto. In addition, of course, there may be a time, even in the near future, where the fundamental question of supply will overshadow the question of economics. In the meantime, however. it is recognized that the costs associated with a recre ation lake, or agriculture irrigation, may be the determining factor as to the actual time at which large-scale reclamation for beneficial reuse will become a reality. In this regard, then, it is important to note that as part of the survey to de termine the agriculture reclaimed ,vastewater market, it was found that farmers today could afford a maximum cost for water, depending upon the type of crop, determined to be at two levels, $3.50 and $20.00 per acre foot. From these figures, a rough estimate of the amount of subsidy ,;hich would be required to supply reclaimed wastewater at these support levelS appears to be at least $15.00 per acre foot. It seems unlikely that the sewering agencies would be justified in paying the foregoing subsidies. Similarly, a limited study was made of the potential offsetting costs for, a recreation development lake-par~ and it appears that an even larger subsidy, from an as yet unknown source, would be required to make this potential reuse program viable. A limited land scape irrigation reclaimed wastewater irrigation program does appear to be more favorable economically. To provide an indication as to the basic economics involved in respect to the possible reclamation programs, the estimates which have been made are summariz ed in Table 8. As can be observed from Table 8, with the possible exception of a limited local landscape irrigation program, economics do not favor the use of reclaimed wastewater under the assumed conditions noted. It should also be pOinted out, the adverse economics could be more severe if any additional costs for waste water treatment beyond those necessary for disposal purposes are added. -13- , .~ TABLE 6 Year 2020 Potential Large-Scale Reclaimed l Wastewater Reuse in Sonoma/Marin Countiesl Estimated Reuse Potential ] Rause 1000', acre.ft'/year Recreation Lake, Chilena (evaporation & infiltration losses) 7 l Recreation Lake, Tolay' (evaporation & infiltration losses) (5) Supplemental Agriculture Irrigation3 1 at $3.50/ac. ft. support level 28 at $20.00/ac. ft. support level 13 Total 48 ] (46) I Additional potential exists in Napa and Solano Counties, overlaps potential local available reclaimed wastewater 2 Assume would construct one recreation lake. ft: 3 Market estimated on basis of price level farmers can pay, assume subs'idy ranging"from $13-$S8/ac. J TABLE 7 Year 2000 Potential Reclaimed Wastewater Supply from Sonoma/Marin Counties Estimated Potential Supply Source 1000's acre·ft'/year Southern Marin 8 Central Marin 15 North Marin/South Sonoma 40 Total 63 Significance to Present Studies -- In evaluating the significance of the foregoing in respect to the Present Studies, the following is concluded: Large-scale wastewater reclamation and beneficial reuse potential is . @ essentially limited to the South Sonoma County area and is seen most clearly as water supply for a recreation lake and/or agriculture irrigation. $ The economics related to the large-scale wastewater reclamation suggest that realization of this potential may be some time into the future, at least until an acceptable method of financing is determined, Local wastewater reclamation for purposes of landscape irrigation @ appears to be limited in the South Marin area and, to a lesser extent, limi ted in the Central Marin area, but should be encouraged where found to be feasible. -14- .", The economics of wastewater reclamation for beneficial reuse are adverse at the present time .. (l) The Water Quality Management Program(s) for the combined North Marin .South Sonoma, Central Marin and South Marin subregions should all pro vide the flexibility whereby the potential large-scale wastewater reclamation and beneficial reuse market to be found in the South Sonoma area could be realized in the future, presumably at such time as the economics or supply factors are more favorable than at present. -15- 11.-' __ ' __ "J t.~"·_"J 1- ___ ._, L~,,_.,--' L_.-->_J L,". . "".' .~ __ J L_..J L--l L .. _. . J J TABLE g Preliminary Estimated Annual Revenues and Benefits from Development of Potential Reclaimed Wastewater Use projects . Recreational Lake Agricultural Irrigation Characteristic Par~ Development by the year 2020 Local Landscape Irrigation Water Priced at Water Priced at Ross La. ESTU'J..l\TED F.EVENUES Current Rates S20/ac.ft. ~ Gallinas ~l:.. Utilization Basis 500,000 user days/year 28,000 ae.ft. 13,000 ac.ft. 385 ac.ft. 567 ac.ft. 1952 ae.ft. (l25,OOO automobiles) Cost Basis $l.OO/car Admission Fee p.50/ac.ft. \ $20/ac.~t. $lOO/ac.ft. $lOO/ac.ft.\ $100/ac.ft. • Estimated Revenues $125,000 $ 98,000 $260,000 $3B,500 $56,700 $95,200 ESTIHATED EXPENSES I Estimated Capitalization $2,000,000 (Park only) $7,656,2S0(l} $3,555,o00{1} $445,000 $560,000 $1,005,000 Annual Debt k~ortization @ 5.5% for 50 years 11B,000 452,000 210,000 26,290 33,070 59,350 Estimated Annual Q&M Costs 100,000 75,000 50,000 3,450 7,200 ~650 Total Estimated Annual Cost $21B,OOO $527,000 $260,000 $29,730 $40,270 $70,000 Estima ted Net Annual Offsetting Costs ($93,000) ($429,000) $ o $25,200 Secondary Benefits 1. Stimulate recreational 1. Stimulate Agricultural 1. Economize on use of water oriented businesses in industry. resources. adjacent communities. 2. Economize on use of .2. Economize on use of fertilizer. 2. Reduce fuel consumption water resources. by prOviding recreational lake close to population centers. _.. - .. -.-.~.--- Remarks .There appears to be a need A case could possibly be UP to 5,000 ac.ft. of water cQuln be for fresh water oriented made for a state:subsidy to used on local landscaping areas recreation in North Marin agriculture to offset the in Eastern Marin and Southern County and Southern Sonoma additional cos~s of delivery. Sonoma; however, their locations County, are generally so dispensed that the cost of the secondary distribution system is far more than the reve nues generated. (1) Assumes installation of 10,000 feet of distribution main. per square mile of irrigated farmland at $35.00/ft. with water . application rate- of 2.ac.ft. per acre of land per year. J ., •... ]--- -.-J REGIONAL ,no!, ALTERNATIVES J .~! J REGIONAL A L T ERN A T I V E S Each of the three subregional studies approached the needs to define and evaluate alternatives, both regional and subregional, following basically the .same format and utilizing the same study objectives. Essentially, the format involved consideration of, (1) the area-wide, regional alternatives involving consolidations embracing all three subregional study areas, and (2) alternatives involving consolidations within each of the sub regional areas as well as the independent, "go-it-alone" base alternative. As previous ly noted, fortuitous ly the three subregional study efforts were .all conducted by consortiums involving the same engineers, so that the study of __ ,-n alternatives, particularly those involving area-wide, regional consolidations, __ 1 were defined and evaluated on essentially a uniform, common basis. The detailed description and evaluation of the combined total of 54 candidate alternatives considered are summarized in the subregional studies as follows: North Marin/South Sonoma Chapter 10 Central Marin Chapters 7 and 8 South Marin Chapter 9 The procedure followed in each subregional study was to screen out all but the most promising alternatives, both regional and subregional, on the basis of both economic and non-economic factors. The evaluation process resulted in the recommended Program(s) defined in each of the subregional reports, the individual Programs being consistent with each other. Regional Alternatives Identified The screening and evaluation process, both as part of the three studies and subsequent thereto, resulted in the narrowing of the area-wide regional alternatives to be given final consideration to four. These final candidate alternative programs are shown graphically in Fig. 2 and are further identi fied as follows: Alternative A -- This Alternative Program would provide facilities for consolidation of wastewater transport, treatment and disposal of combined South Marin and Central Marin wastewater. For central and south Marin, a single consolidated treatment facility would be constructed at the ex isting Sanitary District No. 1 plant site near San Quentin Prison, with disposal of combined wastewater to deep water offshore from Point San Quentin. All north Marin and south Sonoma treated wastewater would be consolidated for combined disposal to the deep water offshore from Point San Pedro. A conSOlidated, subregional treatment plant, located in the Hamilton Field AFB area, would be constructed to serve all of north Marin County, while the Petaluma and Sonoma Valley County S.D. plants would be enlarged. Subsequent reclamation and reuse would be provided by Phase 2 of this -16- Alternative, which phase would include an intertie between the Central Marin and North Marin treatment and conveyance facilities, thus permitting transport of treated south and central Marin wastewater to the north ] Marin/south Sonoma systems, then reversed for conveyance to a storage and possible recreation lake located in south Sonoma County. From this .point, it would be assumed that treated, stored wastewater would be ] utilized for agriculture irrigation purposes. A Phase 3 of this Alterna tive would result in use of the treated and stored, combined wastewater from the entire regional area for direct reuse purposes, assuming tech nology and Health Department needs will combine to make this Phase feasible in time. This Alternative would involve abandonment of 12 existing treatment ] plants and 15 points of existing disposal. At the same time, there would be constructed two new subregional treatment plants and two new central Bay outfalls. ] Alternative B -- This Alternative Program would provide for the same basic consolidations as for Alternative A, except that the subregional plant at ] Point San Quentin would not be constructed, the intertie between the re gions 110uld be constructed as part of Phase 1 and the north Marin subre gional plant would provide for combined treatment of south-central and north Marin wastewater, prior to discharge through use of a single outfall J offshore of Point San Pedro. Phase 2 and Phase 3 of this Alternative Program would involve essentially ] the same facilities, meeting the same objectives as for Alternative Plan A. This Alternative would involve the same consolidations as for Alternative ] Program A, except that there would be one less treatment plant and one central Bay outfall off from Point San Pedro instead of the two outfalls of Program A. ] Alternative C -- This Alternative Program would provide for the same basic consolidations as for Alternative A, except that the intertie between north and central Marin would be constructed as part of Phase I and there ] would be combined discharge of all treated 11astewater from a single out fall offshore from Point San Quentin. 1 Phase 2 and Phase 3 of this Alternative Program would involve essentially the same facilities, meeting the same objectives as for Alternative Plan A. ] Alternative D -- This Alternative Program would provide for consolidation of. all wastewater treatment and disposal facilities for transport to a poi~t of final disposal to the offshore waters of the Pacific Ocean near Tennessee Cove in South Marin. This Alternative would involve abandonment of all IS existing treatment plants in the combined regional area as well as the existing 15 points of disposal. At the same time, there would be constructed one new regional treatment plant in the Tennessee Cove area. There would be no planned major reclamation and reuse Phase associated With this AlternatiVe Program. -17- REGIONAL ALTERNATIVE PROGRAMS As the result of the further evaluation process summarized hereinafter, Alter native Program A did become the recommended Program of each of the three sub regional studies. Evaluation Process Summarized The evaluation process which supported the recommendation for Alternative Program A implementation is established in each subregional study. In parti cular, Chapter 7 of the Central Marin subregional study summarizes the steps followed in the evaluation process which included separate consideration of the following areas of special interest: Criteria of Consolidation -- Fundamental to the evaluation of Program ] alternatives has been recognition of applicable criteri of consolida tion including; (1) all alternatives must meet the same high water quality objectives; (2) alternatives should account for the essential j need for system reliability to meet objectives on a continuous basis; (3) the advantages of consolidation reflected in economies of scale must be carefully evaluated; (4) there must be recognition of the man date for consolidation "where feasible" as part of State grant Regula J tions; (5) consolidations should be considered which enhance the chances of wastewater reclamation for beneficial reuse; (6) concentrations of residual pollutants should not unduly tax the assimilating capacity at 1 the point(s) of discharge; (7) alternatives should account for the pos J sible meeting of a "zero discharge of pollutants" objective required in the future; and (8) alternatives should account for all non-economic and ] environmental factors. Economic Evaluation -- Basic to the economic evaluation of Program alter J''llI , natives was the developing of cost curves setting forth estimated costs for various elements of a proposed Program, including costs for treatment, pumping and transport facilities. Use of cost curves for both capital and operating costs were utilized so as to provide a uniform basis of j comparison. Costs were projected on the basis of carrying the Program to the year 2000 with interest assumed at 6%. Final economic evaluation "'. was made on the basis of "present worth" comparison of all Program costs, I· capital and maintenance and operation. A summary of the economic evalua J tion of the regional Alternative Programs considered is shown in Table 9. As part of the economic evaluation sensitivity factors were considered, including changes in interest rates and ultimate growth. The evaluation of these sensitivity factors did not alter the economic standings of Al ternat i ves . -18- TABLE 9 Summary of Overall Costs of Alternative Regional Programs Initial Total Present Average Construction Cost Worth * Annual Costs* Alte·rnative Program to 1980 (millions $) (millions $) (mil lions $) A $ 73.1 $ 96.6 $ 7.4 B $ 90.5 $112.7 $ 8.7 C $ 80.6 $104.9 $ 8.1 D $106.0 $129.8 $10.0 *At 6% interest, includes Maintenance and Operating Costs to year 2003. Non-Economic Evaluation -- Each of the subregional studies provided essentially the same type of evaluation of non-economic factors as they related to each of the Alternative Programs being considered. Among these factors were included relative advantages and disadvantages of each alternative in respect to, (1) ability to meet water quality objectives, (2) reliability, (3) reclamation potential, (4) flexibility in respect to future changed conditions, (5) environmental impact of treatment and transport facilities, (6) regionalization, and (7) implementation and others. Summary of Evaluation The evaluation of alternative programs is summarized in varying detail within each of the separate subregional studies. The evaluation provided in Chapter 7 of the Central Marin Study deals most specifically with the basic factors, and tempered by the results of some subsequent discussions, these factors are summarized as follows: Economic -- Alternative A is least costly both on the basis of Present Worth and initial cost. Water Quality Objectives -- All Alternatives are considered essentially equal in ability to meet water quality objectives. Reliability -- If assessment of "reliability" is limited to number of treatment plants, (the fewer number of plants, the more reliable is the Program), then Alternative D is most reliable (1 plant), followed by Alternative B (3 plants), and A and C (4 plants). If transport of treated wastewater over long distances and diversity of large-sized treatment plants and alternate points of disposal are con sidered to result in added system reliability, then Alternatives A and C would be more reliable than Alternatives Band D, with Alternative A being . most advantageous in this regard. It was concluded that no Alternative Program provides clear advantages in respect to reliability, all Programs are considered reliable. -19- Reclamation Potential -- Alternatives E and C are considered to provide enhanced possibilities for early large-scale reclamation and beneficial reuse. Alternative C preserves the added opportunity of local reuse in the Central and south Marin subregions. Alternative A provides the same advantages as alternative C, but by postponing the intertie between north and central-south brings in uncertainty factor which does not a~ exist in Alternatives B and C. Alternative D essentially eliminates the possibilities of large-scale reclamation. It was concluded that in the face of some uncertainty of Phase 2 implement ation, Alternative Programs Band C are most advantageous in respect to reclamation potential, with some added advantage to Alternative C. Flexibility -- Assuming completion of Alternative Programs, Alternatives A and C appear to provide some added flexibility in respect to local reclama tion, while Alternatives Band C are somewhat more flexible in respect to meeting a possible future "zero discharge of pollutants" obj ecti ve. It was concluded that no Alternative Program provides clear advantages in respect to flexibility. Environmental Impact -- In respect to long-term environmental impact of the Alternative Programs, it is considered that the same factors relating to "reliability" are significant. In respect to construction impact, Alternative A is preferred and Alternative D is least desirable. In respect to impact upon the receiving water, it appears that no Alternative Program has clearly defined advantages, although there may be more uncer tainty in this regard related to the ocean discharge of Alternative D. It was concluded that there is no clearly established advantage in respect to overall environmental impact betl1een Alternative Programs A, E and C, but Alternative D was considered to be least desirable. Regionalization -- In respect to regionalization, if consolidation of facili ties is accepted as the criteria for regionalization, then Alter native Programs D, E, C and A would be ranked in that decending order. However, it is noted that thirteen existing treatment plants are abandoned in facor of 4 subregional plants instead of 3 in the case of Alternative B and I in the case of Alternative D, so it is considered that all Alternatives provide a high degree of regionalization and acceptable level of consolidation. It was concluded that 11hile Alternative Program D provides for maximum regionalization, there is no clearly established advantage in this regard between the Alternatives. Implementation -- In respect to ease of implementation, it is considered that Alternative A, by reason of both lowest cost and least complicated existing institutional restraints, would be susceptible of easiest implementation. It was concluded that Alternative Program A is most advantageous in -20- respect to the factor of implementation. On the basis of the economic and non-economic evaluations provided as part of 1 the three separate subregional studies, and as partially summarized above, it J was concluded that Alternative A is the best apparent alternative for Progr&~ meeting· both subregional and regional, area-wide, long-range needs. J 1 J l J J J ] 1 -21- ) -' REGIONAL RECLAMATION PLANT---- ! ~- -MUNICIPAL C' -" -' .,,~. NOVATO --'. ~"~i\--!.>~ ~r-':-:::;.", '-- ~J ',-- RECLAMATION INTERCONNECTING LINE , , J FAIR.P~~ . I SAN-- , ANSELMO CENTRAL MARIN JA:;:R E'ATM E N v~ '\.:r.~ - \~' ~t' . .RICHMOND PACIFIC OCEAN LEGEND , .., .. DISPOSAL PHASE '''''''''0.1 2. RECLAMATION PHASE 3 "''''''''''' DIRECT RE-USE PHASE SAN FRANCISCO SOUTH - CENTRAL - NORTH MARIN f SOUTH SONOMA 'WATER QUALITY MANAGEMENT PROGRAM BEST APPARENT REGIONAL PROGRAM r------- ADDITIONAL 1 E V A L U A T ION J ] ADD I T ION A L E V A L U A T ION As discussed hereinbefore, the results of the evaluation of Alternatives found ] in each of the three subregional studies led to the common recommendation to adopt Alternative Program A as the best apparent alternative means of meeting combined, regional, long-range needs. ] However, it is also observed that the results of each subregional study indicated that the essential cost differences betlveen Alternative Programs A, Band C, while representing a spread of some 21% on an initial cost basis, the difference J is reduced to some 10% on a Present Worth basis. It is considered that this dif ference alone is not sufficient to eliminate Alternatives Band C from consider ation. Further, it is acknowledged that several of the non-economic factors ] utilized in the preliminary evaluation of Alternatives are subjective in nature and deserving of more intensive study prior to making the important final de cisions as to which Program should be implemented. 1 It has appeared therefore, quite aside from the mandate from the Regional Water Quality Control Board to do so, and in addition to the required environmental impact analysis, there remains a need for additional evaluation of the regional 1 alternatives. Consistent with these needs for additional evaluation, added information has been developed and provided the Coordinating Committee as summarized hereinafter. This additional evaluation has taken the form of more intensive review of, (1) eliminating from further consideration Alternative Program D for the reasons noted, (2) Alternative Program effectiveness within the framework of cAlternative Program sequencing or staging, (3) presentation and discussion of most signifi cant questions which have been asked in respect to the earlier evaluation of Al ternati ve Programs, and (4) revised economic evaluation based upon most recent State and Federal Guideline criteria for cost/effectiveness alanysis. ELIMINATING OF ALTERNATIVE D As part of the additional evaluation, the total consolidation for ocean disposal Alterncative D has been dropped from further consideration. The reasons for this decision were threefold, (1) Clearly excessive cost, (2) absence of definable reclamation potential, and (3) established negative environmental impact. In connection with the third factor noted above, it is observed that the Ter~e­ ssee Cove area, the only logical point where a regional treatment and disposal system could terminate, is within the newly established Golden Gate National Re creation Area,c part of the Federal Park system. Aside from the obvious limita tions which this factor represents, counsel from the established Environmental Subcommittee of the Marin Municipal Water District indicated very strong reserva tions against any discharge of wastewater to the ocean in any case. This cdecision was based upon both expressed concerns relating to the relatively sensitive aquatic environment of the ocean and commitment to the concepts of lVastelVater reclamation for beneficial reuse as an essential conservation measure , lVhich concepts Al ternati ve D lVould be contrary to. -22- ALTERNATIVE EFFECTIVENESS PROG~! The purpose of the studies summarized hereinbelow has been to evaluate the overall effectiveness of the Alternative Programs, particularly in respect to alternative implementation sequences, or staging, for achieving a large scale wastewater reclamation program. The physical features of the three regional wastewater man agement programs lli~der consideration are very similar in many respects; and therefore, the selection of a regional program may be altered depending on the timing for implementing a large-scale wastewater reclamation and reuse program. For example, a different regional program might be selected if development of large-scale reclamation and reuse is deemed too far in the future to even consider than if there already existed a proven demand for a great amount of reclaimed water somewhere. Accordingly, the following four implementation sequences have been def,ined against which the three alternative regional wastewater reclamation programs ;'Jill be evaluated in respect to both economics and effectiveness. Implementation Sequence I - Phase I - Disposal: On this basis of evaluation,' it would be assumed that the plan would include adequate wastew'ater treatment and disposal only with no planned-for future program of large-scale reclamation and reuse in the future. This evaluation answers the question, "What if large scale reclamation is not really a relevant factor and should be ignored in respect to determining the best al ternative to meet waste,v:ater disposal objectives and requirements only?" Implementation Sequence II - PhaseI- Disposal, Phase II - Reclamation: On this basis of evaluation it would be assumed that the plan would include both inadequate Vlaste w,ater treatment and disposal (1st Phase) and large-scale reclamation and reuse (2nd Phase, assumed by year 1985). This evaluation will answer the question, "Does the eval uation of alternative plans favor a different alternative if future large-scale reclamtion is assumed to be an in tegral part of each alternative?" -23- ' i _- ','0 Implementa't'ioh sequenc'e III 'Pha:s'e I '-' Re'cTamationand i '..c j Disposal: On this basis of evaluation it would be as sUIned that the plan ,wuld include both adequate waste water treatment and disposal and large-scale reclamation and reuse, both as part of the first phase project. This evaluation will answer the question, "Does the evaluation of alternative plans favor a different alter naClve if large-scale reclamation is assumed to be in cluded as part of initial Phase I project construction?" 'Implementation Sequence IV-' Phas'e 1-' Reclamation: On this basis of evaluation it would be assumed that the plan "ould include adequate wastewater treatment for reclamation and would eliminate the outfall pipeline(s) othenlise required for disposal. This evaluation will answer the question, "Does the evaluation of alternative plans favor a different alter native if the program is totally dedicated to reclamation from its inception and to the exclusion of disposal fa cilities?" No Program: To provide a baseline for' comparison, the alternative of not undertaking any program will be com pared against the alternative implementation sequences. Considering the four implementation sequences:, along with the three alternative regional wastewater management pro grams, makes a total combination of eleven different alter natives which must be evaluated. A twelfth combination between Plan A and Implementation Sequence IV does not, exist because the intertie between Central and North Marin would not be of adequate size to accomplish immediate recla mation of all wastes. Economics The estimated project cost for each alternative .pla.n---tl,.nder each implementation sequence is given in Tabl~ -24- 1 ,] Addi ti anal E ffectiVenes 5 Evaluation The questions relating to "effectiveness" of alternatives has been evaluat~. . ~gh the use of a numbering system j as shown in Tabl > nd derived through consideration of the factors smili~arized as discussed hereinafter. It should be noted that the basis for establishing the num bering system, utilizing factors of "importance" and "magni tude," has been a comparison with the impact of the " proposed alternative plan impact upon the environment and other conditions as they exist now, including impact from j presently nonconforming wastewater °treatment and disposal facili ties. a. Emtironment: (1) Water Qualitv Objectives: It is considered that all alternatives will meet waoter quality objectives. On the basis of more detailed evaluation of impact upon the receiving >vaters through Dr. Gustafson' s work and through discussions with the State DeparLrnent of Fish and Game staff, it is concluded that Alternatives C and A have a small advantage in this respect over Alternative B because of the added discharge at the somewhat preferred Point San Quentin discharge. It is assurned that this impact ,vill be positive. In Sequence IV the advantage of no disposal system would be partially offseot by the fact that some initial discharge, presumably to a local creek, would be inevitable, at least during early years of the plan until the reuse potential is fully developed. The alternative of No Project would not meet ~vater quality objectives and therefore "Iould have a highly nega tive impact on water quality. -25- :~ J • I;,opl_nl::. S"'lUl"""'D 1 t:opl_'n~. s"'1u.m<;;o :;! Il:>p1 .._ "t, Scqu(lnClt 3 Impl.. S ...~. . lSI"!:. l'hasr.a - Ha .. po<I.::r.U 131:: Ph",.o - !nl"'p<l,;.",l) bt. Ph"3 .. - (<te<;la"",'elon lat. Ph",,.!) _ ". , 2nd Ph,..so - !ilocl ..m at.lon} a.n, d Disposal) {!I...c1.""",l::lon' ?=jecl:: l"ACTON X p L • ' " II P I L l [ . A N eI Xl P LAN (!.! l'i P l LAN i! l i--:-- COS'rS-tNHU.r.IO~ 00"-''-' In1.'!::la1. C"p1.l:: ... l 73 90 81 73 ~o 81 117 129 1/9 f41 142 CQ.:ot.., (1)13-U73) orat:al l'rO'JraJII C"'pi'::",l 91 104 99 /47 IS? /4J 147 154 /4'7 173 173 CQsl::sr. (1973-2UOO) l\. .. ~r.!lg8 Annual Ca?lul (; 7 & 8 9 8 9· 10 9. 12 12 eo.sI::S (1975-Z000) 1I;"Nrag" Annu.l 0 " K 2 2 2 3 3 3 4 4 1 S 5 co .... (l.913-2aOO) 1"'"01 . : . :4 . 1 . AVer",,]e l\nnua.l 3 "l 8 II 12 /1 13 /4 /3 17 17· (l915_2000) T (1 o 9 t 1 a 3 l ) P A re l . l . " , C nt o . s W u O rth. 97 1/3 105 i34 147 110 154 1&& /i3J 222 ??7 .. . ll:!'l'l!:'C'l":IVzneS s - I!:nrlroltlOl4lntal .. (1) ;I. till;' -i;JU4lit:y ObjectiVl!ls ~1; .,,4 , : ~ - ~~ . 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(l) Public: 1'.ccept::on<;;a- "'4;., ... -r/.., "~/-I 15/1' .!I/-t ... 1/1 "'//., '1'/4 .. ,$/4 -J.~", ..., v.f ·~/4 ") ?!natlchl .." ... ibil.1't:"J "'4/" ... :r/.., ~~/4 -"'1/1 #'4 ",3/.,. -2'/4 • .1/;1 a~/1 -7'/<{ -~4 "51'S (3) 1nIl1:.11::1.I'l:l.o..;o1, C~U.>Cl'l:y -1/, -</~ -J/.J -t, ; .1/.3 -.10 -1/3 -5/ 3 -0 .5,-; ':'4~ "''S/=:. -26- .. ; (2) Biology - Flora, Fauna: It is recognized that there will be some disruption of existing flora and fauna, mostly on a short-term basis, as the result of any project construc tion. The potential damage through a marsh and natural areas related to Alternatives A and B outfall to Point San Pedro is condidered to be an added impact beyond that of Al-ternative C construction. It is assumed that this impact will be negative. It is considered the Implementation Sequence IV will re sult in somewhat less impact in this category by reason of no outfall pipeline construction. The alternative of No Project will have no impact on the flora and fauna. (3) Land Planning Compatibility: It is considered that all alternatives will. have some impact in respect to land plan ning, primarily related to treatment plant existence. It is ass~~ed that this impact will be negative. This impact will be slightly greater under program A and C since there will be four treatment plants, rather than three asunder Plan B. Implementation sequences are assumed to have a slightly greater impact on land planning capability because of the possible existence of a tertia~J trea~~ent plant. Under the No Project alternative, the impact will be sig nificantly negative because the fifteen existing treatment plants in the subregion will continue to exist. (4) Aquatic Life: It is considered that all alternatives will resul-t in improved conditions in respect to aquatic life. For the same reasons noted in respect to water quality objec tives impact, Alternative C is somewhat more advantageous than Alternative B or A. It is assumed that this impact will be positive. It is considered that Implementation Sequence IV will result in an additional improvement in respect to this categor~ by reason of no direct disposal. The NO,Project alternative will have a considerable con tinued negative impact on aquatic life because of -the continued existence of the mUltiple shallmy water discharges around the _ bay. (5) Air Quality: It is considered that all al'berna'tives will have some adverse impact upon air quality as the result of wastewater treatment plant operation. This impact will be slightly more for Alternatives A and C than Hill be -the case for B because of one less treatment plant. It is assumed that this impact will be negative. -27- , It is considered that Implementation Sequences II, III, and IV will result in added impact in this category because of the existence of "tertiary" treatment plant facilities and their operation. ] The No Project alte=ative will have a significant detri mental effect on air quality because of the continued existence of the fifteen treatment plants in the area, which are not now equipped with odor control features. (6) Construction Impact: It is considered that all alter natives ~nll have some impact during project construction. The ] needed construction of a large pipeline through the City of San Rafael related to Alternatives Band C and the need to construct the Point San Pedro outfall under Plans A and C is considered J to be an added impact. It is assumed that this impact will be negative. It is considered that Implementation Sequence IV will result in somewhat less impact in this category by reason of no outfall pipeline construction. There would be no construction impact if No Project is under taken. (7) Population Growth Potential: While it is considered that all alternatives will provide the means of serving addi tional popUlation, the staging of treatment plants in respect to capacity will serve to limit population growth potential to agreed-upon limits. Because of the necessity of construction of the raw sewage intertie line between North and Central Marin related to Alternative B with a commingling of capacity in a larger plant, it is considered that Alternative B has a slightly greater impact in this category. It is assumed that this impact will be negative. Under the alternative of No Project, the population growth potential would be severely restricted l;lecause of a lack of ade quate sewage treatment facilities. It is assumed that this impact will be positive. This environmental factor would be evaluated differently showing little or no impact of the project on population growth potential if positive growth controls are adopted on a planning. agency level. ." (8) Noise Impact: It is considered that all alte=atives will have some impact in respect to noise of facility operation. It is considered that Alternative Plan B will have a somewhat -28- less impact by reason of one less plant. It is as treab~ent sumed that this impact will be negative. Under alternative Implementation Sequences II, III, and IV there will be slightly more noise impact because of the possible existence of a tertiary treatment plant. The noise impact will be substantially greater under -the No Project alternative because of the continuation of the fifteen existing treatment plants, which are not now equipped with noise control features. (9) Aesthetics: It is considered that all alternatives will have some impact upon local aesthetics by reason of treatment and pumping plant existence. Alternative B impact in this cate gory will be somewhat less by reason of one less treatment plant. It is assumed that this impact will be negative. Under alternative Implementation Sequences II, III, and IV there will be further impact on the aesthetics because of the possible existence of a tertiary treab'llent plant. -The impact on aesthetics without any project will be sig nificantly greater because of the continued existence of fifteen treatment plants which are generally lacking in basic architec tural and aesthetic amenities. (10) Cultural: It is assumed that there will be some cultural disruption in this category by reason of construction through developed areas with added impact from Alternatives Band C construction due to thelarge pipeline through the City of San Rafael. Further, there may be some disruption to archaeological sites by the construction of the Point San Pedro outfall under Plans A and B. It is assumed that this impact will be negative. If No Project is implemented, ·there may be no disruption of cultural sites due to construction, but our overall cultural status will be lessened by the lack of good water quality con trol. b. Resource Utilization: (I) Land: All alternatives will utilize some additional ex-· isting lanctto accommodate new facilities. AH:ernative B will_ result in somewhat less impact by reason of one less treatment plant. I-t is assumed that this impact will be negative. It is considered that Implementation Sequence IV will result in somewhat less impact in this category by reason of no outfall pipeline existence. -29- " -i" Without any project, the impact on our land resource will be greater because of the continuation of fifteen existing treatment plants. (2) Water: It is considered that all alternatives under Impfementation Sequences II, III, and IV which involve reclama tion will result in a positive impact in this category by reason of providing means for beneficial reuse of reclaimed wastewater. Conversely, Sequence I ,.ill have a secondary negative impact in this category by reason of utilization of added source water in the future,constituting increased wastewater volume. Implementa tion Sequences III and IV will provide still added positive impact in this category by reason of early recl~~ation. The No Project alternative will result in a negative impact on the water resources because a large-scale reclamation and reuse program could not be implemented, and local reclamation projects could not utilize a significant portion of the.waste water of the area. (3) Energy: It is considered that all alternatives will utilize additional energy for facility operation with still added energy requirements associated with the reclamation facilities. Alternatives Band C will utilize slightly more energy because they involve greater pumping requirements in the full-sized intertie between Central and North Marin. It is assumed that this impact will be negative. The continuation of local treatment facilities if No Project were implemented will have a lesser impact on energy resources. (4) Secondary Resource Use: It is assumed that all· alter natives will utilize natural resources in some form as a func tion of treatment plant operation. Under Alternative B there will be a slightly greater need for secondary resources to con trol odors because raw sewage will be transported for a greater distance. There will be significant added use of resources in the form of various chemicals as part of reclamation plant operation. It is assumed that this impact will be negative. The early opera tion of a reclamation plant under Implementation Sequences III and IV wili use secondary resources for a longer time. The alternative of No Project will utilize a minimum of additional secondary resources. -30- ] c. Flexibility: ] (1) Reclamation: All alternative sequencing programs are considered to be flexible in respect to accommodating reclama tion facilities. Although Implementation Sequence I is ] slightly less flexible, it is considered that Implementation Sequences III and IV will maximize the impact in this category. 1- It is considered that Alternative B has somewhat less flexibility in this category by reason of removing reclaimed wastewater source from South and Central Marin areas for pos sible future local reuse. This impact is assumed to be positive. J The alternative of No Project is only flexible in respect to achieving local reclamation programs. This impact is assumed ] to be negative. (2) Trea~~ent: It is considered that all alternatives will ] provide flexibility in respect to changed conditions relating to treatment needs in the future. Alternative B may have some advantage in respect to this ca·tegory of impact by reason of -, one less treatment plant. This impact is assumed to be positive. j The alternative of No Project is not flexible in respect to changed conditions because of the multiplicity of trea 'G"llent plants. This impact is assumed to be negative. (3) Disposal: It is considered that all alternatives have some flexibility in respect to future changed conditions for disposal, with Al terna ti ves Band C, providing somewha·t more flexibility by reason of the single outfall., It is assumed that this impact will be positive. It is considered that Implementation Sequence IV will have added flexibility in this category of impact by reason of no prior disposal system. The alternative of No Project is considerably less flexible in respect to meeting changed disposal conditions because of the continued existence of the numerous shallow yJater discharges. (4) Changes in Land Use Planning: It is considered that all alterna-tives have flexibility in respect to possible changes in future land use planning by reason of the anticipated staging. -. However, it is considered that Alternative B has somewhat less flexibility in this category of impact by reason of the necessity to construct transport facilities for ,untreated sewage from all of South and central l1arin County sized to ultimate capacity as part of first stage construction. It is asslh'ned that ·this im pact will be positive. -31- .. · : .-- The alternative of No Project is very flexible in respect to possible changes of future land use planning because of the high degree of local control. This impact would be rated differently if positive planning and growth controls were to be adopted at a planning agency level. d. Reliability: (I) Treatment: Because of the large sizes of treatment plants related to all alternatives, it is considered that all 1 alternative treatment plant facilities may be operated with equal reliability. It is considered that the existence of one additional large treatment plant, as in the cases of Alternatives A and C, provides some slight added impact in this category. It is assumed that this impact will be positive. It is considered that Implementation Sequences III and IV will have some added reliability in this category by reason of the added treatment provided for reclamation as part of initial Phase I construction. If·No Project is implemented, the treatment reliability will continue to be very low. It is assumeq that this impact will be negative. (2) Transport: It is considered that all alternatives will have a high reliability factor in respect to transport facilities. The existence of an additional untreated wastewater transport line through San Rafael associated with Alternative B is con sidered to lessen the impact of this alternative. It is ass~~ed that this impact will be positive. With No Project, the reliability of transportation facili ties is of little importance because treatment will be accom plished locally. (3) Disposal: It is considered that all alternatives will have a high reliability factor in respect to disposal since effluent will be disposed of to the deep waters of the bay. It is considered that the two-point disposal system.of Alter native A has a slight advantage in this category. It is assumed that this impact will be positive. It is considered that Implementaton Sequence III provides somewhat more reliability by reason of early construction of reclamation facilities resulting in less volume for disposal. -32- ] The no disposal facility feature of Sequence IV Impl~~entation 1 mi,tigates against the otherJfise added reliability because of J the possible necessity of disposal in any case, but at a less des'irable point. ] Under the No Project alternative the reliability of dis posal is considered to be poor because water quality objectives will not be met; and if there is a breakdown in treatment facili ties, ,the waste will be discharged directly to shallow confined waters, where they have the greatest environmental impact. It is assumed that this impact will be negative. ] (4) Reclamation: All alternatives are considered to be reliabile in respect to achieving the reclamation objective since even under Implementation Sequence I the program is 1 flexible in respect to achieving local as well as large-scale reclamation. Alternatives Band C are considered to be some • what more advantageous in this category of impact by reason of j having provided the north/south intertie as part of initial Phase I construction. However, Alternative B does not provide for the availability of treated effluent for local reclamation in Central Marin. It is assumed that this impact will be posi tive. 1 It is considered obvious that Impl~~entation Sequences III and IV will maximize the impact in this ca'tegory by reason of reclamation facilities being constructed as part of initial Phase I construction. 1 If No Project is implemented, there will be very little flexibility in respect to achieving large-scale reclamation. It is assumed that this impact will be negative. (5) Disaster: It is considered that all alternatives ",ill have a high degree of resistance to disaster, such as earthquake, by reason of judicious design in this regard. The two-plant and two-outfall feature of Alternative A is considered to be somewhat more advantageous in this category of impact, whereas the existence of a single plant and raw sewage interceptor in Plan B is considered less reliable in the event of a disaster. It is assumed that this impact will be positive. The No Project alternative is considered to be somewhat resistant to disaster because of the dispersed nature of the treatment facilities. -33- e. Planning Objectives: (ll Local Agencies: Assuming that local agency planning objectives are to maximize effectiveness through strategic consolidation of wastewater treatment and disposal facilities, . then it is considered that all alternatives will assist in meet ing these objectives. Alternatives A and C may be somewhat more advantageous at this point by reason of greater local con trol of facilities and capacity allocation. It is 1 treaL~ent I - assumed that this impact will be positive. If No Project is implemented, there will be almost complete local control; however, many agencies may be subject to en forcement actions by the State, thus frustrating the local control ability. It is assumed that this impact will be nega tive. (2) State and Federal: It is assumed that the same factors applying to local agency planning objectives will apply, with the on Plan B rather than Plans A and C, because of ~~hasis the greater consolidation involved. It is assumed that this impact will be positive. The No Project have even a greater negative alternativ~would impact in respect to State and Federal planning objectives'. f. Im. plementation: {ll Public Acceptance: It is assumed that all alternatives will be acceptable to the public and can be made supportable. Alternatives A, C, and B may be somewhat more acceptable in that order by reason of ascending initial capital cost require ments. Implementation Sequence II is assumed to be more sup portable than the other sequences because of its flexibility and staging features. It is assumed that this impact will be positive. The alternative of undertaking No Project at all is assumed to be least acceptable because of the continued degradation of environmental quality. (2) Pinancial Feasibility: While it is considered that all alternatives are feasible of being financed by the public, it is considered that Alternatives At C, and B in that order will be more feasible by reason of ascending capital costs require ments. It is assumed that this impact will be positive. -34- -, -.-.. J It is considered that Implementation Sequences III and IV J may be relatively much more difficult in respect to gaining financing approval for implementation by reason of much higher initial capital cost requirements. It is assumed that this impact will be negative. J, The No Project alternative is considered to be completely feasible by reason of its zero cost. ::j----- (3) Institutional Complexity: It is assumed that all al ternatives wlil involve ctl:r:ficulties from the standpoint of institutional involvements. However, because of the separation of North and South Marin feature of Alternative A, it is con sidered that this alternative will result in somewhat less impact in this regard, with Alternative B having the most ] impact. It is assumed that this impact will be negative. It is considered that Implementation Sequences III and IV ''! J will result in added impact in this category by reason of the complexities of administering the reclamation program. There are few institutional complexities if No Project is J undertaken. g. Summary: 'C Applying the considerations noted above and assigning a 'numbering system as part of the eva~r technique has re 1 j sulted in the r su , mm ary shown in Tabl~. From Tab¥~a summary of general conclusions may be made as follows: (1) All alternative regional plans under all four imple mentation sequences result in positive overall effectiveness. (2) The "No Proj ect" al terna tiv e results in a nega tiv e , • effectiveness . 1 (3) ~mile there do not appear to be major differences in effectiveness bet'Neen the alternative programs, it does appear that Alternatives A and C are somewhat preferred over Alternative B. (4) Assuming different implementation sequences does not basically change the effectiveness ranking of the Alternative Programs. -35- QUESTIONS SIG~IFICANT During the course of presenting the three subregional study results to the . sponsoring agencies, and as the result of reviews by Regional Water Quality Control Board and State Water Resources Control Board Staff, questions have 1 been raised in connection with the prior evaluation of regional Alternative Programs A, Band C wi thin the categories of, Costs, Effectiveness, Reclama 1 tion and Other. A summary of these questions and discussion related thereto are presented as fOllows: " a. Costs: Questions which have been ra1s1ng concerning cost factors relating to comparisons between the Alternative Regional Programs basically ask, "Are there any modifications which reasonably could be considered ] which would alter the previous economic comparisons of Alternative Programs?" Included in the additional evaluation, specific responses , relate to the following: J (1) IF "EXCESSIVE" STORM WATER INFILTRATION WERE EXCLUDED FROM THE SUBREGIONAL SEWERAGE SYSTEMS IN THE SOUTH AND CENTRAL MARIN SUB REGIONAL AREAS, WOULD THE RESULTANT NEED FOR A SMALLER SIZE INTER ] CONNECTING PIPELINE TO EFFECT THE IMMEDIATE NORTH/SOUTH CONSOLIDA TION OF PROGRAM B BE SUFFICIENTLY LESS COSTLY THAT THE ECONOMIC BALANCE WOULD SHIFT IN FAVOR OF PROGRAM B? Discussion , It is quite true that there is a considerable amount of storm water infiltra J tion associated with the South and Central Marin Sewerage systems. Detailed analysis has been made which indicates that if these peak flows could be '1 reduced through an intensive program of sewer system re-building and repairs J so that peak flows do not exceed a 3:1 ratio to average dry-weather flows, a savings reSUlting from smaller pipeline size.related to Program B would amount to some 5 million dollars. If such a reduction were feaSible, a cost savings would accrue to Alternate Programs A and C also, but the impact upon·the overall economic analysis of Alternatives lqould still be a "narrowing of the gap" be tlqeen Alternatives A and B by possibly 3 million dollars on a Present Worth basis. A difficulty associated with this economic sensitivity factor, however ~ ~s th~t in order to effect a savings in wastewater transport and treatment fac1l1ty SHe by peak storm lqater flow reducti~n,. preliminary. estimates suggest that. expendi tures in possibly excess of 20 mlll10n doll~r: 1n se~er~ge sy:tem.repa1rs and. reconstruction would be required (to be verlf1ed by lnflltratlon/lnflow analysls). On this basis then it does not appear that a cost-effectiveness relationship exists which '~ould ~ctually result in a Program cost reduction through reduction in "excessive" storm lqater infiltration. In ~y case,. apparently this factor will not in a significant way al~er the baslC comparlson of Alternative Program costs comparisons. -36- (2) IF THERE ARE CONTINUING SAVINGS IN OPERATING AND MAINTENANCE COSTS OF THE SINGLE TREATMENT PLANT OPERATION OF ALTERt'lATIVE PROGRAl\1 B, WHICH ON A PRESENT WORTH BASIS NEARLY OFFSET THE CAPITAL COST ADVAt'lTAGE OF ALTERNATIVE PROGRAM A, THEN WHY IS THERE SUCH A SIGNIFI CANT PRESENT WORTH COST ADVAt'lTAGE STILL RELATED TO PROGRAM A? Discussion There are still additional costs associated with Program B which are offsetting to the -operation and maintenance cost savings of single plant operation includ ing, (1) construction and operating costs of a separate raw sewage pumping station to pump South and Central Marin sewage to the North Marin treatment plant site, and (2) cost for chlorine, air, or peroxide addition to the raw, untreated sewage from South and Central Marin in order to prevent excessive r----"-"---- In addition, and of most importance, a cost factor which appears in the Present Worth analysis as being favorable to Alternative Program A is the time delay in construction of the much smaller dry-weather transport line bet~leen the North and South. The time factor shows as interest saved on the delayed investment in Present Worth, as does the lower cost of the smaller line of Program A. (3) IF THE PROPOSED NORTH MARIN SUBREGIONAL TREATMENT PLANT WERE TO BE LOCATED SOUTH OF THE HAtvlILTON FIELD AFB SITE, THIS WOULD REDUCE THE LENGTH OF THE LARGE At'lD EXPENSIVE NORTH/SOUTH INTERCONNECTING LINE r AS WELL AS THE OUTFALL. WOULD THIS MODIFICATION NOT CHAt'lGE THE ECONOMICS IN FAVOR OF ALTERNATIVE B? Discussion There are basically ree general sites which wer~ considered for the North Marin subregional reatment plant, 1) Hamilton Field APB, 2) existing Las Gallinas Valley S __ D. plant, and 3) McNears Point. The McNears Point site has been abandoned~)serious consideration for reasons both of difficulty to reach l'lith a N~South transport system and also its sensitive location in relationship with planned park areas. By utilizing the Las Gallinas Va11ey S. D. tre~tment plant site i~ the economic analysis of Alternatives, there would be a sav~ngs under Alternat~ve Program B resulting from shortening by about 15,000 feet of the assumed 72-~nch ~orth/ South interconnecting line under Alternative Program B, and correspond~ng le~gth of 102-inch outfall from the subregional treatment plant. However, th~s sav~ngs would be partially offset by the need to increase by a corresponding length. the -54-inch raw sewage transport line from the Novato area to the south plant s1te and the 48-inch effluent transport line from Petaluma and Sonoma. The re:ul~ant overall net savings under Alternative Program B appears to be ab out 1. 8 m1lhon dollars, not enough to basically alter the comparison of Alternative Program costs comparisons. It is noted that Alternative Program C economics would not be affected by either of the plant site location changes. -37- Summary of Cost Factors During the review of reasonably possible modifications to the Alternative Pro grams could basically alter the prior economic comparisons, it does not \~hich appear that such factors do exist. On an overall economic comparison basis, it continues to be shown that Alternative Program A is the most economical, while Alternative Program C and B follow in that order. However, it is recognized that the economic differences between the Alternative Programs, particularly on an overall Present Worth basis, are not compelling and the cost differential favoring Programs A and Cover B could be narrowed somewhat by reason of plant site shift to the South. The signigicant initial capital cost differences favoring Alternatives A and C remain in any case. The possibilities continue to exist that factors other than economics and, in particular, effectiveness factors related to the environment and reclamation, could be developed and shown to be of sufficient Significance to favor imple mentation of either Alternative Programs B or C over the apparently more economical Program A. b. Effectiveness: Questions which have been asked concerning effectiveness factors relating to comparisons between the Alternative Regional Programs have been included within at least the following basic categories: (1) OVERALL ENVIRONMENTAL EFFECTIVENESS, IN PARTICULAR ALTERNATIVE PROGRAMS IMPACT IN RESPECI' TO WATER QUALITY, FLORA AND FAUNA, I LA.!'1/D PLANNING COMPATIBILITY, AQUATIC LIFE, AND AIR QUALITY? Discussion A thorough and detailed environmental impact study and report has been com pleted in draft form at the time of this writing and is summarized hereinafter. The summary speaks in more detail to the foregoing areas of overall environ mental concerns. Basically, however, it does appear that the relative overall environmental impact of the Alternative Programs within the categories noted will not be significant from a numerical standpoint. As a matter of preference, the single point, San Quentin offshore disposal loca tion is favored by State Departments of Fish and Game and Public Health over the San Pedro Point site because of its closer proximity to the Golden Gate. Also there has been some concern established in the EIR in respect to potential dama~e to the marsh land areas over which a possible major outfall line under Alternative Program B would travel to reach Point San Pedro. Other than the foregoing, and recognizing the subtleties which may exist in respect to other as yet to be discussed factors, studies to date do not indi cate significant variations between the three basic Alternative Programs in respect to overall environmental impact, including meeting of water quality objectives, land planning compatibility, construction impact, noise impact, aesthetics and cultural. -38- (2) OVERALL EFFECTIVENESS OF ALTERNATIVE PROGRAMS IN RESPECT TO RESOURCE UTILIZATION, INCLUDING LAND, WATER, ENERGY AND SECONDARY RESOURCES USE? Discussion· All Alternative Programs utilize substantially the same amount of land required for transport facilities. The single treatment plant alternative of Program B utilizes less land than would the two Alternative A and C Programs. ¥*~ __ .. _ It is not considered that any of the Alternative Programs would differ in mean ingful ways in respect to receiving water utilization. Similarly, there do not appear to be meaningful differences between t."te Alternative Programs related to energy or secondary resources use, such as chlorine or other chemicals used during treatment. However, in respect to this category of interest, it should be noted that if and when "tertiary" treatment is considered, such as will be the case under Programs AI, Bl, Cl and B2 and C2 as discussed hereinafter, secondary resource use, in cluding energy, could be substantial. As an example, it has been estimated that for tertiary treatment to remove 1000 lbs. of residual pollutants, it requires use of some 10,000 lbs. of natural resources, such as lime, carbon, methanol, chlorine, etc., and the production of these treatment elements will indirectly result in the emission of 4,000 lbs. of pollutants. (3) EVALUATION OF FLEXIBILITY OF ALTERNATIVE PROGRAMS TO CHANGED ~ffiET CONDITIONS .IN THE FUTURE, PARTICULARLY IN RESPECT TO RECLA~TION, TREAThffiNT A'ID DISPOSAL? Discussion If it is accepted that there would be no future hindrances to the construction of the North/South interconnecting line, then it would appear that Alternative Programs A and C have some advantage over Program B in respect to possible changes in local reclaimed wastewater reuse market. That is, while the engineer ing studies, based upon present known factors minimized a future South/Central Marin reclaimed wastewater reuse market, if such a market were to be developed in the future, Alternative Program B would provide the least amount of flexi bility in respect to making possible the meeting of this local market by reason of having exported out of the South/Central Marin area raw, untreated sewage. Conversely, the availability of highly treated wastewater in the South/Central Marin areas, as would be the case under Alternative Programs A and C, maximum flexibility to meet a potential future local reclamation for South/Central Marin reuse market appears to be preserved. The expressed concern that if the North/South interconnecting line is not con . structed as part of Phase I Program's implementation, then "the line will never be built," could alter the argument in favor of Alternative Program C, or possibly Program B. -39- ] In respect to treatment, there may not be any substantial difference related to flexibility of Alternative Programs. There is some opinion which suggests that in respect to possibilities of tertiary treatment required to meet future dis charge, or reuse standards, a single treatment plant as under Alternative Pro gram B offers more flexibility than would a tl;O plant Program such as under Alternatives A and C. This economic factor may not be particularly significant in the scale of plants under consideration and also noting that costs for tertiary treatment are less subject to economies of scale than for primary or secondary treatment. In any case, the economic comparison and its significance can be seen in the costs analysis of Alternative Programs AI, Bl and Cl. In respect to flexibility factors associated with disposal alternatives, it could be argued that the two point disposal system of Alternative Program A has added flexibility to meet changed future conditions over the single point disposal system of Alternatives B and C. It could also be argued that the single ] point south disposal system at Point San Quentin related to Alternative Program C offers better flexibility in respect to more stringent future disposal require ments by reason of its somewhat more remote location from the more environ mentally sensitive areas of San Pablo Bay. In respect to a possible future requirement of zero discharge, even during peak wet-weather, Alternative Program A appears to offer the least flexibility, while Alternatives Band C could be considered as being equal. In respect to flexibility related to future changes in land-use planning, the ] least capital cost system, Alternative Program A, probably is advantageous, particularly if land use planning results in lower than anticipated future contributing populations. ] (4) EVALUATION OF THE RELIABILITY OF ALTERNATIVE PROGRAMS TO MEET OBJECTIVES IN RESPECT TO TREATMENT, TRANSPORT, RECLAMATION AND DISASTER? ] Discussion There continues to be some disagreement within regulating agencies as to the ] relative reliability of alternative programs inVOlving one, two, or more treatment plants. While there is no question that "small" treatment plants usually do' not prOVide the same reliability as do "large" treatment plants, ] the distinction between "small" and "large" is relative. There is more prom- inent thinking today, that overall reliabil- i ty in respect to protection of receiving l;aters from water pollution can be ] achieved by spreading the residual pollution load through multiple "reasonably" sized treatment plants as the alternative to very large sized regional treat ment works. ] It would appear that while there is no reason to assume that a "small" treatment plant could not be operated in a reliable manner through expenditure of suffi cient funds, nevertheless a higher level of reliability could be assumed for a' ] plant of sufficient size as to normally, (1) have continuous, 24-hour super vision, (2) have mUltiple process units, (3) have full laboratory control, (4) have standby power, and (5) have highly qualified operating personnel. Assuming ] that as part of the accepted Program there will be concerted effort to achieve the foregOing elements of plant reliability for the four plants of Alternatives A and C, or the three plants of Alternative B, then there may not be reason to expect a significant degree of reliability difference between the three Alter ] native Programs in respect to treatment plant operation. -40- ] In respect to reliability of transport systems, it is probably true that all three Alternative Programs are essentially the same. However, it might be argued in favor of Alternatives A and C that transport of treated effluent can be accomplished more reliabily than transport of raw sewage, as would be the case for Alternative B south of the single, north Marin treatment plant. j In respect to reliability to meet the demands for reclamation, the arguments are probably substantially the same as for treatment plant reliability., , The disaster reliability factor possibly favors the two point independent dis posal, two treatment Alternative A and, to a lesser extent, the two treatment plant, single point disposal system of Alternative C. ~,I --­ c. Reclamation: Questions which have been asked concerning wastewater reclamation for beneficial reuse potential associated with each of the Alterna ti ve Programs are probably the most complex of all evaluation factors. Accepting the importance, and in fact the essential nature, of wastewater reclamation as being the ultimate goal of any water quality management program, they key question remains as to which Al ternativ e Progralll lVill faciE tate to best advantage the reaching of this goal? To evaluate the questions and answers in this area of special concern, questions are raised in at least the following categories: (1) REALISTICALLY, WHAT IS THE RECLAI~lED WASTEWATER REUSE MARKET AT THE PRESENT TIME AND IN THE FUTURE, AND WHAT IS ITS SIGNIFICANCE TO THE DECISION ON ALTERNATIVES? Discussion From an overall water resources standpoint, Marin and South Sonoma COWlties have a clear need to develop additional sources of water supply, of Iqhich reclaimed wastelVater may be most logical. The extent of this need may be somewhat temper ed by more recent emphasis upon grolVth limitations within both Counties. How ever, from the combined standpoints of water supply needs 2~d conservation of natural resources, it is agreed that 'every effort should be made to encourage and develop a progra.'1l which will enhance the prospects for wastewater reclama tion for beneficial reuse, the ultimate objective of all of the Alternative Programs under consideration. Defining the potential market for reclaimed wastewater at the present time is somewhat complicated by the facts that, 1) State Health Department restrictions' prohibit the use of reclaimed wastewater as a potable lVater supply resource (this condition may change in the future), and 2) the cost for pro viding red'aimed lVastewater, including the costs for separate distribution systems to meet irrigation water supply needs, is currently high. -41- The subregional studies identified a limited reclaimed wastewater reuse market for landscape irrigation in the Central Marin area and a much larger reuse market for agricultural irrigation in the South Sonoma County area. Tne Central Marin landscape irrigation potential reuse market is estimated to be between 700 and 1,000 acre feet per year, against a predicted available 15,000 acre feet, per year from South/Central Marin. The agriculture irrigation potential in South Sonoma County has been estimated to be about 41,000 acre feet per year against an estimated future available 40,000 acre feet per year from North Marini South Sonoma. A potential large scale wastewater reuse market has also been identified in the Napa/Solano County area but its extent and timing is quite uncertain at the present time. It is important to note, however, that the reuse market, especially in the South Sonoma area, l;ould be significantly dependent upon some form of subsidy to realize. The agricultural irrigation water market is dependent upon a cost of irrigation water of betl;een $3.50 and $20.00 per acre foot, depending upon the crop to be irrigated. A subsidy of from between $13.00 and $58.00 per acre foot could be necessary to meet these support levels, and at this time it is quite problematical as to where this subsidy would be directed. It also appears that the projected volume of wastewater from the North Marin/ South Sonoma subregional area is nearly adequate to meet the presently identi fied potential large-scale irrigation water reuse market, independently of the South/Central Marin subregion supply. This was one of the basic factors which suggested postponing construction of the intertie line and costs related there to between the subregions as shown for Alternative Program A. Under' Al terna tive A, the interconnecting line would be constructed in the future only ,at such time as the reuse market actually is developed to the point where the South /Central Marin wastewater could be reused at a north location. Inasmuch as all three Alternative Programs ultimately provide the means whereby the same potential reclaimed wastewater reuse market can be met, there appears to be no substantive difference between the Alternatives in this regard. The possible exception to this assumption would be in the case of Alternative A, where it has been argued th'at if the intertie line between South/Central Marin and North Marin/South Sonoma is not constructed as part of Phase 1 of the Pro gram, the chances of its being built at a future date simply to serve the cause of reclamation may be remote. In slli~ary, it does appear quite certain that a potential large-scale reclaimed wastewater reuse market does exist in the south Sonoma area. There is a limited market in the Central Marin subregional area and very little potential market within the South Marin subregion. The time at which the South Sonoma reuse market can be developed appears to be uncertain by reason of the unfavorable economics of this market which currently exists. In any case, all three Alternative Programs do provide the means whereby the large-scale reclaimed wastewater reuse market could be accomplished and Alternative Programs A and C enhance the possibilities of meeting the limited Central Marin market as well. -42- (2) WHAT ABOUT THE RECREATION LAKE? Discussion The subregional engineering studies identified a recreation lake in the South Sonoma County area as being a very real possibility for reclaimed 1vastewater beneficial reuse. Two potential lake sites were shown and studied, particularly as part of the North Marin/South Sonoma subregional study, Tolay Lake and Chileno Lake. The recreation lake need has been attested to by County recrea tion departments ~,d the efficacy of reclaimed wastewater for recreation lake water sources has been demonstrated at Santee and Indian Creek (near Lake Ta.hoe). The concept of the recreation lake feature of the proposed water. quality m~age­ ment programs is that lVith the construction and use of a recreatlon lake WJ. th use of reclaimed wastewater, the lake also becomes a storage reservoir from which increasinu demands may be made for a variety of water supply purposes, beginning lVith ~griculture irrigation water and, ultimately, direct supple~ental potable \vater supply. All three Al ternati ve Programs assume this progressJ.on. The limitations relative to recreation lake construction at the present time are primarily related to excessive costs and resource requirements for tertiary treat ment. To ascribe the recreation lake costs to Phase I construction of the lVater quality management program would probably double the initial construction costs, with no encouragement to believe that State and Federal grant monies would be available for the lake and prerequisite tertiary treatment construction and operation costs, inasmuch as studies to date do not indicate a.favorable cost/ effectiveness relationship. This factor may change in time, however, which has been the primary factor in assuming that the recreation lake feature of any of the Alternative Programs ),fOuld be SUbsequent in time to the 1st Phase construction. fu,other possibly misunderstood factor relating to the recreation lake feature is that the lake would not in itself provide the means of accomplishign a zero dis charge of wastewater. The only loss of water from the la.'<:e would be through evaporation and percolation, this loss being considered minor in relation to the total volume of wastewater expected from the three subregional areas. In the absence of developing a total wastewater reuse market there would, of necessity, have to be a discharge from the recreation lake, particularly in any case during winter months during the foreseeable future. As a possible recreation lake relates to the alternative Programs, it is seen that filling and replenishment of the lake itself could be accomplished easily through utilization of South Sonoma and North Marin wastelvater only and into the future, until such time as a reuse market could be developed exceeding the supply, which, according to the earlier studies, may not occur for some time, if ever, into the future. Under these circumstances, it 1<Quld appear that each of the three Alternative Programs are essentially equal in ability to meet the needs for a recreation lake. -43- • (3) WHAT ABOUT ZERO DISCHARGE? Discussion There is· language in the most recent Federal law which points towards ~~ ultimate national goal of zero discharge of pollutants to the environment. Whether this will be interpreted to mean zero discharge of highly treated wastewater is prob lematical at the present time. In any case, it does suggest that any Program should have the capability of being expanded in such a way as to accomplish a zero discharge objective in the future, and in this regard, all three Alternative Programs rna.)' be so modified, with Program A required the most changes. The assumption here is that land disposal of the total combined subregional wastel~ater could be accomplished to best advantage in the Sonoma County area and as an integral part of the expected future large-scale reuse program for agri culture irrigation. Summary of Reclamation Factors There is a limited reclaimed wastewater reuse market in the South and Central Marin areas at the present time. There is an uncertain future reclaimed waste water market in the same area, relating primarily to current prohibitions against direct or indirect reuse as a supplemental, fresh, potable water supply source. Alternative Programs A and C would enhance the possibilities of satisfying What ever reclaimed wastewater reuse potential as does and will exist in the South and Central Marin areas. Al ternati ve Program B would essentially eliminate the use of reclaimed wastewater in the South and Central Marin areas. There is a much larger potential reclaimed wastewater reuse market in the South Sonoma County area, particularly for agricultural irrigation and recreation lake \~ater replenishment, Hi th ultimate probabilities of meeting a supplemental, fresh pot~ble water supply need. To realize both the present and potential future re cla~med wastewater market, however, would require a very significant financial subSidy to account for the approximate doubling of the initial costs for the wastewater management program Phase 1. All three Alternative Programs envision a progression or facility additions which would see three phases of improvements; Phase 1 wi th high levelS of treatment prior to Bay disposal, Phase 2 with added tertiary treatment combined Hith recre ation lake and/or agricultural irrigation, and Phase 3 with still added treatment and direct, potable water supply reuse possibly resulting in zero discharge. All three Alternative Programs accommodate the foregoing, although it can be argued that Alternative Programs Band C facilitate the meeting of these object ives to better advantage than does Program A. If it could be predicted that ~'l early reclaimed wastewater reuse market \vill be realized in the South Sonoma area, a market which exceeds in volume the avail able amounts from the North Marin/South Sonoma areas independently, then the early construction of the interconnecting North/South line inherent with Al ter natives Band C would seem to favor these Alternatives over Program A. Alternative Programs A and C appear to offer the greatest amount of flexibility in respect to changed future conditions relating to reclaimed wastewater reuse wi thin the combined, regional area. -44- d. Other: Questions have been asked concerning a number of other factors thought. to b~ impo~ant co~siderations related to the Alternative Program's evaluatlon, mcludlng pubIlc acceptance, financial feasibility, institutional complexity and meeting of State and Federal planning objectives. (1) PUBLIC ACCEPTANCE OF ALTERNATIVE PROGRAMS? Discussion This is obviously not an easy question to answer. The opinion has been expressed that "the public will not accept any alternative program which does not provide for reclamation in the first phase of implementation." This statement of opinion should, of course, be given careful consideration, and its acceptance as fact would appear to dictate a modification of all Alternative Programs to include Program Phase 2, providing for the interconnecting North/South line to be con structed initially, as \;ell as tertiary treatment and the recreation la.<.e. In other respects related to public acceptance, however, at the present there do not appear to be compelling factors of known consequence which would seem to bear upon the matter, other than possibly costs, which presumably would favor Alternative Program A, then C and B in that order. In respect to financial feasibility, all three Alternative Programs are depend ent upon full State and Federal grants for implementation. The significantly higher first cost of Al ternati ve Program B could be a detraction. frDm a Zinancial feasibility standpoint, but probably not crucially so. In respect to institutional complexity, unquestionably Alternative Programs B and C offer more complications at the present time. However, these complications may not be of such significance as to thwart implementation of either Alterna tives B or C if other factors make either of these Programs most advisable. In respect to the meeting of State and Federal planning objectives, it is prob ably true that Alternative Program B would be somewhat favored by some in the State approving agency because of the three plant versus four plant feature, while Alternative A and C might be considered at least equal in this Progrlli~s regard on a Federal level. -45- RE-EVALUATION .OF ECONOMICS The economic evaluation of Alternative Progra~s derived from the earlier studies is as summarized in Table 9. Subsequent to the completion of the subregional stu.dies and the prior economic evaluations, which included the evaluation of the economics of each Alternative Program, the Federal Environmental Protection Agency promulgated new Regulations describing specific guidelines for an acceptable cost/effectiveness analysis. I ,----- As part of the guidelines, it is noted that the planning period for the cost/ effectiveness analysis, "shall be 20 years," a.'ld interest rate, "of 7 percent per year will be used." Also, a prescribed service life for purposes of affixing a cost for replacement must be included in the analysis. To ascertain the significance of the foregoing prescribed elements of a required cost/effectiveness analysis as applied to the Alternative Programs under present additional evaluation, the prior economic analysis summarized in Table 9 was modified to include the foregoing prescribed elements. This re-evaluation re sults in the cost analysis shown in Table 11. Table 11 - Revised Summary of Overall Costs of Alternative Regional Programs Initial Total . Average Alternative Constr. Cost Present Worth Annual Cos ts Program (Million $'s) (Mi llion $' s)* (Million $'5)* A 73.1 102.9 9.7 B 90.5 123.8 11.7 C 80.6 112.7 10.6 *At 7% interest rate, 20-year Program life and depreciation. To provide a comparison of the estimated additional costs related to Alternative Programs B and C beyond those of Alternative A, the sUIT~ary set forth in Table 12 has been prepared. The costs estab lished in Table 12 are based upon the revised estimates shown in Table 11. -46- Table 12 - Summary of Increased costs of Alternative Programs B and C Over Costs of the Apparent Best Alternative A Additional Cost Item Alternative Program B C Additional Initial Cost, Million $'s 17.4 7.5 Percent Increased Initial Costs 23.8 10.3 i Addi tional Present Worth, Million $'s 20.9 9.8 Percent Increased Present Worth 20.0 9.5 Additional Total Average Annual Costs ,Million $'s 2.0 0.9 Percent Increased Total Average Annual Costs 20.0 10.0 While the estimates of cost shown in Table Nos. 11 and 12' provide a basis upon which the significant differences between the Alternative Programs may be seen, it is considered of some interest to relate the differences in cost to the lowest level of service unit. Accordingly, estimates have been made as to the possible typical costs related to each Alternative Program which would accrue to a single family dwelling unit equivalent, assuming that such a figure can be derived simply by applying the projected total regional population for 1980 divided by 3, against the average annual total Program costs and applied uniformlY over the entire regional service area. The cost estimates deriv'ed in this way may provide an indication of what actual costs, "to the nation" would be, but the real costs to local users would in fact include the reduced costs resulting from State and Federal grants. Bas ed on the foregoing factors, the figures shown in Tab Ie 13 have been prepared. Table 13 - Estimated Average Annual Costs of Alternative for Equivalent Single F&lli1y Pro~rams Dwelling Unit (1) Al ternati ve Program Basis of Comparis on A B C Wi thout Grants, $' s/Year 85 102 93 (2) With Grants, S's/year 44 52 48 ',.i (1) Based on 1980 median population projections and 3 persons per dwelling unit applied to estimated average annual costs as determined through revised estimates of Table 10. (2) Assuming 75% State and Federal grants applied to capital costs. -47- ·, "I ,J J ----- ENVIRONHENTAL "I IMPACT 1 j ~ j J • ENVIRONHENTAL I H PAC T As observed, the evaluations of Alternative Programs discussed hereinbe fore did include consideration of numerous noneconomic factors as well as the economic comparison of Alternatives. Subsequent to the time that the three separate subregional engineering . studies were completed, including the evaluations of Regional Alternative Programs summarized herein, the governing Board of all participating agen cies authorized the preparation of environmental impact reports pursuant to meeting specific requirements of the National Environmental Policy Act of 1969 and the California Environmental Quality Act of 1970. The overvie,,, EIR has been undertaken jointly by participating and coor dinating agencies 'nthin all three subregions of North Harin/South Sonoma, Central tffirin, and South Harin. The overview EIR was undertaken by the engineering consortium of J. Warren Nute, Inc., Jenks & Adamson, and Yoder-Orlob-Trotter & Associates, in consultation with Dr. Joel G. Gus': tafson, Dr. James P. Hackey, Dr. P. H. HCGauhey, Hr. Joseph D. Coons, and others. The EIR deals specifically with all identified environmental impacts of the best apparent Alternative Program, Alternative A, as well as with the corresponding and different impacts associated ,nth the remaining candidate Alternatives, Band C. A fundamental purpose of the separate environmental impact studies has been to provide a still further basis upon which a final decision can be made as to which Alternative Program should be implemented. The following provides a verbatim summary of the environmental impact of the regional consolidation project along 'nth (1) a summary of the environ mental impacts of the best apparent Alternative Program, Alternative A, and (2) a comparison of the different. environmental impacts associated with Alternatives Band C. Project Description The proposed project involves the regional consolidation of t-Tastewater treatment and disposal facilities in Eastern Harin County and Southern Sonoma County for the purposes of enhancing the aquatic environment by meeting long-range water quality objectives as well as by facilitating the implementation of both local and large-scale wastewater reclamation in the region. A schematic layout of the Alternatives is shown in Figure VI-3. -48- 7 hMJAI3.'L!?!?.TBI!;I...l!,Q..L <l~\.!:~~~ o ~ ~ - ~M'IO\-!~l_I!tl:ALL.CMj.~.Q ... /;1A f\FAg~ AS /;;I;!/- MILU/~I...l~,,!LL ~,= =~:"\"'L'J>l NoyATO '0 --- I EI NO.2 Sp. N9· TI PEl.§QtL ' ~ , j .l o ,0 ~l <. / ~' /1 / '<1 . j' PET ; ALUM - A - SONO - MA ~~R,'~"",,,,, ""~O:! Q Q 0 0 0I ? ? ? ? __ .: __ MA~~ tdNrI \ .1- S ~ : S 0T UU ~ BTA Q E RG U IO = NAA = L. _PeL._A ___ _ __ _ I n II ] n t S NO U R ' T '' H '' ON PCANT< !(-S-l">," ,,,' ""• •' 1 2 0 T'RnAR Y "'ATM'NT PLA ", V~AN SAN PEOR i... R"!R~''AI!T'o'"OiN'J ~e: "",. 'po,"., (.1h..w,. "",, , 'RR,MT'ON 0 ROUS' c:· l ? )' ? T--{ l ? ? o--y-o ~ I ' -I " '- ~ [~ I o a Y<O utfall ollminohd under ~' (T. . rllary trealmerl' plan!, Pion a~J J R .. ~r .. "llan loX. and oquolozinq -..... loll, pro~;d,d initially ~nd .. r ( -y._"./ . Pion a-,) , 1::::_, :.C'::.:'.::. ·.:P:. : :::.:;:.V:: ~::;;'Al:~t:·:;=~7':;N~'::;;.::" "" :_ _ "." ;.,,,,., ·-"~'B":2:::,';":;2':;~',::1 ? ?? 0-'7-0 ???? ..... ~J J~ [~ ? II I ~ I ~ I [ ~ 27 (T ~rtlo'y YI Outfall olimlllQI,,1l under """tmQnl plant, PI,," C-I ) A&~reolion loh ond .q~olj"ng ( .,. ...J. P lo l ~ c . n p C ro o v i i l d ed Initial . ly ~nd.r "-\:>• i'"'" p: .. :r:::;·.:. ... ;...: ::u,:;,.;;:. .. ·.:N .. }·CJ·~· ' '' _ '' ,_ ' ' , J ~ o o AflANDONED PLANT SCHEMATIC LAYOUT OF 5U8REGIOrlAL Pl.ANT (Secondory plug Flltrotlon) ALTEnNATIVE AnEA-WIDE. REGIONAL [J c:) TERTIARY PLANT (Futur. . \mdu Pion A,S o. C.lnllially undur Plan a-lor C-I j WASTEWATER TREATMENT. DISPOSAL ~fo<;~r~~~\for~ ;n~t;';e;~~~~!l~ Futur. under Pion A,a or C ·Inltlolly AND RECLAMATION PLANS under PI"n a-I ar C_I I FIGURE :m-3 • Environmental 'Setting Tne project service area lies in the northwesterly portion of the San Francisco Bay Area and is tributary to both San Pablo Bay and Central San Francisco Bay. The overall project service area covers a total of 462 'square miles and has a present population of 257,000. Environmental Impact of Alternative A The overview Environmental Impact Report has been written around Alterna tive A as the best apparent program against which Alternatives Band C have been compared. ' The Alternative A program has been divided into 17 basic project elements as itemized in Table 1=1-- Using a 1 to 5 rating system, with the magni' tude of the impact indicated by the upper left number and the importance of the impact indicated by the lower right number, an environmental evalu ation of the construction impacts and long-term impacts for each project element are given in Tebles ,II-I--l and 1-II--2, respectively. Tne various environmental impacts of the Alternative A program are sum marized briefly below: Construction Impacts: The construction of the project will cause signi ficant short-term impacts on the environment consisting of (a) disturbance to land forms, (b) disturbance to flora and fauna along interceptor pipe line routes, (c) disturbance to the aquatic environment where pipelines are constructed in the ,mter, and (d) disturbance to human activities, such as traffic and commerce.., where facilities are constructed in de.veloped areas .. Most of the construction impacts of the project can be mitigated to some extent; however, most disturbances will be unavoidable, and a certain amount of time will be necessary for recovery and reestablishment of the original flora and fauna. Long-Term Impacts: The primary long-term environmental impact of the project, which is in essence the reason for lli"ldertaking the project, will be the improvement of the aquatic environment by relocating existing waste discharges from the nearshore and confined waters of the bay and estuary system to the deep waters of the bay, as well as the upgrading and con solidation of existing wastewater treatment facilities. Nost of the existing treatment facilities in the Eastern Marin and Southern Sonoma area presently discharge treated effluent to the nearshore "raters of the bay, which are known nursery areas for fish and other aquatic organisms. The upgrading and relocation of the wastewater discharges to the deep waters of the bay will provide greater dilution and dispersion and thereby greater protection of the environment. -50- • -~'\BtE 1-1 Eastern Marin-South Sonoma Haste'>later t!anagement Program S~nary of Phase One Facilities • ACTION -'project Enlarge Element New or Aban R3~ .II No. Basic Facility Map Desi9_ Description Const.. Hadify con Sewage Effluen :~ri - ---~------------------------------------------------------------------------------------------------------ i!0RTR MARIN-smrrH SONOMA Su"'9RECro~ ~taqe I - j , -__1 ., Sonoma ~nterceptor 1'5-51 Treatment Plant Pumping Station X x S-1 Force Main x X 2. Pataluma Interceptor PS-P2 Pumping Station X X P-2 Force Main X X ~ 3. Petaluma-Sonoma Interceptor P-3, 4, 5 Force Main X X 4. pt. San Pedro Regional PS-Rl pumping Station X X Outfall Conveyance N-3~ 4 Force Main ·X X 0-1 Submarine Outfall X X .Staqe II ! j 5. North Harin Regional Treatment TP-NH Regional Treatment Plant x X 6. Bahia Interceptor PS-Bl pwnping ·Station X X -B-1 Force Hain X X TP-B Bahia Trea~~ent Plant x 7. Novato Interceptor PS-Nl Novato Pum~ing Station x Tp-Nl Novato Trea~~ent Plant x PS-N2 Ignacio pumping Station x X TP-N2 Ignacio Trea~~ent plant x PS-H pumping Station X x 8. Hamilton Air Force Base a-1 Force Hain x X Interceptor Tp-4 Base Treatment Plant x 9. Las Gallinas Interceptor PS-L Las Gallinas pumping Station x X L-l, 2 Force Main X X TP-L Las Gallin~5 Treatrnsnt Plant x 10. Marin Bay Interceptor PS-M. Marin Bay P~~ping Stati~n X X -M-~ Force Main X X Tp-M Marin Bay Treatment Plant x ) CENTRA!. !>1ARIN SU3REGION ~ Stag~ I • ll. Central Marin Regional Treatment TP-CM Regional Treatment Plant x X 12 San Rafael Interceptor PS-SR P~~ping Stations x X 5R-l Force Main X X TP-SR San Rafael Treatment Plant x 13 San Quentin Interceptor' PS-SQ Pumping Stations x x 5Q-1 Force Hains X ,X TP-SQ San Quentin Treatment Plant x 14. pt. San QUentin Regional ps-cMl pumping Stations x x Outfall Conveyance CH-l Force Mains X X 0-2 Submarine Outfall X X ...J Stage I! 15. Regional -Interconnect PS-CM2 pumping Station x x CM-2 Force Hain X X _ SOUTE }t\RIN SUS?,EG!QN 16, Shorelina Interceptors SM-l Force Mains & Pumping Stations x X SH-2 Force Mains & punping Stations X X TP-Sm 1, 2, 3, 4 South Marin Treatment plants 17. Southern Harin Connection to Central. Marin SH-3 Force Mains & Pumping Stations x x -51- • , &' 1 c,_ .k: , '1. __ ~",J:i" L~"o, _"~ L,."~.,,.Ii L~,"_"'I I \'L.",_':Jl;i-~'· l)L">'M_:;'~"'- :";,,'1., ~"n,lii' "c t ' "~ , L~ __ • "c., " L., .. .IiI ,1<. TABLE 111-1 surruTiary of Hajor Construction Impacts for Each Project Element of the Harin-South Sonoma Wastewater Hana9cmcnt Program I Egtimstcd project Element Number I Overall Recovery Environmantal Im~act Area 1 2 3 4 5 6 7 II 9 9 I 10 I 11 112 '113 14 15 16 17 Project . Time: 1. EARTH ?il!0lh YiI%I%I% o b a . : -E L f a o n i d ls fo rms 1 J (2 j V ! f 1 1~ t:;{ ~ :> 1 E;i !f{; ~z. WI t1 ?! % *i If ! i 1 1 % f.1 I " I , f f 1 ' ~ 0 2 0; ! 3 ? 2. H a b - A . : ' - l' - E s Q R - u u r a f l a i c t e y . 9 % '2 ~I y I ; ~ +4 h % 11!1 !1 y ~ , ~ 0 ?t c ,p ~% % !f ~ ~ ~ P/ ~ z ~ % i I 3. AIH QUALITY 9.1> ~; %%~??f.(1¥s::,3/z%%f1~%~ % 4 4. a P : R - O -f C '1 E O SS O ES il s %1° '/11 '/.; </11% ~II ~ o h1.;0/5 1%ltf ~4 1 I b. £rosion '/~ 3c¥ %fI f1 vsl~ ?1' Ii c. Deposition % 11 ?z ~ ?Z 0 '-1 '% '/,) <;f 14%'0 ~ /,<, ? 5. FLORA I ~ b c , . r e G Sh e r r a u 9 s b s s " ? t . v / 1 ; , I t v, " y /'G / ' F ! o 1 / , 'n I, , o /} o o I ".{> ' 1 V .1 '/ ~ 2 I I W / '.1 I 2 "/; l0 1 'r ' / . e 3 ? 3 < t' ' / / / < 2 < , , 5 S , N <n c d . . c H r a o r p sh s Plants e.-? f ' A ..1 ! V .J,q . ~/4 "h I/J if? 1'/1 or, v,,1010 4 'Y /; t 4 I I g f . • . A En q d u a a .n ti g c e r P ed l a S n p ts e cies 3-'11 % % V Y I , ? 0; VI' Ve 11'/0 0· v.?!0 11 % VI < 4 I 6. !"AUNA ! :'/'! a:-oirds 0/'2 VI s;'/3 !f~ 0 :t/;, Vo, '>'2 0; ?9 t:"4 ~.?' <'/11% g/s <' b c. . L l: a 'i n s d h A an n d i m S a h ls e llfish : o k /" s e Vi j ' ' / / < c? 0 <:!" / E " > oP/z /.1 ",..-2 % V~ ?Z o iVl 0 VI ? I ' / < J / 0 ~ < . ' 1 / 1 e i i ? ? d. Bent.hic Organisms -i"1 ~5 ~.? 'M o/'z -vt VI <rg "AI .? c. Endangered Species 'Ys Yz 4;t 34 11 11 ~I~ Vi % % ?3 %I~ "/5 '" I I 1% ~NDH~~~anas v211/21'>'31~,1 1 1 111'/31 1 I~t'l 1 ;? 7. h. Agriculture 0 0~ 1/1 ~ '...1, . 0 _ I/{ ) s. RECREN1'ION °11/1 a:--fishIiig o V, 5'/6 5'/. <I b. Boating "-1? 1'/2 iP/2 '/z 14/f ~ "o"/~ <I c. Swimming V, VII 1/1 <I d. nunting 01'/1 1/1 <I e. Uird ;latching Vi P1.? <'/g <I 9. AES'fHETICS AND iJuMP."N-ff?i'tR:£ST '" b ~( . .: O e p l e \ n lC Sp V ~ r c e e v B Q ualities .? ~ /3 ~ " 1 1/ / / / 1 -0 4 2 e / / 4 4 i 1 P / /1 1 11 '/ / 1 1 '/1 " ~ '/ ' 1 ' 'IJJJ'''''''. "I "/e .s c. Landscape I/p ~ '%J <1'//p, :;3; d. Parka and Rauarves Vi ~/" ~ c"''/,? 2 e. Archaeological Sites 1/" 1/2' :14; J'/G 0's "<'4 - " ,p~ 9/6 10. I C t U . LT H Ul e U a \L l th ST A l; ~ I. ' ud U S Sa.fety 1-1 1/<, 01/t!11 V, "'I o 010'<'!~ 4 1° VI I?'? ~3 ? "'I ! > . ~s I 4 c . . C T 6 r "iI a 1l f l', f c i rc c e : tlow i 4 P / / $ ? s/.::r !!/,3 % %% 2?}/ 'V.< :14/ 4 ". / } 4 ; 5 4 / / £ ! , i !f/fj 3 o / f/ . £ .; , < S I d. Sclloolu 2/.;1 ~'4 ;-4 <I <I~ , L.I k b l.k ~ . ".~ lj l~, _,,~_~ L. . ii l .... ~ii L... . L~ L," ___ i2 ly ii ,. ..... 1 le.._. .. .. ..., : (.'<..~ - TABLE IrI-2 Sumrnnl'Y of Major Long-Term Impacts for Each Project Element of the Marin-South Sonoma 11astewater Management Program Project Element Number . I Overall I Environmental Area I I I I I I I In I 1 2 3 4 5 6 7 8 9 110 112 13 114 115 116 117 Project 1. EAP,TIt - Landform % 2/2 2/2 .. 2. HATeR QUALITY '3-1l 1"% 1'% I"'k "1,1 I~% 1'0 '15 +'/1 I I' 72 I + VI '01+% f':;/411-~ r~3 3. ATHOSPHEnE .- Quality 0? 11 /", I " '/z 10 0'2 o 13/5 I 0e' I 0 2/3 1"'/3 </2 ;tr., 4. PROCESSES - Floods "'4 ~ H I I I I I I I I °1 1--1----1 "/2 ~ % ~I 5. - Aquatic Plants 6. FAUNA a:--Fish and Shellfish ?'I I+~ 1+72' 1/" ~%~~~ +%1"'0 +'0 +lk '</s , b. Benthics '0 '92 f0 U1 c. Insects .?/c 0'C'k '%~ ~ ~101~ I?; ,34 '$'-? 11 , tN 7. LAND USE a. Open Spaces e/z l%l?3 3/1 1 3/6 3/5 b. lvetlands "'/6 2/G c. Agriculture 'VI 1"14 ., <'/2 d. Residential "'/3 1/2 e. COlluncrcial "'/.3 ~ 1/2 8. RECREATION b n . . ! B '-"· · o .L- a -s- t h- i i- n n- g g 1 '.1/.1 1' ' [ v ;' ' /1 ! 1 f £ 1/ / j 2 ' 0 /1 Ll%1 'P / I j ' . 1, ~ // 1/1 I + f? 0 ! r,/, <//j I "'/G' I '/'3 " " '' ' f 7 iG e ' 1 ~ ' ' < :; / ' < i3 ' 1 + - 1 1 / / 1 I -------------------r--~ 9. AESTllE'rrcs AND ITlJ1TI\fiIN'i'Im]~ o b a. . O A p r e c n h a S e p o a l c o e g i Q ca u l a l S i i t t ie e s s I ~I 1,11·%1% /,1 le 2/ / z 6 1% 0/.51 3 0 ,< / 3 6 r l ~ / 3 j I 1/1 11/1 < " ' ' / / 4 5 c. Parks and Reserves "Ye Y-¥G ....~ t TC/S 10. CULTURAL STATUS I 11. :E b a :C . . OL E: O 1 : G m l , I ; 8 p C "l A a o, L ,y l ;m t ~el ~ n: S t: ' a ' f '' e ' t '' y ' ''"' I < /2, I V I . Ie ;/ 2 I ? 'z L2/"2 I [ ; ' : ; Iv :> ; I ~ I I ~ 2 o1/ ; " ? '% 's 1" 0 /2 o '/1 % 1 Z 4 . : ,z ; ? 0/ ' 4 z 4 0 /4 : ?'11 //2/ -?-" i. , . ropnication' V-z fJS + ? % 'e ' Y /1 I I ' I + YI I'?" ; ; ~ /t I rh '01,;; rC / /e f'!j I < 7} ,C 1 ' / ,1 1 The consolidation of treatment facilities will have an overall positive long-term environmental impact by improving operational reliability and eliminating existing treatment facilities 1;vhich now find themselves in compatible with adjacent land uses. The treatment plants which ,.,ill • remain as regional facilities will have long-term impacts on adjacent land uses which will have to be mitigated through careful architectural design and landscaping as well as incorporation of modern odor control • and noise control features. ;Secondary"Impatts: The project will have the secondary imp<,ct of being able to meet wastewater disposal needs from the""present as well as an ticipatedfuture population of the area and will enhance the feasibility of implementing both local and large-scale wastewater reclamation pro grams. }litigation treasures Proposed to Ninimize the· Impact Host of the short-term construction imp<'cts of the project can be IDlJ:]. gated to some extent by placing appropriate restrictions on the con struction activity. Dredging activities will be restricted by all • applicable requirements in respect to construction procedures and spoil disposal. A certain amount of time will be necessary for recovery and reestablishment of the original flora and fauna along pipeline routes. The long-term environmental impact of the four treatment plants to re main as regional facilities will·be mitigated through careful architec , tural design and landscaping as well as through incorporation of modern odor control and noise control features. Probable Adverse "Environmental "Effects l-ihith "Cannot Be Avoided Hhile every effort will be made to minimize impacts due to dredging and construction activities, some impacts can only be reduced and ,.,ill not be completely eliminated. There will be some degradation to water quality, fish, shellfish, and benthic organisms due to the dredging j activities as well as disruption of flora and fauna in undeveloped • areas and disruption of traffic and commerce during pipeline construc tion in developed areas. , The pumping stations and treatment plants will be equipped .nth modern odor control measures; however, even the best odor control equipment is not fail-safe and can be subject to failure. Careful architectur ally designed landscape treatment of the pumping stations and treatment • plants can further serve to psychologically mitigate any problems due to the failure of odor control measures. • Comparison of Enviror~ental Impact of Regional Alternatives The four basic alternative regional wastewater management programs have been described in the preceding chapter on Regional Alternatives. For reasons stated therein, Alternative D has been eliminated from further consideration; and thus, the further comparison of the environmental im pact of alternatives ,"rill be limited to Plans A, B, and C. -54- To provida a .. basis· for further evaluation, it should be emphasized that as a result of implementation of anyone of the three alternative regional consolidation programs--Plan A, B, or C--which have been retained for fur ther consideration ana evaluation, a total of fourteen existing wastewater , discharges will be eliminated, and a total of thirteen existing treatment plants will be retired. The treatment function for Eastern Harin County will be consolidated into either one or two regional treatment plants, and both the Petaluma and Sonoma treatment plants will be retained • • Under all three regional programs, all existing wastewater discharge to confined waters of the bay and estuary system will be eliminated. In addition, under all three programs, the interceptor facilities between Northern Marin County and Southern Sonoma County will be reversible to allow the transport of treated effluent to Southern Sonoma County for future reclamation and reuse. All three plans involve a high degree of consolidation of treatment and • disposal facilities but differ in the following major respects: 1. The point of disposal of treated wastewater--either Point San Pedro (Plan B), Point San Quentin (Plan C), or both (Plan A). 2. I'mether or not there should be a single regional treatment plant for Eastern Marin County (Plan B) or two regional treatment plants for Eastern }~rin County (Plan C). 3. The timing for construction size and material to, be handled in the interconnecting line between Central ~~rin and North Marin. The facility elements which each program has in common, along with the material handled, are tabulated in Table·VI-l. An evaluation of the " J differing proj ect elements of the three plans is summarized in Table lLL:L and is discussed below. J~ Point of Disposal The specific project elements which ,,,ill differ because of the alterna tive points of disposal will be Project Element 4, the Point San Pedro regional outfall, and Project Element 14, the Point San Quentin regional outfall. Construction Impacts: Construction of the Point San Pedro outfall fa cility has a much greater environmental impact than does the Point San Quentin outfall since this facility "'ill traverse diked mudflat areas, cross Ga11inas Creek, and will be constructed along the presently unde veloped and important natural habitat area along the north side of Point San Pedro. The Point San Quentin outfall will be constructed in primarilY" developed areas and will have little additional effect on the terrestrial environment other than disruption to traffic and huw3n activities. .... , Long-Term Irnnacts: The long-term environmental impact of discharging treated waste,,,ater through a deep water outfall at either Point San Pedro or Point San Quentin vli11 be minimal. The Bay Node1ing as performed by ivater Resources Engineers reveals that 't{ater quality obj ectives will be -55- ' TABLE VI-I Summary of Phase One Facilities for Alternative Eastern }larin-South Sonoma Wastewater Hanagement Programs Alternative Plan Haterial Handled Action No. Basic Facility A B C Ra>l Sewage Effluent NORTH HARIN-SOUTH SONOHA I, 2, & 3 Interceptors from Sonoma and Petaluma X X X. X , 4 point San Pedro Regional outf~ll X X X e,n 0- 5 North Harin Regional Treatment X X X X 6,7,8,9 & 10. North Marin Raw Se\1age Interceptors X X. X X CENTRAL I-lARIN . Ii 11 Central Harin Regional Treatment X X X 12 & 13 Central Harin Raw Sewage Interceptors X X X X 14 Pt. San Quentin Regional Outfall ,X X X , 15 Regional Interconnect X X X Plan B Plans A (Stage II) (Stage I) Stage I) & C SOUTH ~lARIN 16 Shoreline Interceptors X X X X 17 Connection to Central Harin X X X X , ,--, . -------.----- ----- '._----,_.--- TABLE VI-2 Detailed Environmental Evaluation of Project Elements Common to Plans A, B, and C Point of Disposal Treatment Plants Regional Interconnect Project Elements 4 & 14 Project Elements 5 & 11 Project Element 15 , Impact ABC ABC ABC - Construction Impact Soils 2/2 3/3 2/2 2/2 2/2 1/1 2/2 2/2 Flora 3/3 4/4 1/1 2/2 2/2 2/2 2/2 3/3 3/3 Fauna 3/3 4/4 2/2 3/2 2/2 3/2 2/2 3/3 3/3 Hater Quality 3/3 4/4 2/2 2/2 2/2 , ~'1etlands 3/3 4/4 , . t " ,n Recreation 3/3 3/3 3/3 ; Archaeological Sites 3/5 4/5 Traffic 3/3 3/2 3/3 3/3 5/5 5/5 Commerce 2/2 2/2 3/3 5/5 5/5 Long-Term Impacts \'/ater Quality Objectives +4/5 +4/5 +5/5 Fish and Shellfish 3/5 4/5 2/5 Recreation 2/2 3/2 1/2 Air Quality 3/4 2/2 3/4 Land Use 4/5 4/5 Flooding 3/4 4/4 3/4 Utilities 2/2 3/3 3/3 , Secondary-Impacts Reliability 5/5 3/5 3/5 +3/3 +3/3 +3/3 2/2 4/4 2/2 Local Reclamation +4/3 +2/3 H/3 Large-Scale Reclamation +2/3 +3/3 +3/3 -.. ~- _ .. - -_ ... --.-_. met at either or both points of discharge. Because of their depth and favorable locations in respect to circulation of tidal water, both Point San Pedro and Point San Quentin represent two of the best points of dis ch~rge in the entire San Francisco Bay system. There is a body of opinion among marine biologists and the Department of Fish and Game that. the closer the discharge is to the Golden Gate, the less impact it will have on marine life because of the quicker dilution of the effluent by the ocean. According to this body of opinion, e single outfall at Point San QUentin would be preferable. This suggested effect on water quality due to the proximity to the Golden Gate is not substan tiated by the computer modeling for the two outfall sites under considera tion in the Marin and South Sonoma wastewater management program~ Dr. his studies summarized in the Environmental Impact State Gustafso~in ment, points· out that in the absence of a guarantee that anT· characteristics of the receiving water would exceed the tolerance of any fishes if the entire discharge were to be at Point San Quentin, that a dual discharge of lesser concentrations of effluent at both outfall sites might be pref erable. Furthermore, Dr. Gustafson points out that in the interest of safety, it would seem better to be served by the option of two treatment I plants and two outfall lines. In summary, although the computer modeling of the bay system shows little difference between tha long-term water quality! characteristics of the bay between a discharge at Point San Pedro or Point San Quentin, there is a body of opinion that a discharge point closer to the Golden Gate is pref erable. On the other hand, a dual discharge at both sites might be pref erable in terms of assuming lesser concentrations of effluent and better safety and reliability in protecting the environment. Secondary Impacts: Since both outfall lines will be transporting treated effluent, no connection could be made to provide sewer service to unde veloped areas. Consequently, there should be no secondary or growth inducing impacts attributable to eithar outfall conveyance system. Summary: The primary difference between the t,w points of discharge under consideration is the greater construction impacts attributable to the Point San Pedro outfall conveyance system. On a long-terill basis, there is a body of opinion which prefers the outfall at Point San Quentin because it is closer to the Golden Gate. In terms of assuring protection of the aquatic environment and better dispersion of the effluent, a dual outfall system may be better. Accordingly, in respect to the overall environmental impact of the paint(s) of disposal, Plan C is most preferred, ,lith Plan A next, and Plan B least preferred. -58-· A second major difference between the three alternative regional waste water w~nagement programs is the number of regional treatment plants to be'utilized. In Plans A and C there would be four regional treatment plants, and in Plan B there would be three treatment plants. Under all three plans, the Petaluma, Sonoma Valley, and North Marin areas will each operate a subregional treatment plant; and therefore, the dif ference between the three regional plans becomes a question as to whether or not there should be a treatment plant in Central Harin. Under Plan B Project Element No. 11 is eliminated; and the Northern Marin Treatment Plant, Project Element No.5, will be about twice as large in capacity as it would be under Plan A or C. Construction Imnacts: The environmental impact of constructing a larger North Narin treatment plant, as under Plan B, is not significantly greater than the impact of constructing the basic plant, as under Plan A or C. The site of the Central }~rin treatment plant has already been disturbed by human activity, and thus, the construction impacts "ill be minimal. Long-Term Impacts: The North Harin treatment plant will be constructed in a flood plain area, and a large enough site will have to be acquired to allow suitable ponding area for flood control. Since additional land would, be needed under Plan B, the ponding area for:flood control would have to become proportionally larger. Although the proposed site of the North Marin treatment plant is now relatively isolated, adjacent lands could be developed in the future and eliminate this isolation. The Central Marin treatment plant could have a definite long-term impact on adjacent land uses in terms of possible odors and noise. In order to be compatible with the adjacent land uses and mitigate long-term environ mental impacts, the Central Harin treatment plant will have to be designed «ith full architectural amenities and modern odor control and noise con trol features. The site should be large enough to be attractively land scaped and properly screened from view. In summary, a large North Harin treatment plant, as under Plan B, will have a larger long-term impact on the environment. If a Central }furin treatment plant is constructed, as lli,der Plan A or C, it will have long term impacts on adjacent land uses unless suitable mitigation measures are incorporated into the site development and plant design. Secondary Impacts: The secondary impacts in respect to the number of regional treatment plants to be constructed deal with questions of over all system reliability and the availability or' nonavailability of suitable effluent for local reclamation and reuse purposes in Central Harin County. -59- In terms of an overall wastewater management system, there is a basic question as to whether or not 'one regional treatment plan't would be. more reliable than two regional treatment plants. Hith small plants (less than 1 or 2 mgd) , it is generally conceded that economics dictates that a s~all plant cannot have the same fail-safe features and have the same level of staff competence as can a larger treatment plant to assure maximum reliability. Hith larger treatment plants, duplicate process units can be provided, fail-safe controls can be utilized, and staffing can be, 9'9:', a continuous 24-hour basis. Although there is a body of opinion that believes reliability is directly proportional to size, the question of overall ability to achieve adequate reliability appears to become moot in comparing two large treatment plants against one larger treatment plant because all the necessa~J fail-safe features and proper staffing can be provided with both plants. The ability to economically achieve local reclamation and reuse in Cen tral Harin depends upon the availability of a treated secondary effluent in the area. Under Alternative Plans A and C, treated effluent would be available in Central Marin County. Under Alternative Plan B,the only way to produce effluent for use in Central Marin would be to operate a "scalping" plant to treat as much sewage as is needed for reuse purposes. However, if the cost of operat ing a scalping plant is added into the unit cost of reclaimed water, the project is not economically feasible. Although on an overall water re sources manageeent basis, the quantity of wastewater ~lhich could be used for local landscaping purposes is small in comparison to the total ulti mate discharge from a Central and South Marin regional treatment facility of 22,000 acre feet per year, the fact that some water is reused may be come important in Marin County's present water-short situation. SUID.:.ilary: The primarj differences between the envi:ronrnental effects of having three or four regional treatment plants are: (1) the long-term impacts the Central l'larin treatment plant will have on adjacent land use, and (2) the secondary impacts of not having treated effluent available for reclamation and reuse in Central Marin County if there is no regional treatment plant in Central }larin, as under Plan B. The long-term adverse environmental impacts of the Central Marin treatment plant on the adjacent land uses can be mitigated by proper architectural amenities, landscape screening, and positive odor and noise controls. Not having treated effluent available for reclamation and reuse in CentraJL Narin County under Plan B, Hhere there is a North Narin regional treatnent plant serv~ng Eastern Marin County, cannot be "mitigated economically~ However, the amount of reclaimed water which could be used for landscape irrigation purposes may not be significant in an overall water resources management picture. -60- Accordingly, in respect to the environmental impacts due to the number of subregional treatment plants, Plans A and C are preferred over Plan B. Regional Interconnecting Line A'third major difference between the three alternative regional plans is the size and timing of the construction of a regional interconnecting line between Central and South Marin and North tmrin designated in Proj ect Element No. 15. The regional interconnecting line becomes necessary when enough large scale reclamation and reuse opportunities are developed in North }mrin County and Southern Sonoma County to require additional effluent from c.. ,...: Central and South Marin. The large-scale reclamation and reuse oppor tunities are in the form of possible agricultural irrigation and develop mentof a recreational lake. However, these opportunities are not yet developed and, at this time, can only be stated in the form of potential. Under Plan A, the regional interconnecting line would only be of suffi cient size to transport the average dry weather flows of treated effluent from the Central and South I·mrin areas to the North l'mrin area as neces sary for reuse. Under Plans Band C, the regional interconnecting line would be constructed as a part of the initial disposal program and would be large enough to convey all sewage flows between the subregions. Construction Imoact, The interconnecting line between Central }mrin and North Harin will be constructed through developed areas of San Rafael and diked mudflat areas of North Marin. Under Plans Band C, the pipeline would be larger; and therefore, the construction impacts ,rill be larger. Aside from a disturbance to farming and to wildlife in the diked mudflat area, the primary impact will be to traffic, commerce, and human activi ties of constructing the line through the highly developed downtown San Rafael area. Under Plans Band C, the construction activity for such a large pipeline will cause major disruption to traffic and commerce in San Rafael. Long-Term Impacts: Once the interconnecting pipeline is constructed, there should be few, if any, noticeable long-term impacts. The pipeline will occupy streets and easements and thereby make those areas unavail able for construction of other underground utilities. Secondary Impacts: There are two secondary impacts associated tdth Project Element No. 15 due to (1) possible hazard to the environment in the event of a break or catastrophe, and (2) possible future unwilling ness under Plan A of the public to support construction of an intercon necting line to make available additional 1;"ater for reclamation and reuse up-less it is constructed as a part of the initial project. -61-. In respect to reliability and possible hazard to the environment, the interconnecting pipeline does not cross any known active faults; however, it does cross diked mudflat areas which may be subject to instabilities during an earthquake. Under Plans A and C, the interconnecting pipeline will be carrying treated effluent, whereas under Plan B the interconnect ing pipeline "ill be carrying untreated sewage. Accordingly, the environ mental damage in the event of a catastrophe and breaking of the intercon necting line will be a great deal less under Plans A and C. In respect to possible future public unwillingness to support construction of the interconnecting line between Central Harin and North Harin, it is true that under Plan B or C the line will have to be constructed as a part of the initial project, whereas lli,der Plan A it could be delayed and possibly never would be constructed. Under Plan A the only reason that the line should be constructed would be if a sufficient demand for re claimed water were developed, presumably in the North Harin or South .. ~-. Sonoma area, to require the additional effluent from Central and South Harin. On the other hand, if the pipeline were constructed initially, as under Plan B or C, there is no guarantee that a reclamation potential will be developed to require the effluent from Central Harin. Further more, even though the pipeline under Plan B or C is larger than that under Plan A, the peak wet weather flows from Central Harin could not be transported to Southern Sonoma County without constructing a much larger reversible interceptor system beD1een Harin~ and Sonoma Counties .. Summarj: The construction of the interconnecting pipeline from Central Harin to North Harin will primarily cause a disruption to traffic, com merce, and other human activities in downtown San Rafael. These impects become particularly severe with construction of the larger line under Plan B or C. There are no long-term impacts associated with Project Element No. 15. Secondary impacts include possible damage to the environment in case of a break, which ,viII be much less under Plan A or C because only treated efflUent ,nIl be diSCharged. In respect to achieving reclamation, the existence or nonexistence of this interconnecting line does not in itself promote the development of a large-scale reclamation or reuse program. Accordingly, in respect to th2 environmental impact of the interconnecting pipeline, Plan A is most preferred, with Plan C next, and Plan B least preferred. No Project Alternative The alternative of not undertaking any project has been considered and involves the continued treatment of ~oJa5te't"2.ter at the existing facilitie.s and continued disposal of effluent at the existing point of discharge for each agency_ A continuation of the present conditions is ~nacceptable -62- since Federal and State water quality objectives will not be met, and the aquatic environment will not be adequately protected. Overall Summary of Alternative Reg; onal Programs ~n overall summary of the environmental impact of the Alternative Pro grams, particularly as it relates to the differeing project elements, the following conclusions are presented: 1. In respect to the environmental impact of the point(s) of disposal, Plan C is most preferred, with Plan A next, and Plan B least pre ferred. 2. In respect to the environmental impacts due to the number of subre gional treatment plants, Plans. A and C are preferred over Plan B. 3. In respect to the environmental impact of the interconnecting pipe line, Plan A is most preferred, with Plan C next, and Plan B least preferred. 4. The alternative of not undertaking any project is environmentally unacceptable. Short-Term Use Versus Long-Term Productivity The proposed project will enhance the long-term productivity of the San Francisco Bay, especially with respect to fish, shellfish, and water related recreation. It will also facilitate future «ater reclamation and reuse projects, thereby conserving a valuable resource in short sup ply. To attain these benefits, there. «ill be some short-term loss of productivity due to construction-related activities and SOme possible long-term hazard to public health and the environment in the event of a catastrophe. Irreversible and Irretrievable Cdmmitmentsof Resources The irreversible and irretrievable commitments of resources relate to the commitment of resourCeS for the project construction and long-term operation. The type and degree of treatment which have been selected constitute an optimum resource commitment toward meeting water quality objectives. . The Growth-Inducing Impact of the Project Tne project does not of itself have any growth-inducing impact. Its purpose is to accommodate such growth as the various responsible poli tical bodies may permit within their respective areas by providing ade quate sewage treatment facilities on a timely and economi~al basis~ -63- . Existing facilities for the proj ect service area, even ,·,here their original design capacities are adequate for present population levels, are in many cases not able to achieve those capacities under the in creased stringency of more recent discharge requirements; and in some cases, cannot operate as they are presently constructed at any capacity. Thus, some expenditures on and expansion of sewage treatment facilities are required to accommodate existing population levels and sewer con nections. The project ,;ould provide this renovation and expansion through new facilities which would accommodate both existing and pre dicted additional populations. Such environmental impact as may be expected from the levels of growth proposed by the various responsible bodies should be evaluated as a part of the decision-making processes of these bodies; the decisions relative to this project are fundamentally those of how, rather than whether, to provide the required sewage treatment facilities for an ticipated populations. -64- COMBINED E V A L U A T ION COM BIN E D E V A L U A T ION Combining the results of the additional economic, "effectiveness" and environmental impact evaluations of Alternative Programs set forth hereinbefore in form sUIT~ary has been done and is presented in Table 14. TABLE 14 - Summary of Separate Evaluations of Alternative Programs Alternative Program Evaluation Factor A B C Economic Ini tial Cost, Million $' s 73.1 90.5 80.6 Present Worth, Million $' s 102.9 123.8 112.7 Average Total Annual Costs, Million $' s 9.7 11. 7 10.6 Average Total Annual Cost for Equivalent Single Family Unit, $'s (without grants) 85 102 93 Economic Evaluation Ranking 1 3 2 Effectiveness Water Quality Objective Excellent Excellent Excellent Reliability Good Good Good Reclamation Potential Good Good Excellent Flexibility Good Good Good Overall Environmental Impact Good Good Good Regionalization Good Excellent Excellent Implementation Excellent Adequate Good Effectiveness Evaluation Ranking 2 3 1 Envi ronmen tal Soils 2/2 3/3 2/2 Flora 2/2 3/3 2/2 § Fauna 3/3 3/3 3/3 ';1 1'l Water Quality 3/3 3/3 3/3 g g Wetlands 3/3 4/4 2/2 t ~ Recreation 3/3 4/4 i!J Archaeological Si tes 3/3 3/3 2/2 H 8 Traffic 3/5 4/5 4/5 Commerce 3/3 4/5 4/5 Water Quality Objectives +4/5 +4/5 +5/5 Fish and Shellfish 3/5 4/5 2/5 ~ Recreation 2/2 3/2 1/2 V) ~ t Air Quality 3/4 2/2 3/4 ,:" g. Land Use 4/5 3/5 4/5 §!i Flooding 3/4 4/4 3/4 ..:l Utilities 2/2 3/3 3/3 Environmental Evaluation Ranking 2 3 1 -65- I, A P PEN D I X I I CALIFORNIA REGIONAL HATER QUALITY CONTROL BOARD SAN FRANCISCO BAY REGION RESOLUTIOli NO. 73-12 REGA.11.DING l1..ilRIN/SONONA SUBREGIONAL STUDISS COORDINATION I.. HHEREAS, the dischargers in Narin and Southern Sonoma Counties are partici pating in the developme.nt of three su.bregional \.Jater quality management programs, and II.. ~\THEREAS, these sub!"egions have been divided as follows: Southern Harin Subregion Sausalito-Harin City Sanitary District Sanitary District No. 5 City of Hill Valley Richardson Bay Sanitary District Central l1arin Subregion Sanitary District No. I San Rafael Sanitation District (Hain Plant) North }larin-Sonoma Sonoma valley County Sanitation District City of Petaluma Harin County Sanitary District No.6 Las Gallir.as Valley Sanitary District San Rafael Sanitation District (Harin Bay Plant) Hamilton Air Force Base, and III.. HHERE.tlS, the subregional studies for the North Marin-Sonoma and Central Narin Subregions have been completed and the dischargers in these subregions are preparing to move into the project report stage for grant applications, and IV. WHEREAS, ~he dischargers in Southern Marin are prEparing a project report for grant application, and v. WREREAS in order to obtain a grant for constructio!l of sewerage faCilities, j these projects must receive certification from the Regional Board, and VI. 1;.JfIEREAS ~ the subregional study reports for Central Narin and North Marin Son0ffia have indicated the possibility of alternative facility plans involving consolidation of the three subregi.ons, and VII~ WEEREAS; these alte:rnat'ive plans include alternatiVeS for consolidation of treatment and/or discharge for all dische.rgers in the three subregions, including the alternative cf one treataent facility and discharge point for all the \Vaste flows ·in -che three subregions, and VIII. \]HEREAS) Sec tion 2131 of the Sta te Water Resources .Control Board Grant Regulations states: - 1 - " "Consolidation or waste1vater treatment systems shall be required in all cases ...,here feasible and desirable to accomplish good water quality management" and IX. WHEREAS, both the State and Federal Grant regulations require a thorough evaluation of alternatives before a grant will be issued, and X. WHEREAS, the Marin County Board of Supervisors has formed the Wastewater Planning Coord;t.nating Committee to further study the possibilities of consolidation of the subregions. This committee is comprised of repre sentatives of each subregional group but does not provide for direct representation of all the dischargers in each subregion, and XI. WHEREAS, the Ha.tewater Planning COOl:;dinating Committee can only recommend a course of action to the various subregions, and XII. WHEREAS, agreement among the dischargers in the subregions will be necessary for any alternative involving consolidation of subregions t.o proc<2ed.; nm-i" XIII. THEREFORE, BE IT RESOLVED, that this Regional Board commends the efforts of the Wastewater Planning Coordinating Committee. XIV. BE IT FL'RTHER RESOLVED, that this Regional Board finds that full evaluation of alternatives involving consolidation of subregional facilities will be necessary prior to any grant certification by the Regional Board. xv. BE IT FURTHER RESOLVED, that this Regional Board finds that, in order to assure this evaluation, any project report s'ubmitted by the three subregions for facilities for the subregional programs 'mus-t be accompanied -by an "over vieH" report and environmental impact statement ,.,hich fully evaluates the consolidation alternatives. XVI. BE IT FURTHER RESOLVED, that this Regional Board recommends that early effort be ma.de, either through the Waste,,,ater Planning Coordinating Committee or other appropriate arrangement, to provide for direct representation of all discharging agencies in the guidance of the development of the over-vie\-l report. I, Fred H. Dierker, Executive Officer, do hereby certify the foregoing is a full, true, d.no. correct copy of a Resch:.tion 2.d.opted by the California Region.J.l Hater Quality Control Board, San Francisco Bay Region on June 26, 1973. Executive Officer - 2 - AB 1232 How We Got Here and Where Do We Go From Here Almonte Sanitary District March 21, 2011 An examination of the issues surrounding AB 1232 and SASM Member Agency response. Table of Contents The Regulatory Environment .................................................................................................................. 3 Regulatory and Enforcement Action ....................................................................................................... 5 Agency Compliance Record ................................................................................................................... 14 Initial Blame for 2008 SASM Spill ........................................................................................................... 20 Independent Studies: Collection Agency Wet-Weather Flow Impact on SASM ........................................ 22 Independent Studies: Actual Causes of the January 25, 2008 Spill .......................................................... 25 Proactive and Collaborative Actions Taken by SASM and its Member Agencies ...................................... 27 Consolidation: An Answer in Search of a Problem ................................................................................. 34 Appendices (A-F) ................................................................................................................................... 44 2 The Regulatory Environment: UNITED STATES ENVIRONMENTAL PROTECTION AGENCY STATE WATER RESOURCES CONTROL BOARD CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD, San Francisco Bay Region CALIFORNIA LEGISLATURE MARIN LAFCO FEDERAL WATER POLLUTION CONTROL ACT (CLEAN WATER ACT) CALIFORNIA CODES WATER CODE SECTION 13260-13274 SANITARY DISTRICT ACT OF 1923: [CAL. HSC. CODE § 6400 - 6408] CORTESE-KNOX-HERTZBERG LOCAL GOVERNMENT REORGANIZATION ACT OF 2000 AB 1232 Recent Evolution of Regulatory Requirements: Increasing EPA awareness and scrutiny of sanitary system overflows (SSOs) began in 2001 as a nationwide proposal for adoption of Capacity, Management, Operation, and Maintenance (CMOM) requirements for all wastewater agencies which include satellite collections systems like Almonte, Homestead Valley, Alto and Richardson Bay that collect and discharge wastewater to a publically owned treatment works (POTW) such as SASM. (see below for a chronology of CMOM by CMOM.net) Welcome to CMOM.net, a reliable source of information about the US EPA's Capacity, Management, Operations, and Maintenance (CMOM) regulations. CMOM.net is maintained by members of the Collection Systems Committee of the Water Environment Federation (WEF). 2009/03/29 This entry is being posted to give the status of CMOM following the inauguration of the Obama administration. Eight years after the original proposed rulemaking was quashed by the Bush administration (see below), there is no change in the status of the SSO Proposed Rule, which contained CMOM. It was never moved for publication in the Federal Register nor adopted during the Bush administration and there has been no publication action to date by US EPA. What has happened in lieu of publishing the SSO Rule has been activity in two areas: 1) A guidance document (http://www.cmom.net/cmom_guide_for_collection_systems.pdf) was published by US EPA in 2005 that contains most of what was in the original SSO Rule concerning CMOM. By referring to it as a "guidance" document, it avoided the rule-making process that would have spelled certain death during the Bush administration. 3 2) Individual US EPA regional offices - who have the authority to act independently of US EPA Headquarters - have taken action to create and enforce CMOM regulations in different parts of the country. Some states that have regulatory authority delegated to them by US EPA have also taken action to develop CMOM requirements for the collection system agencies under their jurisdiction. An example of one of the most wide-ranging state actions is the California "Collection Systems Waste Discharge Requirements". http://www.waterboards.ca.gov/water_issues/programs/sso/index.shtml Of note, cloned pieces of the original CMOM language as well as the later guidance document have found their way into the regulatory language of both the US EPA regional offices and the states that have taken action. 2003/01/31 At the conference planning meeting of the Water Environment Federation's (WEF) Collection Systems Committee, it was announced that the proposed SSO/CMOM rule had not yet been submitted to the Office of Management and Budget for financial analysis. (See more about OMB's role below.) This delay is likely to cause the rule to not be released for publication until sometime in the Fall of 2003, with publication in the Federal Register most likely in the Spring of 2004. 2002/11/15 At the meeting of the Water Environment Federation's (WEF) Government Affairs Committee Wet Weather Group, officials from US EPA announced with reasonable certainty that the SSO rule (which incorporates the CMOM provisions) would be delivered in November 2002 to the Office of Management and Budget for financial analysis. (OMB's input is required in order to establish the likely impact of imposing a regulation.) WEF's Government Affairs Committee is preparing a document for consideration by OMB that addresses the funding/need gap that the SSO rule is likely to create. Following the review by OMB, the SSO rule would be scheduled for comment in the Federal Register, most likely in the Spring of 2003. There is considerable consensus for moving ahead with publishing the rule even though there are continuing disagreements in the industry about portions of the rule, specifically the affirmative defense and stormwater blending proposals. Publishing the rule will at least allow undisputed portions to be implemented including CMOM and the permitting of satellite collection systems. 2001/11/08 EPA announces that Tracy Mehan the Asst. Administrator for the Office of Water has given the go-ahead for the development of the SSO/CMOM Notice of Proposed Rulemaking. This action effectively re-starts the process that had been halted in January by the then-incoming Bush administration. The contents of a note from Kevin Weiss at EPA reads as follows: "I am pleased to announce that Tracy Mehan, the Assistant Administrator for the Office of Water, has given OWM (Office of Water Management, ed.) the go ahead and work on the SSO/CMOM NPRM. As you know, Administrator Browner signed a draft SSO NPRM on January 4, 2001. However, in accordance with the memorandum of January 20, 2001, from the Assistant to the President and Chief of Staff, entitled A Regulatory Review Plan,@ published in the Federal Register on January 24, 2001, 66 FR 7701, EPA withdrew the SSO NPRM from the office of Federal Register to give the Administrator an opportunity to review it. Since January, EPA has received a number of comments on the January, 2001 draft NPRM. Tracy Mehan has directed OWM to develop an SSO/CMOM NPRM that: - proposes regulations consistent with those recommended by the SSO Federal Advisory Subcommittee on October, 1999; - summarizes in the preamble the comments received since January, 2001; and - provides preamble discussion regarding those comments. I continue to strongly believe that broad-based NPDES permit requirements for CMOM, reporting, record keeping and public notice for SSOs as well as expanding NPDES program to municipal satellite collection systems will ultimately have a dramatic impact on changing the way the nation invests in its sewer infrastructure, which in turn will improve the performance of these systems and lead to reduced health risks. We will keep you posted as we work through this effort." 4 2001/01/20 The incoming Bush administration issues a memo calling for a "Regulatory Review Plan" requiring a review of all pending regulations by the new administrators. EPA withdraws the Notice of Proposed Rulemaking (NPRM) for CMOM. Note: The EPA address also contains links to EPA's CMOM documents. 2001/01/04 USEPA Administrator signs the Notice of Proposed Rulemaking (NPRM) for CMOM. This begins the process of publication in the Federal Register which, in turn, will provide for a public comment period. Federal, State and Regional Board Regulatory and Enforcement Action: RWQCB 13267 Letter dated July 7, 2005 SWRCB Order No. 20006-0003-DWQ issued May 2, 2006 As noted, in the absence of federal rulemaking, continued development, implementation and enforcement of SSO/CMOM requirements fell to regional EPA offices and state and local water boards. Preliminary preparation for developing a SSMP program and online SSO reporting system began as a collaborative effort between our local RWQCB and The Bay Area Clean Water Agencies (BACWA), as local sewer agencies, concerned about the scope and impact, both in terms of manpower, dollars and the functionality of the proposal in accomplishing common goals sought to provide input. (See: Appendix, A) Marin agencies began actual SSO reporting in 2004 when the RWQCB‟s online reporting system went live. The online reporting and SSMP development process culminated on July 7, 2005 with the issuance of a “13267” letter requiring sewer system authorities to prepare a Sewer System Management Plan (SSMP) pursuant to Section 13267 of the California Water Code. The SSMP was to be implemented in phases with complete adoption and implementation of the SSMP by August 31, 2008. On May 2, 2006 the State Water Resources Control Board issued Order No. 2006-0003-DWQ on May 2, 2006 which imposed similar SSMP requirements statewide. All of our agencies developed, adopted and implemented the required SSMP pursuant to both the RWQCB letter and SWRCB Order No. 2006-0003-DWQ. Almonte adopted their SSMP in August 2006. Federal and State Enforcement Actions: Beginning in August 2007 the EPA began a series of Clean Water Act Compliance Evaluation Inspections of SASM and its member agencies. Almonte, Alto, Homestead Valley and Tamalpais Community Service District were inspected in August 2007. SASM and Richardson Bay in October 2007. The City of Mill Valley was inspected on February 12, 2008. (http://www.epa.gov/region9/water/npdes/compliance.html) 5 These inspections were quickly announced and rather short in duration, maybe a few hours. Our agencies attempted to provide requested information to the inspectors, however, some information was provided in a form that was agency specific, not in a form that the inspectors were expecting (such as hot spot cleaning programs represented in vendor cleaning contracts). Some information provided to the inspectors, such as excel spread sheets documenting cleaning, repairs, emergencies, etc. over many years or district maps that color-coded lines as they were cleaned as a tracking mechanism were omitted from the report. A major complaint from some of the inspected agencies, especially Richardson Bay and Almonte, is that these reports were quickly prepared, posted to the EPA website immediately after the spills from SASM prior to being transmitted to the inspected agencies for comment or correction. (See press report below). (San Francisco, California -- 02/12/2008) - Following the recent large sewage spills to the San Francisco Bay from a Marin Co. treatment plant, the E.P.A. today finalized and released inspection reports for 5 of 6 sewage collection systems that flow to the Sewerage Agency for Southern Marin wastewater facility. The EPA's October inspections confirmed that the sewage collection systems for Almonte, Tamalpais, Alto, Homestead Valley and Richardson Bay have significantly deteriorating sewage pipes that are overwhelmed by rainwater during wet weather, which affect operations of the Sewerage Agency for Southern Marin plant and its discharge to San Francisco Bay waters. "The public may be surprised to learn we have many neglected sewage collection systems, which are small, underfunded and undermanaged. These systems will continue to pose threats to San Francisco Bay if communities fail to upgrade and maintain their systems sustainably," said Alexis Strauss, the EPA's Water Division director for the Pacific Southwest region. "We at the E.P.A. will continue, as we've done elsewhere in California, to work with the California Regional Water Quality Control Boards and the systems directly to achieve long-overdue assessment, repair and replacement." "The best way to deal with sewer spills is to prevent them from ever occurring," said John Muller, chair to the San Francisco Bay Regional Water Board. "I would prefer to work with local government and other leaders to make sure the Bay Area has the finest infrastructure possible. That is how we all should protect water quality." On Friday the Regional Water Board issued an order to the SASM requiring a full report on the recent spills to the Bay, and requiring the agency to audit its operations. The audit report is due April 7. Deteriorating pipes, combined with extreme peak flows from rainwater, overwhelmed the SASM facility, causing the Jan. 25 flows to exceed capacity at the emergency holding basins at the plant, and overflowed to San Francisco Bay waters. The subsequent Jan. 31 spill occurred when the treatment plant failed to operate all of its discharge pumps designed to achieve higher levels of treatment offsite, thus also leading to another spill to Bay waters. When sewage spills occur, prompt posting of affected beaches is required to protect the public. Co. health departments should be prepared to post waterways immediately when these types of discharges occur. The Sewerage Agency of Southern Marin treats wastewater from about 28,000 people in the Mill Valley area. The sewage is collected from homes and businesses in networks of sewer pipes that are owned and maintained by 5 separate sanitary districts and the city of Mill Valley. Almonte‟s inspection report excerpted below is reflective of the reports issued to other SASM members. USEPA Region 9 SSO Inspection Report Almonte Sanitary District 6 Background On 8/7/2007, USEPA Region 9 and its contractor inspected the Almonte Sanitary District‟s (the “District”) sanitary sewer system located in Mill Valley, California. Spills and sanitary sewer overflows (SSOs) from the sewer system are prohibited by the Clean Water Act. Additionally, spills and SSOs from the District‟s system are prohibited by Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, WQO No. 2006-0003. The District is an enrollee under the Statewide General Waste Discharge Requirements. Additionally, the Agency is required to comply with the San Francisco Bay Regional Water Quality Control Board‟s July 2005 Section 13267 of the California Water Code letter that establishes earlier deadlines for submittal of Sewer System Management Plan (SSMP) components than the SSMP deadlines present in WQO No. 2006-003. As such, the Agency must comply with both the Section 13267 letter and WQO No. 2006-003 requirements. The primary purpose of the inspection was to document the history of sewage spills, determine the adequacy of the District‟s spill response and prevention programs, evaluate sewer maintenance activities, and assess the accuracy and reliability of its spill reporting procedures. The District‟s representative during the inspection was Mr. Bonner Buehler. Mr. Max Kuker from PG Environmental, LLC led the inspection accompanied by Mr. Rick Sakow from USEPA Region 9. The weather at the time of inspection was sunny. The District owns and operates approximately 5.5 miles of gravity sewer pipe. The District does not own or operate any pump stations or force mains. Sanitary sewage generated within the District gravity flows to the Sewage Agency of Southern Marin (SASM) wastewater treatment plant. According to Mr. Buehler, the District has approximately 780 sewer connections in its collection system. The District also has three restaurants discharging to the collection system. Discharges from the SASM wastewater treatment plant into Raccoon Strait (Central San Francisco Bay) are regulated under NPDES Permit No. CA0037711. The District currently estimates their average dry weather flow at 110,000 to 130,000 gallons per day (gpd) and their average peak wet weather flow at approximately one million gallons per day (mgd), indicating a peaking factor of approximately 7.5 to 9. The District is billed by the SASM wastewater treatment plant based on the number of connections rather than flow which provides no incentive to reduce I&I. Mr. Buehler stated that SASM completed a significant Inflow and Infiltration (I&I) study, but did not specify if the Almonte system was included in the report. Upon further investigation SASM personnel stated that the I&I study was conducted by Black and Veatch for all member agencies in 1983/1984, but that a project was underway to summarize current I&I reduction measures through the member agencies and to identify and evaluate potential I&I projects throughout the WWTP's collection system as a whole. According to Mr. Buehler, the District has not undertaken any activities to prevent I&I in the collection system because capacity has not been a major cause of spills and overflows for the District. The District currently and historically has had an un-written agreement with Roto-Rooter for system maintenance and spill response. This agreement is for „on-call‟ sewer maintenance, blockage, and spill response. The extent of sewer maintenance completed by Roto-Rooter was unclear due to a lack of documentation provided to the inspectors. According to Mr. Buehler, if an individual calls his office to report an overflow or blockage, the individual is directed to call Roto-Rooter, which investigates and corrects the problem. Roto-Router provides documentation to Mr. Buehler regarding the volume of the spill, the cause of the spill, and the corrective actions taken to mitigate the spill, along with an invoice for its services. The invoices are tracked via a spreadsheet briefly describing the invoice, the service provided, and the amount charged. The District does not have any staff or equipment for spill response. 7 Under section 301(a) of the Clean Water Act (CWA), it is unlawful for any person to discharge any pollutant from a point source into "waters of the United States” except in compliance with a NPDES permit. The Almonte Sanitary District does not have an NPDES permit that authorizes the discharge of sewage spills. Therefore, any sewage spill from the District's collection system that flows to "waters of the United States" constitutes a violation of the Clean Water Act. Findings 1. Occurrence of spills. Discharges to waters of the United States without a permit are prohibited under Section 301(a) of the Clean Water Act. Additionally, as per Part C.1 Prohibitions of the Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, WQO No. 2006-0003, any spill that results in a discharge of untreated or partially treated wastewater to waters of the United States is prohibited. The District reported two sewage spills in calendar year 2005, three sewage spills in calendar year 2006 and one spill through May 1, 2007 from its collection system. These spills were reported to the San Francisco Bay Regional Water Quality Control Board. According to the reports, all of the reported spills were blockages as a result of root intrusion. Based on 5.5 miles of gravity sewers in the Almonte Valley Sanitary District, the spill rate was 36 spills/100 miles/yr in 2005 and was 54.5 spills/100 miles/yr in 2006. A listing of the reported spills is provided in Table 1 below. Since May 2007, the District has been required to report all sewage spills to the State Water Resources Control Board via the California Integrated Water Quality System (CIWQS) website. The spills reported to the CIWQS system were not included in this report. Table 1. Reported Spills from January 1, 2005 through SSO SSO Estimated April 30, 2007 Estimated Volume SSO Destination Cause of SSO from the Volume (gal) Recovered District’s Collection System Incident Date STREET/CURB & BLOCKA ROO May 1, 2007 10 0 GUTTER GE TS STREET/CURB & BLOCKA ROO November 4, 2006 300 0 GUTTER GE TS BLOCKA ROO April 19, 2006 150 0 YARD/LAND GE TS BLOCKA ROO February 13, 2006 200 0 YARD/LAND GE TS December 31, BLOCKA ROO 600 0 BUILDING/STRUCTURE 2005 GE TS STREET/CURB & BLOCKA ROO February 5, 2005 300 0 GUTTER GE TS 2. Failure to maintain adequate records for reported and unreported spills. As per Part B.5 of Monitoring and Reporting Program (MRP) No. 2006-0003-DWQ, the District is required to maintain records of all SSOs. A review of District files indicated that the field “Sanitary Sewer Overflow Report” used by Roto-Rooter for reporting of spills was not consistently completed with all of the required information. For example, the June 30, 2007 report (see attachment 3) has not been completed in its entirety with all of the required information as listed on the form. The report does not include the Caller‟s Name, Spill Start Time, Name of City Staff or Contractor Dispatched, Source of Spill, Cause of Spill, Final Spill Destination, or Date and Name of individual responsible for completing 8 the Field Report. In addition, the “Time Call Received" was recorded on the field log to be 5:15 (no AM or PM), providing insufficient documentation as to if the response was immediate or whether 12 hours elapsed prior to stopping the spill. 3. Failure to contain and mitigate the impacts of an SSO. As per Part D.3 of the State Water Resources Control Board Order No. 2006-0003-DWQ, in the event of a spill, the enrollee shall take all feasible steps to contain and mitigate the impacts of an SSO. The District does not have the staff, equipment, or training to respond to and contain spills and mitigate the impacts. This is demonstrated in Table 1 and by the fact that the District is not able to recover sewage after it exits the collection system. The District relies on a verbal agreement with Roto-Router to respond to spills and correct problems which may have caused the spill. The average distance between Mill Valley and Roto-Rooter in Novato is approximately 18 miles; therefore, it is unlikely that a response time would be less than 25 minutes. Other factors could lengthen the time considerably, e.g., traffic on US 101. The response time for Roto-Router varies, but according to Mr. Buehler, typically ranges between 0.5 and 1 hour. The quicker response times are typically due to spills occurring during normal Roto-Router working hours because the responders may be conducting maintenance or other activities in an area closer to the District. There is no written or verbal agreement between the District and Roto-Router regarding the maximum response time for SSOs. In addition, the District is limited to tasking Roto-Rooter with small jobs (under $15,000 for any one project) without procuring the work through a contract with a bid and proposal process. This limitation could possibly prevent Roto-Rooter from properly responding, in the event of a catastrophic spill. 4. Efforts to reduce I&I and wet weather peaking ratios. While acknowledging that the inspection focus and time spent on-site was limited, it appeared that the District has no, or limited, incentive to investigate or minimize I&I flows because capacity has not been a major cause of spills and overflows for the District. In addition, the District is billed by SASM per connection rather than for the actual flow to the WWTP. As mentioned previously, the District has an apparent peaking factor of approximately 7.5:1 to 9:1. This significant difference in dry weather and wet weather flows has a significant impact on the SASM WWTP. The District is encouraged to initiate a more aggressive approach to I&I reduction and to actively participate in SASM sponsored studies and activities. Focused and sustained efforts to reduce I&I and ultimately reduce wet weather peaking ratios will benefit both the District and SASM by reducing unnecessary and costly wastewater treatment plant upgrades, and the potential for blending and/or bypasses at the wastewater treatment plant. Summary The information gathered during the inspection indicates a lack of adequate documentation of maintenance and spill records, reporting, and tracking. The lack of this documentation appears to stem from a failure to implement a mechanism to clearly track the operation and maintenance of the sewer system, spills and associated activities, and planning for future maintenance activities. These mechanisms are essential for enabling the District to evaluate its activities to decrease the number or eliminate spills completely from its sewer system. Tracking spills and maintenance is important to identify areas where increased maintenance may be necessary. For example, Mr. Buehler stated that the entire system (approximately 5.5 miles) is cleaned annually, but the documentation provided to the inspection team did not clearly substantiate the statement. Mr. Buehler also stated that Roto-Rooter is responsible for tracking their maintenance activities, but again the documentation provided did not appear to be a sufficient tracking system to adequately document activities. The evaluation of the tracking of spills and maintenance is important to identify areas where increased maintenance may be necessary. 9 The District should augment their current spill data acquisition and tracking to collect all required information for all SSOs and vital information such as what was the source and mechanism of initial identification of a spill (e.g., resident via government pages listing for Sanitary District) and response time. The District collected relevant information on a field tracking form that was completed by field teams; however, better tracking and evaluation of the information could allow for future performance tracking and reporting. The District has no equipment or staff available to contain or mitigate SSOs, and relies on Roto-Rooter to correct problems as they arise. According to Mr. Buehler, Roto-Rooter should be cleaning and repairing “hot- spot” areas within the system as part of routine maintenance as time allows; however, as stated previously, the inspection team could not verify that these activities were completed by the documentation provided by the District. According to Mr. Beuhler, routine maintenance would include both cleaning and if necessary TV inspection of the “hot-spot” areas. Mr. Buehler did not maintain a list of hot-spot areas for the District‟s system, but provided a Roto-Rooter document “Roto-Rooter Plumbing, Contract Listing” of those locations. The inspection team was not able to determine if the frequency of cleaning and TV inspection listed on this document was actually completed. In addition, since no written contractual agreement has been prepared between the District and Roto-Rooter defining on-going maintenance requirements for the collection system, routine maintenance may be overlooked or not completed. From the information gathered during the inspection it appears the routine and event driven maintenance of the District‟s sanitary sewer collection system has been and will continue to be contracted to Roto-Rooter. The use of the contractor is indicative of a reactive program rather than proactive program and response times tend to be slower. Additionally, the details provided in work orders to the contractor, records of work performed by the contractor and spill response and reporting were judged to be minimal. SSO frequency was increasing when measured on a SSO per 100 miles/year basis, but it was unclear if this was indicative of more overflows or an improved reporting process. The data shows that additional efforts remain necessary to reduce the occurrence of SSOs. The majority of the spills were the result of blockages from root intrusion which are directly related to and attributable to operation and maintenance issues. According to the District‟s SSMP, adopted by the Almonte Board of Directors August 28, 2006, the District is in the process of developing and electronic preventative maintenance and cleaning tracking program. The District did not provide any evidence that this activity had been initiated. The District is encouraged to prioritize the development of this tracking system to be completed as soon as possible. I eventually communicated to the EPA concerns about conclusions and statements contained in the reports (see below) based on the limited time and scope of the actual onsite inspections, failure to clarify or update document requests, etc. and the lack of review afforded our agencies prior to publication of the reports.  “The use of the contractor is indicative of a reactive program rather than proactive program and response times tend to be slower” is simply opinion stated as fact with no supporting evidence provided.  The assertion that the District has no personnel or equipment for spill response is untrue. The district manager lives in the district and as a matter of district policy, responds to all spills occurring in the district and many times is the first responder on site. While we do not 10 own rodding or flushing equipment Almonte does have expertise and equipment to mitigate the impact of spills.  Use of a “spills per 100 miles” equivalency is extremely misleading for agencies that have relatively small collection systems and inflate the actual impact of a limited number of relatively small spills.  There seemed to be little interest in following up the initial inspection by requesting clarification or additional information when questions arose, as reflected in comments in the report about the ability to understand documents provided or to verify assertions made by district personnel during the inspection. Regulators Issue Orders: RWQCB Cleanup and Abatement Order No. R2-2008-0010 issued 2/8/2008 EPA Administrative Order Docket No. CWA-309(a)-08-030 issued 4/10/08 Federal, state and local regulatory agencies responded swiftly following the spill of January 31, 2008, both in reaction to that spill itself but also in response to the massive amount of press coverage of the January 31, 2008 spill and the subsequent revelation that another “spill” had occurred on January 25, 2008. On February 8, 2008, the RWQCB issued Cleanup and Abatement Order No. R2-2008-0010 (Available here: http://www.swrcb.ca.gov/rwqcb2/board_decisions/adopted_orders/2008/R2-2008- 0010.pdf). The order required SASM to cleanup and abate the effects of partially treated sewage discharged into Richardson Bay and take other necessary remedial action to prevent threatened conditions of pollution or nuisance. Among other requirements, SASM was instructed to hire and independent external auditor to conduct a comprehensive audit to “demonstrate that the ongoing threat of discharge of wastes into the waters of the State and the threat to create a condition of pollution and nuisance have been abated by verifying the Discharger‟s effectiveness in complying with Order No. R2-2007-0056, Attachment D, Section I.D., Federal Standard Provisions for Proper Operation and Maintenance. The EPA, having already conducted Clean Water Act Compliance Evaluation Inspections for most of the SASM member agencies, moved forward with the issuance of orders of its own. On April 4, 2008, administrative orders were issued to SASM and its member agencies and the Sausalito-Marin City Sanitary Districts and their satellite systems, the city of Sausalito and Tamalpais Community Services District. 11 Administrative Orders Issued for Marin County Sewage Collection Systems Sanitary Districts of Southern Marin Click for a larger view The U.S. Environmental Protection Agency today issued enforcement actions requiring nine sewage collection systems in the Sausalito and Mill Valley areas of southern Marin County, Calif. to address chronic sewage spills, improve sewer maintenance and implement long-term programs to renew aging sewer pipes. The deteriorated condition of the sewer systems became evident in January 2008 when heavy rains overwhelmed the systems resulting in large spills to Richardson Bay and San Francisco Bay. The EPA enforcement orders were issued to the cities and sanitary districts that convey wastewater to the sewage treatment plants operated by the Sewerage Agency of Southern Marin in Mill Valley and the Sausalito-Marin City Sanitary District at Fort Baker. » Press Release 4/10/08 Adminstrative Order for Sausalito- Adminstrative Order (amended) Marin City Sanitary District - for Sewerage Agency of Southern Amended (PDF) (34 pp, 1.5M) Marin (PDF) (31 pp, 1.8M)  City of Sausalito  Almonte Sanitary District  Tamalpais Community  Alto Sanitary District Services District  City of Mill Valley  Homestead Valley Sanitary District  Richardson Bay Sanitary District  Tamalpais Community Services District Deteriorated conditions of the sewer systems became evident when heavy rains overwhelmed the systems causing several large sewage spills into Richardson Bay and San Francisco Bay in January 2008. Rainwater infiltrated into cracked pipes, causing January 25 flows to exceed the capacity of the emergency holding basin at the SASM wastewater treatment plant, where 2.45 million gallons overflowed to Richardson Bay. Another spill occurred on January 31 when operators at the SASM treatment plant failed to operate all of its discharge pumps leading to a 2.7 million gallon spill to Richardson Bay. In Sausalito, the January 25 storm led to a 63,000 gallon spill from a sewer manhole on Marinship Way. EPA inspections of the collection systems revealed that they have a history of chronic spills. Most spills are relatively small volume and caused by roots growing into cracks in the pipes. This pattern of spills is commonly found in aging sewer systems in which many pipes were installed in the 1950’s and earlier. During winter storms, rainwater leaking 12 into defective pipes leads to even greater problems including large volume spills and disruption of wastewater treatment plants. Sewage spills are reported to the State Water Resources Control Board and these reports are available to the public on the Board’s Web site . The EPA orders require the sewer systems to employ a number of strategies to reduce sewage spills. In the short- term, the systems are required to implement aggressive sewer cleaning programs aimed at the most problematic pipes. The systems are also required to inspect their sewer pipes and measure wet weather flows that are passed on to the sewage treatment plants. Finally, the systems must develop plans to manage excess flows and implement long- term programs to repair and replace deteriorated sewer pipes. The wastewater collection and treatment systems in southern Marin County are managed by several small sewer districts and cities. The small size and fragmented nature of the sewer agencies has made it difficult to adequately fund and effectively manage wastewater. As the sewer systems have aged and deteriorated, the cost of repair and rehabilitation has increased considerably placing further strain on the small districts and cities. The Sewerage Agency of Southern Marin treats wastewater from about 28,000 people in the Mill Valley area. The sewage is collected from homes and businesses in networks of sewer pipes that are owned and maintained by five separate sanitary districts and the city of Mill Valley. Sausalito-Marin City Sanitary District treats wastewater from about 16,500 people in Sausalito, Marin City and Tam Valley. With the Orders, EPA encourages the cities and sewer districts to coordinate their responses to the orders and collaborate in actions to finance, operate and renew their wastewater infrastructure. EPA and its contractor conducted compliance evaluation inspections of the Marin County sewage collection systems last fall and earlier this year.  Mill Valley Inspection Report (PDF) (13pp, 130K)  Sausalito-Marin City Sanitary District Inspection Report (PDF) (38pp, 4M)  City of Sausalito Inspection Report (PDF) (26pp, 1.5M)  Almonte Sanitary District Inspection Report (PDF) (23 pp, 1.29M)  Alto Sanitary District Inspection Report (PDF) (21 pp, 915K)  Homestead Valley Sanitary District Inspection Report (PDF) (18 pp, 650K)  Richardson Bay Sanitary District Inspection Report (PDF) (19pp, 649K)  Tamalpais Community Services District Inspection Report (PDF) (23 pp, 1.4M)  Sewerage Agency of Southern Marin Inspection Report (PDF) (19 pp, 990K) *Home phone numbers and names of private citizens that appear in the report attachments have been redacted from the Web posting of the inspection reports. 13 Agency Compliance Record: The EPA Order required the SASM and its member agencies to submit a Sewage Spill Reduction Action Plan (SSRAP) as detailed in the order and to implement their current programs for controlling sewage spills. The agencies were also required to immediately implement improvements to their current programs that are consistent with the requirements contained in the order. If a program currently being implemented by SASM or the member agencies fails to meet the requirements of the Order, SASM or a member agency, as appropriate, must implement the improvements necessary to satisfy the Order. To the extent that an existing program satisfies the requirements of the Order, SASM or a member agency may submit a description of its program for review and approval by EPA. The main elements of the order are detailed below: I. ELIMINATION OF COLLECTION SYSTEM SPILL II. SPILL RESPONSE, RECORDKEEPING, NOTIFICATION & REPORTING III. COLLECTION SYSTEM MAINTENANC AND MANAGEMENT IV. COLLECTION SYSTEM ASSESSMENTS V. CAPACITY ASSURANCE VI. INFRASTRUCTURE RENEWAL VII. IMPLEMENTATION STUDY AND REPORT VIII. PLAN REVIEW AND APPROVAL IX. QUARTERLY SPILL REPORTS X. ANNUAL PROGRESS REPORTS To a large extent these elements are similar to those contained in the existing SSMP regulatory requirements. However, the order required EPA review and approval of existing SSMP and agency programs and practices as well the requirement to conduct new investigations to detail existing conditions and/or demonstrate compliance or future corrective action. To facilitate agency response to the order, SASM and its member agencies retained RMC Water and Environment, a respected consulting firm, to assist in response to and implementation of the order. SASM and its member agency are currently in compliance with the order as reflected in the compliance timetable below: 14 15 Agency SSRAP submittals are available under “other documents” at almontesd.org here: http://www.almontesd.org/documents.php SASM and its member agencies are in compliance with the requirements of all orders issued by regulators. Agency Success in Reducing SSOs: SASM and its member agencies have made a concerted effort to reduce both the number and volume of SSOs. The information graphed below is from the CIWQS database. 16 17 Although a “zero-spill” record is the goal of every agency, SSOs continue to occur despite agency implementation of best management practices (BMPs) and are more of a problem for some agencies than others due to a variety of factors. Please note the number of SSOs experienced by the four sanitary districts, Almonte, Alto, Homestead Valley and Richardson Bay are substantially less than those experienced by the City of Mill Valley even though the four districts have about equivalent miles of sewer in their respective collection systems. These four sanitary districts have had aggressive cleaning programs in place for years. The analysis of spill volumes below indicates that spills occur infrequently, are of relatively small volume, are responded to and resolved rapidly, pose little threat to public health and are likely to have little impact on “waters of the state” which have been interpreted to include spills that may reach a storm drain (although the storm drain may be far away from any creek, stream, marsh or bay). Spill Volume Analysis (5 Agencies – Almonte, Alto, Homestead Valley, Richardson Bay and Mill Valley) Previous 4-Years Homestead Richardson City of Mill Almonte Alto Valley Bay Valley 2010 150 0 35 540 2,589 2009 150 150 700 1,158 11,171 2008 0 15 100 2,315 11,316 2007 1,580 0 0 1,575 10,124 Total SSO Vol. 1,880 165 835 5,588 35,200 Total SSOs 10 4 10 45 187 Avg. Gal/SSO 188 41 84 124 188 Total Volume Recovered (5 agencies) 6,347 Total Number SSOs 256 Avg. Gal/SSO Recovered 25 Previous 2-Years 18 Homestead Richardson City of Mill Almonte Alto Valley Bay Valley 2010 150 0 35 540 2,589 2009 150 150 700 1,158 11,171 Total SSO Vol. 300 150 735 1,698 13,760 Total SSOs 3 3 4 12 66 Avg. Gal/SSO 100 50 184 142 208 Total Volume Recovered (5 agencies) 2,537 Total Number SSOs 88 Avg. Gal/SSO Recovered 29 Last 1-Year Homestead Richardson City of Mill Almonte Alto Valley Bay Valley 2010 150 0 35 540 2,589 Total SSO Vol. 150 0 35 540 2,589 Total SSOs 2 0 2 3 19 Avg. Gal/SSO 75 0 18 180 136 Total Volume Recovered (5 agencies) 580 Total Number SSOs 26 Avg. Gal/SSO Recovered 22 Spill Volume Analysis (4 Agencies – Almonte, Alto, Homestead Valley, Richardson Bay) Previous 4-Years Almonte Alto Homestead Valley Richardson Bay 2010 150 0 35 540 2009 150 150 700 1,158 2008 0 15 100 2,315 2007 1,580 0 0 1,575 Total SSO Vol. 1,880 165 835 5,588 Total SSOs 10 4 10 45 Avg. Gal/SSO 188 41 84 124 Total Volume Recovered (4 agencies) 580 Total Number SSOs 69 Avg. Gal/SSO Recovered 8 Previous 2-Years 19 Almonte Alto Homestead Valley Richardson Bay 2010 150 0 35 540 2009 150 150 700 1,158 Total SSO Vol. 300 150 735 1,698 Total SSOs 3 3 4 12 Avg. Gal/SSO 100 50 184 142 Total Volume Recovered (4 agencies) 580 Total Number SSOs 22 Avg. Gal/SSO Recovered 26 Previous 1-Years Almonte Alto Homestead Valley Richardson Bay 2010 150 0 35 540 Total SSO Vol. 150 0 35 540 Total SSOs 2 0 2 3 Avg. Gal/SSO 75 0 18 180 Total Volume Recovered (4 agencies) 580 Total Number SSOs 7 Avg. Gal/SSO Recovered 83 Collection Agencies Blamed for SASM spills of 2008 The assignment of blame for the January 25, 2008 SASM spill focused on “deteriorated” collection systems and the small districts that operate them for allowing wet-weather I&I to “overwhelm” the SASM treatment plant. Even the January 31, 2008 spill focused on the wet-weather component although it clearly resulted from operator error. The EPA press release below and your comments in quoted in the Marin IJ on February 6, 2008 and March 10, 2008 are representative of many of the public and governmental comments reported in the press coverage. U.S. EPA orders Marin County sewage collection systems to address chronic sewage spills Release date: 04/10/2008 Contact Information: Wendy Chavez, 415/947-4248, chavez.wendy@epa.gov (San Francisco, Calif. -- 04/10/2008) The U.S. Environmental Protection Agency today issued enforcement actions requiring nine sewage collection systems in the Sausalito and 20 Mill Valley areas of southern Marin County, Calif. to address chronic sewage spills, improve sewer maintenance and implement long-term programs to renew aging sewer pipes. Deteriorated conditions of the sewer systems became evident when heavy rains overwhelmed the systems causing over 5 million gallons of sewage to flow into Richardson Bay and San Francisco Bay earlier this year. “These small, underfunded and undermanaged systems will continue to pose threats to San Francisco Bay if communities fail to upgrade and maintain their systems sustainably,” said Alexis Strauss, the EPA’s Water Division director for the Pacific Southwest region. “We urge the systems to begin to work together and invest in long-overdue assessment, repair and replacement of their wastewater infrastructure.” Marin IJ 2/6/08 Assemblyman Jared Huffman, D-San Rafael, said the spills highlight local sewage agencies' failure to maintain their pipes and plants. And, he said, the spills point to the need to break free of the "parochial" nature of small local sewer boards that ring Richardson Bay and to create a governmental structure that will resolve problems. The situation reflects a "fractured governance system" where small, low-profile boards operate with little public discussion of possible problems. The spills are "serious stuff and it's unacceptable," he said. Marin IJ 3/10/08 ASSEMBLYMAN Jared Huffman says consolidating the "little banana republics" that run Southern Marin's sewerage system may be the key to fixing problems that have prompted massive sewage spills. Huffman says analyzing the problem is a starting point. "I don't come to the table with any locked-in view of the solution, but I want to make sure we're all talking about the problem and getting some tools to deal with it," said Huffman, D-San Rafael, the most outspoken proponent of consolidating smaller sewer districts. Huffman is pushing for meetings between district officials to examine mergers and other ideas. He also would consider a pipe-funding ballot measure he compared to the multiyear fire flow tax used by the Marin Municipal Water District. "Any benefits you would see of the highly localized control are more than overshadowed by the downsides you see," Huffman said. "Who pays when all the contaminated sewage spills into Richardson Bay? We all have an interest in making sure that stops." He said the frequency of fines levied on Bay Area sewage districts highlights flaws in the system. 21 Independent Studies: Agencies Wet-Weather Impact on SASM Treatment Plant The assignment of blame for the January 25, 2008 SASM spill focused on “deteriorated” collection systems and the small districts that operate them for allowing wet-weather I&I to “overwhelm” the SASM treatment plant. Even the January 31, 2008 spill focused on the wet-weather component although it clearly resulted from operator error. However, review and analysis by two independent consultants tell an entirely different story. These studies were conducted to address requirements imposed by the RWQCB cleanup and abatement order and the EPA‟s administrative order. The first, conducted by John Larson as a part of the Larry Walker Associates independent audit required by the cleanup and abatement order, analyzed the flows to the WWTP for the January 25, 2008 storm event and demonstrates that flows to the SASM plant from its member agencies were in accordance with design expectations. The second, conducted by RMC Flow and Environment as part of the SSRAP requirement of the EPA order, confirms that SASM‟s member agencies have not allowed their lines to deteriorate over the past 30 years based on original flow and I&I design parameters (Black & Veatch 1980 Sewer System Evaluation Survey). For a detailed examination of the original plant wet-weather design please see (Appendix: B, September 16, 2008 letter to EPA). (The RMC report is excerpted below, highlighting added) Section 4 Capacity Assessment 4.1 Introduction 4.1.1 Purpose This portion of the SSRAP submittal presents the results of the collection system capacity assessment to comply with subsection IV.B.3 of the Order. This subsection of the Order requires that the agencies identify areas, sources, and quantities of infiltration/inflow (I/I) in the collection system; identify bottlenecks to conveying wet weather flows; and discuss the impact of flows from one agency to another and on SASM‟s wastewater treatment plant (WWTP). This capacity assessment for SASM and its member agencies is based on flow monitoring data obtained during the 2008/09 and 2009/10 wet weather seasons and hydraulic modeling of the SASM conveyance system and key portions of the member agency collection systems. The capacity assessment has been used to develop a Capacity Assurance Plan as required under Section V.B of the Order (see Section 5 of this report) and to complete the Pump Station Reliability Certification 22 4.5 Design Event Since flow response to wet weather events varies with storm rainfall (as well as other factors), quantifying I/I in the system and identifying hydraulic constraints must be referenced to a “design” condition or “design event.” In the case of SASM, the design event has been defined as the storm of January 25, 2008, a notable event in recent memory that resulted in high flows to the SASM WWTP and a major wet weather spill. Another recent large storm event that has been used by some agencies as a design condition, the storm of December 31, 2005, caused widespread surface flooding and drainage problems in many areas of Marin County, including the SASM service area; therefore, it was not considered appropriate for SASM for use in assessing wastewater system capacity. Rainfall amounts for the January 25, 2008 storm were obtained for two rain gauges in Mill Valley and one gauge maintained by TCSD at its district offices on Bell Lane. The design event rainfall pattern is depicted in Figure 4-10 for the TCSD and one of the Mill Valley rain gauge sites. Figure 4-10: Design Rainfall Event Based on available rainfall depth-duration-frequency statistics, the January 25, 2008 storm is estimated to have been an approximate 20-year return frequency event in the Mill Valley area for 24-hour duration, and a 5- to 10-year frequency event for shorter (e.g., 4- to 6-hour) durations. Therefore, this storm is considered an appropriate event for assessment of both collection system and WWTP capacity. The I/I estimates and system capacity analysis results presented in the remaining sections of this Capacity 23 Assessment are based on the analysis of the system, using the hydraulic model, for the design wet weather 4.8 Impact to SASM from Member Agency Collection Systems The peak wet weather flow to the SASM WWTP for the design event is predicted by the model to be approximately 31 mgd. This is very close to the original design peak wet weather flow capacity of the WWTP of 32.7 mgd and slightly lower than the peak influent of flow of 33 mgd that was recorded at the plant during the January 25, 2008 storm event (the actual influent flow may have been slightly lower based on 2009 influent meter calibration records). To validate the predicted modeled peak flow, the model was also run for a synthetic rainfall event assumed to have a total 24-hour rainfall amount of 4.82 inches, representing a 20-year return frequency event for the Mill Valley area1, and an SCS Type IA temporal rainfall distribution. (Note: for this model run, the rainfall was assumed to be the same throughout the SASM service area. While this assumption does not reflect the actual variation of rainfall with location and elevation, it provides a reasonable approach for assessing the total flow in the system.) The peak flow to the WWTP based on the synthetic 20-year return frequency rainfall event was approximately 32 mgd, again very close (within 3 percent) to the original WWTP design flow and the model-predicted and recorded flow for the January 25, 2008 event. These results indicate that the flows to the SASM WWTP are similar to those projected during the design of the system, and that overall flows do not appear to have changed significantly over the past 25 to 30 years. However, the peak wet weather flows in the SASM system are still very high, representing a design event peak flow to the WWTP of about 15 times summertime average dry weather flow. These high peak flows result in surcharging of SASM pipelines and, in some cases, adverse backwater impacts on member agency sewers. Furthermore, it appears that the distribution of flows within the system may be different than originally estimated, resulting in more severe capacity deficiencies in some areas of the system than had been previously calculated. Flows from Alto, Almonte, HVSD, and Mill Valley have the most significant capacity impacts on the SASM system, as indicated by the areas of predicted high surcharge during peak wet weather conditions. Table 4-2 summarizes the contribution by agency to the average dry weather and total design event peak wet weather flow to the SASM WWTP. Note that in this table, the peak flows by agency represent the sum of the sub-basin peak flows, which is about 5 percent higher than the modeled peak flow to the WWTP due to flow attenuation and existing capacity restrictions in the system. It should also be noted that I/I into SASM pipelines cannot be specifically isolated and may be included in the estimated flow values for some of the member agencies, most notably Almonte. As noted previously, all of the flow 24 meters used to isolate Almonte flows were installed on SASM pipelines. The SASM pipelines upstream of the Almonte flow meters comprise 15 to 20 percent of the total length of sewers tributary to these meters and may be subject to significant infiltration. 1 California Department of Water Resources precipitation depth-duration-frequency data for Mill Valley (Table C-1, Sewerage Agency of Southern Marin, Sewer System Evaluation Survey, Black & Veatch, 1980) Independent Studies: Causes of SASM spills of 2008 The graph above is based on the original John Larson graph and analysis of the storm flows recorded by the SASM influent and effluent meters during the January 25, 2008 storm. It has been modified by RMC to include additional curves based on the RMC model-simulated flows, influent flows derived from a combination of actual effluent flows augmented by flows pumped to the equalization basins, spill volumes reported to regulators and flows drained back from the equalization basin for treatment and disposal. I have also included two horizontal reference lines, the first at 24.7 mgd which represents original design effluent flow. The second, at 26 mgd, represents expected when all six effluent pumps are online and pumping to the outfall at Raccoon Straight (see: Appendix C, SASM wet-weather SOP) 25 Item 5 below, from the findings section of RWQCB Cleanup and Abatement Order No. R2-2008- 0010, indicate that SASM reported influent flows of 44 MGD received from its member agencies. (http://www.swrcb.ca.gov/rwqcb2/board_decisions/adopted_orders/2008/R2-2008-0010.pdf) Although the original SASM influent flow recorders do show short-duration peak flows of 44 mgd, it was clear to investigators and former plant staff, that these short-duration peaks and precipitous plunges in recorded flow, were anomalies caused most likely by surcharging of the influent flow meter, high water levels in the influent wet well and automatic closing and subsequent opening of the main head-gate which accounts for the ping-pong flow pattern. . What is also clear from the multi-curve graph of the various influent flows is that effluent flow green line) remained substantially below both the 24.7 mgd original design flow and the 26 mgd expected flow based on all of the effluent pumps (6) operating. Examination of plant records indicate that plant 26 staff ran only five of the six available effluent pumps during the storm event. Typically, according to longstanding procedure, only flow in excess of the pumping capacity of the six effluent pumps, approximately 26 mgd, is to be pumped to the equalization basins (see attachment 3, WWTP wet- weather SOP). This is done to conserve storage and minimize potential discharges to the bay. In terms of the multi-curve graph, this means that flows below the horizontal lines but above the green effluent curve were pumped to the equalization basins instead of being treated and pumped out the outfall resulting in premature filling of the equalization ponds which in turn eventually filled and overflowed via the plants old outfall structure to Richardson Bay as the rain continued throughout the day. Calculations indicate that had staff operated the plant per SASM‟s wet-weather SOP, which would have maximized pumping through the plant at 26 mgd, the equalization basins would have had sufficient capacity to contain flows from the storm without discharging to the bay. Subsequent to the spills, SASM substantially increased equalization volume to over 3 million gallons to guard against future spills. Also, all recirculation and effluent pumps have been replaced to assure maximum secondary treatment and effluent pumping capacity. SASM also has a history of strict compliance with reporting, sampling and posting requirements for spills (see: Attachment 5) The bottom line is that SASM member agencies‟ collection systems performed pretty much as expected based on the original plant design. They may even be performing better than designed based on pump station improvements made over the years that should have increased the expected peak flows received at the treatment plant. The original design expectations for plant and member agency collection system performance (on which EPA and SWRCB grant funding was based) was that SASM and its members‟ collection systems and the SASM treatment facility could successfully, collect, treat and dispose of flows related to a 20 year storm event (sewage and I&I flows with a 32.7 mgd peak). This still appears to be the case. Proactive and collaborative actions taken by the various agencies: SASM and its member agencies, both boards and staff, have been characterized by some government officials, special interest groups, politicians, residents and members of the press, etc. as being small, parochial, dysfunctional, fragmented, underfunded, undermanaged, self-interested, and by implication environmentally insensitive, narrow-minded, self-serving, short-sighted and frugal to a fault. Officials or employees who are incapable of cooperative, collaborative behavior and unwilling, unable or incapable of providing effective operation of the agencies they serve. Nothing could be further from the truth. All of our agencies, both elected officials and staff, have spent years working to provide cost-effective, environmentally-responsible service to their communities. The Sewerage Agency of Southern Marin, by its inherent structure, is a collaborative enterprise. Formed in 1979 to spearhead improvements required by the Clean Water Act and made possible through federal and state grant funding programs, SASM and its member agencies have largely succeeded in providing cost-effective and environmentally responsible wastewater collection, treatment and disposal services to its residents. SASM has contracted operation of its facilities to the 27 City of Mill Valley (the largest SASM member representing about 50% of the service area) since the plant went online in 1983. By and large, Mill Valley has operated the plant well and SASM (with the exception of the January 2008 spills) has enjoyed a fairly exemplary compliance record. Over the years SASM and its member agencies have frequently collaborated on projects or investigate issues and possible solutions to common problems, many times related to wet weather issues. History and Common Challenges: Most if not all wastewater agencies in Marin County are in the same boat, saddled with leaky sewers, both private laterals and public pipes, that make handling wet-weather flows a challenge. All have traveled the same path regarding I&I. Collection systems are concerned with keeping the sewage in the ground and flowing. Treatment plants are concerned with treating the waste they receive - ultimately discharging the effluent to some receiving water, all in accordance to ever more stringent permit requirements. In order to qualify for grant funding in the 1980‟s when federal and state monies made upgrading aging and inadequate facilities possible, agencies were required to take a stab at tightening up their collection systems. To qualify for grants, the EPA required a cost-effective analysis of collection systems to identify and correct “excessive infiltration and inflow conditions in sewer systems” (please see Appendix: B for a discussion of the original design process) These studies showed vast amounts of infiltration and inflow entering our pipes during storms, which can as a surprise to no one operating a treatment plant or collection system. For years agencies had bypassed wet-weather storm flows directly to the bay. This was done with full knowledge of the RWQCB. Agencies were required to only eliminate I&I that was economically feasible, defined essentially to mean “cheaper to fix the pipes than to build a bigger treatment plant. Because I&I reduction is so expensive to cure and pursuing a “convey and treat” strategy is generally more cost-effective, most plants were built to accommodate large peaking factors of 10 or greater. SASM‟s original peaking factor based on a 32.7 mgd peak and a 2.9 mgd average dry weather flow was 11.3. When calculated based on actual dry weather flow received, these peaking factors are even greater, as RMC noted up to 15 times summertime dry weather flow. Most agencies, while recognizing that in a perfect world they would have tight sewers and less wet weather headaches, have found it cheaper to pursue a “convey and treat strategy” rather than fixing leaky pipes. This is partly because a significant portion of the leaking pipes are privately owned sewer lines and it has been difficult to find a strategy that effectively motivates homeowners to fix their lines. Also, it has proven more cost-effective to convey and treat the sewage than to fix the pipes. Relief sewers, larger pump stations and force mains, larger treatment, storage and disposal facilities have been the corrective measures of choice. This strategy makes a lot of sense. It helps prevent wet-weather related SSOs and conveys the sewage to POTWs for treatment and discharge according to permit standards designed to protect the receiving waters and public health. 28 The recently completed Central Marin Sanitation Agency (CMSA) wet weather improvements are an example. From the CSMA website http://www.cmsa.us/assets/documents/WWIP/20100526144917437.pdf During winter, rainwater flows into manholes and cracks in home laterals and sewer pipelines, dramatically increasing flows and exceeding the capacity of the plant. Over $50 million in Wet Weather Improvement Projects are underway to expand the facilities capacity. We have completed the expansion of our storage pond, which doubles its capacity to 7 million gallons. The purpose of the Wet Weather Improvements Project was to increase the Central Marin Sanitation Agency‟s treated capacity from 90 Million Gallons per Day (MGD) to 125 MGD and hydraulic capacity from 90 MGD, at highest tides, to over 155 MGD. This was done to ensure that the plant would meet NPDES permit requirements and not overflow wastewater or partially treated effluent into the drainage systems adjacent to the plant. Why didn‟t CMSA simply fix the pipes? Because it was cheaper to accommodate the additional flows at the treatment plant rather than eliminate them at the source. Given the sea change in regulatory enforcement posture (essentially strict liability for spills), witness the huge fines levied on SASM, agencies are reluctant to risk fines for spills, even those due to extreme storm events in excess of a 20 yr. return frequency, while the agency waits years for the repair or replacement of leaky pipes to produce significant reductions in I&I. What SASM has done to investigate and address the problem of wet weather flows and other SASM-wide issues, Examples of Collaborative Action:  Southside Sewer System Surcharge Study: Begun in 1997 and spanning many years SASM and four of its members (Almonte, Tamalpais Valley, Homestead Valley, City of Mill Valley) collaborated on projects to address surcharging in the sewer system serving the agencies. This collaboration resulted in various improvements such as pump station upgrades, sewer improvements, and ultimately in the construction of the Rosemont pump station force main directly to the SASM plant. (see Appendix: D)  Private sewer lateral testing: The SASM Board directed staff in November 1997 to research the feasibility of implementing a private lateral certification program in the SASM service area. (see: Appendix E)  Response to Spills of 2008: SASM and its members responded in a variety of collaborative efforts in response to the RWQCB, SWRCB and EPA including hiring counsel, consultants and engaging staff in various responses to the continuing regulatory requirements. This included joint efforts on the EPA SSRAP plan. Common contract with maintenance and emergency contractor  Common GIS program: The agencies collaborated on purchase and implementation of a common GIS system (SSGIS) to aid in managing their collection systems.  Joint Sewer Rehab Project: In 2010, four agencies had a joint project valued at over a million dollars to rehabilitate sewers in Almonte, Alto, Homestead Valley and Richardson Bay.  SASM continues to supply laboratory services to member agencies as well as other treatment plants (Sausalito-Marin City and Sanitary District No. 5). This includes fish bioassay, various lab analysis (Coliform, BOD, SS, salinity, chlorine residual, turbidity, etc.) 29  Monthly District Manager Meeting: Managers from SASM and its members meet at least monthly to discuss issues that impact all the agencies.  Richardson Bay collection system surcharging: In response to the huge storm on December 31, 2005 and surcharging experienced in Richardson Bay, SASM undertook actions to address a variety of problems. The letter and agenda items provided are indicative of the collaborative approach taken between staff on a routine basis: (see below pg. 30-33) sorry for the poor quality of some scans as some originals were on purple paper. 30 31 32 33 Consolidation: An Answer in Search of a Problem? Much has been made over the past seven plus years about the need for collaboration among or consolidation of the sanitation agencies of southern Marin. What began as a dispute over whether or not Tamalpais Community Services District (in an attempt to save money for their ratepayers) would end their contract for treatment services with Sausalito-Marin City Sanitary District and send all of their sewage to SASM has devolved into a fight between three small and one not-so-small sanitary districts and LAFCO about the benefits local governance. LAFCO‟s position has been bolstered by AB 1232, state legislation that gives LAFCO the ability to unilaterally consolidate four agencies against their wishes. Throw into the mix a couple of cursory Grand Jury reports, a contested LAFCO study, 2 sewage spills, $1.6 million in fines, hundreds of thousands in consultant fees, lawyers, politicians, environmental groups, a severe recession, the RWQCB, SWQCB and EPA, newspaper editorials, press releases, a host of elected officials and employees who think way too much about sewage and are doing their jobs as best they can, mix together with a variety of complex technical issues and philosophical debates - “water cooler discussions” with no real right or wrong answers and it‟s not so unusual that everyone seems to have an opinion about some aspect or issue but little agreement on the facts. Here are some facts that I think all should agree on:  The sanitary districts in southern Marin have been in existence for around sixty years. Over that time, tens if not hundreds of residents have volunteered to serve their communities in dealing with a host of issues that most would prefer not to worry about  Over those years, there has been no public outcry about rampant sewer overflows not being responded to, no history of complaints to public health officials regarding sewage exposure or public nuisance, no complaints to regulators about SSOs going unreported  No recall efforts, no scandals involving enrichment at the public expense, no outcry about the rates being charged or taxpayer money being squandered  Compensation for the directors is very modest, the costs of local governance are minimal  Districts have consistently attempted to fully comply with all regulatory requirements in a timely manner, all have met or exceeded the requirement of the EPA order  SSOs within the SASM agencies have decreased substantially, with the four smaller agencies leading the way  Almonte, Alto, Homestead Valley and TCSD have all gone through Prop. 218 rate increases. Mill Valley has just approved their own. Richardson Bay presently has sufficient reserves and income to finance their O&M and CIP needs. All agencies have committed to an aggressive infrastructure replacement program  Two independent reports confirm that SASM member agency flows are the same as they were 30 years ago and have not been allowed to deteriorate  These same reports indicate that the spills in January 2008 were not attributable to excessive flows from SASM‟s member agencies  The cost to ratepayers will likely rise due to EPA pressure to reduce I&I rather than simply convey and treat the sewage. Unfortunately, in the short term, because of the threat of fines many agency will feel pressured to do both resulting at some point in overbuilt facilities  The lack of state or federal funding means that the cost all improvements will come from local coffers. 34 Why AB 1232? With regard to AB 1232, the legislative history and legislative analysis of the bill provides some interesting observations and concerns. (See Appendix: F) Legislative analysis of an early draft of the bill excerpted below: SUMMARY: Allows the Marin County Local Agency Formation Commission (LAFCO), when specific conditions are met, to initiate and approve the consolidation of small wastewater agencies, without protest hearings. Specifically, this bill: 1) Provides the Marin LAFCO, after notice and hearing, with the power to initiate and approve a reorganization or consolidation of small wastewater agencies, without protest hearings, if all of the following conditions exist: a) The Marin LAFCO, in its municipal services review (MSR) of the wastewater agencies, completed within the last 10 years, makes findings or determinations related to reorganization or consolidation, that if implemented, would improve the financial and service level benefits, improve government accountability, improve operational efficiencies, and provide cost savings for the ratepayers; b) The wastewater agencies have not implemented LAFCO's findings or determinations as provided in the MSR; and, c) The wastewater agencies affected have had three or more illegal discharges in the last five years, based on violations identified by the San Francisco Regional Water Quality Control Board (SFRWQCB) that exceed 5,000 gallons of untreated or partially treated wastewater to waters of the state. LAFCO LAW: PROCESS FOR CONSOLIDATION OF DISTRICTS 1) Current law specifies various ways that special districts and other agencies can be reorganized and modified, including consolidation, dissolution, including dissolution with annexation, a merger, or establishment of a subsidiary district. AB 1232 focuses on consolidation – the formal restructuring transactions that would combine two or more agencies into a single organization and would require a formal LAFCO review and approval process – as the means to modify special districts. A consolidation can be initiated by a petition of registered voters or landowners, by a resolution of the governing body of an affected local agency, or by LAFCO itself. BACKGROUND OF MARIN SITUATION 2) AB 1232 originates from problems in eleven sewer services agencies located in southern Marin County, including six sanitary districts, three cities, one community services district and one joint powers agency. Three of the agencies operate wastewater treatment plants – Sanitary District No. 5 (Tiburon), the Joint Powers Agency (Sewerage Agency of Southern Marin – SASM), and the Sausalito-Marin City Sanitary District (SMCSD). Ten of the eleven agencies operate sewerage collection systems and pumping stations. All of the special districts providing sanitary sewer services are governed by 35 independent boards, except for SASM, whose members are appointed by each of its six member agencies. 3) The author notes that "the frequency and size of illegal sewage spills of raw or partially treated sewage are increasing often because of the improper sewer system maintenance. By providing limited new authority to a LAFCO, AB 1232 would increase the cost effectiveness and efficiency of small wastewater agencies and reduce the impacts on water quality due to illegal sewage spills. The San Francisco Bay Regional Water Quality Control Board reports that over 2,000 separate illegal sewage spills occurred in the bay and coastline between 2004 and 2007. Over 500 of the spills exceeded 1,000 gallons. One of the largest spills was 2.5 million gallons in Marin County which illegally discharged both untreated and partially treated sewage into the San Francisco Bay." PROVISIONS OF AB 1232 4) This bill sets up a process that would allow Marin LAFCO to force the consolidation of small wastewater districts, when specific conditions are met, without protest hearings. The specific conditions provided in the bill are the following: a) Small wastewater agencies provide services for up to 10,000 service connections; and b) The Marin LAFCO's MSR (completed in the prior 10 years) recommends consolidation or reorganization that, if implemented, would improve the financial and service level benefits, improve government accountability, improve operational efficiencies, and provide cost savings for the ratepayers. c) The wastewater agencies affected have had three or more illegal discharges of untreated or partially untreated wastewater that exceed 5,000 gallons in the previous five years, as identified by the San Francisco Regional Water Quality Control Board. IS CONSOLIDATION OF DISTRICTS THE ANSWER? 5) Protest proceedings are established in existing law to allow registered voters and landowners to give oral or written protests against a change of organization. AB 1232 removes the ability of the Marin LAFCO to hold protest hearings for public input and for an affected district to speak and deliberate in a public forum on the issue of forced consolidation and whether it is the best option for the community. Protest proceedings are removed from the bill because, according to the author, "there has been strong local agency resistance to consolidation. That resistance has made it impossible under existing laws to implement the LAFCO consolidation recommendation because existing law requires a majority of voters in the affected districts to approve the consolidation." 6) There is the potential that a district would be forced, against its will, under the provisions of this bill, to consolidate with other districts or agencies. An unwilling district could then sue LAFCO because LAFCO would be the entity that initiates the forced consolidation. The Committee may wish to consider whether Marin LAFCO would ever use this process, given the legal implications. 7) In their initial letter of concern, the California Association of Sanitation Agencies (CASA), writes: 36 "CASA's major concern is that LAFCOs have little expertise in water quality or wastewater treatment issues. CASA feels the more appropriate way to address sanitary sewer overflows (SSOs) is pursuant to existing statutory and regulatory requirement under the Clean Water Act and Porter Cologne Act, or direct consolidation such as designating agencies to be consolidated in legislation. To provide a consistent, statewide regulatory approach to address SSOs, the State Water Resources Control Board adopted Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, Water Quality Order No. 2006-0003 (Sanitary Sewer Order) on May 2, 2006. The Sanitary Sewer Order requires public agencies that own or operate sanitary sewer systems to develop and implement sewer system management plans and report all SSOs to the State Water Board's online SSO database. Consequently, we feel that the [CAL] EPA, State Water Board, and Regional Boards are in a far better position to address SSOs than are LAFCOs. In fact it is our understanding that the particular agencies contributing to recent spills are currently under EPA orders." 8) Clean Water Action and San Francisco Baykeeper, writing in support of AB 1232, note that "illegal sewage spills of raw or partially treated sewage occur frequently in the Bay Area when heavy rains infiltrate aging pipes and overwhelm poorly maintained sewer systems. This problem has been particularly evident in Marin, where small wastewater agencies have had a history of capacity and compliance issues….the problem is a systemic one and requires a change to the wastewater management framework." Additionally, "small wastewater agencies, like the eleven small agencies in southern Marin, are often unable or unwilling to bear the high cost of maintenance and repair of sewer lines and treatment plants." 9) In their opposition letter, Ross Valley Sanitation District (located in central Marin County), notes that "(1) it is unfair for any LAFCO to impose reorganization or consolidation of any public agency without the opportunity for a protest hearing, and (2) if the bill is intended to affect southern Marin then the language should be explicit to southern Marin." 10) While consolidation of smaller agencies may increase administrative effectiveness and provide for better management of those agencies, there are no guarantees that consolidation is the answer to the question of how to prevent illegal sewage discharges. There may be other avenues to pursue that would help sanitary districts update their aging infrastructure including federal and state grants or funding, or heavier enforcement if negligence is found on the part of the sanitary districts. The Committee may wish to consider whether the approach in the bill is the correct approach to address illegal sewage discharges. 11) Right now this bill gives Marin LAFCO the power, under narrow circumstances, to initiate consolidation of agencies without protest hearings. The Committee may wish to consider whether it makes more sense to have SFRWQCB serve as the petitioner for the reorganization or consolidation through Marin LAFCO because of SFRWQCB 's expertise in water quality issues and enforcement actions related to sewage spills. 12) This bill will set a precedent of giving LAFCO more power than under current law. This bill, if signed into law, could pave the way for other instances where power could be taken away from agencies and their customers and given to LAFCO. The Committee may wish to consider the future implications that this bill may set. THRESHOLDS, TIMELINES AND BILL SCOPE 37 13) AB 1232 specifies several thresholds and timelines that would need to be met in order for consolidation to be forced by the Marin LAFCO. First, the bill specifies that there must be three or more sewage discharges of 5,000 gallons in a five-year period. Second, the definition of small wastewater agencies applies to those sanitary districts that have 10,000 service connections or less. Lastly, the municipal services review done by the commission has to be completed within the prior 10- year period and make findings that reorganization or consolidation would improve the financial and service level benefits, increase operational efficiency, and provide cost savings for the ratepayers. The Committee may wish to discuss whether these thresholds are appropriate. 14) AB 1232, if signed into law, will take effect on January 1, 2011. The assumption for the smaller wastewater agencies in southern Marin is that they have a few years to figure out a plan to consolidate on their own terms, and then can initiate consolidation before the bill's effective date. However, this is not explicitly spelled out in the bill. The Committee may wish to consider giving a date certain to have LAFCO start the consolidation process, but only if a solution has not been reached locally by the agencies. 15) Currently AB 1232 only deals with Marin County, because of the unique nature of the problems in southern Marin. The Committee may wish to ask the author to narrow the scope of the bill further, specifically to the agencies in southern Marin County, and provide for a one-time special statute, rather than setting up a process that can be used in the future anywhere in Marin County. REGISTERED SUPPORT / OPPOSITION: Support Clean Water Action San Francisco Baykeeper Opposition Ross Valley Sanitary District Analysis Prepared by: Debbie Michel / L. GOV. / (916) 319-3958 Of interest is that the AB 1232‟s original focus seemed to be on environmental protection, in that the original bill had three thresholds or triggers that had to be met before LAFCO could consolidate agencies without protest. Provision c) below required the affected agencies to have had 3 or more spills that exceeded 5,000 gallons in the past 5 years to the waters of the state. This would have given the affected agencies the ability to demonstrate that they had complied with the bill in a concrete way. In fact, the four agencies targeted by LAFCO (Almonte, Alto, Homestead Valley and Richardson Bay) would not have triggered the consolidation provision because they have not had 3 or more spills that exceed 5,000 gallons to the waters of the state a) Small wastewater agencies provide services for up to 10,000 service connections; and b) The Marin LAFCO's MSR (completed in the prior 10 years) recommends consolidation or reorganization that, if implemented, would improve the financial and service level benefits, improve government accountability, improve operational efficiencies, and provide cost savings for the ratepayers. 38 c) The wastewater agencies affected have had three or more illegal discharges in the last five years, based on violations identified by the San Francisco Regional Water Quality Control Board (SFRWQCB) that exceed 5,000 gallons of untreated or partially treated wastewater to waters of the state. AB 1232 Moves Forward: As the bill proceeded, the Senate substantially narrowed the focus by targeting only SASM and its member agencies and removing objective triggers such as c) above and substituted language that that is ambiguous in its expectations and vague as to how compliance is demonstrated. (i) It is the intent of the Legislature that SASM and its member districts take action immediately to increase the effectiveness and efficiency of its operations in order to provide more cost-effective customer service and to reduce the impacts on water quality due to illegal sewage spills. It is also the intent of the Legislature that if SASM and its member districts do not act to address the inefficiencies of their operations, that the Marin LAFCO shall have the authority to require consolidation of SASM and its member districts into one new district. The agencies are required to reduce the impacts on spills but there are no concrete guidelines or benchmarks to signal compliance. Also, the requirement to “immediately increase the effectiveness and efficiency of their operations to provide more cost-effective customer service” suffers from the same lack of specificity – determination of compliance is apparently left simply to LAFCO‟s discretion. Failure to address “inefficiencies” of their operations is apparently what is required to trigger LAFCO‟s authority to consolidate. There are a couple of admonishments contained in the commentary that bear repeating: The first is CASA‟s point that LAFCO‟s have little expertise in running sanitary districts and that many aspects of district operation are governed by terms and conditions contained in EPA orders. In their initial letter of concern, the California Association of Sanitation Agencies (CASA), writes: "CASA's major concern is that LAFCOs have little expertise in water quality or wastewater treatment issues. CASA feels the more appropriate way to address sanitary sewer overflows (SSOs) is pursuant to existing statutory and regulatory requirement under the Clean Water Act and Porter Cologne Act, or direct consolidation such as designating agencies to be consolidated in legislation. To provide a consistent, statewide regulatory approach to address SSOs, the State Water Resources Control Board adopted Statewide General Waste Discharge Requirements for Sanitary Sewer Systems, Water Quality Order No. 2006-0003 (Sanitary Sewer Order) on May 2, 2006. The Sanitary Sewer Order requires public agencies that own or operate sanitary sewer systems to develop and implement sewer system management plans and report all SSOs to the State Water Board's online SSO database. Consequently, we feel that the [CAL] EPA, State Water Board, and Regional Boards are in a far better position to address SSOs than are LAFCOs. In fact it is our understanding that the particular agencies contributing to recent spills are currently under EPA orders." The second is the admonition that: 39 While consolidation of smaller agencies may increase administrative effectiveness and provide for better management of those agencies, there are no guarantees that consolidation is the answer to the question of how to prevent illegal sewage discharges. There may be other avenues to pursue that would help sanitary districts update their aging infrastructure including federal and state grants or funding, or heavier enforcement if negligence is found on the part of the sanitary districts. The Committee may wish to consider whether the approach in the bill is the correct approach to address illegal sewage discharges. Additionally, I would note there is no guarantee that consolidation will increase administrative effectiveness or provide for better management. The last observations and concerns come from a document for the Senate Local Government Committee, Senator Patricia Wiggins, Chair. (See attachment D) 3. Resetting the threshold. For their first three decades, LAFCOs couldn’t initiate proposals to change special districts’ boundaries. The 1993 bill that let LAFCOs initiate district proposals balanced that new power by reducing the protest threshold needed to trigger an election from 25% to 10% (AB 1335, Gotch, 1993). It’s easier to force an election if LAFCO initiated the proposal. If legislators worry that it’s too easy for Marin County’s small sewer districts to rally their constituents to protest a LAFCO-initiated reorganization, then the Committee may wish to consider restoring the 25% protest threshold instead of sidestepping protests. 5. Progressive or Populist? California’s boundary change statutes reflect the state’s curious blend of Progressive and Populist political impulses. The Progressive Era touted representative government, expert advice, and orderly government. The Populist cause championed direct democracy, common sense, and responsive governments. While the two goals aren’t antithetical, reconciling them can be hard. By creating LAFCOs composed of local elected officials whose decisions must follow expert plans, the Cortese- Knox-Hertzberg Act clearly reflects the Progressive tradition. By requiring petitions, allowing protests, and providing for voter review, the Act also acknowledges Populist themes. More than a century ago, the United States Supreme Court explained that there is no constitutional right to vote on local boundaries. The Cortese-Knox-Hertzberg Act’s provisions for protest hearings that may lead to elections are statutory opportunities, not constitutional rights. What the Legislature has created, it can waive. Does LAFCO Need AB 1232? To LAFCO‟s credit, the proposed review process should allow for a comprehensive examination and discussion of the issues. However, it seems to me that the value of local governance is really a question for the local community to answer. Also, implementation of suggested changes identified by LAFCO is not guaranteed by simply consolidating the districts. LAFCO may point to potential savings from various courses of action but final evaluation and implementation will be left to elected public officials, regardless of their ultimate number, but whose job it is to make those determinations. Currently, LAFCO has the power now to initiate consolidation proceedings. If their arguments for consolidation are so persuasive they should encourage a full public debate and allow the merits of their positions to carry the day. The districts subject to consolidation still would have to muster the required protest threshold to trigger an election and prevail. 40 LAFCO‟s arguments may not be as cut and dried as they claim. Below is an excerpt for their own 2005 study upon which they rely to demonstrate the benefits of consolidation. Please note the highlighted section below which apparently represents the objective conclusions of the consultant. Important Drivers for Change, highlights two drivers for change, SSMP/SSO requirements and investment in infrastructure replacement that have already been addressed to a significant degree in complying with the terms and conditions of the EPA administrative order. , Why Isn’t This Happening Now? (Barriers to Change) There are many reasons why these changes have not occurred to date. As illustrated in Figure 6-6, the agency survey, in sharp contrast to the generally positive support for collaboration, was more negative about the benefits of political consolidation. For starters, the current agencies, as structured, have been providing generally good levels of service, at affordable and fairly stable sewer rates. They have been operating in compliance with historic regulatory and permit requirements. Moreover, the decentralized agency structure with independent board/city council oversight provides an organization structure and governance structure that places a very high priority and importance on local control of sewer rates and service level polices. They believe that local control and low overhead organizations will allow them to maintain low sewer services rates. The sewer agencies are also staffed by competent managers, engineers, operators and staff. The existing agency structure has evolved with development within the small individual areas for which they provide service. Residents with questions or issues know the part-time GMs and can call them at their residence The general thrust of objections seems to focus around loss of local control coupled with increased overhead expenses and paperwork to administer multi-agency activities. Individual agencies talk about personal relationships and attention to follow-up on service-related questions. The implication is that this kind of personalized customer follow-up and prompt response, for example to a blockage incident, would not occur in an integrated agency. There seems to be a general belief that the status quo is quite stable. Important Drivers for Change. Circumstances are changing and some level of change to the methods and structure of the Southern Marin sewer agencies may be inevitable. The opportunity exists to proactively chart the course and manage the process. The current 11-agency structure is no longer the ideal configuration for serving the highly urbanized areas they now serve in Southern Marin County. Major investments in aging collection system infrastructure replacement and rehabilitation represent a brand new investment cycle for these agencies. The estimated replacement cost for providing current modern sewer collection piping for the 242 miles of collection system range from $130 to $260 million in 2005 dollars. This investment cycle will begin over the next 10 years, sooner for some agencies. In addition, the SSMP/SSO requirements, as discussed in the report, impose a new regulatory program with the need for significant increases in operational expenses to competently implement the program. Two of the three agencies with treatment plants also anticipate significant future capital investment needs. Some of the agencies have recently implemented or are planning rate increases (e.g., Mill Valley from the $243/EDU to $297 per EDU; Belvedere from $700 per EDU to $900 per EDU as part of SD#5 annexation). The City of Sausalito, SD #5 and TCSD are also 41 planning rate increases. The upcoming investment cycle will gain advantage through either JPA- based collaboration and/or actual political consolidations. Page 50 of 99 (the full report is available here: http://lafco.marin.org/staff_reports/pdf/Sewer%20Services%20Report%20FINAL_29Jul05.pdf ) Rates Are Going Up For Everyone: As noted, the EPA‟s has focused on and encouraged reduction of I&I as the preferred approach to reduce high wet-weather flows. This emphasis coupled with the willingness to use enforcement actions such as substantial fines and/or administrative orders, consent decrees, etc. to drive the point home has gotten the attention of the wastewater community. The problem for collection and treatment plant operators is that they are operating facilities that were designed to meet certain criteria, in SASM‟s case - a 20-year return storm. Unfortunately, the current enforcement posture of regulators (EPA, SWRQB and RWQCB) has not provided assurance that agencies experiencing SSOs or unauthorized discharges related to storm events in excess of their plant design will not be subject to substantial fines and/or other enforcement action. Without that guidance from regulators as to what they considered an appropriate design event (above which fines or other enforcement action will not result) agencies are forced to either undertake costly short-term improvements to guard against potential fines or roll the dice, hoping that the next big storm in excess of current plant design capabilities does not occur before long-term infrastructure replacement reduces I&I to manageable levels. Presently, agencies seem to prefer to err on the side of caution. This will add to the overall cost of doing business. At some point these long-term infrastructure improvements will reduce or eliminate the original need for these short-term improvements. Maybe doing both is the right thing to do. However, it is the job of regulators to make specific determinations as to what is required to protect water quality and public health. Zero-tolerance and strict liability for SSOs or “illegal discharges” under all circumstances is a tough task master. Some question whether all of the attention to SSOs and wet-weather discharges has actually produced concrete, verifiable improvement in water quality or produced significant gains in protecting public health. While large spills, especially dry weather spills, do pose a significant threat to the environment or public health, most spills that occur in our districts are small (averaging substantially less than 200 gallons over the past 4 years) and are rapidly responded to. Large releases such as the controlled release from SASM‟s treatment plant on January 25, 2008 typically do not produce long-term impacts on the nearby receiving waters because of their extremely dilute nature and the additional flushing from storm runoff. Urban runoff may actually present a greater ongoing threat to receiving waters than the relatively rare releases from treatment works resulting from extremely large storm events. 42 Simply reporting SSOs to a database and tracking trends without connecting their impacts to actual quantifiable benchmarks such as receiving water quality or spill related health problems provides little evidence to demonstrate that just reducing SSO numbers has actually solved a real problem. Impairment of receiving waters can occur for any number of reasons. The recent adoption of the TMDL for coliform in the bay is an example. While SSOs may be a component in raising bacterial levels, there may be many more significant causes, such as urban runoff, existing bird and animal populations, etc. that play a more decisive roll. The point is that in an environment of limited or decreasing resources, it becomes increasingly important that action is taken to address real, scientifically-confirmed problems and that proposed solutions are prioritized by their effectiveness in providing concrete, verifiable solutions. 43 CHAPTER 1 INTRODUCTION In recent years the natural scenic and climatic sound and workable policy regarding septic tanks and assets 6f Marin County have attracted an increasing similar individual disposal systems. number of people to the county. As a result, those portions of the county most accessible to the other Objectives and Scope of Sewerage Study bay area metropolitan centers have lost much of the The present conditions of sewerage service in small-town atmosphere of 30 years ago and have as dicate the need for a comprehensive plan under which sumed many of the characteristics of a major urban provision would be made for the systematic, orderly, area. The continuing trend of increasing population and economical construction of the sewerage facilities has brought to Marin County many of the problems required to serve the county for an extended future common to any rapidly-growing urban area, not the period. Such a plan can be developed by means of a least of which ooncerns the collection, treatment and comprehensive engineering study which takes into disposal of sewage. account and evaluates all facts pertinent to the needs At present, many areas of the county are faced of both the local agencies and the county as a whole. with serious sewerage problems which are signifi Recognizing the need for long-range sewerage cant not only from the standpoint of public health, but planning, the Board of Supervisors of the County of also because they involve such matters as recreational Marin engaged the engineering firm of Brown and activity, orderly community growth, and the value of Caldwell to make the necessary engineering studies land and property. Among the factors contributing and to prepare a report setting forth recommended to both present and anticipated future problems, the sewerage improvements. Under an agreement dated most significant are: March 15, 1966, the work of the study included, but 1. The county is divided by steep ridges into was not limited to, the following phases: numerous individual watersheds, making infeasible 1. A review of county and city land-use maps the development of any unified scheme for regional and population projections for areas subject to urban gravity sewerage. The result has been the formation development, to the extent that these maps and pro of a large number of independent sewerage agencies jections govern sewerage planning. of small size and local concern without regard for the 2. A review of the physical environment as it possible advantages of long-range regional planning. affects sewage collection, treatment and disposal. 2. Increased sewage flows have in some areas Topography, geology, climate and oceanographic fac resulted in degradation of receiving water quality at tors were considered important to the study. the same time that increased recreational use of re 3. The establishment of sewerage service areas ceiving waters has caused a demand for improved and subareas as defined by topography and other con water quality. The net result is that 12 of the 14 siderations, and an estimate of the distribution of major sewerage agencies within the county which dis future population and of land use in each of the sew charge to receiving waters were listed by the Regional erage service areas. Water Quality Control Board in March, 1966 as being 4. The analysis of existing sewerage systems and in violation of discharge requirements established their proposed expansions within the county with re by the Board. spect to their adequacy, deficiencies, and suitability 3. Excessive storm water infiltration occurs in for inoorporation into a long-range plan either as tem most of the older sewage collection systems during porary or as permanent works. The analysis was periods of moderate to heavy rainfall to the extent limited to major trunk and interceptor sewers and that sewage transmission and treatment facilities are to treatment and disposal works. Current costs of overloaded. During and immediately after any ap sewerage service and sources of revenue were re preciable rainfall, it is necessary to bypass raw sew viewed. age to drain channels, creeks and estuaries to prevent 5. The determination of existing sewage and sewage from backing up into streets and houses. wastewater characteristics with respect to volume, 4. A wide diversity of opinion exists between de composition, and the seasonal effects of rainfall. velopers, administrative agencies and control agen 6. The development of unit design factors and cies regarding the part which septic tanks and leaching criteria for preliminaryd~sign based on experien~e systems should play in the orderly development of un in Marin County and including allowances for trends· sewered areas. In some areas which are not tributary which will affect their future values .. ---.------ to existing sewerage systems, development is pres 7. The investigation of present and probable fu . ently stalled, pending the adoption of a technically ture requirements for disposal of sewage and waste- 1 2 MARIN COUNTY SEWERAGE STUDY water, including a review of the beneficial uses of tributary area in Sonoma County. receiving waters, both fresh and salt, and where ne Information and Data Avai lableto Survey cessary, the investigation of tidal movement and dis- \ , persian at appropriate discharge points. Full use has been made of previous studies and Ii 8. An investigation of the effectiveness of in reports prepared by agencies of Marin County. Ad i I I i dividual waste disposal systems and the develop';;;;;t ditional information has been obtained from cities ,I - of datalor incluslOn in a county ordinance relating and local sewerage agencies arid their consultants , ! to construction, monitoring, and operation of indi from the Regional Water Quality Control Boards, the vidual systems. U. S. Army Corps of Engineers, and from various , ' 9, An investigation of the possible uses, the econ- state agencies. omy, and the future need for water reclaimed from Operating records of treatment plants have been sewage effluents in Marin County. referred to wherever they were available. Size and 10. The development of preliminary layouts and location of sewer lines and capacities of pumping sta costs of alternative plans for sewage and wastewater tions have been taken from available records, and collection, treatment, and disposal systems to meet generally have not been verified in the field. Mea the needs of the county for the next 50 to 60 years. surements of area and distance were made on U. S. 11. A detailed description of the recommended Geological Survey topographic maps, using 1" = 2000' plan. scale for detailed work, and 1" = 5280' scale for 12. The development of a program for stage con COlll1ty-wide considerations. struction of the recommended sewerage works to cor Literature and other references cited by super rect present deficiencies and keep pace with the de scrips in the text of the report are listed in Appendix veloping needs of the county. A. Unnumbered references listed in Appendix A were 13. A review of governmental structures for pro used as sources of background material but are not vision of sewerage service, including the contractual specifically referred to in the text. For simplicity, relationships between existing agencies and the pos abbreviations have been used in this report for many sible need for the formation of additional agencies to technical and nontechnical terms. Each abbreviation provide for the construction and operation of works is defined where it first appears, and all abbrevi common to more than one agency. ations are listed alphabetically in Appendix B. 14. Preparation of the report. Along with des cription of all recommended facilities and estimates Acknowledgments of the cost of each increment in the long-range pro Successful completion of a study of this type is gram, the report contains background data in suffic dependent on the advice and cooperation of a great ient detail to substantiate the findings and recojillUend many individuals and organizations. We are particu ations. Design assumptions and criteria are fully larly indebted to John F. Barrows, Assistant County described to permit their review and up-dating be Administrator, for his valuable advice and direction fore construction of later stages of the recommended in policy matters; to Paul Zucker, County Planning program. Director, and his staff, who have devoted countless hours to the definition and discussion of Marin County's future; and to William L. Desmond, Director of En Extent of Study Area vironmental Health, Marin County Department of Pub Basically, the area studied in detail includes the lic Health, long an advocate of planned sewerage and a entire county of Marin from the Golden Gate north to prime mover behind the authorization of this report, the Sonoma county line and from San Francisco Bay whose knowledge of present and historical sanitary west to the Pacific. On the three sides of the county conditions in Marin County has been a great asset to us. bounded by water, definition of the study area cer The collection, analysis and interpretation of the tainly presents no problem. Along the northern boun data upon which this report is based could not have dary, however, the county line divides four water been accomplished without the willing and generous sheds, with a portion of each watershed falling in each help of a group of dedicated people too numerous to of the two counties. Since greatest economy in con mention. We wish to express our gratitude to all of struction and operation of a sewerage system is gen the directors and the administrative and operating erally achieved by planning based on watershed boun personnel of the public agencies, their consultants, daries rather than political bOlll1daries, sewerage in the state and regional agencies, and the many private the northern area has been considered on the basis of citizens who have so generously contributed to this topography. Long-range sewerage projects recom phase of the work. mended for northern Marin County thus, in some The cover photograph is by courtesy of Aero Pho cases, have a capacity allowance for the naturally tographers, Inc. CHAPTER 4 EXISTING SEWERAGE SYSTEMS One of the basic objectives of the present study local control agencies and are discussed in detail later is that of determining the extent to which existing in this report. sewerage facilities can be incorporated into a long Despite the multiplicity of agencies and facilities, range program of sewerage improvements. Accord only about 67 percent of the county residents are ~ ingly, all major components of existing systems were served by public sewers. The remaining residents evaluated in terms of their ability to meet future rely on individual disposal systems, principally in the needs. Information presented in this chapter was form of septic tanks, for disposal of sanitary wastes. derived from interviews with officials of the various In the case of most of the public sewerage agen sewerage agencies, from a review of plans and re cies, watershed boundaries have played animportant ports, and from field investigations. part in the definition of service areas. As an aid in Responsibility for providing sewerage service in the description of existing sewerage facilities, and Marin County is divided among three cities, eleven in keeping with the concept that sewerage can be most sanitary districts, one COlUlty sanitation district, four economically accomplished by considering topographic sewer maintenance districts, two public utility dis rather than political boundaries, existing systems tricts, two COWlty water districts, one municipal water are grouped and described by the major watershed district, and seven state and federal agencies, in in which they occur. State and federal agencies are cluding military installations. Of the 24 cities and described separately at the end of this chapter. county agencies, 19 are presently engaged in the op eration of sewerage facilities. The remaining five Richardson Bay Watershed are either in various stages of planning for sewerage Within the Richardson Bay watershed, respon service or are inactive. sibility for sewerage service is divided among ten public agencies. Four of these, the city of Mill Val- . ley, Sausalito-Marin County Sanitary District, Rich ardson Bay Sanitary District, and Sanitary District No.5, operate sewage treatment plants. The remain ,I ing agencies operate collection systems and contract with one or the other of thQSe four for sewage treat ment. In addition, Seafirth Estates operates a small private sewage collection system and treatment plant serving 30 homes on the north shore of the Tiburon Peninsula. Land area within the Richardson Bay watershed totals 20 sq mi, of which 14.5 sq mi is en compassed by sewerage agencies, and over 13 sq mi is reported to be sewered. Principal sewerage facili ties within the Richardson Bay watershed are shown in Fig. 4-2. MILL VALLEY SEWAGE TREATMENT PLANT provides sec ondary treatment for sewage from communities at the head of City of Mill Valley. Incorporated in 1900, Mill Richardson Bay. Valley ranks as one of the oldest communities in The present status of sewerage in Marin County Marin County. The corporate limitS' presently con is indicated in Fig. 4-1, while Tables 4-1,4-2, and tain an area of 3.8 sq mi and a population of 12,000. 4-3 give a brief resume of pertinent statistical in The sewage collection system comprises two pumping formation on each publi c sewerage agency. Together, stations and 57 miles of sewers ranging in size from the various agencies operate and maintain about 700 6 to 30 inches. miles of sewers, 92 pumping stations, and 12 sewage The first sewers, some of which are still in use, treatment plants. Three additional treatment plants were constructed about 1892 and discharged raw sew are operated by state and federal agencies, and one age to Arroyo Corte Madera Del PreSidio, commonly by a private developer. Available information indi known as Widow Reed Creek. In 1912 the town con cates that there remain only two locations within the structed one of the first Imhoff tanks in the State, but county where raw sewage is continuously discharged it was abandoned about 1918 because of odor com to surface waters. Both situations, at the towns of plaints, and sewage was again discharged raw to the Tomales and Bolinas, are well known to all state and creek. In 1926 the raw sewage outfall was extended 20 EXISTING SEWERAGE SYSTEMS 21 to Widow Reed Slough at the head of Richardson Bay in excess of this amount must be bypassed directly near the present point of discharge. to Richardson Bay. The influent pumping station has The first units of the present plant were con an installed pumping capacity of 16.7 mgd, of which structed in 1952, and consisted of the inlet works, 10.2 mgd is electric motor driven and 6.5 mgd is operations building and pumping station, a rectangu engine driven. The hydraulic capacity of the head lar primary sedimentation tank 82 ft by 16 ft by 10 ft works preceding the pumps, however, limits the prac deep, and a heated sludge digester with a capacity tical maximum pumping rate to about 10 mgd. of 30,000 eu ft. Additions in 1958 comprised a second In addition to the flow from Mill Valley, the plant primary sedimentation tank and two secondary sedi treats sewage from Homestead, Alto, and Almonte mentation tanks identical to the first, two 80-ft di Sanitary Districts, and Kay Park Sewer Maintenance ameter standard rate trickling filters, a second di District. The total average dry weather flow as mea I gester with a capacity of 47,000 cu ft, and a centri sured at the plant during the summer of 1965 was fuge for sludge dewatering. 1. 36 rilgd. Laboratory test records for the summer The present design capacity of the treatment plant of 1966 show plant efficiency to be 85 percent in terms o .1 is 1. 6 mgd (million gallons per day). Peak hydraulic of BOD (biochemical oxygen demand) removal and 80 I capacity, as limited by the maximum permissible percent in terms of suspended solids removal. I flow throngh the sedimentation tanks, is 4 mgd. Flows As is often the case with older sewerage systems, I Table 4-1. Sewerage Agency Statistics, Fiscal Year 1965-66 Area, square miles Population Date agency formed Total Sewered Total Connected Sanitary Districts Nwnber 1 1922 18.0 12.8 36,400 36,000 Number 2 1901 3.1 3.1 9,9{}O 9,000 Number 5 1924 1.4 1.2 7,000 6,500 Number 6 1925 15.0 10.0 30,000 27,400 Almonte 1949 0.5 0.3 1,500 1,500 Alto 1950 0.2 0.2 1,000 1,000 Homestead Valley 1931 0.7 0.7 2,400 2,400 Las Gallinas Valley 1954 6.6 6.6 24,000 24,000 Richardson Bay 1949 2.4 2.4 9,000 9,000 a a Sausalito-Marin City 1952 3.3 10,000 a a Tamalpais Valley 1954 1.5 4,500 COl.mty Sanitation Districts San Rafael 1947 9.7 9.2 30,000b 29,000b Sewer Maintenance Districts Kay Park Number 2 1953 0.07 0.07 530 530 a a Murray Park 1949 0.10 0.10 San Quentin Village 1964 0.01 0.01 100 100 Tomales c 1956 0.17 a a a Public Utility Districts a a Bolinas 1926 1.8 380 Bolinas Beach d 1939 0.7 0 600 0 Col.illty Water DiJtricts Stinson Beach 1962 10.9 0 550 0 Cities Belvedere 1896 0.6 0.6 2,600 2,600 Larkspur 1908 2.8 2.8 8,750 8.750 Mill Valley 1900 3.8 3.8 12,000 12,000 Based on data submitted by sewerage agencies or obtamed from County of Marm. alniormation not available. b Based on population estimates by Marin County Development Association. San Rafael Sanitation District personnel estimate about 20 ,000. c Tomales Sewer Maintenance District is presently inactive. d At present there are no sewers in the district. I' , .. . 'II : .•.. I'i' , i. I1,1. ·1'; I1I ; 22 MARIN COUNTY SEWERAGE STUDY Table 4-2. Summary of Financial Information for Sewerage Agencies, Fiscal Year 1965-66 Bonds outstanding Annual 0 &M cost Assessed Connection $1,000 $1,000 valuation Service chargeb f •• General Treatment Agency $1,000,000 Tax, ' le ; v ya dollars dollars obligation Revenue only Total p Sanitary Districts ,~ "'-[J '';;::~ Number 1 71.11 "1L 0/14 ....;:. 0 0 16 0 59.6 129.0 Number 2 21.43 31/120 0 150c,d 962 0 21. Ie 101.4 f g Number 5 9.25 5/44 0 39 0 54.7 ~---N~ber(f" - 39.98 11/50 0 0 418 0 55.9 h 167.1 Almonte 3.04 16.5/41. 5 .. ~- 300 e 45 87 lO.Oi 17.7 Alto 2.51 5/50 0 65 13 0 1. 9 i 2.9 --~stead Valley 4.34 13/47.5 0 17S c 15 0 11. Oi 16.5 -. --Las-Gallinas Valley 40.56 4.5/21 12 lOOe 967 275 53.0 112.9 Richardson Bay 16.43 0/50 0 400 c 0 0 j 161. 7 .- ._S-au-salito-Marin City 26.08 0/16 12 35 c 645 0 25.0 55.3 k -'--I amrupais Valley 5.92 12/33 ----2=9 .~ 350 c 126 116 15.8] 41. 7 ~- County Sanitation Districts c g San Rafael 72.88 6/37 0 12S 470 0 122.0 Sewer Maintenance Districts Kay Park Number 2 0.84 0/49 0 f 0 0 3.4i 6.0 MurraY' Park 0.32 0/71 0 12S c 0 0 g 2.0 f g San Quentin Village 0.08 0/155 0 0 0 0.6 ro Tomales 0.07 0 0 0 0 0 0 0 Public Utility Districts Bolinas 1. 73 O/145.5 n 0 200 c 25 0 0 1.2 0 Bolinas Beach P 1.17 O/186Q 0 0 75Q 0 0 0 County Water Districts Stinson BeachP 2.76 0/27 n 0 0 0 0 0 0 Cities Belvedere 12.1 42/75.3 0 150 445 0 11. Sr 28.4 c e Larkspur 10.1 7/75 0 125 10 0 21.1 44.1 c Mill Valley 30.0 15.5/32 ~ 235 330 0 52.S 80.9 '" Based on data submitted by sewerage agenCles or obtamed from County of Marm. aportion of general tax levy designated for sewerage except as noted. Cents per $100 assessed valuation. Bond redemption rate/Total rate. ---=t:o~ ~ otherwi~e b lffiless indicated. c Charge for single-family connection. Multiple dwellings and commercial charged on the basis of fhture units. d The district also imposes an annexation fee of $250 per gross acre. e Amount paid to Sanitary District No.1 for sewage treatment. f Charge based on fixture units. g Information not available. hO & M costs; Novato plant, $37,200, Ignacio plant, $18,700. i Adjusted amount paid to Mill Valley for sewage treatment. j Cost for treatment only at the Trestle Glen Plant not available. $18,100 paid to Sausalito-Marin City Sanitary District for s~wage treatment. kDoes not include 0 & M for City of Sausalito sewers. I Amount paid to Sausalito-Marin City Sanitary Di.!'}trict for sewage treatment. llbistrict is presently inactive. n Total district tax rate, no specific rate for sewerage only. o Total cost for maintaining water and sewer lines. p At present, there are no sewers in the district. qTotal district tax rate and outstanding bonds are for water seI:Y,~ce only. _r A:r;n~)Unt paid to Sanitary District No. 5 for sewage treatment. EXISTING SEWERAGE SYSTEMS 23 9 storm water infiltration creates serious problems Bureau of Sanitary Engineering indicate that prob for the Mill Valley collection system and treatment lems of this nature have beerr more or less persistent plant. Overloaded sewers are not a new problem. for more than 40 years. Records of the State Department of Public Health, Under present conditions, moderate rainfall re- Table 4-3. Sewerage System Statistics, By Agency Sewers Treatment plants Diameter Number of Capacity Agency Miles c Y on ea st r r u fi c r t s e t d range pumping Type a co Y n e s a tr r u f c i t r e s d t b average Discharges to inches stations mgd Sanitary Districts Number 1 135 1895 4-36 8 ST 1949-62 4.5 Corte Madera Creek Number 2 31 1906 4-27 12 c Number 5 48 1924 6-18 6 P 1949-61 1.6 Racoon Strait Number 6 130 1949 6-30 9 STA 1948-56-64 2.7 Novato Creek ST 1956 0.9 Novato Creek SA 1966 0.2 Petaluma River Almonte d 1953 6-15 0 f Alto 3.5 1940 e 6-8 0 f Homestead Valley 7 1948 6-12 0 f Las Galliuas Valley 80 1951 6-24 11 ST 1955-59-65 2.1 San Pablo Bay Richardson Bay d 1945 6-15 9 ST 1958 0.3 Richardson Ba~ SausaUto-Marin City ~4 1893 6-24 7 P 1952 2.0 San Francisco Bay Tamalpais Valley 1955 4-14 1 h County Sanitation Districts San Rafael 83 1920 e 6-27 14 IA 1949-62-65 5.0 San Rafael Bay I IT 1962 0.16 San Pablo Bay Sewer Maintenance Districts Kay Park Number 2 2.0 1952 6-12 1 f Murray Park d d 6 0 c San Quell:tin Village 0.4 1964 4-6 1 i Tomales] 0.2 d 4-8 0 k Keys Creek Public utility Districts k Bolinas 1.7 1906 6-8 0 Bolinas Bay Bolinas Beach! 0 County Water Districts Stinson" Beach 1 0 Cities Belvedere 10 1900 6-15 9 m e c Larkspur 29 1908 6-18 2 Mill Valley 57 1892 6-30 2 ST 1952-58 1.6 Richardson Bay Based on data submitted by sewerage agencies a P, primary treatment; I, intermediate treatment; S. secondary treatmentj A, activated sludge; T, trickling filters. b Where two years are shown, second indicates major "enlargement. c Sewage treated at Sanitary District No.1 plant. d Information not available. e Approximate value. f Sewage treated at Mill Valley plant. g Sewage generated in approximately one-half of the district is treated at Sausalito-Marin City plant. hsewage treated at Sausalito-Marin City plant. i Sewage treated at San Quentin plant and then discharged to San Francisco Bay. j Tomales Sewer Maintenance District is presently inactive. kDischarged Wltreated. 1 At present there are no sewers in the district. lllgewage treated at Sanitary District No. 5 plant. 24 MARIN COUNTY SEWERAGE STUDY sults in sewage flows which exceed the capacity of of the sanitary district in 1950, a pumping station the plant treatment units. Severe or prolonged rain was constructed at the southern boundary to lift all fall causes sewage flows in excess of the capacity of of the district's sanitary sewage into the Mill Valley the plant inlet works and pumping station. In the lat trunk sewer system. ter case, flow in the influent sewer must be throttled Some 3. 5 miles of 6- and 8-in. sewers now serve and excess flow bypassed by gravity to the bay. Since the entire district population of about 1000 persons. the bypass is several feet higher than the inlet sewer, The system is apparently functioning satisfactorily, sewage backs up in the collection system causing man and no unusual problems are reported. Sewage treat holes to overflow at low points in the system, notably ment is provided at the Mill Valley plant under a con at Ryan Avenue. Recent efforts to pinpoint the sources tract with terms similar to that for Almonte Sanitary of infiltration in the older portions of the collection District. system by television inspection of pipe interiors have been largely unsuccessful due to inadequate access Homestead Valley Sanitary District. Residential and misalignment of the sewers. development of the Homestead Valley area began The treatment plant is now approaching its design shortly after the turn of the century and was fairly ex capacity and the City of Mill Valley has engaged a tensive by the end of World War 1. As early as 1926 consultant to prepare preliminary plans and cost esti the City of Mill Vailey undertook assessment proceed mates for the construction of additional sedimentation ings to finance construction of sewers in Homestead, tanks. Planning has not, however, proceeded to the but the number of protests by the Homestead residents design phase. was sufficient to cause abandonment of the project. Although the Homestead Valley Sanitary Districtwas Almonte Sanitary District. The Almonte Sanitary formed in 1931, the area continued to rely on septic District collects sewage from a small area southeast tanks until 1948. In 1944 the sanitary conditions were of Mill Valley and delivers it by gravity to the Mill described by the State Bureau of Sanitary Engineerin; Valley trunk sewer system. Of the total district area as follows: "As characterizes individual sewage dis of 0.5 sq mi, nearly half consists of undeveloped tide posal in this part of Marin County, the sanitary con marsh and mud flats. ditions are extremely unsatisfactory. For over 20 Prior to district formation in 1949, sewage dis years pollution of the creek and numerous premises posal was accomplished through individual septic tanks has continued unabated. Since July 14 of last year, under sanitary conditions described by the State Bu the Marin County Health Department reports 14 sew reau of S~itary Engineering as !1 extremely unsatis age disposal complaints." factory", including "a great deal of difficulty with Construction of sewers was finally undertaken in overflowing sewagelT Sewers ranging in size from 1948. The system now consists of seven miles of • 6 to 15 inches were constructed in 1951, and the en sewers ranging in size from 6 to 12 in. and serving tire district population of 1500 is now reported to be all of the district's 2400 residents. Sewage is de connected to the collection system. livered by gravity to the Mill Valley trunk system Treatment of sewage from Almonte Sanitary Dis and is treated by Mill Valley under a contract similar trict is performed at the Mill Valley plant under a to that for Ahnonte and Alto Sanitary Districts. contract which apportions treatment costs on the basis of assessed valuation. Kay Park Sewer Maintenance District. The sew- Storm water infiltration causes wet weather flows erage system for the subdivision known as Kay Park which exceed the capacity of the 15-in. trunk sewer No.2 is a tiny anachronism which offers mute testi and result in overflowing manholes during major mony to the lack of regionai sewerage planning in the storms. 10 This problem is reportedly due in part to Richardson Bay watershed. Constructed in the early inadequacies in the Mill Valley trunk sewers which 1950's on the tidal marshlands at the mouth of the receive the flow from Almonte, but in any case the Tamalpais and Tennessee Valleys, Kay Park con district is faced with the necessity for corrective ac tained the first sewers in that general area. A pump tion. ing station and 4000 ft of gravity sewer and force main were constructed to convey the sewage to the Mill . Alto Sanitary District. The Alto Sanitary District Valley system. About a year later, Almonte Sani comprises an area of less than 150 acres located north tary District constructed a trunk sewer which paral of Mill Valley and adjacent to Highway 101. The first lels the Kay Park sewer and force main throughout sewers were constructed sometime prior to 1945, its entire length. Some three years after Kay Park discharging to a community septic tank which in turn connected to Mill Valley, Tamalpais Sanitary Dis discharged to Widow Reed Slough. After formation trict constructed its trunk sewer along the southern EXISTING SEWERAGE SYSTEMS 25 edge of Kay Park and located its main pumping sta Fort Baker pumping station. Pumping system curves tion on the Kay Park district boundary. Logically, for the Main Street station presented in a 1959 report the entire Kay Park area should have sewered di to the district by M. Carlton Yoder, 11 together with rectly to the Tamalpais Valley pumping station. the !mown characteristics of the Fort Baker station, Serving an area of about 50 acres, Kay Park Sewer indicate that the probable peak flow arriving at the Maintenance District has a total population of 530, plant is 8 mgd. all connected to the system. storm water infiltration Historically, the Sausalito-Marin City system into the collection system is excessive. Though the has suffered both from stormwater infiltration and totai magnitude of infiltration is small because of the from salt water infiltration into bay front sewers. district size, the unit infiltration rate is the highest Since Tamalpais Valley and Richardson Bay Sanitary of any encountered in Marin County. As with Home Di stri cts both contribute flow to the upper end of the stead, Almonte and Alto, Kay Park contracts with Sausalito-Marin City system, it is difficult to say Mill Valley for sewage treatment. precisely where the storm water infiltration occurs. Reoords indicate that the problem is common in some Sausalito-Marin City Sanitary District. As its degree to all three districts. During periods of heavy name implies, the Sansalito-Marin City Sanitary Dis rainfall, typically two or three times a year, the trict encompasses the City of Sausalito and the ad Sausalito-Marin City district has found it necessary jacent uninoorporated area of Marin City. The 10,000 to relieve the overburdened trunk system by opening residents within the district's 3.3 sq mi area are a bypass valve near the U. S. 101 highway bridge and served by a sewage collection system compriSing 34 bypassing up to 2 mgd or more of raw sewage to Rich miles of sewers from 6 to 24 in. in diameter, seven ardson BaY. Records kept by the district indicate that . pumping stations, and a primary treatment plant. In in the last four years this bypass has been opened nine addition to serving its resident population the district times for a total period of 169 hours. provides sewage treatment on a contract basis for In 1958 M. Carlton Yoder conducted a study of Tamalpais Valley Sanitary District, Fort Baker, and salt water infiltration into Sausalito-Marin City bay ll the Strawberry Point area of Richardson Bay Sanitary front sewers which indicated heavy infiltration at District. high tidal elevations. While not all of the conditions Ranking with Mill Valley as one of the oldest com have been corrected, the district feels that the loca munities in Marin, the City of Sausalito was also one tions of all trouble spots are known and that oorrection of the first to construct sewers. From 1893 when is only a matter of a110 cating the necessary money the first sewers were constructed until the present and manpower. bay front interceptor sewer and treatment plant were placed in operation in 1953, sewage was discharged raw to San Francisco Bay at a number of points along the waterfront. All sewage is now intercepted and pumped to the treatment plant, which is located on the shore of San Francisco Bay about 800 ft south of the Sausalito city limit. The primary-type treatment plant was imagina tively designed to fit an extremely limited site at the foot of the steep coastal bluff. It consists of a 55-ft diameter, 9. 5-ft deep clarifier constructed on top of a 75-ft diameter, 13-ft deep heated sludge digester. Plant effluent is discharged through an outfall line about 300 ft in length which terminates 30 ft below the surface of the bay. Digested sludge is also dis charged through the outfall line on a falling tide. The plant has a.design capacity of 2.0 mgd, com TREATMENT PLANT of the Sausalito-Marin City Sanitary Dis pared to a measured average dry weather flow of 1. 37 trictdischarges primary effluent to deep water in San Francisco mgd during the summer of 1965. The peak hydraulic Bay. capacity of the plant is not precisely !mown. However, Tamalpais Valley Sanitary District. Tamalpais the plant superintendent reports that the clarifier will Valley was the last populated area in the Richardson carry hydraulically the maximum flow which can be Bay watershed to construct a public sewerage system. pumped to the plant by the Main Street pumping station, In 1954 the Tamalpais Valley Sanitary District was which handles all flow from the district, and by the formed, and a sewage collection system was con- 26 MARIN COUNTY SEWERAGE STUDY structed the following year. Prior to 1954, the entire berry. area depended on septic tanks, with resulting sanitary The present district boundary encompasses a total conditions comparable to those described for Home area of 2.4 sq mi containing 9000 residents, all of stead Valley and Almonte. whom are reported to be connected to the sewerage Tamalpais Valley Sanitary District encompasses system. District facilities include a sewage collection an area of 1. 5 sq mi containing a present population system having sewers ranging in size from 6 to 15 in. , of 4500. Sewage from the district is conveyed by eight pumping stations in the collection system, a ter gravity to a pumping station located at the mouth of minal pumping station at Ricardo Road which transfers Tennessee Valley, from whence it is pumped throngh flow to the Sausalito-Marin City system, and the some 9200 ft of 15- and 16-in. force main to the upper Trestle Glen sewage treatment plant. end of the Sausalito-Marin City gravity trunk system. Storm water infiltration into the sewage collection All but 3300 ft of the force main is owned by Sausalito system has been a problem for many years. DUring Marin City Sanitary District and is used jointly by periods of heavy rainfall raw sewage must be bypassed that district as well as by Tamalpais Valley and Rich to Richardson Bay to prevent surcharged manholes ardson Bay Sanitary Districts. The Tamalpais Valley from overflowing into the streets. The problem is pumping station is reported to have a pumping capacity particularly severe in that portion of the collection of about 2.5 mgd12 which at present exceeds the cap system tributary to the Ricardo Road pumping station. acity of the force main system to which the flow is In a 1963 report to the district board of directors13 discharged. Provision was made in station design J. Warren Nute reported that during the winter of for doubling the present installed pump capacity. 1962-63 the Ricardo Road pumping station operated A 1963 report on system capacity by Edward B. at full capacity for a total of 293.5 hours, equivalent 12 Beattie indicates that the district sewage collection to 12-1/4 days. It may be assumed that during a system has a capacity adequate for present flows even major portion of this period sewage was being by under wet weather conditions. Reported values for passed to the bay upstream of the pumping station. storm water infiltration are lower than the average Somewhat ironically, the records from Sausalito for the Richardson Bay watershed, due in pari, no Marin City indicate that during 80 hours of this period doubt, to the fact that the sewers were recently con Sausalito-Marin City Sanitary District was bypassing structed and show the benefits of improved construc sewage to the bay at a point near the Ricardo Road tion and techniques. force main connection. The rate of bypass at this Treatment of Tamalpais Valley sewage is per point is unknown, but was probably at least equal to formed at the Sausalito-Marin City plant under a con the flow pumped by the Ricardo Road Station. At the tract which apportions the cost of treatment on the Trestle Glen plant the chief operator states that wet basis of the ratio of total annual flow from Tamalpais weather flows 0 ccasionally exceed the capacity of Valley to the total annual flow at the plant. secondary treatment units but that it has not been necessary to bypass raw sewage ahead of the plant. Richardson Bay Sanitary District. The Richardson Sewage flow from Richardson Bay Sanitary Dis Bay Sanitary District serves the Strawberry area and trict during the dry weather summer months of 1965 about half of the area on the Tiburon Peninsula which drains to Richardson Bay. The first sewers were installed in the Strawberry area in 1945 after indi vidual septic tanks throughout the area had failed. Treatment was initially provided by community septic tanks which discharged to the bay, and by 1948 three such systems were in service. Shortly after for mation of the district in 1949, two trickling filter "package" plants were constructed to serve newly developed areas. In 1953, a pumping station and force main were constructed to deliver sewage from the Strawberry area to the Sausalito-Marin City system for treatment. At that time the community septic tanks were abandoned and one of the small trickling filter plants was converted to a pumping station. In 1958 the second trickling filter plant was replaced by the Trestle Glen plant, which now treats sewage TRESTLE GLEN PLANT of Richardson Bay Sanitary District pro collected from the district area to the east of Straw- vides secondary treatment for a dry weather flow of 0.15 mgd. EXISTING SEWERAGE SYSTEMS 27 ,veraged 0.5 mgd, of which 70 percent was pumped to Cove has been annexed to the district, and current lausalito-Marin City Sanitary District and 30 percent plans reqnire the developer to build a small secondary vas treated at the Trestle Glen sewage treatment treatment plant to be operated by district personnel. llant. The latter plant has a design capacity of about J. 3 mgd. Laboratory tests indicate that the plant is City of Belvedere. Incorporated in 1896, the City lchieving a BOD reduction of 88 percent and a sus of Belvedere is entirely residential in character and ~ended solids reduction of 87 percent. Plant units occupies an area of about 0.6 sq mi consisting prin include an influent pumping station with a capacity cipally of Belvedere Island and the adjacent lagoon. of 1 mgd, a primary and a secondary clarifier each The first sewers, installed over 60 years ago, con 30 ft in diameter, a 24-ft diameter high-rate trickling veyed sewage to the southern tip of the island, where filter, two 26-ft diameter spirovortex mixing tanks, . it was discharged raw into Raccoon Strait. and an unheated digester with a capacity of 10,500 Except for local improvements and expanSion of cu ft. Chlorinated plant effluent is discharged through the collection system, this mode of operation pre a short outfall line to the adjacent mud flats of Rich vailed until 1961. At that time the collection system ardson Bay. Early in 1967, a digested sludge incin was further improved and a terminal pumping station eration unit was placed in operation, replacing the and force main were constructed to convey all of the open air drying beds previously used. city's sewage to the Sanitary District No. 5 plant for treatment. The city sewerage system now serves Sanitary District No.5. Most of the eastern end all of the 2600 city residents by means of 9 pumping of the Tiburon Peninsula lies within the boundary of stations and some 10 miles of sewers and force mains Sanitary District No.5. Formed in 1922, the dis ranging in size from 6 to 15 inches. trict now comprises a total of 1. 4 sq mi and contains Storm water infiltration into the collection sys 7000 residents, 6500 of whom are served by the dis tem is very high on a unit basis, but because of the trict sewerage system. small area involved, peak wet weather flows are The first sewers in the area were constructed in usually within manageable limits. The terminal pump 1924, and until 1949 all sewage was discharged raw ing station on the city system has a capacity of 1. 5 to San Francisco Bay. District facilities now include mgd, and maintenance personnel report that this cap six pumping stations, some 48 miles of sewers and acity has been exceeded only once in the last four force mains ranging in size from 6 to 18 inches, and years. When peak flow exceeds pumping capacity, a a primary sewage treatment plant. In addition to manually-operated bypass is opened and excess flow treating the sewage from District 5, the treatment is diverted to the old raw sewage outfall·, which ter plant serves the City of Belvedere under a contractual minates about 20 ft below the surface of Raccoon arrangement which bases treatment charges on total Strait. sewage flow from the city. First constructed in 1949, the treatment plant Corte Madera Watershed was expanded in 1961 to its present design capacity Public sewerage within the Corte Madera water of 1. 6 mgd. Average dry weather flow during the shed is controlled by five agencies: Sanitary Districts summer of 1965 amounted to 0.7 mgd for the district and Belvedere combined. Principal plani units consist of an influent pumping station with a capacity of about 7 mgd, two rectangular primary sedimentation tanks, each 56 ft by 14 ft by 10 ft deep, a heated primary digester with a capacity of 16,500 cu ft, a 5300 cu ft unheated secondary di gester, and a 2600 cu ft chlorine contact chamber. Peak hydraulic capacity of the treatment units is re ported to be 7.5 mgd. Plant effluent is discharged directly to Raccoon Strait, and digested sludge is trucked away for agricultural use. The limited data available on treatment efficiency indicate that results obtained are typical for a well-operated primary treatment p !ant. Sanitary District No. 5 has agreed to assume sew PRIMARY TREATMENT PLANT at left serves Sanitary District erage responsibility for a proposed subdivision in the No.5 and the City of Belvedere. Structures at right are private Paradise Cove area. A 60-acre area near Paradise homes on the shore of Raccoon Strait. :'; .~. 28 MARIN COUNTY SEWERAGE STUDY fI!' ... No.1 and 2, the City of Larkspur, and the Murray Park and San Quentin Village Sewer Maintenance Dis tricts. Together, these agencies cover 21 of the 30 .... sq mi of land area within the watershed. In addition, the State of California operates a sewerage system which serves San Quentin Prison. The latter system is Ii?' described in the section on state and federal agenCies. The only public sewage treatment plant in the #If' watershed is operated by Sanitary District No. 1. (I!" Sewage from the other public agencies is conveyed to the District 1 plant for treatment with the exception ". of San Quentin Village Sewer Maintenance District, which is served by the San Quentin system. ". Of the total present watershed population of 56,000, ... about 50,000 are connected to public sewerage sys (If' tems. Principal sewerage facilities within the water SECONDARY TREATMENT PLANT ofSamtaryDistrictNo. 1 dis shed are shown in Fig. 4-2. charges chlorinated effluent to the mouth of Corte Madera Creek . ..,. Sanitary District No. I. As first organized in 1899, Plant records show the plant to be achieving a 90 per Marin County Sanitary District No.1 included Kent cent efficiency in the removal of both BOD and sus ,. field, Ross, and the southerly part of San Anselmo. pended solids. fII" The district was reorganized in 1922 under the 1918 The sewage collection system comprises about Sanitary District Act, and by 1936 had grown to snb 135 miles of sewers from 4 to 36 inches in diameter stantially its present size of 18 sq mi. All but a few and includes eight pumping stations. As in many other hundred of the district's 36,400 residents live within areas of Marin County, the system has inadequate the sewered area of 13 sq mi. The remaining 5 sq mi capaCity to carry peak wet weather flows. The State within the district boundaries is almost totally un Bureau of Sanitary Engineering, in a report dated developed. May 28, 1945,14 reported five major points of wet The earliest history of the sewer system is vague; weather overflow along the route of the main trunk however, several miles of trunk and lateral sewers sewer and stated that the overflows had been reported appear to have been in service prior to 1923. In that since shortly after the trunk was constructed in 1923. year a major trunk, which is still in service, was To date, no additional sewers have been constructed constructed from Manor to Greenbrae. The 1923 to augment the capacity of the 1923 trunk. On the proj ect also included construction of an Imhoff tank contrary, expansion of the collection system to serve near Greenbrae discharging to Corte Madera Creek. a burgeoning population has caused a steady increase This situation existed until 1949, when the first units in sewage flows. As a result, the five points of over of the present treatment plant were completed. flow mentioned in the 1945 Bureau of Sanitary Engi Enlarged in 1962, the sewage treatment plant now neering report now overflow with an increaSing fre has a design capacity of 4. 5 mgd and a peak hydraulic quency, and in addition, overflowing manholes are capacity of at least 15 mgd. The latter figure is based common along the route of the trunk sewer during on the actual flow through the plant as recorded on moderate to heavy rains. To complicate matters, January 4, 1966. Dry weather flow during the sum the upper end of the Sanitary District No.1 service mer of 1965 averaged 3.6 mgd. area receives the heaviest rainfall of any sewered The treatment plant affords secondary treatment area in Marin County. by means of a two-stage biologic filtration process. Operating personnel report that all of the eight Principal plant units include two primary clarifiers, pumping stations have adequate capacity to pump the each 70 ft in diameter, two primary trickling filters, peak flows which arrive at the stations. Sewage over each 11 0 ft in diameter, a 95-ft diameter secondary flows at the pumping stations therefore occur only trickling filter which is expandable to 170 ft, a 100-ft in the unusual event of power outage or eqUipment diameter secondary clarifier, and a heated sludge di failure. gester with a capacity of 130,000 cu ft. The lagoon originally employed for digested slndge has been aban Sanitary District No.2. Sanitary District No.2 doned, and sludge is now dewatered by centrifuge. was officially incorporated in 1901, and in 1906 the Chlorinated plant effluent is discharged throngh a first major sewer construction program was under short outfall to the mouth of Corte Madera Creek. taken. From that date until 1950 sewerage system • EXISTING SEWERAGE SYSTEMS 29 enlargements consisted of the construction of local 0.5 mgd. sewers as the need arose. The total length of sewers in the Larkspur system Shortly after completion of the Sanitary District is about 29 miles with pipe sizes ranging from 6 to No.1 sewage treatment plant in 1949, District 2 nego 18 inches. The city operates two pumping stations, tiated an agreement with District 1 for sewage treat including the terminal station which delivers sewage ment. The original agreement, which granted Dis to Sanitary District No. 1. trict 2 a capacity right of 0.175 mgd in the District 1 No accurate information on wet weather flows is plant, was renegotiated in 1960 to provide District 2 available for the Larkspur system. However, city a capacity right of 1. 175 mgd based on average dry personnel report that except for a single four-inch weather flow. The cost of treatment is proportioned overflow point which operates during heavy rainfall, on the basis of total flow. it is not necessary to bypass raw sewage from the The present boundary of Sanitary District No.2 collection system. encompasses an area of 3.1 sq mi containing 9000 residents, most of whom are connected to the sew Murray Park SMD. The Murray Park Sewer Main- erage system. The collection system comprises about tenance District was formed in 1949 to provide public 31 miles of gravity sewers and force mains ranging sewerage to an area of about 60 acres which is natu in size from 4 to 27 inches. Because much of the raly tributary to the City of Larkspur but lies out distri ct lies on the marsh lands adjacent to San Fran side the city limit. All service and maintenance func cisco Bay, a total of 12 pumping stations are required. tions are performed by the City of Larkspur. Many sewers in the hilly portion of the district are 50 to 60 years old, of substandard construction, San Quentin Village SMD. The San Quentin Village and some are badly deteriorated. Some storm drain Sewer Maintenance District was formed in 1964 to connections to sanitary sewers have been discovered serve the small residential area which honses prison and corrected, but others undoubtedly exist. Storm employees. Prior to formation of the district the water infiltration, as a consequence, is very high. 60 or so homes in the village discharged raw sewage Some sewers built in the reclaimed marshlands have to San Francisco Bay. In 1965 a pumping station was suffered the effects of settlement, which has resulted constructed to divert the sewage flow to the San Quen in cases of sheared and broken pipes. Groundwater tin Prison sewerage system. Though it exists as a infiltration into the low lying sewers, while not as public sewerage agency of Marin County, the district serious as the storm water problem, adds a year may for all practical purposes be considered a part round increment to sewage flows. of the prison sewerage system. Since 1957 the district has been engaged in a con tinuing program to upgrade its collection system. San Rafael Watershed Starting in 1963, a ten-year program was undertaken The area which drains to San Rafael Bay, a total of with the objective of gradually replacing about seven about 11 sq mi, is identified as the San Rafael water miles of older sewers, and when completed it is an shed. San Rafael County Sanitation District is the ticipated that major sources of storm water entry will only public sewerage agency within the watershed. and have been largely eliminated. includes within its boundaries all but about 2 sq mi of the watershed. Principal sewerage facilities of San City of Larkspur. Incorporated in 1908, the City Rafael County Sanitation District are shown in Fig. of Larkspur now covers an area of 2.8 sq mi contain 4-3. ing a population of 8750. The city retains responsibil Substantially all of the 30,000 residents within the ity for sewage collection within its boundaries, and in San Rafael watershed are included in the San Rafael addition accepts flow from the collection system of County Sanitation District and are connected to the tiny Murray Park Sewer Maintenance District. Sew district sewers. Early history of the sewerage sys age from the city is pumped to the nearby main trunk tem is vague, but it is reported that the first sewers of Sanitary District No. 1. were installed prior to 1920. The present system The first sewers were constructed in Larkspur consists of 14 pumping stations, about 83 miles of some time prior to incorporation, and until 1949 sew sewers and force mains ranging in size from 6 to 27 age was discharged raw into Corte Madera Creek. In inches, and two treatment plants. 1949 Larkspur negotiated an agreement with Sanitary The main San Rafael treatment plant is located District No. 1 for the treatment of Larkspur sewage on the marshland at the shore of San Rafael Bay and in the new District 1 plant. The agreement is similar discharges to the bay. The treatment process is mod in scope and terms to that between Districts 1 and 2, ified activated sludge, and provides an intermediate except that Larkspur's capacity right is limited to degree of treatment higher than primary but lower 30 MARIN COUNTY SEWERAGE STUDY than secondary treatment by the conventional activated passing of raw sewage to the bay. Plant records indi sludge process. cate that during the two-year period from July 1964 to May 1966, all or a portion of the flow was bypassed at the plant during 57 days. The capacity problem is not confined to the treatment plant. OverflOwing man holes in the collection system are reportedly a com mon occurrence during rainy weather. SAN RAFAEL SANITATION DISTRICT sewage treatment plant provides an intermediate degree of treatment by a modification of the activated sludge process. The original plant units, constructed in 1949, con sist of a 70-ft diameter primary clarifier, a 76,000 cu ft capacity heated sludge digester, and an opera MARIN BAY PLANT of San Rafael CountySanitationDistrlctpro., tions building. Additions in 1962 included an aeration vides intermediate treatment for sewage from the Peacock Gap tank, two 40-ft square secondary clarifiers, and an area and discharges to San Pablo Bay. unbeated secondary digester with a capacity of 39,000 cu ft. The rectangular aeration tank has a capacity Las Gallinas Watershed of 14,500 cu ft. Currently nearing completion is a The drainage area which comprises the water construction project which includes two additional sheds of Gallinas, Santa Margarita, and Miller Creeks secondary clarifiers, identical to the 1962 additions, is designated as the Las Gallinas watershed. The and pile foundations for a future second aeration tanl<. western half of the 21-sq mi watershed area is very Design flow for the present plant is reported to sparsely inhabited, while the eastern half contains be 5 mgd, compared to an average dry weather flow of over 23,000 residents. A single public sewerage 2.3 mgd recorded during the summer of 1965. Treat agency, Las Gallinas Valley Sanitary District, pro ment plant efficiency, based on five laboratory test vides sewerage service within the watershed. Prin reports during 1965 and 1966, averaged 77 perceut cipal sewerage facilities within the watershed are for removal of BOD and 75 percent for removal of shown in Fig. 4-3. suspended solids. The most recently formed of the major operating The second treatment plaut operated by San Rafael pnblic sewerage agencies in Marin County, Las Gal County Sanitation District is a small intermediate linas Valley Sanitary District serves the fastest treatment plant which serves the Peacock Gap de growing area in the county. From its formation in velopment on Point San Pedro. Designed for a sewage 1954 when it included 245 acres, the district had grown flow of 0.16 mgd, the plant is presently treating a by 1966 to 4200 acres, or 6.6 sq mi. Virtually the dry weather flow of a little more than half that amount. entire watershed population of 24,000 is included with Plant units include a primary clarifier, a trickling in the district and connected to the sewerage system. filter and an unbeated sludge digester. Disinfected The first sewers in the area were constructed in plant effluent is discharged through a short outfall 1947 and 1948 in the Portola Gardens development, line to San Pablo Bay, and digested sludge is dis followed shortly thereafter by developments in San charged to a lagoon on the plant site. No data are Rafael Meadows, Gallinas Village and Terra Linda. available on plant operating efficiency. In each case the developer constructed a small treat The San Rafael sewerage system has its share of ment plant to serve the local area. Shortly after its difficulties caused by storm water infiltration. During formation the district began to annex the separate the rainy season, sewage flows frequently exceed the developments and retire the plants or convert them to capacity of treatment facilities and necessitate the by- raw sewage pumping stations. With the connection EXISTING SEWERAGE SYSTEMS 31 ; I of the Gallinas Village system in the summer of 1966 passes are installed in all trunk lines upstream of I the process was completed, and the district now re pumping stations, but district personnel report that tains full responsibility for the collection and treat actual overflows are rare except in cases of stoppage I ment of all sewage within the watershed. or mechanical failure. Occasional overflows were The district collection system now includes about reported upstream of the Terra Linda pumping station, I 80 miles of sewers, from 6 to 24 in. in diameter, attributed primarily to a lack of pumping capacity and 11 pumping stations. A central treatment plant rather than a lack of trunk capacity. An additional I is located east of Gallinas Valley and about a mile pump was installed in this station in 1966, and the from the shore of San Pablo Bay. capacity of the force main to the treatment plant was increased. Novato Creek Watershed I ! The Novato Creek watershed, one of the largest Ii drainage basins in the county, covers an area of over : 'i 50 sq mi and contains a present population of about Ii 32,500. The developed portions of the basin are served by a single public sewerage agency, Sanitary District No.6. Hamilton Air Force Base maintains its own sewage collection system and treatment plant to serve the major portion of the base, though part of the bar racks and family housing are connected to the Sanitary District No. 6 collection system. The Hamilton Field sewerage system is discussed later in this chapter. lji Principal sewerage facilities within the watershed I are shown in Fig. 4-3. Ii TREATMENT PLANTaf the Las Gallinas Valley Sanitation Dis Although it was formed in 1925, Sanitary Dis trict employs the biologic filtration process for secondary treat trict No.6 remained essentially inactive until 1947 . i ment and discharges to the shallow waters of San Pablo Bay. In 1948 and 1949 construction was completed on the I I' The first units of the present treatment plant were first units of the collection system and the Novato I constructed in 1955, and consisted of a 41,200 cu ft treatment plant. Rapid population growth has since I capacity digester and half of the present primary occasioned major expansions both of the district boun trickling filter. Expansion in 1959 added two 65-ft daries and of the sewage collection and treatment diameter clarifiers and expanded the trickling filter facilities. The district boundary now encompasses to its full diameter of 110 ft. The third increment 15 sq mi containing 30,000 people, over 27,000 of of expansion in 1965 added a second digester with a whom are connected to the sewerage system. The capacity of 70,000 cu ft, a 90-ft diameter secondary remainder still rely on individual disposal systems, clarifier, a 90-ft diameter secondary trickling filter principally septic tanks. which is expandable to 150 ft, and chlorination facili The district has already expanded itsborders be ties. Chlorinated plant effluent is discharged to San yond the northern boundary of the Novato Creek water Pablo Bay via a channel dredged some 8000 ft across shed and now includes some areas which are topo the mud flats to mean lower low water. Digested graphically tributary to the Petaluma River. A long sludge is discharged to a lagoon on the plant site. range plan prepared for Sanitary District No. 6 in The present plant can provide secondary treat 1965 by Jenks and Adamson15 considered the ultimate ment for a design flow of 2. 1 mgd. During the sum service area of the district to include all of the San mer of 1965 the average dry weather flow was mea Antonio Creek watershed which lies adjacent to the sured at 1. 35 mgd. After connection of Las Gallinas Petaluma River. The Jenks and Adamson report has Village and installation of a new plant flow meter, been used as a major source of reference for infor the measured flow in the fall of 1966 was 1. 85 mgd. mation on Sanitary District No.6. Plant records show treatment efficiencies averaging About two-thirds of the district area of 15 sq mi 86 percent for removal of suspended solids and 89 is presently served by sewers. The sewerage sys percent for BOD removal. tem comprises some 130 miles of sewers from 6 to 30 Since most of the sewers in the district have been in. in diameter, nine pumping stations, and three constructed within the last 15 years, construction treatment plants known as the Novato, Ignacio and practices were generally better and infiltration rates Bahia plants. The Novato and Ignacio plants have both are therefore lower than in much of the county. By- been in service for ten years or more, while the 32 MARIN COUNTY SEWERAGE STUDY TWO TREATMENT PLANTS of Sanitary District No.6 discharge effluent to Novato Creek. The Novato plant (left) has a design capacity of 2.7 mgd, and the Ignacio plant (right) is designed for 0.9 mgd. Both plants provide secondary treatment. Bahia plant was under construction as this report mgd utilizing 29,000 cu ft of aeration tank capacity was written. and two final settling tanks, each 36 ft long, 6 ft wide, The Novato treatment plant, which was constructed and 12.5 ft deep. A third tank identical in size to in three stages, now has a rated design capacity of the settling tanks will provide aerobic digestion of 2.7 mgd compared to the 1965 average dry weather the waste activated sludge. The plant will serve a flow of 1. 55 mgd. The treatment process is a com developing area along the Petaluma River northof bination of biologic filtration and modified activated Novato and will discharge to the river. sludge treatment using the spirovortex system. Lab Problems of lack of capacity in the district sew oratory test results since the latest additions went erage system are confined to wet weather periods into service in 1964 show that the plant is achieving and then occur primarily in that portion of the system an over-all suspended solids removal of 90 percent tributary to the Novato plant. During and immediately and a BOD removal of 86 percent. after heavy rainfall the major portion of the trunk Principal plant units include a 90-ft diameter pri system undergoes serious surcharging despite the mary clarifier, a 100-ft diameter trickling filter, fact that the treatment plant influent pumping station a 6000-sq ft deck aerator, two 55-ft diameter vortex is running at full capacity and two auxiliary engine type mixing tanks, a 75-ft diameter secondary clari driven pumps are bypassing raw sewage directly to fier, and a heated sludge digester with a capacity of Novato Creek. The surcharge often reaches the point 70,000 cu ft. Chlorinated plant effluent is discharged where manholes overflow. Jenks an<l Adamson 15 re to Novato Creek and digested sludge is discharged to port that the present problem is due primarily to a sludge lagoons. lack of terminal pumping capacity rather than a lack The Ignacio plant is a smaller plant which serves of trunk capacity. During the period from January a separate collection system to the south of Novato. 1965 through February 1966 plant records show that Designed for a flow of 0.9 mgd, the plant is presently the Novato sewage treatment plant bypassed raw sew treating an average dry weather flow of 0.6 mgd. age to Novato Creek on 19 days for a total of 226 Laboratory reports do not show the strength of the hours. raw sewage, but assmning these values to be the same as at Novato, the Ignacio plant is achieving removal Bolinas Watershed rates of 95 percent of suspended solids and 94 percent The Bolinas watershed covers an area of 28 sq mi of BOD. and includes the popular recreation areas of Stinson Principal plant units consist of primary and sec Beach and Bolinas. While there are only about 1,000 ondary clarifiers, each 65 ft in diameter, a 120-ft permanent residents in the drainage area, the sum diameter trickling filter, and a heated sludge digester mer population is approximately doubled by vaca with a capacity of 70,000 cu ft. Chlorinated plant tioners and summer homeowners. The illlusual rec I'!'T' effluent is discharged to Novato Creek and digested reational opportunities afforded by the area sur sludge is dewatered on sludge drying beds. rounding Bolinas Lagoon attract additional thousands (T' When completed, the Bahia plant will provide ex of swimmers, picknickers, surfers and bird watchers tended aeration treatment for a design flow of 0.2 who use the area on a daytime basis. As many as ~ FJ" f"f' EXISTING SEWERAGE SYSTEMS 33 :i ~ I 15,000 day visitors may crowd the available facilities of Sanitary Engineering show that the original outfall, on a summer weekend. at that location, broke off in 1939 and was replaced ,I Three separate local agencies, Stinson Beach by a cast iron outfall line in 1940. County Water District, Bolinas Beach Public Utility Bolinas Public Utility District was organized in District, and Bolinas Public utility District, have 1926 for the primary purpose of developing a water 'I I the authority to provide public sewerage service. Of supply for the district residents. In 1962 Sanitary these, only the latter actually provides any sewerage District No. 3 entered into an agreement transferring service. Bolinas Beach Public Utility District is con funds to Bolinas Public utility District, and the fol cerned primarily with supplying water to the district lowing year Sanitary District No. 3 was dissolved. residents. Stinson Beach County Water District, while Bolinas Public Utility District how holds full respon formed specifically for the purpose of providing sew sibility for water and sewerage service within the 1.8 i erage for the Stinson Beach area, has not yet pro sq mi district area. Size and location of district sew , , I! ceeded beyond the study stage, of which this report ers are shown on Fig. 9-5. is the culmination. Present district resident population is estimated ! i Bolinas and Bolinas Beach Public Utility Districts to be 380. In a report prepared for Bolinas Public 16 have proposed a consolidation of the two districts into Utility District by Kennedy Engineers in 1964 the a single entity, to be called Bolinas Community Public maximum summer population was estimated at 540. Utility District. Consolidation was approved by the voters in the two districts in February 1967 and will Stinson Beach County Water District. The Stinson become effective on July 1, 1967. Beach area relies entirely on septic tanks and sub surface leaching systems for sewage disposal. The Bolinas Beach Public Utility District. Organized Marin County Health Department has received over in 1939, Bolinas Beach Public Utility District en the years a number of complaints about overflowing compasses an area of about 450 acres, most of which septic tanks, and in June 1961, the Board of Super lies on the top of Bolinas Mesa. While it is legally visors directed the Sanitation Division to conduct a empowered to engage in sewerage, the district has survey of the adequacy of sewage disposal in the Stin taken no steps toward the development of a sewerage son Beach area. The resulting report stated in Sum system, and all of the residents depend on septic tanks mary !lIt is our considered opinion that a public j for sewage disposal. Performance of septic tanks health problem does exist in this area, and its solu has been spotty, and leaching system failures re tion lies with the formation of some sort of a publicly sulting in surfacing of septic tank effluent have been owned district in order that the problem can be uni reported. In at least one case a homeowner was formly dealt with both at the present time and in the served with an eviction notice by Marin County auth future. II ities because of the public health hazard created by On November 6, 1962, the Stinson Beach County failure of his leaching system. Topography prohibits Water District was formed for the purpose of pro sewering the area by gravity into the Bolinas sewage viding sewerage service to the area. With the in collection system. tent of providing a base for unified sewerage planning, Population figures for Bolinas Beach Public Utility the district boundary was established to include vir District are contradictory, probably due to the large tually all of the area adjacent to Bolinas Lagoon which number of homes which are occupied only during the is not included in Bolinas Public utility District. The summer. Based on census data and water connections total district area of 11 sq mi includes only about 550 it appears that the summer population is about 600 and permanent residents, virtually all of whom live in the winter population about half that number. Stinson Beach. Summer residents swell the total to about 1200, and as many as 13,000 day visitors have Bolinas Public Utility District. The first sewerage been accommodated at Stinson State Beach. agency in the Bolinas area was Bolinas Sanitary Dis Shortly after its formation the district engaged a trict, formed in 1906. That same year the first sew consulting engineer to undertake studies both of a sew ers were constructed, apparently discharging raw erage system for the district and of the possibilities of sewage into Bolinas Lagoon under the wharf. The joint sewerage action with the other agencies within district was later reorganized as Sanitary District the watershed. The complexity of the problems in No.3, and in 1927 the collection system was extended volved indicated the need for a study of wider scope, to a portion of Bolinas Mesa. It is believed that the and further action has been withheld pending the com outfall line was extended at that time to its present pletion of this study. location on the west bank of the channel at the mouth of the lagoon. In any event, records of the Bureau Joint Sewerage Action. Residents of the Bolinas 34 MARIN COUNTY SEWERAGE STUDY watershed generally endorse the common goal of pro February, 1964. tecting the local marine environment from pollution Kennedy Engineers16 recommended that Bolinas due to sewage disCharge. There has been, however, Public Utility District build a small treatment plant wide disagreement as to how this goal can best be near Wharf Road with discharge through the existing achieved. In the interest of better understanding the outfall, a project not considered feasible for jOint situation as it now exists, it is worthwhile to present Bolinas-Stinson Beach sewage treatment. ~ a brief chronological summary of the major events of May, 1964. the last five or six years which concern the status of M. Carleton Yoder18 recommended further con f"'" sewerage in the Stinson Beach-Bolinas area. The sideration of joint sewerage action between Stinson chronology of events was abstracted principally from Beach County Water District and Bolinas Public Utility f"'" a May 1964 report by the San Francisco Bay Area District, possibly on the basis of land disposal of ef Regional Water Quality Control Board. 17 fluent. r'" November, 1964. ,r . September 21, 1961. Kennedy Engineers, in a report to Bolinas Public The Regional Water Qnality Control Board adopted Utility District, 19 found land disposal of sewage ef Resolution No. 372 prohibiting the continued discharge fluent to be infeasible in view of the Water Quality of raw sewage by Sanitary District No.3. Control Board prohibition of effluent discharge to Bo rF September, 1961. linas Lagoon. The Marin Department of Public Health recom December 17, 1964. mended formation of a public sewerage agency to serve The Water Quality Control Board adopted Resolu the Stinson Beach area. tion No. 617, a long-range plan and policy for pol November 6, 1962. lution control in the Stinson Beach-Bolinas area. In Stinson Beach County Water District was formed. addition to establishing receiving water qnality objec February 2, 1963. tives from Rocky Point to Point Reyes National Sea Sanitary District No.3, Bolinas Beach Public shore, Resolution No. 617 requires dischargers to Utility District, and Stinson Beach County Water report on the feasibility of joint sewerage action. jointly appealed to the Marin County Board of Super July, 1965. visors for assistance in conducting a sewerage study Marin County Board of Supervisors, upon recom of the entire Bolinas watershed. mendation of the Department of Public Health, auth April 18, 1963. orized a study aimed at preparing a county-wide sew The Regional Water Quality Control Board adopted erage master plan and designated the Bolinas water Resolution No. 458 ordering Sanitary District No.3 shed for special detailed consideration. to cease and desist violation of Resolution No. 372. March 15, 1966. Resolution No. 458 is still in effect, though enforce Marin County Board of Supervisors executed a ment has been held up pending the outcome of this contract with Brown and Caldwell for preparation of study. the countywide sewerage study and report. All three July 1, 1963. Stinson Beach-Bolinas districts agreed to partiCipate Bolinas Public Utility District formally assumed with the county in the cost of the detailed study of the the authority of Sanitary District No.3. Bo linas watershed. July 5, 1963. April 1, 1967. Bolinas Public Utility District authorized the en Brown and Caldwell submitted to the county an gagement of Mr. G. A. Horstkotte as engineering interim report setting forth a long-range sewerage consultant for the district. Mr. Horstkotte subse plan for the Bolinas watershed. All of the information quently recommended that Bolinas Public Utility Dis contained in the interim report is also included in this trict proceed on its own to solve its sewerage prob report. lems, and as a result the district withdrew its sup port from the area-wide study. Tomales Bay Watershed September 20, 1963. The Tomales Bay watershed, with a present popu Bolinas Public Utility District engaged Kennedy lation of only abont 3000, contains. a single small pub Engineers to conduct a study and recommend an ap lic sewerage agency, the Tomales Sewer Maintenance propriate method of sewage treatment and disposal. District. Fewer than 400 people reside in the district, September, 1963 (approximate). and the remainder of the watershed popnlation is scat Stinson Beach County Water District engaged M. tered along the shores of the bay in a number of small Carleton Yoder to study collection, treatment and unincorporated communities. disposal of sewage for Stinson Beach. Once a thriving agricultural community, the un- , EXISTING SEWERAGE SYSTEMS 35 I incorporated town of Tomales has over the years lost are shown on Fig. 4-1. Marin Municipal Water Dis , most of its commercial activity to Petaluma, which is trict has accepted responsibility for sewerage in the I now only 20 minutes away by car. The only industry, developing community of Marincello, while North I a cheese factory, ceased operation ahout 1958. The Marin County Water District has begun preliminary I remaining residents of the town, as well as the union planning for sewerage service in a recently-annexed high school and grade school, either use individual area along the eastern shore of Tomales Bay. I11 disposal systems or discharge sewage raw to Keys Creek. As early as 1926 the State Bureau of Sanitary State and Federal Agencies Engineering characterized the condition of Keys Creek Seven state and federal agencies operate separate below Tomales as "truly shocking." sewage collection and disposal systems within Marin In 1953 the North Coastal Region Water Quality County. Of these, only Hamilton Air Force Base, Control Board adopted requirements prohibiting the San Quentin Prison, and Samuel P. Taylor State Park discharge of untreated sewage to Keys Creek. To are of major COncern to this study. The others are males Sewer Maintenance District, formed in 1956, Fort Baker, Forts Barry and Cronkhite, Mill Valley subsequently submitted to the State Department of Air Force Base, and Angel Island State Park. Public Health two plans for collection and treatment Fort Baker, which now pumps its sewage to the of sewage. Neither plan received the approval of the Sausalito-Marin City sewage treatment plant, is ex Department of Public Health, and the district is now pected to be abandoned before long. Forts Barry and inactive, standing with Bolinas as one of the two agen Cronkhite, which utilize a septic tank and subsurface cies in the county which now discharge raw sewage leaching field for sewage disposal, will also soon be to the waters of the state. abandoned. I Mill Valley Air Force Base is a radar installation County-wide Sewerage Agencies situated on the top of Mt. Tamalpais at the extreme I By virtue of their roles as principal water pur southern end of the Lagunitas Creek watershed. The veyors in the county, Marin Municipal Water District normal base complement of about 150 persons is a and North Marin County Water District have assumed stable figure, and the present technique of hillside \ the responsibility for meeting county-wide water re spray disposal of sewage effluent should remain ade- quirements as the need arises. Each agency has the quate for future needs. . statutory authority to provide sewerage service as Angel Island State Park uses a septic tank for well, and each is presently engaged in preliminary sewage treatment, discharging the chlorinated ef planning for sewerage of areas which lie within the fluent to Raccoon Strait. The number of persons water districts but outside the planning area of other visiting Angel Island State Park will undoubtedly show public sewerage agenCies. At the time this report was a future increase commensurate with increases in written neither agency was engaged in the actual con population and small boat ownership. However, the struction or operation of sewerage facilities. park is entirely administered by the state and is lo The policy of both agencies with regard to annex cated next to Raccoon Strait, which is one of the most ations, service area planning, and provision of sew sultable areas in San Francisco Bay for efficient sew erage service is presented in a Joint Statement of ag'e effluent disposal. Angel Island may therefore be Policy prepared in 1965. 20 In reference to sewerage excluded from Marin County sewerage planning. service, the statement reads as follows! "The Dis tricts are willing to consider the possibility of sewer Hamilton Air Force Base. Aside from that portion servi ce in presently unsewered areas lying outside of the housing area which is served by Sanitary Dis the logical master plan areas of existing sanitary trict No.6, all sewage from Hamilton Air Force Base agencies which may be within or without the boun is conveyed to the base treatment plant which is lo daries of the present Water Districts. The Districts cated on the shore of San Pablo Bay. Constructed and acknowledge their power to undertake the waste dis operated by the Air Force, the plant provides pri posal, but believe tbat the public health aspects of mary treatment and separate sludge digestion for a individual waste disposal systems are the primary present average flow of about one mgd. Effluent is responsibility of the county of Marin. The Districts discharged to the adjacent tidal flsts of San Pahlo Bay. recognize the need for over-all coordination of waste The Chief Civilian Engineer at Hamilton reports disposal programs, particularly those in presently that studies have been made of the economic feasi undeveloped areas, and will cooperate in achieving bility of delivering sewage from the base to either this objective. Sanitary District No.6 or Las Gallinas Valley Sanitary IT The present boundaries oithe two water districts District. The studies showed that the cheapest al and the mutually-accepted boundary for future planning ternative was for Hamilton to continue to treat the 36 MARIN COUNTY SEWERAGE STUDY sewage at its own plant. Asa result, the firm of Consoer, Townsend and Associates was engaged to desigu secondary treatment facilities for the present plant. Construction drawings for the expanded plant, which will have a capacity of 1. 5 mgd, are now com pleted, and construction is expected to begin in 1967. \Vhen construction is completed, base personnel ex pect that the plant will be adequate for the ultimate requirements of the base. SAN QUENTIN PRISON sewage treatment plant serves the prison community. After intermediate treatment the sewage is dis charged to the adjacent shallow waters of San Francisco Bay. the primary clarifier through the trickling filter and back to the clarifier, the average plant efficiency of 37 percent BOD removal reported for 1965 is little better than that normally attaiuable by primary treat ment alone. A request has been submitted by prison authorities for $200,000 to finance construction of another trickling filter and a secondary clarifier, HAMILTON AIR FORCE BASE sewage treatment plant discharges thus providing full secondary treatment. State of effluent to the shallow waters of San Pablo Bay after primary ficials have also indicated that they would consider treatment. Secondary treatment will soon be added. with favor a plan to abandon the San Quentin plant if San Quentin State Prison. Located on the south this study shows a centrally located plant to be econ side of Point San Quentin, the state prison accom Omically advantageous. modates an inmate population of about 3800. Sewage from the prison and from San Quentin Village Sewer Samuel P. Taylor State Park. Samuel P. Taylor Maintenance District is treated at the prison plant, State Park includes over 2500 acres of rugged hill which is located about 3500 ft east of the Sanitary sides and redwood canyons at the lower end of San District No. 1 plant. Geronimo Valley. Lagunitas Creek, a year-round Prison sewage comprises not only the domestic stream at this location, runs through the park for wastes from the inmates, but also the wastes from more than three miles. In a typical year monthly the prison industrial complex. Both fresh and salt park attendance by both campers and day visitors will water are used in the prison, the former at a rate vary from an August high of 40,000 to a December of about 1 mgd and the latter O. 4 mgd. The sewage, low of 2000. Attendance by 2500 or more persons as a result, is about one-third sea water. Present can be expected on several days during the summer. plans call for abandonmeut of the salt water system in The park has its own sewerage system, which the near future and use of fresh water only. consists of about a mile of 4-in. to 8-in. sewers, two The sewage treatment plant consists of an influent lift stations, a sewage treatmeut plant, and a hillside pumping station, a 60-ft diameter primary clarifier, spray field for land disposal of effluent. The treat a 60-ft diameter trickling filter, and a 25,000 cu ft ment plant has a desigu capacity of 50,000 gallons per capacity unheated sludge digester. Chlorinated ef day and provides secondary treatment by means of pri fluent is discharged through a short outfall line to mary and secondary sedimentation tanks, a standard San Francisco Bay. The plant is desigued for a flow rate trickling filter, and an unheated sludge digester. of about 1. 0 mgd, compared to a 1965 average dry Plant effluent is pumped to a four-acre hillside dispo weather flow of O. 93 mgd. Peak hydraulic capacity sal site and sprayed over a wooded area where the of the plant is not precisely established, but is known ground is heavily covered with forest litter. to be at least equal to the maximum pumping rate of No flow or treatment data are aVailable, but based about 3.5 mgd. on a sewage flow of 10 gallons per visitor per day the Although the plant is desigued to provide an inter plant is operating at about half capacity on the maxi mediate degree of treatment by circulating flow from mum day of use. CHAPTER 5 5EW AGE CHARACTERISTICS Design of facilities for collection, treatment, and Storm Water Inflow. Water originating as rainfall disposal of sewage is dictated primarily by the load which finds its way into the sewage collection system ings anticipated during the design period under con either by infiltration or by direct inflow. sideration. In order to develop estimates of future D,y W.athe, Flow. Sewage flow during periods of loadings it is necessary first to determine unit quan no rainfall. Rates of flow exhibit hourly and daily tities for the components affecting both the volume of variations. A certain amount of infiltration may be sewage and its strength and composition. Since the present. characteristics of sewage may vary from one com Wet Weather Flow. Sewage flow during periods munity to the next, depending on the physical and of moderate to heavy rainfall. Storm water inflow economic enVironment, unit quantities for design may increase the wet weather flow to a rate many purposes must be based on an evaluation of the sew times greater than the dry weather flow, and unless age characteristics in the area under study. Where provided for in sewerage system design can produce indicated, appropriate allowances for future change hydraulic overloads which result in sewage overflows must be included, to public streets or watercourses. Biochemical Oxygen Demand. The quantity of Definition of Terms oxygen required to support biologic oxidation of the As a preface to a discussion of sewage charac organic matter contained in sewage. Usually referred teristics, it is helpful to define some of the terms to as BOD, this characteristic defines the strength used in this report. of a sewage and often determines the degree of treat Sewage. A combination of the water-carried wastes ment which must be provided to produce a reqUired from residences, business buildings, institutions, and effluent quality. industrial establishments, together with such ground, Suspended Solids. The suspended material trans- surface and storm waters as may be present. ported in sewage. Suspended solids and BOD are two Domestic Sewage. Sewage principally derived from principal criteria used in defining the strength of a the sanitary cOliveniences of residences or produced sewage or the quality of an effluent. The quantity of by normal residential activities. suspended material removed during treatment varies Commercial Sewage. Sewage generated in pre- with the type aud degree of treatment and has an im dominantly business or commercial districts, includ portant bearing on the size of many mechanical and ing not only sanitary wastes, but also the wastes from process units. the commercial activities themselves. Typically, commercial sewage might include wastes from res SEWAGE VOLUME taurants, laundromats, and service stations. Industrial Wastes. Liquid wastes from manufac- Study of sewage flows in the existing sewerage turing and industrial processes as distinct from san systems of Marin County provides a rational basis itary wastes. for projection of future flows. With minor exceptions, Infiltration. The unintentional entry of water into all of the sewage collected by public sewerage agen the sewage collection system from the surrounding cies is treated before discharge, and each of the soil. Common points of entry include broken pipe major treatment plants contains a recording flow and defective joints in the pipe or in walls of manholes. meter. The data available to this study therefore Infiltration may result from sewers being laid below included several years of flow records for each major the grouud water table or from saturation of the soil sewerage agency. Because of the difficulties inherent by rain or irrigation water. in measuring sewage flows, the accuracy of a single Direct Storm Inflow. Rain water which enters the set of flow records is often open to question. Where sewage collection system through known openings in data are available from several different sources, sewage condUits. Points of entry may include roof as in the present case, the overall reliability of the and patiO drain cormections, catch basin COlUl8ctions, figures derived as a basis for design is considerably and holes in the tops of manhole covers in flooded enhanced. .1 streets. Direct storm inflow is distinguished by the A total of ten agencies, including San Quentin ,I , . rapidity with which it begins and ends after a period Prison, maintain flow records of a length and ac . n' , of rainfall. Storm water infiltration, on the other curacy suitable for use in this study .. Between them, .':! (' hand, may persist for an extended period after the these agencies account for about 90 percent of the : 'Ii , i cessation of rainfall. sewage collected in Marin County. A summary of I 37 Ii I, 38 MARIN COUNTY SEWERAGE STUDY the average dry weather flow (ADWF) and peak wet Table 5-1. Summary of Present Sewage Flows weather flow (PWWF) for the ten agencies is shown in Table 5-1. The dry weather flows, recorded dur ADWF PWWF Plant mgd mgd ing the summer of 1965, may be considered quite a accurate. The wet weather flows, due to bypasses, Sausalito-Marin City 1.37 11 a overflows, and limits in meter capacity, must in Mill Valley 1.36 13 a Richardson Bay S.D., TrestleGlen 0.15 1 most cases be regarded as estimates only. Wher Sanitary District No.5 0.82 5 ever peak flows exceeded meter capacity or where b Sanitary District No. 1 3.58 15 bypasses were known to occur an attempt was made San Quentin 0.94 3 6 to estimate the probable quantity of unmeasured flow 0 San Rafael, Main Plant 2.31 9 by inspecting bypass structures and questioning oper Las Gallinas Valley S. D. 1.85 lOa a ating personnel. Sanitary Dist. No.6, Novato Plant 1.55 14 The first week of January, 1966, was selected for Sanitary Dist. No.6, Ignacio Plant 0.61 2 determination of wet weather flows, because a major Total 15 85 storm during that week resulted in heavy rainfall a Estimated. throughout Marin County. A recording rain gage maintained by the Marin County Department of Public b Measured at plant. Large unknown quantities were bypassed. Works at its Mill Valley corporation yard shows that heavy rainiall during the last week of December, 1965, ardson Bay Sanitary District, the unit dry weather was followed by two clear days on January 1 and 2, flow was 85 gcd (gallons per capita per day). This light rain on January 3, and heavy rain on January 4 compares favorably with a 1959 estimate of 68.5 gcd and 5. Maximum 24-hour rainfall on the 4th and 5th by Yoder, 11 which was based on a high population as indicated on the rain gage charts amounted to 3.17 estimate obtained by projecting 1950 census data. inches, a rainfall intenSity which may be expected to Corrected on the basis of 1960 census figures, Yoder's recur about once in three years. Since a review of computed per capita flow rate is 82 gcd. flow records indicates that at most plants a lesser The graph of wet weather flow clearly illustrates storm will produce flows of comparable magnitude, the effect of rainiall on sewage flows. During the first sewage flows during the selected period are consid two days of January, flow was consistently higher than ered representative of the peak wet weather flows during the corresponding dry weather period as a re which must be accommodated in the design of future sult of storm water inflow from the heavy rains during sewerage faCilities. the preceding week. Most of the storm water inflow For each of the plants for which records are avail undoubtedly occurred in the form of infiltration from able, a graph was drawn shOwing dry weather flow the rain-saturated soil. Within a few hours after the during a typical seven-day summer period and wet start of heavy rain on January 4, sewage flow in weather flow during the week of January 1-7, 1966. creased sharply as a result of direct storm inflow The resulting flow charts are presented as Figs. 5-1 to the collection system. At mid-day the operator through 5-10. The rainfall plot, repeated for com opened the bypass near the US 101 highway bridge, parison with wet weather flows at the various plants, and the flow at the plant immediately dropped 2 mgd, presents hourly rainfall as recorded at Mill Valley. the amount being bypassed to Richardson Bay. De spite the open bypass, flow contioued to increase and Sausal ito-Marin City Sewage Flow by evening exceeded the capaCity of the plant flow Reference to Fig. 5-1 shows that dry weather meter. For a period of 10 hours thereafter the chart sewage flows at the Sausalito-Marin City sewage trace continuously exceeded the meter capacity of treatment plant follow a regular and predictable pat 6 mgd, and it is logical to assume that for at least a tern, as is the case with most of the public sewerage portion of that period the influent pumping station was agenCies investigated. The minimum daily flow is operated at its maximum capacity of about 8 mgd. quite high, amounting to about 44 percent of the daily It is further reported by Nute13 that during major average. A portion of the daily minimum is attribut storms overflows occur in the tributary portion of able to the sea water infiltration which is known to Richardson Bay Sanitary District. The peak wet occur in certain parts of the collection system. weather flow, then, consists of 8 mgd pumped to the Dry weather flow during the months of June, July, plant, 2 mgd bypassed by Sausalito, and perhaps 1 August and September of 1965 averaged 1. 37 mgd. mgd or more of overflow in Richardson Bay Sanitary Based on the estimated 1966 population of 16,100 for District and at other unreported points, making a total the tributary area, including Sausalito, Marin City, peak wet weather flow of at least 11 mgd. Within a Tamalpais Valley, Fort Baker, and a portion of Rich- few hours after rainfall stopped the peak flow rate SEWAGE CHARACTERISTICS 39 dropped sharply to a value representative of the sum ferent process arrived at an estimated storm water of normal dry weather flows plus storm water in inflow rate of 10.5 mgd. filtration. For purposes of estimating future quantities of The difference between normal dry weather flow storm water inflow it is convenient to express that and peak wet weather flow represents the storm water constituent in terms of gallons per day per unit of inflow rate, which in this case amounts to 10.4 mgd. area. For the sewered area of approximately 2400 It is interesting to note that in 1959 Yoderll by a dif- acres tributary to the Sausalito-Marin City system, Fig. 5-\. Hourly Variation in Flow at Sausalito Sewage Treatment Plant , , , ~~~I ~,~ ~~* ;~; ~;; : : : : : : I , , , , 14 7r-, ESTIMATED TOTAL FLOW--...... I " 12 \ IrMAXIMUM METER I CAPACITY I I -~ 10 I \ WET WEATHER 0 JAN. 1-7, 1966~ ~ ~ ~ ~ f\/ ! ~ 0 J ,; ~ ~ D JU R L Y Y W 2 E 7 A - T A H U E G R UST 2,19651 . w~ . ~ f\ ~ 4 ~ ('\ 0--/ ) . 0~ ~. 1'---' ~ 0 2 --V '{J' I,j\/ I~ ~ ~ IV ~ ~l{ ~ U~ 1.47 1.46 1.42 \.34 o -' 12M 6 12N 6 12M 6 lEN 6 !2M 6 lEN 6 12M 6 12N 6 12M 6 lEN 6 12M 6 12N 6 12M 6 lEN 6 12M Fig. 5-2. Hourly Variation in Flow at Mill Valley Sewage Treatment Plant 40 MARIN COUNTY SEWERAGE STUDY a storm water inflow rate of 10.4 mgd may be ex uary 4 the flow at the plant rose to 0.7 mgd. For pressed as 4300 gad (gallons per acre per day). That about three hours, a portion of the flow was bypassed value represents a uniform areal rate of inflow and before receiving secondary treatment, but as flow no attempt has been made to determine whether all continued to increase the secondary treatment process portions of the tributary area are equally susceptible was bypassed completely for 48 hours. Since the flow to storm water inflow. meter is installed on the effluent from the secondary treatment process, no record is available for the peak Mi II Vall ey Sewage Flow flow period. However, the plant operator states that As at Sausalito, the Mill Valley dry weather flow the flow did not exceed the influent pumping station chart (Fig. 5-2) indicates high daily minimum flows, capacity of one mgd. The latter figure is assumed suggesting that some infiltration is occurring at a to be the maximum flow during the storm period. fairly constant rate in the tributary collection sys terns. Typically, the daily minimum flow is 50 per Sanitary District No.5 Sewage Flow cent or more of the average daily flow. During the Sewage flow from Sanitary District No.5 and months of June, July, August and September of 1965, from the city of Belvedere is recorded at the District the average daily flow at the Mill Valley treatment 5 plant (Fig. 5-4). The high minimum dry weather plant was 1. 36 mgd, eqnivalent to 84 gcd for the flow rates indicate the presence of appreciable amounts 16,200 residents in the five tributary agencies. of ground water infiltration, probably originatiug in The paitem of wet weather flow for the first week the low-lyiug areas adjacent to Belvedere Lagoon. in January, 1966, is similar to Sausalito except that Dry weather sewage flow measurements for the Bel storm water inflow dropped off more slowly after vedere Lagoon area, conducted by Brown and Cald rainfall stopped. For two days or more the flow rate well in 1960,21 indicated a per capita flow of 102 was still two to three times higher than the equivalent gcd, of which one-third was estimated to consist of dry weather flow. On January 4 and 5, the peak flow infiltration. at the treatment plant exceeded the 10. 5-mgd capacity Plant records of average daily flow are lackiug of the flow meter for 22 hours. During this period for the summer season of 1964 and are rather incon the plant influent sluice gate was throttled, forcing sistent for the summer of 1965, varyiug from a re an umneasured quantity of sewage to bypass by gravity ported average daily flow of 0.59 mgd in June to 1. 01 to Richardson Bay. During a portion of this period mgd in August. sewage was also overflowing the manhole at Ryan For the six-month period from April through Avenue. The peak flow in the trunk sewers is esti September, 1965, the average daily flow was 0.82 mated at 13 mgd, but there is no way of knowing what mgd, equivalent to 90 gcd for the combined areas of the flow might have been if all storm water inflow Belvedere and Sanitary District No.5. could have been accommodated in the sewers without The graph of wet weather flow on Fig. 5-4 shows surcharge. The selected value of 13 mgd for peak peaks of rather short duration associated with rain flow may well be a low estimate. fall. This is due in part, no doubt, to the fact that Of the 13 mgd peak wet weather flow, 12.3 mgd the collection system is comparatively small, and may be attributed to storm water inflow. For the direct storm inflow has a short travel period to reach sewered area of approximately 2440 acres included in the plant. The flow at the plant on January 5 reached the five tributary agencies, this represents a uniform a peak of 5 mgd, of which 4.5 mgd represented storm areal storm water inflow rate of 5000 gad. While ad water inflow. During the storm period, flow in the mittedly high, this figure is considered to be entirely Belvedere collection system exceeded system capac consistent with observed and reported conditions. ity, and an umneasured portion was bypassed through the old raw sewage outfall. This additional flow in Richardson Bay Sanitary District Sewage Flow crement is ignored, because the Sanitary District 5 A graph of sewage flow at the Trestle Glen sewage plant superintendent reports that his unofficial rain treatment plant, which serves about a third of Rich fall reco rds showed a substantially higher rainfall ardson Bay Sanitary District, is shown in Fig. 5-3. at Tiburon than was recorded at Mill Valley. The Dry weather flow is normal, with little or no infiltra probability of recurrence of the total peak flow con tion indicated. For the dry weather months of June, dition may therefore be too low to be accepted as a July, August and September, 1965, average flow was design condition. 0.15 mgd. Unit dry weather flow, as reported by Based on a developed area of 900 acres, 4.5 mgd Nute in 1963,13 amounts to 70 gcd. of storm water inflow represents an average unit rate The wet weather flow graph on Fig. 5-3 shows of 5000 gad. A 170-acre section of Belvedere inves that shortly after the start of heavy rainfall on Jan- tigated by Brown and Caldwell in 196021 also showed SEWAGE CHARACTERISTICS 41 a storm water inflow rate of 5000 gad. ence of major quantities of infiltration. A report by Brown and Caldwell in 196122 derived a unit flow rate Sanitary District No. I Sewage Flow of 76 gcd for the Corte Madera area, which at that Sewage flow from Sanitary Districts No. 1 and 2 time had a population of about 6000. and the city of Larkspnr is measured at the District 1 The graph of wet weather flow clearly shows the sewage treatment plant. The graph of dry weather effect of both storm water infiltration and direct storm flow (Fig. 5-5) shows that daily minimum flow is inflow. Although the peak flow at the plant on January about 40 percent of average daily flow, due in part 5, 1966, exceeded 15 mgd, of which nearly 13 mgd to infiltration which is known to occur continuously represented storm water inflow, unknown additional in the marshland sewers. In a system of this size, quantities were being bypassed at five points along however, maximmn and minimum points are naturally the trunk sewer or were lost at overflowing manholes. somewhat dampened out by the flow time in the collec The plant flow records indicate only that the unit rate tion system. The unit flow rate of 73 gcd, computed of storm water inflow exceeds 1500 gad. Based on on the basis of a population of 49,000 and a summer wet weather flow measurements made in connection average flow of 3.58 mgd, does not indicate the pres- with a 1961 study for Sanitary District No. 2,22 ,.o,---.-,----.-,----.-,----r-r---r-,---r-r--,--,-,-_,~-, :c-="f~",--,-,--,--,--,--,--,-,--,--,---, "- // ,ESTIMATED I TOTAL FLOW 't:"::I WET WEATHER· JAN. 1-7,19I6 6 I ' / SECONDARY TREATMENT'BYPA$SEO ~ DRY WEATHER " c::. JULY 27-AUG. 2,1965 ' ...... ~a5~--++--~~~---I~~~~~~~~~~~+---~-----~~-~~~~+--~---~ t; lj ::; oL--L~~~O~.1~5~~~~±=~~~;d~db~~~~~~~O~14~~~~k=~~~~~~~~~~~~_~~ !2M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M Fig. 5-3. Hourly Variation in Flow at Richardson Bay Sanitary District Sewage Treatment Plant .. ~~.~ ~ ~o; ; .~ I I r 6~~~~~~~--'-1 5~-------4---------~---------4----------4~~-----~-------41---------~1 I WEATHERl--~ I '" 4 WET ~ I JANUARY 1-7,1966 I J ~ ~---------~-----------+-----------~----------~t-----~~-+I--------- DrLRYV WEATHER ~ 3 13-20, 1965 1 ~ ~2~----------~------------+------------~--+4~-.~ I O~~~======~========O=.6=4=t==~========t===~====O.=6=7J====t=======t==~====~==t===~~~~ I 12M 6 lEN 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 lEN 6 12M I Fig. 5-4. Hourly Variation in Flow at Sanitary District No.5 Sewage Treatment Plant 42 MARIN COUNTY SEWERAGE STUDY Brown and Caldwell concluded that a unit storm water flow of 3.6 mgd, recorded on January 5, 1966, in inflow rate of 4000 gad was appropriate for all of the cluded about 3 mgd of direct storm inflow. Within a District 2 service area except for portions sewered few hours afier rainfall stopped the flow rate dropped since 1957. Those portions were assumed to have to a level typical for dry weather. sewers of better construction with lower storm water For an institution such as San Quentin, present inflow rates. patterns of water use and sewage flow may be ex pected to remain Virtually nnchanged in the future. San Quentin Sewage Flow Since no expansion of the prison complex is contem As might be expected, sewage flows at San Quentin plated, the measured values for wet and dry weather bear no relationship to those of a normal residential flow are adequate for planning purposes. community. In addition to the domestic sewage from the inmate popnlation of 3800, a Significant industrial San Rafael Sewage Flow waste volume originates in the prison's shops. Daily Dry weather flow as measured at the San Rafael water use amonnts to about 1 mgd of fresh water and sewage treatment plant during the summer of 1965 0.4 mgd of salt water, with approximately two-thirds averaged 2.31 mgd (Fig. 5-7). For the estimated of the total showing up as sewage. connected population of 27,500, this represents a Average dry weather sewage flow in 1965 amonnted nnit flow of 84 gcd. An additional 1500 persons in to 0.94 mgd. As indicated on Fig. 5-6, the sewage the Peacock Gap area of San Rafael County Sanitation flows exhibit a fairly predictable pattern. Infiltration District contributed sewage to the Marin Bay plant is practically non-existent as evidenced by the fact at a dry weather rate of 63 gcd. The difference in that wet weather and dry weather flows are virtually unit flow rates is probably due at least in part to the identical except during periods of rainfall. The peaks fact that Peacock Gap is strictly residential, while on January 7 and August 3 may be due to periodic the San Rafael main plant receives a combination of dumping of industrial wastes. The peak wet weather domestic, commercial and industrial sewage. , , , , ".;:;' '": :~~~~ ... ~O; : : : I : , 16 _~~AXIMUMIMETER CAPACITY ~ ~'" 14 ) \, 12 / 0 G• /"\ WET WEATHER o ~ j h JAN. 1-7, 1966- f\ ~ ~ i\ /'\ ,~ ' \ \. ) "~ '-.. I~[\ ~ IrDRY WEATHER JULY 27 -AUGUST 2, 1965 ~ 1 ~ !\r ~(' ~ ~ § ~ ~ ~ w 4 v !\ / / \ 1\ \ 2 V V V \. 'J V 3.7 3.4 3.5 3.5 3 .• 3.' , o 12M 6 fEN 6 12M 6 lEN 6 12M 6 lEN 6 12M 6 lEN 6 12M 6 lEN 6 12M 6 lEN 6 12M 6 lEN 6 /PM Fig, 5-5, Hourly Variation in Flow at Sanitary District No, I Sewage Treatment Plant SEWAGE CHARACTERISTICS 43 The collection system tributary to the main plant received at the plant during high storm flows, sug is reported to receive some salt water infiltration, gesting the possibility that some catch basins and though the low minimum dry weather flows (Fig. 5-7) street inlets are connected to the sanitary sewers .. would indicate that the problem is not serious. A small amonnt of rainfall causes a sharp rise Las Gallinas Sewage Flow in sewage flow at the main treatment plant. The wet During the summer months of 1965 sewage flow weather flow graph indicates that the maximum ca at the Las Gallinas Valley Sanitary District sewage pacity of the plant flow meter was exceeded at 6 a. ill. , treatment plant averaged 1. 35 mgd. This figure does January 4, nearly six hours before the start of the not include sewage from Las Gallinas Village, which major storm on January 4th and 5th. At that time did not join the district until 1966. For purposes of total storm water inflow amounted to over 8 mgd, comparison of wet and dry weather flows, 1965 sum representing a nniform areal nnit rate of 1600 gad. mer flow is shown on Fig. 5-8. Shortly thereafter the plant operator began to bypass In the spring of 1966 a new flow meter was in a portion of the flow, and it is impossible to deter stalled at the plant, and during that summer the Las mine the magnitude of the peak flow during the storm. Gallinas Village system was connected to the district The operator reports that large amonnts of grit are sewers. A check of dry weather flow in October, , , , 4 I I ' I ,I ~I I:; I : ' : \ V,'\ .,,"\ j;E JA T NU A W R E Y A T 2 H -7 ER ,1 966 I ~ , • 3 ii Y r~R JU Y LY W 28 E - A A T U H G E U R S T 3,1965 . 1'\) d z~ l I I ~ \ I 'I I I l / ' r 1 l 1 , , 1 I , I I 'J I r ~ ~- " - f : \ I I IJ , ~ '" I . .. o(\A, , , I i I, I ' J I I I I 1. ~~ ' ,, I ,\ ~ - ' ,J ~,"I I !\ /\ \ \ , , ,1I \..'1 '- , , \ \J ' " _ V JI I -" \\ __ ' l ~, I f'x.., '-..../ V P , ~I " 1.06 l.00 1.00 0.80 0.91 0.98 1. 09 o 12M 6 12N 6 12M 6 f2N 6 12M 6 12N 6 12M 6 leN 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M Fig. 5-6. Hourly Variation in Flow at San Quentin Sewage Treatment Plant ~~' ~O.I 0 l ' , , , , , 12 I I I PORTION OF FLOW BYPASSED UNTIL 5:30PM JAN. 10 10 MAXIMUM MEITER CAPACITy-rrJ r~8~- ---/--- '-~\-- ----/--- -~-----------f1-J-t-------t------i----t-----------r----------~ : A WET WEATHER -JAN I-~ '- ~r----+-"'~'--'"~-fr- --+---+----------+---+----+---l n't----f V'( -r;;c-"\---k-1V--+--f-\----+------+-----+----t--ft---+------I ~ 4f-------------t 2 ---~--~-----~--1_~r-~r__t------~--~----~ IV V ( 2.24 \ 2.53 2.38 o I 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 Fig. 5-7. Hourly Variation in Flow at San Rafael Sewage Treatment Plant 44 MARIN COUNTY SEWERAGE STUDY 1966 showed that the flow had increased to 1. 85 mgd. more than twice the normal dry weather rate as a Part of the increase is believed to be attributable to result of infiltration of rainfall which occurred during improved meter accuracy, and the latter figure is the preceding week. Immediately after the start of accepted as representative. Based on the district's rainfall on January 4, the flow rate increased beyond estimate of 24,000 connected population, a dry weath the capacity of the plant flow meter and remained er flow of 1. 85 is equivalent to a unit rate of 77 gcd. continuaily above meter capacity for nearly two days Wet weather flow peaks in the Las Gallinas sys after rainfall stopped. The peak flow arriving at the tem do not appear to be as severe as in many other plant was estimated by district personnel to be about areas of Marin County, but because of the limited 14 mgd, and additional quantities were lost throngh capacity of the plant flow meter it is difficult to es overflowing manholes at various points in the col timate the magnitude of the peaks. The peak flow lection system. shown on Fig. 5-8 was estimated from a survey of Of the 9600 acres included in Sanitary District pump capaCities and running times at all of the pump No. 6 about 6300 acres is undeveloped or is tributary ing stations which deliver sewage to the treatment to the Ignacio plant or the Bahia plant. Assuming plant. Most of the pumps are equipped With running the peak storm flow at the Novato plant to be 14 mgd, time meters which are read daily by district person substantially all of which represents storm water nel. Using the district estimates of pump capacity inflow, the unit rate of storm water inflow for the and the running time records for January 5, 1966, 3300~acre tributary area is 4200 gad. In 1965 dis the probably peak flow was estimated to be 9 to 10 trict personnel studied a 290-acre area in Novato and mgd. This includes an estimated 2 mgd bypassed concluded that the storm water inflow rate was ap upstream of the Terra Linda pumping station, be proximately 4000 gad. lieved to be the only significant quantity bypassed Storm water inflow in the system tributary to the during the storm. Ignacio plant (Fig. 5-9) is a lesser problem. The The district service area in 1965 prior to the an maximum meter capacity of 2 mgd was exceeded for nexation of Las Gallinas Village was 3700 acres, sub a few hours at the height of the storm, but the pattern stantially all of which is developed. For an area of of pump starts and stops on the meter chart shows 3700 acres and a storm water inflow rate of 9 mgd that the peak flow was not far above 2 mgd. Developed the uniform unit rate of inflow is 2400 gad. area tributary to the Ignacio plant, including portions of Hamilton Air Force Base, amounts to about 1900 Sanitary District No.6 Sewage Flow acres. For a storm water inflow rate of 2 mgd, the Sewage flows from Sanitary District No.6 are unit rate of inflow is 1100 gad, the lowest rate en measured at two points, namely, the Novato and countered in this study. Ignacio sewage treatment plants. For the four sum mer months of 1965 the average daily flow was 1. 55 Dry Weather Flow Summary mgd at the former and 0.61 mgd at the latter, for a A sununary of all dry weather flow data developed total district flow of 2.16 mgd. Connected population in the course of this study and in other recent engi was estimated by the District Manager of 18,900 for neering studies for Marin County communities is Novato and 8,500 for Ignacio, the latter figure in presented in Table 5-2. The unit flow values vary cluding the 3,900 residents of Hamilton Air Force from a low of 55 gcd for Tamalpais Valley to a high Base. On this basis unit dry weather flows amount of 102 gcd for Belvedere, with a county-wide average to 82 gcd for Novato and 72 gcd for Ignacio. The of 79 gcd. As might be expected, the widest varia Ignacio fignre probably reflects the typically lower tion in values occurs in the smallest communities, per capita water use at military installations. On where local conditions or standards of development a district-wide basis, the dry weather flow was 79 create the maximum deviation from the norm for the gcd, which is the same value developed by Jenks and county as a whole. For areas with a population of Adamson15 using 1964 flow fignres. more than 3000, the unit flow varies only from 70 to Graphs of hourly sewage flows for the IgnaciO and 90 gcd, and for communities larger than 10,000 the Novato treatment plants are presented in Figs. 5-9 variation is from 73 to 85 gcd. It is apparent that and 5-10. The low minimum dry weather flows indi for purposes of a county-wide study the figure of 79 cate that neither system receives appreciable amounts gcd for present dry weather sewage flow may be ac of infiltration during the dry season. cepted with confidence. The graph of wet weather flow at the Novato plant Collected as they were at the terminal point for (Fig. 5-10) shows severe problems occasioned both each sewerage agency, the dry weather flow data by direct storm inflow and by storm water infiltra represent all of the liquid wastes of the community, tion. On the first three days of January flows were whether domestic, commercial or industrial in origin. SEWAGE CHARACTERISTICS 45 - , I , /'"' ..... ESTIMATED TOTAL FLOW, I \ i \ . B I a \ I I , '" ; \ \ I '" \ I ;: DRY WEATHER rWET WEATHER I '3 \ \ t AUGUST 4-10,19657 JANUARY 1-7, 1966 I I r-e~ "- \VMAXIMUM METER CAPACITY I -- -- / it .~ /~ ---v~ ~ ~ ~ ,; '" '-..../ ""-../ '-/ IV! '-' '-" \:A ~ ~ ~ ~1I I~ it 1.29 1.37 1.36 1.36 \.32 .41 • • Fig. 5-8. Hourly Variation in Flow at Las Gallinas Sewage Treatment Plant MAXIMUM METER CAPACITY .. . 2.0f-------+------f------t----;r .. .. .. oL-~~~~~~~~~~~~d=~~==~~~~h=~~~~~~~h=~~==~~_L~ 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M 6 12N 6 12M ... Fig. 5-9. Hourly Variation in Flow at Ignacio Sewage Treatment Plant ... PEAK FLOW ESTIMATED AT ABOUT 14 MGD .... Br---------i---------~--------~----------t---------._--------_+--------~ Fig. 5-10. Hourly Variation in Flow at Novato Sewage Treatment Plant .. 46 MARIN COUNTY SEWERAGE STUDY «Ii'" Table 5-2. Dry Weather Sewage Flow Dryweather flow ... ~ Agency Population mgd gcd Date of Reference a study Sausalito-Marin City Sanitary District 7,800 0.64 82 1959 11 Sausalito-Marin City Sanitary District, Ci!J" Taroalpais Valley Sanitary District, Fort Baker, and portion of Richardson Bay fit Sanitary District 16,100 1.37 85 1966 Tamalpais Valley Sanitary District 55 1963 12 fit Mill Valley. Almonte Sanitary District, tiff Homestead Valley Sanitary District, Alto Sanitary District, Kay Park Sewer Main- tenance District 16,200 1.36 84 1966 (1ft Richardson Bay Sanitary District 5,700 0.4 70 1963 13 tJf Belvedere 2,200 0.22 102 1960 21 Sanitary District No.5 and Belvedere 9,100 0.82 90 1966 Sanitary District No.2 6,000 0.45 76 1961 22 Sanitary Districts No. 1 and 2, and Larkspur 49,000 3.58 73 1966 San Rafael Sanitation District Main plant 27,500 2.31 84 1966 Marin Bay plant 1,500 0.09 63 1966 Las Gallinas Valley Sanitary District 24,000 1. 85 77 1966 Sanitary District No. 6 24,000 1. 90 79 1965 15 Ignacio plant 8,500 0.61 72 1966 Novato plant 18,900 1. 55 82 1966 Average, all observations 79 Average, 1966 observations 79 aSee Appendix A. Since Marin County presently has a minor amount of ends, as would be expected if industrial flows were industry and is almost completely devoid of industries Significant. which produce significant amounts of process wastes, In like fashion no separate allowance need be made the industrial component of each community may be for dry weather iufiltration. Since the areas for included in the unit flow allotted to each community which flows were measured represent all sections resident. Similarly, the commercial areas in Marin of the county, the average dry weather unit flow in are mostly of the community service type, and on an cludes an amount of iufiltration which is typical for area-wide basis their wastes may be expressed in the county as a whole. High infiltration in local areas terms of the unit flow per community resident. Thus, such as that which occurs at Belvedere must be con it is not considered necessary for the purposes of sidered in local planning, but on a c01Ulty-wide basis this study to attempt to determine what portion of these areas will be offset by others where no dry present sewage flows is attributable to industrial or weather infiltration occurs. commercial activity. The fact that present commercial and industrial Wet Weather Flow Summary flows are not of sufficient Significance to warrant Wet weather sewage flows throughout much of the separate consideration is borne out by inspection of county exceed not only the capacity of the various the flow records at the San Rafael County Sanitation treatment plants but also the capaCity of the sewage District main plant. Though the San Rafael area ac collection and trunk systems. The Ignacio system of counts for about half of the total C01Ulty commercial Sanitary District No. 6 appears to be the only sys activity, and in 1964 provided nearly three-fourth of tem in the county which was capable of conveying and the total industrial employment, the per capita dry treating all of the flow generated within the service weather flow as measured at the main plant is only area during the wet weather period selected for in 6 percent higher than the county average. Further vestigation. more, no perceptible drop in flow occurs on week- A sunnnary of unit storm water inflow rates mea- SEWAGE CHARACTERISTICS 47 sured in the course of this study and reported by pre inflow include holes in manhole covers where street vious investigators is presented in Table 5-3. Mea drainage is inadequate to prevent flooding of the cov sured unit rates vary from 1100 gad for Ignacio to ers, catch basins and street inlets connected to the 9300 gad for Kay Park Sewer Maintenance District, sanitary sewers, and roof and patio drain connections. with only three of the 12 measurements falling below Most of these points of entry can be economically cor 4000 gad. Unfortunately, in two of the largest service rected through a vigorous program of inspection and areas, Sanitary District No. 1 and San Rafael County enforcement. The urgent need to undertake such a Sanitation District, such large quantities of flow es program should be recognized by each agency which caped measurement through bypasses and manhole suffers from high wet weather flows. As a part of overflows that no meaningful estimate of peak flow this program each agency should adopt and rigorously could be obtained. The figures in Table 5-3 consist enforce a sewer use ordinance which prohibits roof in each case of measured or estimated peak flow at and area drain connections to the sanitary sewers. a treatment plant or pumping station plus estimated The cost of eliminating direct storm inflow is far losses at known upstream points. Quantities which less than the cost of constructing trunk sewers and escaped through overflowing manholes are in addition plants to convey and treat it. to the listed figures. Storm water infiltration, while lower in voilUll8 Peak wet weather flow is composed of three com than direct storm inflow, is of importance in sewer ponents. These are (1) the normal dry weather sew age planning because it may perSist for many days age flow, (2) storm water infiltration, and (3) direct after rainfall has stopped. Infiltration rates shown storm inflow. A glance at Figs. 5-1 through 5-10 in Table 5-3 were determined from Figs. 5-1 through clearly indicates that direct storm inflow, which oc 5-10 by measuring the greatest difference between curs while rain is falling, is the major component of the dry weather flow and the wet weather flow either the peak rate of flow. Typical pOints of direct storm before the start of rainfall or 24 hours after rainfall Table 5-3. Storm Water Inflow Rates , ! a Infiltration Total inflow Date of b Agency Area, acres Reference gad gad study Sausalito-Marin City Sanitary District, TamaJpais Valley Sanitary District, and portion of Richardson Bay Sanitary District 2,400 950 4,300 1966 Tamalpais Valley Sanitary District 370 1,300 1963 12 Richardson Bay Sanitary District (portion tributary to Sausalito) 610 4,100 c 1959 11 Mill Valley, Almonte Sanitary District, Homestead Valley Sanitary District, Alto Sanitary District, and Kay Park Sewer Maintenance District 2,440 1,400 5,000 1966 c Kay Park Sewer Maintenance District ·14 9,300 1964 10 Sanitary District No. 5 and Belvedere 900 900 5,000 1966 Belvedere 170 5,000 1960 21 Sanitary Districts No. 1 and 2, and Larkspur 8,700 750 1966 Sanitary District No.2 183 4,000d 1960 22 San Rafael Sanitation District 5,000 600 1966 Las Gallinas Valley Sanitary District 3,700 350 2,400 1966 Sanitary District No. 6 Novato area 290 4,000 1965 15 3,300 800 4,200 1966 Ignacio area 1,900 250 1,100 1966 a Area measured is developed and sewered. with average population density ranging from 5 to 10'persons per acre. II b See Appendix A. c Computed from reported flow and measured service area. dFor areas sewered prior to 1957. 48 MARIN COUNTY SEWERAGE STUDY had stopped. Infiltration rates obtained in this fash ing at and leaving the plant. In several cases the ion vary from 250 gad for the Ignacio system to 1400 only tests routinely conducted are those required to gad for Mill Valley, with a median value of about complete the quarterly reports to the Regional Water 800 gad. Quality Control Board, and these reports deal only Points where storm water enters the sewers by with the quality of the plant effluent. Nevertheless, the process of infiltration through loose joints and ten of the principal plants in the county maintain rec broken pipes are more difficult to locate and more ords which are useful in assessing sewage strength. costly to correct than are the points of direct storm These data, together with plant efficiencies calculated inflow. New techniques of television inspection may where sufficient data are available, are presented in be employed to advantage in locating and correcting Table 5-4. For those plants which have been recently deficiencies in laterai and trunk sewers. Where the enlarged, effluent quality and calculated efficiency difficulty lies prinCipally in poorly laid or deterio- are based on analyses made after the enlargements rated house sewers, however, the cost of detection were placed in operation. and correction is usually prohibitive. Unfortunately, As is commonly the case with BOD and suspended in many cases defective house sewers have proved solids tests on raw sewage, the values listed vary to be the principal source of storm water inflow. A over a fairly wide range. Furthermore, the analyses 1956 sewerage study for Central Contra Costa Sani at each plant represent a different flow rate and a tary District42 determined that in certain areas de different total tributary population. The most mean fective house sewers were responsible for more than ingful information on sewage strength characteristics 80 percent of the total storm water inflow, which can be obtained by calculating sewage strength in was measured at unit rates as high as 7500 gad. De terms of applied load per capita (Table 5-5). The fective house sewers have been identified as a major loadings thus calculated, which are representative of source of storm water inflow in the older sections of three-fourths of the county population for BOD and Sanitary District No.2, and similar conditions no half the population for suspended solids, show that on doubt exist throughout the county. a county-wide basis the average contribution is 0.16 pcd (pounds per capita per day) of BOD and 0.18 pcd of suspended solids. These values are typical for SEWAGE COMPOSITION California communities which are predominantly res- Of the many biological and chemicai characteric- idential in character. tics of sewage, the two of principal concern in selec- The mineral content of sewage is a composite of tion and design of the treatment process are BOD and the mineral content of the water supply, the minerals suspended solids. For specific purposes, such as added as waste materials, and the minerals present water reclamation or reuse of effluent, knowledge of in ground and surface waters which may enter the the concentration of various mineral constituents may sewage collection system. The areas of Marin County also be required. where groundwater infiltration occurs on a year- Not all of the plants in Marin County maintain round basis are principally the lOW-lying areas adja systematic records of the strength of sewage arriv- cent to the bay. Groundwater in those areas has ap- Table 5-4. Sewage Strength BOD Suspended solids Plant Influent Effluent Influent Effluent efficiency. Plant percent No. of No. of No. of No. of Mg/I Mg/l Mg/l Mg/l samples samples samples samples BOD SS Mill Valley 245 4 37 4 202 17 41 17 85 80 Richardson Bay Sanitary District 243 2 28 6 193 2 25 6 88 87 Sanitary District No. 5 143 2 52 3 Sanitary District No.1 196 7 19.6 11 24 11 90 San Rafael main plant 237 5 54 5 269 5 66 5 77 75 Las Gallinas 323 7 36 2 253 18 36 18 89 86 Sanitary District NO.6 Novato Plant 256a 36 6 347 a 34 6 86 90 Ignacio Plant 16 7 19 7 San Quentin Prison 172 b 11Zb 35 a Average values reported by Jenks and Adamson. 15 b Average of reported monthly values for 1964 and 1965. SEWAGE CHARACTERISTICS 49 Table 5-5. Calculated Loadings BOD Suspended solids Tributary ADWF Plant mg/! !bs/day mg/! lbs/day population mgd Mill Valley 16,200 1. 36 245 2,760 202 2,280 Richardson Bay, Sanitary District 2,100 0.15 243 300 193 240 Sanitary District No. 1 49,000 3.58 196 5,840 San Rafael main plant 27,500 2.31 237 4,560 269 5,180 Las Gallinas 24,000 1.85 323 4.970 253 3,900 Sanitary District No. 6 Novato plant 18.900 1. 55 256 3,300 347 4,480 Total 137,700 21,730 16,080 a Per capita loadings 79 0.16 0.18 aSee Table 5-2. proximately the same mineral content as sea water. eral constituents. The plants sampled were those Determinations of chloride concentration have in fact with an average dry weather flow in excess of 0.5 been used in several Marin County studies aimed at mgd (Sausalito, Mill Valley, Sanitary District No.1, pinpointing sections of sewerage systems with high San Rafael main plant, Las Gallinas, and Novato). rates of groundwater infiltration. At least one analysis from each of the first fonr plants From 1955 through 1962 the Department of Water shows the presence of significant amounts of salt wa Resources conducted a study of the mineral quality of ter infiltration. A summary of the Department of sewage effluents throughout the State of California. 23 Water Resources analyses is presented in Table 5-6. In the course of this study 12 composite samples of For domestic sewage, the mineral content can the effluent from six different Marin C01ll1ty treat be accurately predicted by adding to the minerals in ment plants were collected and analyzed for min- the water supply the mineral quantities which are Table 5-6. Chemical Analyses of Sewage Effluents Las Gallinas Marin County sewage effluentsa Water supply Normal mineral Calculated effluent Determination Average Maximum Minimum average pick_upb effluent qualityC June, 1961 Cations Calcium (Ca) 42 114 16 19 -4 15 16 Magnesium (Mg) 84 288 25 12 +4 16 28 Sodium (Na) 556 2,230 74 9 +63 72 98 Potassium (K) 30 92 13 ( 1 +10.7 12 14 Ammonium (NH4) 32 45 19 32 29 Anions Sulfate (SO 4) 144 562 40 14 +28 42 40 Chloride (CI) 990 4,090 85 15 +41 56 102 Nitrate (N0 ) 8.5 58 0.2 8 0.9 3 Phosphate (PO ) 24 32 5 24 c;(60 Bicarbonate 3) 256 314 78 81 +189 270 296 Total hardness (CaC0 ) 450 1,470 154 98 +13 111 154 3 Silica (Si02) 19 23 15 19 21 Boron (B) 0.6 1.4 0.4 +0.5 0.6 0.4 I Fluoride (F) 1.6 3.2 0.2 0.12 1.6 1.0 Total dissolved solids 2,010 7,600 467 135 +293 428 467 • pH 7.8 6.6 7.4 7.8 • All results are expressed as mg/l except pH. aSource of data: DWR Bulletin No. 68-62, 12 analyses at 6 different plants from 1956 to 1961. • bNorrnal change in concentration after domestic use, Source: DWR "Residential Unit Water Use Survey, • Monterey Hills Tract, Los Angeies County, for March 1962 - March 1964" February, 1966. c Obtained by adding normal mineral pickup to average concentration in water supply. 'Where data are lacking on water supply or mineral pickup, values are average for Marin County sewage effluents. Not applicable in areas where salt water infiltration is anticipated. 50 MARIN COUNTY SEWERAGE STUDY normally added as domestic waste materials. The Table 5-7. Unit Design Loadings Department of Water Resources, in a study which covered a two-year period, 24 derived the quantity Volume Domestic and commercial sewage of mineral pickup associated with domeatic water use Average flow. gcd 100 in a Southern California commlmity. By adding nor a Peak flow, gcd mal mineral pickup to the average chemical analysis Industrial wastes of Marin water supplies, an anticipated effluent min Average flow. gad 3,500 eral quality was obtained (Table 5-6) which is as Peak flow, gad 10,000 Storm water infiltration sumed to be applicable to domestic and commercial All existing sewered areas except sewage effluents where no salt water infiltration is Las Gallinas and Ignacio. gad 1,000 present. For comparison, an analysis of Las Gal Las Gallinas Valley Sanitary Dist. ,gad 400 linas sewage effluent is included in the table. At the Ignacio area, gad 300 time the sample was collected the Las Gallinas sys All future sewered areas, gad 300 b Total storm water inflow tem was located almost entirely in areas where salt All existing sewered areas except water infiltration would not be expected to occur. Las Gallinas and Ignacio, gad 5,000 A comparison of the tabulated values indicates Las Gallinas Valley Sanitary Dist., gad 3,000 Ignacio area, _g ad 1,500 that the calculated domestic sewage effluent mineral All future sewered areas. gad 1,000 quality compares very closely with the analysis of BOD Las Gallinas effluent. Both are markedly lower in Domestic and commercial sewage, pcd 0.20 mineral content than the average of all analyses for Industrial wastes, pad 7 the county because of the salt water infiltration which Suspended solids occurs in other parts of the county. Domestic and commercial sewage, pcd 0.22 Industrial wastes, pad 7 UNIT DESIGN QUANTITIES aDepends on contributory population. See Fig. 5-11. b Unit quantities developed from the analysis of Includes storm water infiltration. Marin County sewage characteristics provide the basic information necessary for planning and design of household water and therefore increase domestic of sewerage works. These unit design factors must sewage flow. It is interesting to note that Mill Valley, include allowances for antiCipated future changes not which now has a unit dry weather sewage flow of 84 only in the standard of living of the contributo ry pop gcd, was estimated by the State Bureau of Sanitary 9 ulation and the characteristics of the service area, Engineering in '1945 to have a flow of only 60 gcd. but also in the materials and techniques of sewer con Similarly, the dry weather sewage flow from Sanitary struction. A tabular summary of the design factors District No.1 was measured at 46 gcd in 1940,14 referred to in the following discussion is given in compared to the present flow of 73 gcd. In the ex Table 5-7. pectation that the past trend will continue in the fu ture, an average contribution of 100 gcd is considered Sewage Volume suitable for planning purposes. This value .allows Each of the several components of sewage volume for a future increase of 25 percent above the present discussed previously must be considered separately county-wide average of 79 gcd. in determining applicable design factors. The maximum rate of dry weather sewage flow is ..... always higher than the average rate by a ratio which Domestic and Commercial Sewage. The present varies with the contributory population. Typically, average dry weather sewage flow amounts to 79 gcd. the ratio varies from 2.5 to 1 for a population of 1000 This flow consists of domestic sewage, commercial to 1. 5 to 1 for a population of 100,000 or more. Max sewage generated in comml.Ulity-service type com imum flow rates were computed by the use of Fig. mercial areas, minor amounts of industrial wastes, 5-11, which shows the relationship between contribu and the small amount of groundwater infiltration which tory population and the ratio of peak to average dry occurs even in dry weather. Between 80 and 90 per weather domestic sewage flow. cent of the total is estimated to consist of domestic sewage. Industrial Wastes. Areas presently devoted to Historically, the trend has been toward increased industry in Marin County are negligible, and indus uses of household water. For example, labor-saving trial wastes need to be considered oniy for those cases appliances such as garbage grinders, automatic home where land use planning deSignates large areas for laundries, and dishwashers increase the consumption industrial development. As discussed in Chapter 2, SEWAGE CHARACTERISTICS 51 2.6 Total storm water inflow, which includes storm I 2.5 1\ water infiltration, was assumed to be 5000 gad for all i, iii L C ~ ~.. ) . 2 2 . . 3 4 \ a ag re a a in s f e l x ow ce p m t e L a a s s u r G e a m ll e in n a ts s i V n a d l i l c e a y t e a n t d h a I t g n 3 a 0 c 0 i 0 o , g a w d h a e n re d ( i ( ': , ~ ~ ~ 1500 gad, respectively, are more appropriate. In ~ 2.2 " the case of areas to be sewered in the future, it has <t ' ~ " 2. 1 \ been assumed that adequate storm drainage will be , I , 1I:t\ > C - ) 2. 0 9 p a r c o te v d id e a d n d a n e d n f t o h r a c t e a d p p to r o p p r r e ia v t e e n t l e d g i i r s e la c t t i o c n o n w n i e ll c t b i e o n e n o f ! I , , Ii: I I I , " I. ~ storm water inlets and roof and area drains. On this I'": ! ~ I. 8 '" i!I, basis an allowance of 1000 gad is considered adequate C). I ;::: f. ? to account for storm water inflow in areas with a pop ' i I r ' ' < " t I. 6 ~ i'- ulation density of 5 or more persons per acre. For I Ii i i'l I. 5 areas developed to a lower density, a lower rate of iii storm water inflow can be expected to occur. As I. 4 [' 2 5 10 20 50 100 200 500 1000 population density decreases, the length of sewer line !i!! POPULATION, THOUSANDS per acre also decreases, offering less opportunity Fig. 5-11. Ratio of Peak to Average Flow of for storm water to enter the sewers. At the same lilli, Sanitary Sewage time, however, the sparser development results in ill it is expected that industries locating in Marin will more length of sewer line per resident. As a ration , be primarily of the light industrial and mannfacturing al approach to the problem of storm water inflow in variety which are neither large water users nor pro areas with a density of less than five persons per ducers of problem wastes. Typical waste flow for acre, total inflow has been taken as 250 gad plus 150 this type of industrial development, as determined gad times the population density in persons per acre. through the analysis of similar developments in var Use of this formula will give an inflow rate of 400 gad ious California comrrull1ities, is 3500 gad. Since the for one person per acre and 1000 gad for five persons waste flow is usually confined to an eight-hour period, per acre. the peak rate has been taken as 10,000 gad. This is roughly the same flow which would result if the area Sewage Compositi on should develop as multi-family residential instead of In recent years a general increase in the strength industrial. of sanitary sewage has been noted in many cities, primarily as a result of increased use of garbage Storm Water Inflow. Improvements in construc- grinders both in private homes and in some commer tion practices, coupled with new developments in pipe cial enterprises, notably food markets. In the case jointing techniques, have demonstrated in many com of domestic and commercial sewage, therefore, unit munities that both infiltration and direct storm inflow values for design purposes were selected as 0.20 pcd can be reduced to values substantially below present for BOD and 0.22 pcd for suspended solids. These rates. Provision of adequate storm drainage, cou values represent about a 25 percent increase over pled with a continuing program aimed at locating and the present county-wide average of 0.16 and O. 18 pcd eliminating obvious sources of inflow, could bring for BOD and suspended solids, respectively. Com about significant flow reductions in several Marin bined with the anticipated increase in per capita water communities. YVherever possible, construction of use, the effect of the increase in strength will be to sanitary sewers in new areas should always be ac maintain BOD and suspended solids approximately at companied by construction of adequate storm drain present levels in terms of milligrams per liter of age, thereby eliminating many of the common sources sewage (mg/l). of direct storm inflow. Wastes from the type of industrial development The infiltration component of storm water inflow anticipated for Marin County are primarily sanitary was taken as 1000 gad for all presently-sewered areas in character, though they may also include fairly of the county except Las Gallinas Valley Sanitary Dis large amounts of cooling water and minor amounts of trict and the Ignacio area, where flow measurements process wastes. It is anticipated that the industrial indicate that lower rates of 400 gad and 300 gad, re wastes will have a strength no greater than that of spectively, should be applied. For all new construc domestic sewage, and the strength may therefore be tion it is assumed that quality materials and meth expressed in terms of equivalent population loadings. ods will be employed which will limit infiltration to On this basis the industrial areas would have a pop 300 gad. ulation equivalent of 35 persons per acre, and the 52 MARIN COUNTY SEWERAGE STUDY corresponding figure of 7 pad (pounds per acre per The mineral content of future sewage effluents in day) has been assumed for both BOD and suspended these areas has therefore been taken for design pur solids. poses as equal to the average of present effluents as The mineral quality of Marin sewage will vary shows in Table 5-6. In those watersheds which drain .@ widely depending on the amount of salt water infiltra to the Pacific Ocean, on the other hand, there are no tion which occurs. For those drainage areas tribu significant tideland areas where salt water infiltra tary to San Francisco Bay, it has been assumed that tion is likely to occur. For these drainage areas the the ratio of tidal flat to upland development will re mineral quality of sewage effluents has been assumed .E main about the same as at present and that present to be equal to the calculated effluent quality shown in sources of salt water infiltration will go uncorrected. Table 5-6. .E .e 41 III d 7 SOUTHERN MARIN SUBREGIONAL WASTEWATER MANAGEMENT PLAN Prepared for SOUTHERN MARIN SUBREGIONAL SEWERAGE AGENCY Almonte Sonitary District Alto Sanitary District City of Belvedere Homestead Valley Sanitary Di.strict Kay Park Sewer Maintenance District City of Mill Valley Richardson Bay Sanitary District Sanitary District No.5 Sausalito-Marin City Sanitary District Tamalpais Valley Community Services District J. WARREN NUTE.INC/J ENKS AND ADAMSON a YODER-TROTTER- ORLOB ASSOCIATES Chapter 1 INTRODUCTION The recent environmental awakening has led both the citizenry and the regulatory agencies to take a much closer look at the aquatic environment and the waste treatment and disposal practices necessary to protect that environment. In general, this review of the aquatic environ ment has led to Q substantial upgrading of waste discharge requirements, not only in the bay area, but throughout the state and the nation. As a result, the sewerage agencies in the southern Marin area are currently faced with making substantial modifications ~o their wastewater treatment and disposal facilities. There are a number of reasons why major improvements are required in the existing waste treatment and disposal systems. First, the Regional Water Qua lily Control Board has identified several potential water quality problems in Richardson Bay. Specifically, the Board is concerned about the relatively high algal concentrations present and the public health hazard associated with the discharges from the two secondary treahnent plants tributary to Richardson Bay. Another problem common to the southern Marin area is the bypassing of untreated wastewater to Richardson Bay during wet weather periods when either trunk sewers or treatment plants are unable to handle· these exceptionally high flows. This problem is partly the result of limited capacity in trunk sewer and treatment foci I ities but, it is more a problem of substantial infiltration that occurs during wet weather periods. Previous studies have found peak wet weather sewage flows to be between five and ten times overage dry weather flows. It is these very high wet weather flows that, in the past, hove necessitated the bypassing of untreated wastewater to Richardson Bay . . Bypassing has become a considerable concern of all regulatory agencies and the Regional Water Quality Control Board now intends to prohibit all such bypossing. Another recent development that will necessitate major improvement to certain of the southern Marin treatment plants is the recent Environmental Protection Agency (EPA) requirement that necessitates secondary treatment at all plants. As a result of this requirement, the two primary treatment plants in southern Marin are faced with installation of full secondary treatment. In summary, each of the four existing wastewater treatment and disposal systems must be modified substantially to come into compliance with recently enacted state and federal requirements. The two secondary treahnent plants currently discharging to Richardson Bay are faced with transporting their effluents to other, more acceptable waters prier to disposal. The two primary treatment plants, although they are discharging at acceptable locations, are faced with providing full secondary treatment in order to comply with the EPA requirements regarding minimum levels of treatment. Thus, each of the four dischargers in the southern Marin area is faced with substantiar modifications_ to its existing facilities. These mutual needs on the part of all four dischargers suggests a coordinated effort and consideration of a regional approach in solving these related problems. This is the primary reason for undertaking these present studies on a subregional basis. There have been two previous regiona I wastewater management studies that have addressed themselves j'o southern Marin water pollution control needs. These are the 1967 County Sewer age Study prepared by Brown and Caldwell (1) and the 1969 Bay-Delta Study prepared by Kaiser Engineers (2). Both of these studies recommended a solution to the Richardson Bay problems which involved the collection and transmission of untreated wastewater westward over the Marin peninsula to a regional treatment plant near the coastline and the discharge of primary or advanced primary treated wastewater to the ocean in the vicinity of Tennessee Cove. While it has been only a short time since these studies were completed, there are numerous reasons why the plan recommended in these studies should not be implemented prior to further study. Both of the previous studies were completed just prior to the start of the great environmental awakening that has spread across the country. Both studies recommended treatment systems for ocean disposal that would not be adequate based on recently upgraded standards for ocean disposal. Further, over the past several years, there has been a growing concern and awareness of the sensitivity of the ocean environment to waste discharges. In the past, the ocean was considered a great sink capable of diluting and receiving all the waste discharges with only minimal treatment. This is not the case today and, in fact, in Marin County there is a great concern over the possibility of even discharging a highly treated waste to the ocean. This concern is further magnified because the southern Marin coastline is a part of the Golden Gate National Recreation Area. Another reason why previous recommendations must now be reevaluated is the growing feeling, among not only the people of Marin County but noted experts and officials throughout the nation, that reclamation and reuse of our wastewater is inevitable. If reclamation is inevitable, waste water treatment and disposal systems should be so designed as to facilitate future reclamation. Past regional studies have not examined the possibility of reclamation in enough detail to determine how best reclamation can be foci I ita ted • In summary, past recommendations must be reevaluated because of new ocean discharge require ments, because of increased concern as to the sensitivity of the ocean environment, especially in the Tennessee Cove area, and because of the concern and interest in water reuse rather than wastewater disposal. Another change that has taken place in the few years since the two past planning studies were completed is the availability of much greater federal and state aid on construction projects. Back in the late 1960's, only 30 and possibly 33 percent federal aid was available for construction of wastewater treatment and disposal facilities. Today, 75 percent federal aid in combination with 12-1/2 percent state aid means that the local agencies must now pay only 12-1/2 percent of the total project cost. Thus, it is possible that past projects having high initial construction costs may have been dismissed from consideration because of the inability of the local area to finance them. Today, this reason for eliminating a particular project does not exist. AUTHORIZATION Subsequent to the completion of the Bay-Delta Study in 1969, a number of subregional wastewater management studies were initiated throughout the bay area. The purpose of these subregiona I studies was to evaluate solutions to the problems in a particular area in greater detail than was possible under the comprehensive, 9-county Bay-Delta Study. -'--JS' In 1970,seven sewerage agencies in the Richardson Bay watershed banded together and asked the Marin Municipal Water District to act as their agent. The purpose of combining these seven agencies was to conduct a subregional wastewater management study for the southern Marin area. A joint powers agreement was entered into between each one of the seven agencies and the Marin Municipal Water District. The resulting new district was called Improvement District uAIi of the Marin Municipal Water District. Subsequent to the formation of Improvement Distr'ict HAil, an additional agency have entered the joint powers agreement and became a part of District IIAn. Recently, Improvement District "A was disbanded and nine agencies have entered into a II ioint powers agreement for the formation of the Southern Marin Subregional Sewerage Agency. On November 10, 1971, the wate r district, acting on behalf of District HA and its supporting II agencies, entered into a contract with a joint venture of consulting firms familiar with the area to conduct the necessary studies. The joint venture consisted of the three consulting engineering firms of J. Warren Nute, Inc., Jenks & Adamson, and Yoder-Trotter-Orlob & Associates. DEFINITION OF STUDY AREA The southern Marin area, or the Richardson Bay watershed, includes the following sewerage agen I cies! Almonte Sanitary District Alto Sanitary District City of Belvedere Homestead Valley Sanitary District Kay Park Sewer Maintenance District City of Mill Valley Richardson Bay Sanitary District Sanitary District No.5 of Marin County Sausalito-Marin City Sanitary District Tamalpais Valley Community Services District The study area for the southern Marin subregional wastewater management study is shown in Figure 1-1. There are four existing wastewater treatment plants to serve these ten agencies. The Sausalito-Marin City Sanitary District has a primary plant discharging to San Francisco Bay serving not only that district, but also Tamalpais Valley Community Services District and the Strawberry portion of Richardson Bay Sanitary District. The City of Mill Valley has a secondary treatment plant discharging to the northwest portion of Richardson Bay and serving not only the city, but the Homestead Valley Sanitary District, the Almonte Sanitary District, the Kay Park Sewer Mainte nance District, and the Alto Sanitary District. The portion of the Richardson Bay Sanitary District not sewered to the Sausalito-Marin City plant is served by the Trestle Glen plant operated and maintained by that district. This is a small secondary treatment plant which discharges to the northeastern shore of Richardson Bay. Sanitary District No .. 5 has a primary treatment plant which serves not only the district, but also the City of Belvedere, and discharges to Raccoon Strait. i PURPOSE AND SCOPE OF STUDY This study was divided into hvo maior phases. The objective of the first phase was to conduct a subregional wastewater planning study for the purpose of developirg a realistic solution to the problems facing the southern Marin area now and in the future. As a part of Phase One, all possible alternative management plans were to be evaluated in sufficient detail to select a recommended 1-4 FIGURE 1-1 SOUTHERN MARIN STUDY AREA ,--0'-' --,~", W'" ,. , ,\.".,CJS CO HA "",'-"<-fU,-- "-, " -. '-. ~"'" " 0" 1-5 plan, and a draft report was to be prepared. The objective of the second phase of this study was to prepare preliminary engineering design and cost estimates for the recommended wastewater management plan and to produce a final report covering both phases of the study. In addition to the immediate study area, it is also necessary to consider the adjacent subregional areaS shown in Figure 1-2. In accordance with the contract, the engineers were charged with performing the following tasks during Phase One of this study. A. Conduct a thorough review of all previous engineering studies pertinent to the 'Southern Mad n wastewate r management needs. B. Review with the Regional Water Quality Control Board the present and projected ocean and bay water quality and effluent standards as well as grant requirements of state and federal agencies to determine the treatment requirements for given disposal locations under both dry and wet weather flow conditions. C. Review the potential market and time elements for reclaimed wastewater in or adjacent to the study area and develop the necessary basis for evaluating its impact on disposal alternatives. D. Develop alternative subregional wostewater management systems involving treatment, conveyance, disposal, and reclamation for stage construction on the basis of foregoing dota along with all necessary related capital and annual cost data. These alternative wastewater systems should be developed and evaluated on the basis of capital and annual costs and on the basis of sensit.ivity changes in certain projections involving water quality standards, wastewater reclamation, and regional consolidation. E. The study shall include an analysis of the present and future worth of the existing wastewater foci! ities. Particular attention sholl be given to the work underway at the present time to correct wet weather flow problems and relate this information to any influence the wet weather flow may have on both disposal locations and wastewater management systems feasibility and cost. F. The information derived by this study and the analysis contained in the study sholl be reviewed from time to time as the study progresses in depth with the Regional Water Quality Control Board and their stoff to assure complete coordination with the body, the Environmental Protection Agency, and the State of California Resources Agency, the Advisory Committee of Improvement District !lAH, ABAG, and other interested groups and agencies. G. Phose One of the study sholl be concluded with a detailed draft report which will be prepared presenting the findings and recommendations as they relate to the disposal of wastewaters for Improvement District rlAIl. Specific items which will be included in the draft report are: 1. Findings and recommendations relating to the point of discharge for waste water disposal. 2. Water quality and wastewater requirements. J -6 FIGURE 1-2 MARIN - SONOMA SUBREGIONS N \ ~ jPfNOLE PACIFIC OCEAN 1-7 3. A description of the alternative systems to provide for wastewater management. 4. A comparison and evaluation of the various combinations. In Phase Two, the engineers were to perform the following tasks: A. The study shall include sufficient preliminary engineering layouts to develop accurate cost estimates for the interceptor line and routes, pumping plant locations and capa cities. B. Recommended modification to existing facilitie~ and associated cost estimates. C. Produce a final report covering both Phases One and Two of this study. CONDUCT OF STUDY Initial phases of the work Were concerned primarily with assessing and evaluating previous reports and information pertient to the study. Data relative to existing wastewater facilities and present wastewater flows and loadings were obtained from the various sewerage agencies. Past and pro jected land use and population figures were obtained from various sources, including previous engineering studies, the local agencies, and the county. Based on the variations in previous projections, a design range of population was projected, including high, median and low values. Based on present wastewater flows and characteristics, unit design values Were developed. These were used in conjunction with the population projections, to develop projections of wastewater loadings through the year 2000. Infonnation was obtained from various state and federal agencies regarding water quality objectives in the receiving waters under consideration. These were used along with the projected waste loadings and mathematical models of the boy to determine what levels of treatment and points of disposal are necessary to comply with state and federal requirements. At the same time, a recon naissance level investigation was conducted to determine the potential use of reclaimed wastewater in and adjacent to the study area. Using the information developed regarding existing facilities, waste flow projections and treatment and disposal requirements, alternative plans for treatment and disposal were developed and evalu ated. These alternatives were then compared on the basis of economics, environmental impact, and reclamation potential and on the basis of other qualitative factors. Based on this comparison, a recommended treatment and disposal plan was developed. This plan was then used in conjunction with the information developed on reclamation to develop a recommended wastewater management plan for southern Morin. STUDY LIAISON Throughout this study, the engineering consortium has maintained close liaison with the agencies involved in this study. The three groups involved include the staff and board of the Marin Municipal Water District, the Advisory Committee to Improvement District JJAIl, subsequently the board of the Southern Marin Subregional Sewerage Agency, and the Environmental Advisory Subcommittee to the Advisory Committee. The Advisory Committee included a board member or council member from each of the ten sewerage agencies participating in this study. The Environmental Advisory Sub- committee was made upcf24 environmenta!ly concerned people, many of them active in local conservation groups. The membership of the Environmental Advisory Subcommittee included people from throughout the entire Marin Municipal Water District, which includes the southern Marin area .. the central Marin area and extends all the way to Hamilton Field. The consortium has maintained close liaison with the staff of the water district. In addition, we have made ~everal progress reports to the district Board of Directors. We have met with-and reported to the Advisory Committee on a monthly basis, since January 1972. We have met twice a month with the Environmental Advisory Subcommittee starting in October of 1971 until November of 1972. The engineering consortium has received 0 considerable amount of valuable input from each of these groups. The Environmental Advisory Subcommittee has been especially helpful in making the engineers aware of the concerns of environmentalists in Marin County. In addition, this committee has issued a number of resolutions which have expressed their feelings regarding envi ronmental protedion and wastewater reclamation. Also .. this committee has issued several special reports. One on the environmental sensitivity of alternative discharge locations includes written comments from various local conservation groups. Another special repOrt suggests means of minimizing environmental impact of wastewater management plans. Finally, one report suggested specific water quality criteria necessary to insure environmental protection. Each of these special reports and the resolutions passed by the Environmental Advisory Subcommittee is reprinted in Appendix G. One resolution of special interest is the one passed February 10, 1972, suggesting specific criteria to help guide this wastewater management study. ORGANIZATION OF THE REPORT This final report contains the findings and recommendations of the wastewater management study. In addition, sufficient detail is presented in this report to justify the conclusions reached and to allow periodic updating of this study in the future. The report is organized as follows: Chapter 2 contains a summary of the study, the recommendations and an implementa tion schedule. The remainder of the report contains the detailed information and data necessary for the development and analysis of alternative management plans and the selection of a recommended plan. Chapter 3 contains a brief historical background of the souther-n Morin area and describes various physical and environmental characteristics- of the area. Chapter 4 has a description of the ten sewerage agencies involved in this study and their existing wastewater facilities. Chapter 5 contains the basic planning information and projections that are necessary to develop alternative wastewater management plans. This information includes land use and population projections. Chapte r 6 contains the methods and proiections of waste loads to the year 2000. Chapter 7 contains the wastewater treatment and disposal requirements necessary for alternative management plans. 1-9 Chapter 8 is an analysis of the wastewater reclamation potential in southern Marin and adiacent areas, Chapter 9, alternative plans for wastewater transport, treatment and disposal are developed and analyzed. Based on this analysis, a recommended plan for wastewater treatment in southern Marin County is proposed. Chapter 10, the recommended wastewater management plan is described and a cost summary of the necessary facilities is presented. A detailed description of the proposed facilities and a detailed cost estimate is included in this chapter. The appendices to this report include Appendix A which lists the abbreviations used in this report; Appendix B which includes a glossary of technical terms used in this report; Appendix C which lists the references used; Appendix D which in cludes the design criteria for sewers, pump stations, treatment facilities, and outfalls; Appendix E which contains the criteria which was used to economically evaluate the alternative management plans; Appendix F which presents the detailed costs for each alternative; Appendix G which includes the resolutions and special reports of the Environmental Advisory Subcommittee; and Appendix· H which answers some commonly asked questions about the study. ACKNOWLEDGMENTS For their assistance during this study, we wish to express our appreciation to the staff of the Marin Municipal Water District, and especially to Mr. William R. Seeger, General Manager and Chief Engineer, and to Mr. John T. Schulte, Administrative Officer of the Southern Marin Subregional Sewerage Agency. We further wish to acknowledge the Advisory Committee and the Environmental Advisory Subcommittee for the many hours and the valuable comments and suggestions which they have contributed to this study. Chapter 4 EXISTING WASTEWATER FACILITIES In order to develop alternative wastewater management plans, it is essential that all existing waste water treatment and disposal facilities be evaluated as to their present cOfXlbilities. In this chapter each of the existing treatment facilities are described along with the responsibility of each of the sewerage agenci es. GENERAL The southern Marin study area encompasses the Richardson Bay watershed and contains ten separate agencies wi th various degrees of responsibi lity for sewage collection, treatment and disposal. Four I of the sewerage agencies operate their own sewage treatment and disposal facilities. The other six agencies contract with three of the four agencies for treatment and disposal. The various sewerage agencies in southern Marin, along with the basic sewerage facilities, are shown in Figure 4-1. A general background of the development of the southern Marin sewerage agencies and a background on each existing agency is given below. BACKGROUND The first ~wers in the southern Marin area were constructed in the communities of Sausalito and Mill Valley in the late 1800's. However, sewage was discharged untreated to the bay, and creeks and sloughs tributary to the ba)',until the end of World War". On March 11, 1946, the State Board of Public Health adopted a resolution prohibiting the discharge of row untreated sewage to the waters of the State of California. Most wastewater dischargers into I San Francisco Bay, including all the dischargers into Richardson Bay, were faced in 1946 with both the legal requirements and the basic civic responsibility to provide adequate wastewater treatment prior to bay discharge. Subsequently, a considerable amount of-discussion and effort was in evidence in-the sou-thern Mart" area toward formation of a coordinated program of wastewater treatment and disposal. This dis cussion led to the Southern Marin Sanitation District which embraced the major portion of the Richardson Boy watershed. Two separate engineering studies by Harry N. Jenks on behalf of the Southern Marin Sanitation District recommended construction of common-use facilities involving collection of all southern Marin County sewage and transport for treatment and disposal into Richard son Bay at Marinship as an initial alternative. Following the failure of a district bond issue in November of 1946, a second alternative program was devised which involved transport of sewage generated within the district boundaries to a common point for treatment and disposal into the Pacific 4-3 Ocean at Tennessee Cove. With failure of this second alternative program offered by the Southern Marin Sanitation District, the district dissolved, leaving the local sewering agencies with the continuing problem of how best to meet the requirements for wastewater treatment. It is necessary to recognize this background of failure of the Southern Marin Sanitation District in order to understand the present southern Marin situation with ten separate sewerage agencies and four separate sewerage treatment plants. Consequently, in order to solve the then pressing pollution problem, each community had to proceed on its own as best it could. Now facing a complete prohibition of discharge of any sewage-bearing wastes to Richardson Bay, the southern Marin sewerage agencies have come together in these present studies to develop a coordinated wastewater management program to meet this new water quality objective. It is sincerely hoped that the studies summarized herein will lead to a successful program which can be implemented to the benefit of all of southern Marin. ALMONTE SANITARY DISTRICT The Almonte Sanitary District collects sewage from a small area southeast of Mill Valley and delivers it by gravity to the Mill Valley trunk sewer system. Of the total district area orO.5 square miles, nearly half consists of undeveloped tide marsh and mud flats. Prior to district formation in 1949, sewage disposal was accomplished through individual septic tanks under sanitary conditions described as extremely unsatisfactory. There was a great deal of difficulty with overflowing sewage to the watercourses. In 1951, sewers ranging in size from 6 to 15 inches were constructed, and the entire district population of 1,500 is now reported to be connected to the collection system. Treatment of sewage from Almonte Sanitary District is performed at the Mill Valley plant under a contract which apportions treatment costs on the basis of assessed valuation. To solve a stormwoter infiltration problem which causes overflowing manholes along the 15-inch trunk sewer, the City of Mill Volley is now constructing a pumping station which will intercept sewage flows from the Almonte and Kay Park areas and pump them directly to the Mill Valley treatment plant. ALTO SANITARY DISTRICT The Alto Sanitary District comprises an area of less than 150 acres located north of Mill Valley and adjacent to Highway 101. The first sewers were constructed sometime prior to 1945, discharging to a community septic tank which, in turn, discharged to' Widow Reed Slough. After formation of the sanitary district in 1950, a pumping station was constructed at the southern boundary to lift all of the district's sanitary sewage into the Mill Valley trunk sewer system. Some 3.5 miles of 6 and 8-inch sewers now serve the entire district population of about 1,000 people. Sewage treatment is provided at the Mill Valley plant undera contract with terms similar to that for Almonte Sanitary District. 4 CITY OF BELVEDERE The City of Belvedere was incorporated in 1896 and is entirely residential in character. The city occupies an area of about 0.6 square miles consisting principally of Belvedere Island and the 4-4 adjacent lagoon. The first sewers, installed over 60 years ago, conveyed sewage to the southern tip of the island, where it was discharged into Raccoon Strait, Except for local improvements and expansion of the collection system, this mode of operation prevailed until 1961, at which time a pumping station and force main were constructed to convey all of the city's sewage to the Sanitary District No.5 plant for treatment. Stormwater Infiltration into the collection system is very high on a unit basis, but because of the small area involved, peak wet weather flows are usually within manageable limits. HOMESTEAD VALLEY SANITARY DISTRICT The Homestead Sanitary District was established by the Board of Supervisors on July 7, 1931 under an the Sanitary District Act of 1919 after electiol1 which favored its formation. This election was precipitated by a controversy between residents in the area and the Board of Supervisors, in which the latter attempted to construct sewers in the Homestead Valley area. The Board of Supervisors finally abandoned the proceedings on assurance that the sanitary district would diligently proceed with construction of sewers. In 1932, the district was recognized under the Sanitary District Act of 1923 as the Homestead Valley SaniTary District. Some sewers were constructed in the lower part of the district which connected to Mill Valleyls outfall I ine on Miller Avenue. However, this arrangement was unsatis factory since the tide would occasionally back the sewage intohouses. Plans for the sewers in the rest of the district were prepared by 1933. The sanitary board, however, did not proceed because of the problem of tidal backups in the Mill Valley outfall. Between 1933 and the end of World War II, the district concerned itself with inspection of septic tank installcrtions. With increasing development following the war, the sanitary hoard undertook the installation of sewers in the district. In 1948, the district sold bonds and, with the assistance of a state grant, a contract was awarded to construct sewers which now form the major part of the present sew~r system. In order to dispose of the sewage from Homestead Valley, the sanitary district negotiated a contract with Mill Valley which granted the district a license to use the cHyls system. The capital and operating costs of the Mill Volley treatment pl~nt are allocated on the basis of the respective assessed valuations of the two agencies. In 1970, the Homestead Valley Sanitary District undertook on analysis of their sewer system. This analysis determined that stormwater infiltration to the sewer system is a problem. As a result, over the last two years, the district has been conducting an extensive smoke testing and infiltration correction program. KAY PARK SEWER MAINTENANCE DISTRICT The Kay Park Sewer Maintenance District"serves an area of about 50 acres and has a population of l "530. The Kay Park sewerage system was constructed in the early 1950 s on the tidal marsh lands at the mouth of the Tamalpais and Tennessee Valleys. Kay Park contained the first sewers in that gene ra I area. A pumping station and 4,000 feet of gravity sewer and force main were constructed to convey the sewage to the Mill Valley system. As with Homestead, Almonte and Alto, Kay Park contracts with Mill Valley for sewage treatment. 4-5 Stormwater infiltration into the Kay Park collection system is very high; and, at the present time, the Kay Park Sewer Maintenance District, in coniunction with the Tamalpais Community Services District, is undertaking an extensive infiltration correction program. The Tamalpais Valley Community Services District has agreed to take over the Kay Park system once the sewers are brought up to standard. CITY OF MILL VALLEY The community of Mill Valley began in the late 1800ls as a resort for residents of San Francisco. The first sewers were constructed by subdividers in 1892. The city was incorporated in September of 1900, an~ following the earthquake of 1906, Mill Volley rapidly changed from a resort commu nity to a year-round residential community. Originally, the first sanitary sewers, some of which are still in use, discharged raw sewage into Arroyo Corte Madera del Presidio in the vicinity of Evergreen Avenue. In 1912, the city con structed an Imhoff tank on the west side of Miller Avenue between Reed and Evergreen Avenues, and the effluent from the tank was discharged into a tidal slough approximately 600 feet northeast of the Tamalpais High School. The odor'from the Imhoff tank proved to be more offensive than the odor from the previously used Arroyo, and for this reason, the tank was abandoned in 1919. In 1926, the outfall sewer line was extended further down the slough to a point in the vicinity of the railroad bridge over the Arroyo. In 1946, a new trunk line system and an outfall sewer was constructed, terminating in the vicinity of the present treatment plant. In 1948, a pumping station was built, and the effluent was dis charged into the Widow Reed Slough. The first units of the present treatment plant were constructed in 1952. Much of the sewage collection system serving Mill Valley is quite old and is subiect to large stormwater infl~w and infiltration flows exceeding 800 percent of the average design capacity of the treatment plant. Most of the existing trunk sewers are inadequate to handle the wet weather flows. Similarly, the treatment plant cannot handle the peak flows and, consequently, during wet weather a great deal of pretreated or partially treated sewage overflows to the bay. Recognizing this deficiency, in 1967 the voters in the city passed a $500,000 bond issue for improvement and upgrading the existing san itary sewer system. Recently the city has undertaken I a smoke testing program and general system rehabilitation program to rebuild and seal manholes and broken sewers. Contracting Agencies Four separate sewerage agencies contrgct with the City of Mill Valley for sewage treatment and disposal. The agencies are the Homestead Valley Sanitary District, the Almonte Sanitary District, the Alto Sanitary District, and the Kay Park Sewer Maintenance District. Treatment Plant The city's piesent sewage treatment plant is located on Sycamore Avenue east of Camino Alto. The original plant built in 1952 provided a primary degree of sewage treatment and discharged effluent into the head end of Richardson Bay. 4-6 In 1958, the plant was enlarged to provide secondary tre.atment utilizing trickling filters; and, in recent years, a sludge centrifuge has been added. The present plant design capacity is 1.3 mgd with the capacities of the principal units listed in Table 4-1. Present Needs Although the Mill Valley treatment plant provides secOndary treatment with effluent disinfection, there is essentially a prohibition of discharge of any sewage-bearing wastes to Richardson Bay. In June 1971, the Regional Water Quality Control Boord issued a cease and desist order from dis charging wastewaters not in compliance with the Board's strict requirements, and therefore, the city needs either advanced treatment facilities or Q ne ....... point of discharge in deep water. The only deep waters available are a considerable distance from Mill Valley, thereby necessitating careful consideration of a coordinated subregional approach to meeting the new water quality objectives. Table 4-1. CITY OF MILL VALLEY TREATMENT PLANT SIZE AND CAPACITY OF PRINCIPAL UNITS Plant Design Capacity - 1.3 mgd - Secondary BASIS OF DESIGN CHLORINE CONTACT TANK Design Population 18,000 Number 1 Design Flow Length, ft. 16 Average Dry Weather, mgd 1.3 Width, ft. 16 Peak Dry Weather, mgd 2.7 Depth, ft. 15 Peak Wet Weather, mgd 15.1 Detention Time, min. 30 Design Loading Biochemical Oxygen Demand, mgll 230 SLUDGE DIGESTER (Heated) Biochemical Oxygen Number 1 Demand, ppd 2,840 Diameter ft. 40 Suspended Solids, mgll 225 I Side Water Depth, ft. 24 Suspended Solids, ppd 2,780 Volume, 1,000 cu. ft. 30 PRIMARY CLARIFIER Number 2 SLUDGE DIGESTER Length, ft. 82 Number 1 Width, ft. 16 Diameter, ft. 50 Side Water Depth, ft. 10 Side Water Depth, ft. 24 Detention Time, hrs. 3.6 Volume, 1,000 cu. ft. 47 SECONDARY SEDIMENTATION TANKS Number 2 SLUDGE BEDS Length, ft. 82 Number 4 Width, ft. 16 Length, ft. 146 Side Water Depth, ft. 10 Width, ft. 51 Detention Time, hrs. 3.6 Depth, ft. 1.17 Volume, 1,000 cu. ft. 35 TRICKLING FILTERS Number 2 Diameter, ft. 80 PLANT OUTFALL Side Water Depth, ft. 6 Diameter, in. 30 Volume, 1,000 cu. ft. 60 Length, ft. 900 -----------------------~------------------- 4-6 In 1958, the plant was enlarged to provide secondary treatment utilizing trickling filters; and, in recent years, a sludge centrifuge has been added. The present plant design capacity is 1.3 mgd with the capacities of the principal units listed in Table 4-1 . Present Needs Although the Mill Valley treatment plant provides s~condary treatment with effluent disinfection, there is essentially a prohibition of discharge of any sewage-bearing WQstes to Richardson Bay. In June 1971, the Regional Water Quality Control Board issued a cease and desist order from dis charging wastewaters not in compliance with the Board's strict requirements, and therefore, the city needs either advanced treatment facilities or a new point of discharge in deep water. The only deep waters available are a considerable distance from Mill Valley, thereby necessitating careful consideration of a coordinated subregional approach to meeting the new water quality obi ectives. Table 4-1. CITY OF MILL VALLEY TREATMENT PLANT SIZE AND CAPACITY OF PRINCIPAL UNITS Plant Design Capacity - 1.3 mgd - Secondary BASIS OF DESIGN CHLORINE CONTACT TANK Design Population 1 B, 000 Number 1 Design Flow Length, ft. 16 Average Dry Weather, mgd 1.3 Width, ft. 16 Peak Dry Weather, mgd 2.7 Depth, ft. 15 Peak Wet Weather, mgd 15.1 Detention Time, min. 30 Design Loading Biochemical Oxygen Demand, mg/I 230 SLUDGE DIGESTER (Heated) Biochemical Oxygen Number 1 Demand, ppd 2,840 Diameter, ft. 40 Suspended Solids, mg/I 225 S ide Water Depth, ft. 24 Suspended Solids, ppd 2,780 Volume, 1,000 cu. ft. 30 PRIMARY CLARIFIER Number 2 SLUDGE DIGESTER Length, ft. 82 Number 1 Width, ft. 16 Diameter, ft. 50 Side Water Depth, ft. 10 Side Water Depth, ft. 24 Detention Time, hrs. 3.6 Volume, 1,000 cu. ft. 47 SECONDARY SEDIMENTATION TANKS Number 2 SLUDGE BEDS Length, ft. 82 Number 4 Width, ft. 16 Length, ft. 146 Side Water Depth, ft. 10 Width, ft. 51 Detention Time, hrs. 3.6 Depth, ft. 1.17 Volume, 1,000 cu. ft. 35 TRICKLING FILTERS Number 2 Diameter, ft. 80 PLANT OUTFALL Side Water Depth, ft. 6 Diameter in. 30 T Volume, 1,000 cu. ft. 60 Length, ft. 900 4-7 RICHARDSON BAY SANITARY DISTRICT The Richardson Bay Sanitary District was formed in 1949 as a consolidating agency for the several small community sewage disposal systems along the north shore of Richardson Bay. The district has continued as a consolidating agency and, finally, in 1963 extended sewerage service to the Hawthorne Terrace area adjacent to Tiburon and thereby eliminated the Hawthorne Terrace Sewer Me intenance Distri ct. Prior to the districtls formation, the first sewer system was installed in the Strawberry area about 1945 to serve the Bayview Terrace subdivision after septic tanks throughout the tract had failed. A collecting system was constructed in the rear of the houses to intercept septic tank effluent, and an outfall line was run to the Salt Works Canal which discharged without further treatment into the bay. In 1946, development of the Strawberry Point properties was started with the construction of homes along Belvedere Drive. Two community septic tanks were installed by the developer to serve this tract with approval of the County Health Department. Subsequently, in 1948, a third community septic tank was installed on the west slope to serve the Strawberry Manor tract. This tank was located south of Ricardo Road with an outfall to the bay on the east side of De Silva Island. Approval of these facilities by the county health authorities was with the understanding that they were temporary in nature and that they would have to be replaced with better treatment and disposal facilities in the near future. It became evident to the new residents of these tracts that the facilities provided by the developer would soon become entirely inadequate; and, since the proposed Southern Marin Sanitation District had been reiected by the voters, the residents of the Strawberry area formed the Richardson Bay' Sanitary District in February 1949. Upon its formation, the district became the owner of the three community sewage disposal systems. To solve the problem of the east side of Strawberry, a small package-type sewage treatment plant was constructed in 1950 on the Tiburon Highway adjacent to the Salt Works Canal. A second biofilter package treatment plant was constructed by the developer of Belveron Gardens at the location of the present Trestle Glen plant. Each plant was designed to provide complete secondary treatment for a population of 800. Rapid growth of the Strawberry Point area had, by 1953, made the Salt Works Canal plant and the two community septic tanks on the west side entirely inadequate. After studies to seek the most economical solution, the district contracted with the Sausalito-Marin City Sanitary District for treatment of sewage at their new plant near Fort Baker rather than attempt to enlarge the Salt Works Canal plant or to construct another package-type plant to serve the west side of Strawberry Point. Connection to the Sausalito system was made into an 8-inch force main with limited capacity which connected with a larger main at Marin City. This line was replaced by the Sausalito-Marin City District in 1959 with a 16-inch pipeline to Serve both the Richardson Bay and Tamalpais Valley systems. It has been expected that the connection to the Sausalito system would provide adequate service for the future needs of the areas served by the Ricardo Road and Salt Works pumping stations. However, the Sausalito system is of limited capacity to handle peak flows, and operating experience has indicated that the present system will be inadequate to serve the ultimate needs of the district. Trestle Glen Treatment Plant That portion of the district served by the original package treatment plant at Trestle Glen was growing rapidly, and by 1956 it became evident that the plant should be enlarged. About 1,200 persons were being served by the plant which amounted to about a 50 percent overload, and the degree of treatment was rapidly deteriorating. hi view of the high degree of treatment necessary at the Trestle Glen location, the design for the enlarged plant incorporated a modified activated sludge process known as the Spiro-Vortex system. The plant was designed to serve a population of 4,000 and to be cars tructed in two stages. The first stage was constructed in 1958, and the secondary clarifier was constructed in 1963. The present capacities of the plant and prindpal units is listed in Table 4-2. Table 4-2. RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT SIZE ~ND CAPACITIES OF PRINCIPAL UNITS Plant Design Capacity - 0.3 mgd Secondary BASIS OF DESIGN RECIRCULATION PUMPS Design Population 4,000 Number 2 Design Flow Capacity, ea~h Average Dry Weather 1 mgd 0.3 Low Speed, gpm 3,300 Peak Wet Weather, mgd 1.0 High Speed, gpm 4,500 Design loading Biochemical Oxygen AUX IliARY A IR BLOWERS Demand, ppd 680 Number 2 Suspended Sol ids, ppd 680 Capacity, each, scfm 300 INFLUENT PUMPS SECONDARY CLARIFIER Plant Pumping Units 3 Number Capacity, each, gpm 100 Diameter ft. 30 1 Side Water Depth, ft. 6 Detention Timer hrs. 2.5 SCREENING UNITS Barminutors 2 SLUDGE THICKENER Max. Capacity, each, mgd 1.7 Number Diameter, ft. 15.67 PRIMARY CLARIFIER Side Water Depth, ft. 7 Surface Area sq. ft. 193 Number I I Volume, gal. 10,100 Diameter, ft. 30 Side Woter Depth, ft. 7.5 SLUDGE INCINERATOR Detention Time, hrs. 3.2 Number Capacity, Dry Solids, lbs/hr 85 MIXING TANKS Combusflon Temp., deg F 1,600 Number 2 Diameter I ft. 26 EFFLUENT SPRAY FIELD Depth, ft. 6 Area, sq. ft. 8,000 Total Capacity, gal. 47,600 Disposal Capacity, mgd 0.025 SUPERATE FILTER PLANT OUTFALL Number Diameter! in. 18 Diameter, ft. 24 Length, ft. 200 Media Volume! cu. yds. 17 Depth celow MSL, ft. o Present Needs In February 1971, the Regional Water Quality Control Board adopted stringent new waste discharge requirements for the Trestle Glen plant. The new requirements mandate a very high degree of tertiary treatment and, in essence, essentially prohibit future discharge of sewage effluent at this point. In June 1971, they issued a cease and desist order from discharging wastewaters not in compliance with those requirements. SANITARY DiSTRICT NO.5 Sanitary District No.5 was 'formed in 1922 and serves most of the easterly end of the Tiburon peni nsula. The first sewers in the area were constructed in 1924 and until 1949 all sewage was discharged untreated to San Francisco Bay. District facilities n(,w include six pumping stations, some 48 miles I of sewers and force mains ranging in size from 6 to 18 inches and a primary sewage treatment plant. i --In addition to treating the sewage from District No.5, the treatment plant serves the City of Belvedere under a contractual arrangement which bases treatment charges on total sewage flow from the city. Sanitary District No.5 has assumed sewerage responsibility for a proposed subdivision in the Paradise Cove area on the east ~ide of the Tiburon peninsula. A 60-acre area near Paradise Cove has been annexed to the district~ and the developer built a small secondary treatment plant to be operated by district personnel. Treatment Plant The district1s treatment plant, originally constructed in 1949, was expanded in 1961 to its present design capacity of 1 .4 mgd. Principal plant units consist of an influent pumping station with a capacity of 7 mgd, two rectangular primary sedimentation tanks, a heated primary digester, a smaller unheated secondary digester, and a chlorine contact chamber. Peak hydraul ic capacity of the treatment units is reported to be 7.5 mgd. Plant effluent is discharged directly to Raccoon Strait and digested sludge is trucked away for agricultural use. The plant outfall extends only 24 feet offshore into Raccoon Strait. The present capacities of the plant and principal units are listed in Table 4-3. Present Needs The district needs to extend the plant outfall into Raccoon Strait to beyond the 200-foot limit to comply with the shallow water discharge prohibition and to upgrade the treatment level to a minimum of secondary treatment by 1977 to conform to the Federal Water Pollution Control Act. If the district undertakes. these improvements on its own, it could conceivably meet 011 water quality requirements until 1983 at which time the best practicable treatment technology shall be utilized. The district is presently investigating, on a pilot plant basis, the possible use of a new tertiary treatment process to upgrade effluent quality. At the district1s small Paradise plant, there may eventually be need to expand service to additional areas on the north side of the T ihuron peninsula. NvJny of the present homes now have septic tanks which are failing and causing potential health problems. To expand service to this area, it will probably be best to make a connection to either the southern Marin subregional system to be devel oped here in or to the Corte Madera system to the north. • 4-10 Table 4-3. SANITARY DISTRICT NO.5 TREATMENT PLANT SIZE AND CAPACITIES OF PRINCIPAL UNITS Plant Design Capacity - 1.4 mgd Primary BASIS OF DESIGN SLUDGE DIGESTER (Heated) Design Population 10,900 Number 1 Design Flow Diameter, ft. 25 Average Dry Weather, mgd 1.4 Side Water Depth, ft. 34 Peak Wet Weather, mgd 7.4 Volume, 1,000 cu. ft. 16.5 Design Loading Biochem:cal Oxygen Demand, ppd 2,100 Suspended Solids, ppd 2,800 SLUDGE DIGESTER PRIMARY CLARIFIER Number 1 Number 2 Length, ft. 56 Diameter r ft. 18 Side Water Depth, ft. 20 Width, ft. 14 Volume, 1,000 cu. ft. 5.3 Side Water Depth, ft. 10 Detention Time, hrs. 2 CHLORINE CONTACT TANK Number 1 PLANT OUTFALL Length, ft. 30 Width, ft. 10 Diameter, in. 24 Side Water Depth, ft. 8.5 length, ft. 70 a Detention Time min. 30 Depth below MS L, ft. f SAUSALITO-MARIN CITY SANITARY DISTRICT In the face of the need to provide 9dequate sewage treatment and disposal facilities after the failure of the Southern Marin Sanitation District, the Sausalito-Marin City Sanitary District was formed by the vote of the people residing within the corporate limits of the City of Sausalito and the Marin City area with the election of a 5-man District Boord of Directors. A bond electron was presented by the board to the electorate on April 8, 1952, which approved the expenditure of $775,000 by the district for construction of a system of intercepting sewers, pumping, and treatment works. The major project was completed in 1953 and eliminated all sewage pollution from the entire shore line of Sausalito and Marin City from Richardson Bay Highway Bridge on the north to Fort BCJker on the south, a distance of some four miles. This accomplishment was made possible through installation of a senes of sewers and pressure mains ranging in size from 10 to 24 inches intercepting raw sewage "that formerly flowed directly into the bay through the numerous individual outlets along the waterfront. The force mains, serving two booster stations and three main pumping plants, handle the flow between successive gravify sections and the treahnent plant itself. The plant is located on the rocky sliore of San Francisco Bay at the foot of the bluff some 800 feet south of the city limits. In respect to operating experience related to district collection sewer and pumping plant system, it may be pointed out that while functionally the system has worked well, inherent problems in respect to stormwater infiltration, both within the district and derived from contracting agencies sewerage 4-11 systems has resulted in some necessary bypassing in the past. This inherent weakness of the system, J mainly the result of antiquated IIleaky" local sewers, has been mitigated through recent improve ments providing increased pumping plant capacity. Nevertheless, it is acknowledged that basic improvements must be made to the old sewer systems in order to insure that nO bypassing of untreated wastewater occurs: in the future under expected condi tions of peak loading. Contracting Agencies The Sausalito-Marin City Sanitary District basically accepts sewage for treatment and disposal. The district provides treatment and disposal for the sewage from the City of Sausalito, while the city retains responsibility for maintenance of the sewer system. Furthermore, an essential aspect of the original Sausalito-Marin City district formation was an agreement to serve the wastewater treatment and disposal needs of adjacent Fort Baker, a consi deration which entered into the Favorable negotiations for the treatment plant and outfall line sites. Subsequent to district formation, the district entered into service agreements with Richardson Bay Sanitary District to provide wastewater treatment and disposal for a portion of that district's service area, as well as an agreement to serve Tamalpais Valley Community Services District. Treatment Plant The district treatment plant provides a primary degree of treatment and has a design capacity of 2.4 mgd. The plant utilizes a unique arrangement of plant structures, whereby the entire plant was built within an aD-fool circle to overcome extrcrordinary space limitations at this location. To accomplish this, the clarifier was constructed on top of the sludge digestion tank, with the control house adjacent to the clarifier. Ordinarily, these are separate structures, comprising a dispersed layout. The plant effluent is discharged through a submarine outfall extending 400 feet offshore and terminating. in 30 Feet of water. The sizes and capaciti es of the principal treatment units are listed in Table 4-4. Table 4-4. SAUSALITO-MARIN CITY SANITARY DISTRICT TREATMENT PLANT SIZE AND CAPACITY OF PRINCIPAL UNiTS Plari.t Design Capacity - 2.4 mgd Primary with Chemical BASIS OF DESIGN SLUDGE DIGESTER (Heated) Design Population 23,500 Number 1 Design Flow Diameter, ft. 75 Average Dry Weather, mgd 2.4 Side Water Depth, ft. 13 Peak Wet Weather, mgd 8.3 Volume, 1,000 cu. ft. 57.5 Design Loading Biochem ical Oxygen Demand, ppd 3,350 Suspended Solids, ppd 3,350 PRIMARY CLARIFIER PLANT OUTFALL Number 1 Diameter, ft. 55 Diameter, in. 20 Side Water Depth, ft. 9.5 Length, ft. 300 Detenti6n Time, hrs. 1.7 Depth below MSL, ft. 30 4-12 A distinct asset in respect to the treatment plant site location is its proximity to deep waters. Enormous volumes of bay water pass over the submarine outfall and greatly minimize the effects of the discharge. This provides one of the most strategic points of wastewater discharge to be found in the entire San Francisco Bay area. Present Needs Since the Sausalito-Marin City Sanitary District plant does not discharge to Richardson Boy it f is not faced with the same discharge prohibition as two of the other southern Marin agencies. The plant outfall extends beyond the 200"loot limit from the extreme low waterline 01 the bay and with slight modification of the outfall diffuser, the plant can meet all present water quality requirements in the bay. There is a need, however, to upgrade the present degree of treatment from primary to full secondary by 1977, to meet the basic requirements of the Federal Water Pollution Control Act Amendment of 1972. Construction of a full secondary plant is a major undertaking, particularly at the present plant site and, therefore, Sausalito should carefully consider other alternatives. TAMALPAIS VALLEY COMMUNITY SERVICES DISTRICT The Tamalpais Valley Sanitary District was formed in January 1954 and was the last sanitary district to be formed in the Richardson Bay watershed. Prior to its formation, the community of Tamalpais Valley depended on individual septic tanks for sewage treatment and disposal. The first subdivisions of land took place in the early 1900ls and, as the val ley developed the use t of septic tanks for sewage disposal became increasingly unsatisfactory, with many overflowing septic tanks. The district constructed a sewage collection system in 1954 and entered into an agreement with the Sausalito-Marin City Sanitary District for sewage treatment and disposal. Sewage from the district is pumped to the Sausalito system via a l5-inch and 16-inch force main from the district pumping station at the mouth of the Tennessee Valley. In 1967, the Tamalpais Valley Sanitary District was reorganized as the Tamalpais Valley Community Services District expanding their public services. I SUMMARY Each of the southern Marin sewerage agencies have present needs in respect to meeting more stringent waste discharge requirements. Both Sausalito and Tiburon must upgrade their treatment plants to full secondary treatment and Mill Valley and Richardson Bay Sanitary District must remove their discharges from Richardson Bay. These mutual needs suggest a coordinated effort, which is the primary reason for undertaking these present studies on a subregional basis. 17 Chapter 2 SUBREGIONAL ALTERNATIVE ANALYSIS INTRODUCTION The regional alternatives developed as part of prior studies in volving the southern Marin plannin.g area were summarized in Part I, Chapter 6. As a result of prior analysis, it was concluded that a large scale regional project involving south, central, and north Marin, as well as Sonoma County, would not be the most cost effective wastewater management plan. Local alternatives involving both southern and central Marin appeared to be more acceptable from both economic and environmental standpoints. This chapter summarizes the analysis of subregional alternatives conducted in the "Marin Sonoma Wastewater Program Analysis," 1975, and further screens various subalternative combinations of the smaller sanitary districts within the southern Marin area. SCREENING OF ALTERNATIVES Many alternatives for the southern Marin area were identified and evaluated in the previous regional and subregional studies. The basic feasibility of local disposal alternatives for the four souther Marin discharging agencies is summarized in Table 2-1. Land disposal options in southern Marin County are severely limited. Agriculture near urban areas is e,ssentially nonexistent and much of the land is already committed to watershed for the municipal water supply or for open space or parklands. Wastewater reclamation potential in Marin, which is discuss ~outhern in the following chapter, is generally limited to golf course and park irrigation and possibly for marsh creation or enhancement. Marsh enhancement is uiscussed in detail in Volume I, Chapter 8. A marsh creation project would require pilot investigations to determine sizing requirements and operational procedures that would mitigate possible nuisance effects, such as mosquito propagation. Implementation of such a project would require several years and is considered only as a possible second stage project after implemen tation of a subregional project with a primary discharge location outside of Richardson Bay. Reclamation potential in southern Marin could therefore only utilize a small portion of the wastewaters generated in the area and is not considered as an option to plans utilizing discharge to San Francisco Bay. Table 2-1 SUMMARY OF BASIC FEASIBILITY OF LOCAL DISPOSAL ALTERNATIVES All Year Bay Disposal Seasonal Land Local with 10:1 Total Disposal with Service Area Disposal to Minimum Land Local Winter Confined Waters Initial Dilution Disposal Discharge --- Tiburon-Sanitary Excellent Poor PI:)or District No. S • Richardson Bay Poor Moderate Poor Moderate Sanitary District Mill Valley Poor Moderate Poor Poor --- Sausalito - Excellent Poor Poor Marin City The actual evaluation of alternatives summarized in this chapter consisted of a three-step process. The first step consisted of screening alternatives from previously developed information in the South Marin Subregional Wastewater Management Plan and comparing those results to possibly changed conditions or criteria to ascer tain if previous conclusions are still valid. The next step was to refine cost estimates and criteria for comparison of alternatives selected for evaluation by the initial screening process. Based upon the economics, environmental, reclamation, and intangible factors, the more viable alternatives have been identified and analyzed in greater detail in Chapter 4. ' 2-2 EVALUATION CRITERIA The monetary evaluation of alternatives has been based upon a determi '1 nation of capital, operation and maintenance, and replacement costs for each alternative and comparison on a total present worth basis. Present worth of total annual cost, both capital and operation and maintenance, is based on an interest rate of 7 percent and an economic life of twenty years. In addition to the economic evaluation, various factors, including environmental and social impacts, are included in the overall cost effectiveness analysis. A separate Environmental Impact Report (EIR/EIS) for the entire Marin-Sonoma planning area is being prepared by J. B. Gilbert & Associates. This EIR/EIS will evaluate the speci fic social and environmental impacts for each of the more viable alternatives analyzed in Chapter 4. SUBREGIONAL ALTERNATIVES SCREENING There are four existing discharging agencies in southern Marin County: the Sausalito-Marin City Sanitary District, the City of Mill Valley, the Richardson Bay Sanitary District, and Sanitary District No. 5 serving Tiburon and Belvedere. Agencies which contract with the above include the City of Sausalito, Tamalpais Community Services District, Almonte Sanitary District, Homestead Valley Sanitary Dis trict, Alto Sanitary District, Kay Park Sewer Maintenance District, and the City of Belvedere. Two of the southern Marin discharging agencies, the Sausalito-Marin City Sanitary District and Sanitary District No.5, have excellent points of disposal to the deep waters of the bay at Yellow Bluff and Raccoon Straits, i;espectively. However, these two agencies i: have only primary treatment facHi ties and in order to comply wi th the federal law, they will have to upgrade their facilities to provide full secondary treatment. The other two discharging agencies, the City of Mill Valley and the Richardson Bay Sanitary District, have secondary treatment facHi ties but discharge to the sha,llow waters of Richardson Bay. Since the Regional Water Quality Control Board has adopted a prohi bition of discharge to Richardson Bay, these two agencies mllst relocate their discharge points to the deep 'waters of San Francisco Bay. Description of Alternatives The following alternatives have been selected for evaluation herein: PLAN SM-l involves continued operation of independent treatment plants and outfalls with Tamalpais Valley disconnecting from the 2-3 Sausalito system and reconnecting to the Mill Valley system. The Richardson Bay Sanitary District would treat all its wastewater at an expanded Trestle Glen treatment plant. The Sausalito-Marin City and Sanitary District No. 5 treatment plants would be upgraded to provide full secondary treatment and discharge to the nearby deep waters of the bay. The Mill Valley and Richardson Bay Sanitary District treatment plants would be upgraded to provide nitrification and effluent filtration and effluent would be discharged to Richard son Bay intermittently on high tides through shallow water outfalls. This is a theoretical alternative since the Regional Water Quality Control Board has prohibited discharge to Richardson Bay. PLAN SM-2 involves an independent Sausalito discharge to the deep waters of the bay without either Valley or Richardson T,~malpais Bay Sanitary District wastewater. The remainder of the subregion would retain each of its treatment plants and discharge effluent through a common outfall off Racco,)n Straits. All treatment plants would provide full secondary treatment. PLAN SM-3 involves construction of a regional treatment pla1t in southern Marin and disposal of all effluent to land. A storage lake and land disposal area are assumed to be In the Golden Gate National Recreation Area. Evaluation of Alternatives Economic Evaluation - A schematic of each alternative, toge1:her wi th the total present worth and initial capital cost, is shown in Table 2-2. Environmental Impacts - with respect to water quality, each of the alternatives would have a beneficic.l effect due to improved treat ment. Plan SM-I would be less advantageous due to the lower dilution capacity of Richardson Bay, while Plan SM-3 would eliminate all discharge but would have an adverse effect on land and air <,uality due to the spraying of effluent on hillside areas in the Gol.den Gate National Recreation Area. social Impacts - Social impacts of Plans SM-I and SM-2 are r,egli gible, although Plan SM-3 would have a negative effect by utilizing park areas for waste disposal. Flexibility - Due to the long length of pipeline carrying treated effluent, Plan SM-3 would be very flexible for reclamation end reuse. It would also not be subject to changes in discharge require ments. Plan SM-I would not be flexible in regards to changes in discharge requirements which could necessitate additional treatment processes. Reliability -Reliability in respect to ability to meet discharge requirements appears to be similar for each alternative. 2-4 Sausalito system and reconnecting to the Mill Valley system. The Richardson Bay Sanitary District would treat all its wastewater at an expanded Trestle Glen treatment plant. The Sausalito-Marin City and Sanitary District No. 5 treatment plants would be upgraded to provide full secondary treatment and discharge to the nearby deep waters of the bay. The Mill Valley and Richardson Bay Sanitary District treatment plants would be upgraded to provide nitrification and effluent filtration and effluent would be discharged to Richard son Bay intermittently on high tides through shallow water outfalls. This is a theoretical alternative since the Regional Water Quality Control Board has prohibited discharge to Richardson Bay. PLAN SM-2 involves an independent Sausalito discharge to the deep waters of the bay without either Tamalpais Valley or Richardson Bay Sanitary District wastewater. The remainder of the subregion would retain each of its treatment plants and discharge effluent through a common outfall off Racco()n Straits. All treatment plants would provide full secondary treatment. PLAN SM-3 involves construction of a regional treatment pla1t in southern Marin and disposal of all effluent to land. A storage lake and land disposal area are assumed to be in the Golden Gate. National Recreation Area. Evaluation of Alternatives Economic Evaluation - A schematic of each alternative, togecher with the total present worth and initial capital cost, is shown in Table 2-2. Environmental Impacts - With respect to water quality, each of the alternatives would have a beneficicl effect due to improved treat ment. Plan SM-l would be less advantageous due to the lowel' dilution capacity of Richardson Bay, while Plan SM-3 would eliminate all discharge but would have an adverse effect on land and air (~uality due to the spraying of effluent on hillside areas in the Gol.den Gate National Recreation Area. Social Impacts - Social impacts of Plans SM-l and SM-2 are r,egli gible, although Plan SM-3 would have a negative effect by utilizing park areas for waste disposal. Flexibili ty - Due to the long length of pipelin.e carrying treated effluent, Plan SM-3 would be very flexible for reclamation and reuse. It would also not be subject to changes in discharge require ments. Plan SM-l would not be flexible in regards to changes in discharge requirements which could necessitate additional treatment processes. Reliability -'Reliability in respect to ability to meet discharge requirements appears to be similar for each alternative. 2-4 Table 2-2 SOUTHERN MARIN PROJECT ALTERNATIVES SCREENING 'rotal Initial Plan Present Capital Sausalito San. Dist. 5 Richardson Bay Mill Valley Worth $1,000 '" SM-l $31,490 $19,010 s t s NH t3 + F NH:3 + F I '" ~ :s s •s •s SM-2 36,280 23,870 t- s ,"" SM-3 69,410 57,310 0 0 0 0 11111\ . w . .A ~ i * >PT,, ' 17;!? 1 .,_ W "-' c I! J ( " " I J i i F h t f : f r i e "!'lW __ \7 , !iT , . ' 1 _ , W j? " ; P ; l\ ; J N " " ,:e; 3 . M , $ib 5,.; ,Ki.l" j~l' ],~~ll,_,W,i·<-, n._ .., Ai tif,,L.iMM!l ;;;;" • ,- Reclamation - Plan SM-l would be conducive to small-scale reclama tion projects located near the local treatment facilities. The long effluent outfall to Tiburon proposed in Plan SM-2 would promote reclamation along its entire length. Plan SM-3 would utilize raw sewage intercepters and would abandon local treatment facilities which would make reclamation more difficult. Evaluation Summary Since Plan SM-l proposes to retain local treatment and disposal into Richardson Bay, implementation of this alternative is problema tical with respect to the discharge prohibition to Richardson Bay. With the assumed treatment level of nitrification and effluent filtra tion, one must consider this alternative as an absolute minimum degree of treatment with a high probability for increased treatment requirements should discharge be allowed to Richardson Bay. Plan SM-2 retains and upgrades each existing plant to a secondary level of treatment. Effluent from the Sausalito area would be dis charged at Yellow Bluff, while effluent from the remaining communities in the planning unit would be conveyed to Tiburon and discharged into Raccoon Straits. When compared to Plan SM-l, this plan has a higher initial capital cost and a higher present worth cost because of the higher capital investment in pipelines to Tiburon. However, since all effluent would be disposed of outside of Richardson Bay, there would be a reduced risk of having to undertake future modifi cations due to adoption of more stringent discharge requirements. A final alternative, Plan SM-3 involves construction of a consoli dated plant for land disposal in southern Marin. Again, implementa tion of this plan is a very problematical solution because much of the land is either contained in the Golden Gate National Recrea tional Area or is part of the Marin Municipal Water District watershed. In either case, discharge of wastewater onto these lands would not be compatible with existing and proposed uses. Even if allowed, this alternative is the most costly of those evaluated. From strictly an economic basis, Plan SM-l is the most economical. However, it must be remembered that this plan is only theoretical because it involves continued discharge into Richardson Bay. Accord ingly, it is concluded that Plan SM-2 is the best treatment and disposal alternative entirely within the southern Marin planning area because of its better discharge location. COMBINED SOUTHERN AND CENTRAL MARIN ALTERNATIVE SCREENING The southern Marin and central Marin planning units each serve dis crete watersheds in eastern Marin County, which are separated by the Corte Madera Ridge and Tiburon peninsula. The elevation of this ridge varies froml60 feet at Highway 101 to over 1,000 feet as it joins the slopes of Mt. Tamalpais. There are, however, two \ 2-6 '.{ s j , % I 1. , I abandoned railroad tunnels through the ridge which, if used for .1 I a connecting pipeline right-of-way, could allow a low-level con li nection between the planning units. I Description of Alternatives The previous subregional reports assumed that a low-level connection could be made and recommended a single consolidated facility at Point San Quentin. These previous evaluations of alternatives for central Marin identified a single consolidated treatment and disposal facility as the most economical plan for central Marin. To test the validi ty of the previous recofilmenda tion regarding southern Mar in's participation in a common facility, four additional alternatives involving combined facilities were screened. PLAN is a combination of the two least costly plans for the S/C~i-l separate planning units. For southern Marin, this plan would be the theoretical alternative of independent facilities with continued discharge into Richardson Bay, Yellow Bluff, and Raccoon. Straits. For central Marin, the plan consists of a consolidated facility with discharge offshore of Point San Quentin. PLAN S/CM-2 is a combination of Plan SM-2 for southern Marin and Plan CM-3 for central Marin. Plan SM-2 provides for independent treatment and disposal at Sausalito with the remaining dischargers retaining the existing plants and discharging through a common outfall into Raccoon Straits. Plan CM-3 involves the consolidated treatment and disposal facilities for central Marin. PLAN S/CM-3 is the plan previously recommended in the individual subregional reports. This plan involves construction of a single regional treatment plant in Marin to serve both planning centr.~l units with deep water disposal of the effluent off Point San Quentin. ! : It is assumed that a low-level cO ..1 nection through one of the railroad l tunnels would be available for the intercepter from Mill Valley , to central Marin. ! , PLAN S/CM-4 is a variation of the single consolidated facilities of Plan S/CM-3 but allows for the continued local discharge of waste water from Sausalito and Tiburon-Belvedere into the deep waters of San Francisco Bay. ) PLAN S/CM-S involves construction of a consolidated regional treat ment plant in central Marin serving all of southern and central Marin with total land disposal of all effluent in western Marin. 2-7 ; Alternatives Evaluation Economic Evaluation - A schematic of each alternative, together with the total present worth and initial capital cost, is shown in Table 2-3. Environmental Impacts - with respect to water quality, each of the alternatives would have a similar beneficial impact due to improved treatment and disposal. Plan S/CM-S would have an adverse impact on land quality due to the dis~osal of effluent on hillside areas. Plan S/CM-3 would have lesser impacts on land since six treatment plants would be eliminated, altho~gh a larger land area would be necessary at the regional plant Site. Implementation - Plan S/CM-5 would be,the most difficult to imple ment due to the large land areas,requlred. Plan S/CM-3 would also be difficult to implement since lt,would require consolidation of the greatest number of local agenCies. Flexibility and Reliability _,Flex~bili~y,for future changes would be greatest for Plan S/CM-S Since it ellmln~t:s discharge, followed by Plan S/CM-3 since a single treatment fac~llty would be easier to upgrade. Plan S/CM-I would ?e less fleXible due to continued \ discharge to Richardson Bay. Sln7e larger treatment plants and deep water disposal are utilized In P~ans S/CM-3 and S/CM-4, they would also be considered the most reliable. Reclamation - Plans SjCM-3, S/C~-4, and S/CM-~ w?uld make local reclamation in the southern Marin ~rea more difficult. Reclamation in Ross Valley and the western Marin area would be encouraged by Plan S/CM-S. Plans SjCM-I and S/CM-2 would facilitate small scale local reclamation in both southern and central Marin. Evaluation Summary The estimated costs for the combined southern and central Marin alternatives are summarized in Table 2-3. On an overall present worth basis, Plan S/CM-4, involvin~ a conso~idated southern and central Marin facility with Sau7allto and Tiburon :-emaining separate, is the least expensive alternative. Plan,S/CM-3, Involving a total consolidation of southern and central,Marln facilities, is slightly more expensive. This same close ranking between these two plans was found to exist in the Southern Marin Subregtonal Report, which indicated that the selection should be determined on the basis of intangible and environmental factors. The separate alternatives for the two planning units, Plan S/CM-I and S/CM-2, are more expensive, on ~ pres:nt worth basis than Plan SjCM-3. Considering that discharge ln~o Richardson Bay is proble matical because of Regional water Quality Control Board pOlicies, Plan S-CM-l can be omitted from further consideration. I 2-8 ~ .. '-",",rf;l'~""<!'"'1~"'I¥"""'"",~,~,~" ;'1 c· Table 2-3 COMBINED SOUTHERN AND CENTRAL MARIN ALTERNATIVES SCREENING Total Ini Hal Plan presegt Capital SA US S.O.S. R.B. M.V. S. D. I S.Q. S.R. Worth $1,000 :s s NH 3 +F NH 3 +F S S/CM-l 76,260 47,620 f f t ! 0 0 (SM-l + CM-3) s s •s •s :s S/CM-2 81,050 52,480 t t 0 0 IV (SM-2 + I \0 CM-3) s , S/CM-3 75,230 54,440 OOOO! 00 ~\. t s t s or----!_s! _ __ S/CM-4 ''73,140 49,940 0 ----.,O 0 s S/CM-5 125,010 98,610 0 0 0 0 0 O~ aENR = 3800 $1,000, 7 percent at 20 years eva1 Instead of discharging treated wastewaters into the bay, another Mil: flo' alternative would be to distribute treated effluent onto land as nat envisioned in Plan S/CM-5. Obviously, a substantial area would be required if all wastewaters are to be disposed of in this manner; In and, furthermore, the land would have to be able to receive this ta water without adverse environmental or social impact. Assuming Ta tha t large parcels of lan.d are available, probably in western Marin dl County, the overall costs on a present worth basis of Plan S/CM- 5, a' exclusive of land costs or possible credits, is 1.7 times that S of the most economical alternative. Without an identified potential t use of the water, the large cost differential for this total land disposal option becomes very and, accordingly, will sign:~ficant not be considered further. Based on the above evaluations, SM-2, involving separate treat P~an ment in southern Marin and dischaJ:ge to the deep waters of San Francisco Bay, and Plan S/CM-4, combining southern and central Marin facilities with Sausalito remaining separate, have been retained for further detailed analysis in Chapter 4. Plan SM-2 is the least costly plan for separate southern Marin facilities which removes discharg" from Richardson Bay. This plan would be easier to implement than a combined subregional facility since local agencies would have to consolidate. Plan SM-2 fe~ler would also promote local reclamation projects in the southern Marin study area since more treated effluent would be locally available. Plan S/CM-4 is the least costly combined southern-central ,"Iarin Plan. This plan would retain separate treatment with deep water disposal at Sausalito and Sanitary District No.5. Although this requires two addi tional treatment plants than Plan S/CM-3, it would be somewhat easier to implement since fewer agencies would need to consolidate and also would require less pipeline construction through the Sausalito area which would have adverse short-term environmental and social impacts due to disruption of traffic and commercial activities. The following section evaluates various subalternatives which are applicable to both Plans SM-2 and S/CM-4. This subalternative evaluation will determine the most cost effective combination of local sanitary districts within the southern Marin area • .', SUBALTERNATIVE EVALUATION SCREENING As described in Chapter 1, the Sausalito-Marin City treatment plant currently serves Tamalpais Valley and a portion of Richardson Bay Sanitary District. The existing Sausalito trunk line does not have capacity to handle projected peak wet weather flows from these pre sently-served areas. The Marin-Sonoma Wastewater Program Analysis 2-10 it J ,I I I evaluated costs for rerouting Tamalpais Valley from Sausalito to f Mill Valley and treating all of Richardson Bay Sanitary District flows at an enlarged Trestle Glen treatment plant as a subalter native to Plan SM-l. In order to determine the most cost effective combination of transpor tation, treatment, and disposal costs, six combinations involving Tamalpais Valley Community Services District and three separate drainage areas within Richardson Bay Sanitary District were evalu ated for inclusion with either Mill Valley, Richardson Bay, or Sausalito. These six subalternatives are applicable to either of the two viable alternatives SM-2 and S/CM-4. Also included in this analysis are three possible routings for transporting flows from southern Marin to central Marin in Plan S/CM-4. Figure 2-1 shows the pipeline routings and treatment plant locations for Plan SM-2. Alternate pipelines, which would be included under the various six subalternatives, are shown "dashed." The effluent line from Mill Valley to Tiburon would be nearly six miles long and would be either 24 or 27 inches .in diameter depending on the subalternative. Storage provided at the Mill Valley Plant would equalize the projected 3-hour wet weather peak flows to allow a smaller pipeline sized for the daily wet weather flow. Figure 2-2 shows the location and pipeline routings for Alternative S/CM-4 facilities. Flows from the Salt Works, Ricardo Road, and Tamalpais Valley pump stations would either continue to be pumped to Sausalito, or be rerouted to Sanitary District No.1, depending on the subalternative utilized. Also shown in Figure 2-2 are three possible pipeline routings to Sanitary District No.1. Route TG would follow the abandoned Northwest Pacific right-of-way east of Highway 101. The force main would be routed through the abandoned railroad tunnel between Trestle Glen and Corte Madera which would minimize the pumping head and power requirements. Route HW would utilize the existing bicycle path which parallels Highway 101 between Mill Valley and Corte Madera. At the bottom of the hill near Corte Madera, the line would cross under the high way and follow the railroad right-of-way as in Route TG. Route MV would follow the abandoned railroad right-of-way on the west side of Highway 101 from the existing Mill Valley plant site about one and one-half miles north, then it would rise over the hill to Corte Madera, and then follow the frontage road on the east side of the highway to Sanitary District No. "1 facilities. Route MV would require pumping flows over a hill 300 feet in elevation while the highway cut utilized in Route HW would be 160 feet in elevation. Pipelines for these two routes could decrease in size downstream of the high point to fully utilize the elevation head and help maintain higher velocities during low flows. Route TG would have a maximum elevation of 80 feet where the line from Mill 2-11 i Figure 2 -I MARIN ALTERNATIVE SM-2 il II < \~,~ / \ . \ \/ r", \~I"' .•. ,' :J\ r\ 1 S~~T EXIST. ) WORKS PJ- \ ~E -<='--- EXIST \ ~ .. \ GLEN T.P. ~~ .. " ~,\-,,~ v,' 4S,t. S~ITARY ',. ~J . NO. ~ P. \\ \. i~. '\ ~."., ". ,. --, __ ~ ~ ' 1 \ .\ \ 2-12 r:::::::='~"" '""'~~",---' I [ Figure 2 -2 r MARIN AI_TERNATIVE S/CM- 4 , , r '. "-- ~XIS'T, SANITARY DIST, ~C, I 'T"REATMENT PLANT '101'" •• " , ,,"-v ' 1 \ I / \ EXIST, TRESTLE GI:.§'N p, S -- ----.......---. \ ~ 1\ "NGE~ ,SL.AND I , • __ .L _ 'ALT Ei'lNA ~ FACILlTl~ ,~' p, s, '. PUfJP S'li TION '",:: '1< ,. ,\ • ". T f'- - TRf~:l,l._T~N T £PLA"N"T'/f,'J .:-:.-\~' .- " + '~' ~\\ <., 2-13 i Valley crosses Strawberry Point and 60 feet through the railroad tunnel and would, therefore, allow the lowest pumping presE.ures and power usage. Wet weather peak flows would be equalized at Mil.l Valley in order to minimize pipeline and pumping costs. Subalternatives SA-l to SA-6 Six subalternatives, involving Tamalpais Valley and the three sepqt t drainage areas within Richardson Bay Sanitary District, are summatia ~ in Table 2-4. The particular areas which would be treated or pump~~e at the four existing plants are sblwn along with projected dry and wet weather flows for the year 1993. Pipelines were sized for 20- year retu::n level wet weather flow, in 1998, while treatment facili_ ties were based on average dry wea:her flows estimated fOr 1988. One of th.! most important factors in the subalternatives analysis is the capaci ty of the existing Sallsali to trunk system whic.j pres~l\tl handles fiows from Tamalpais Valle:" Ricardo Road, and Salt Works y pump stat:.ons. In order to handle peak wet weather flows pcojected for these areas, various improvements at pumping stations .. and pipelines leading to the Sausali to-Marin ci tl' treatment plant would b,~ neces_ sary. In all of the subalternativ(!s, Sanitary District No.5, in Tiburon, ~70uld retain its present !!ervice area and would not vary in capac i ty. Subalterna.tive SA-l - The present !;ervice pattern would be retained under Plan SA-I. As shown in Figure 2-3, Ricardo Road, Salt works and Tamalpais Valley would continuE' to be treated at the Sausalito~ Marin city plant, while Mill Valley and Trestle Glen would retain their present service areas. In older to accommodate projected wet weather flows, a parallel 12-irch force main would be construCted from Ricardo Road pump station to /J.arin City and a 22-inch force main would extend from Marin City r.early four miles to the Sausalito treatment plant. Subalternative SA-2 - Subalternative SA-2, shown in Figure 2-4, would separate Salt Works pump station from the Sausalito system and include it with the Trestle Glen plant for treatment Or transP~rt north to Sanitary District No.1. About 6,700 feet of l8-inch for~e main would be constructed between Marin City and Sausalito to parallel an existing gravity pipe with insufficient capacity. Locust and Main Street pump stations in Sausalito would also be modified to provide additional capacity. Mill Valley would retain its present service area . - -",S.::u.=b",a",l;-.:t:.,;;e:.,;;r",n",a=.-t::,;I=-v· ;..;e=--S",A'i'--:; ,3 - S uba 1 te rna ti v e SA - 3 , sh own in Fig u r e 2 - 5 , would separate RIcardo Road and Sal': Works from Sausali to and incl\.la them with Mill Valley for treatment or pumping. Only pump station e modi fica tions would be required in t:he Sausali to trunk system to handle the wet weather flows from Tamalpais Valley and the Sausali t _ Marin City area. Trestle Glen would retain its present service 0 area. A 14-inch pipeline about one mile long would connect Ricardo Road and Salt Works areas to Mill Valley. A more costly longer route, avoiding the marshland area, could be used, depending' on the environmental impacts of the shorter route • . ~ ~- 2-14 Table 2-4 SOUTHERN MARIN SUBALTERNATI\E DESIGN FLOWS, MGD (1998) Subalternative Facility SA-l SA-2 SA-3 SA-4 SA-5 SA-6 Sausalito Areas S+TV+RR+SW S+TV+RR S+TV S+RR S+RR+S\~ S ADWF 2.35 1.90 1.58 1.32 1.77 1.0 PWWF 17.7 14.6 12.3 10.4 13.5 8.1 Mill Valley Areas MV MV MV+RR+SW MV+TV MV+TV MV+TV+RR+ SW ADWF 1.95 1.95 2.72 2.53 2.53 3.3 PWWF 24 24 29.6 28.2 28.2 33.6 Richardson Bay .Areas TG TG+SW TG TG+SW TG TG ADWF 0.23 0.68 0.23 0.68 0.23 0.23 PWWF 2.7 6.0 2.7 6.0 2.7 2.7 Tiburon Areas T T T T T 'r ADWF 0.98 0.98 0.98 0.98 0.9E 0.98 PWWF 9.0 9.0 9.0 9.0 9.0 9.0 I Abbreviations: ADWF - Average Dry weather Flow PWWF - Peak Wet Weather Flow over 3 hours, 20-year return period = PWWF 1.5 x Daily Wet Weather Flow S - Sausalito-Marin City MV - Mill Valley TG - Trestle Glen Pump Station SW - Salt Works Pump Station RR - Ricardo Road Pump station TV - Tamalpais Valley T - Tiburon ~ Sanitary District No. 5 2-15 ,. Figure 2-3 MARIN SUB -ALTERNATIVE SA-I " i I} II ,/i \ \ " , --~~ I c I '. E8 ~ \ cot: ~ \ \ iO\ 'G\. .... ,,\), i r \ I \ \ .~Q ) r~ ! !I \ / \ ( \ ~\~ , EXI ST',lsANITARY 7~,·'O'IST I'! 0, 5 T p, I , \ + ... 2-16 Figure 2- 4 SOUTHERN MARIN ~UB -ALTERNATIVE l ;F/ ~~ 1/ \. '. I ! I EB ~ \ i ) \ 0, , \~:j\r eoo. '- ,,\J \ I ~ I) 1,p, ~~EXIST,\,MILL VALLEY \ / , WORK~ EXIST, SALT p, S, \ ~ ~ \ ~ \ Xl~Z.~TLE GLEN T.P. >, \ -~~ \, / LEGEND + . '- , ~ ~ , "~, "~E\y ~ PI \ '----"~ •••••••~ EX)ST. "'I< ~' + 1'., P 2-17 -;;S' ,w::..;g;;;;;;:zm * Figure 2 - 5 SOUTHERN MARIN SUB-ALTERNATIVE SA-3 \. ~ '\ \ ( c., ' t. b -o / EXISf'. SAUS ........ MA~IN CITY ~­ L , ~_"o _'.0:-"1 p. S~ ~ P MP ,!?fA'noN ___R \ ' J\; + . \ T.'B " "",0 '''To.'e . \ 2-18 Subalternative SA-4 - Subalternative SA-4, shown in Figure 2-6, would transport flows from Tamalpais Valley to Mill Valley and from Salt Works to the Trestle Glen treament plant. Ricardo Road pump station would continue to pump into the Sausalito-Marin city system which would have sufficient capacity to handle the projected flows without major modifications. The pipeline from Tamalpais Valley would be about two miles long and 14 inches in diameter. Subalternative SA-S - Subalternative SA-S, shown in Figure 2-7, would separate Tamalpais Valley flow to Mill Valley while Ricardo Road and Salt Works areas would ce'ntinue to pump into the Hausalito Marin City trunk system. Trestle Glen would retain its present drainage area. The force main fre,m Ricardo Road pump station would be paralleled by a 12-inch force main and a 6,700 foot long gravity line between Marin City and Sausalito would be paralleled by a 16- inch force main. Pump station modifications in Sausalito would also be required to transport the peak wet weather flows. Subalternative SA-6 - Under Subalternative SA-5, shown in Figure 2-8, Tamalpais Valley, Salt Works, and Ricardo Road would all be removed removed from the Sausalito system and pumped to Mill Valley for either local treatment or transport to Sanitary District No. l. No modi fica tions would be necessary in the Sausali to-Marin city I trunk system. 1 Monetery Evaluation ~ 1 A summary of the estimated costs for the various subalternatives combined with the two major alternatives, SM-2 and S/CM-4, are presented in Table 2-S. The total present worth values, including operation and maintenance and replacement costs over a 20-year life at 7 percent interest, are shown together with the estimated capital and O&M costs. Alternative S/CM-4 includes the incremental capital and O&M costs for treatment at Sanitary District No.1. Treatment costs for the various alternatives were on the results of detailed ~ased analyses of each of the plants which are presented in Chapter 4. While cost differences for the various subalternatives are within S - 7 percent, Subalternative SA-3, which would reroute the Ricardo Road and Salt Works area to Mill Valley, while retaining Tamalpais Valley with Sausalito-Marin City, the lowest present worth and ~as capital costs for both Alternative, SM-2 and S/CM-4. Alternate Route TG is the least costly route in combination with Plan SA-3, partially due to its lower power costs. 2-19 I11III Figure 2 - 6 MARIN SUB -ALTERNATIVE SA-4 /il/' "'~ // if ; , --- \ -- ~-,--- \ \ /""""~ ST1 EX I , , + 2-20 Figure 2-7 SOUTHERN MARIN SUB -ALTERNATIVE SA-5 I " , It I I / ;) , , , i \ \ I , '--J ",",",.n '; EB \ ~.'"!'"". \ 'r ~ R) ~-EXIS~. ~T.P. MILL VALLEY =~ "\ (\, R~.S. E.. XIST.iRICARDO .\ ,(Irm:LUDING SALT W K \ \ \ /4-""'" EXt~ri-RESTLE GL EN T. P \ ., '.~"T'" ) . SA~ITARY 1K~f:!K ST. NO. 5.~P. ~~ ~ """" ""- ISAUSAL\I~~ 'J~~-.~/ XIST. .. MARIN! CITY T:R.---- '= ! R S. ( T. R~ . -"--.---, L ........ IV + 2-21 Figure 2 -8 SOUTHERN MARIN SUB-ALTERNATIVE SA-6 ~?/ /" / ;;1 ! I ttl '. 'j '\0'\" "« I ,,->J \ \ ~ I \ \ \ I ARI}Q-'R-Q. P.S. SAL.T ,WORKSl \ \, LEGEND p. s. ~" ', PO)MP "" T:.g Ti"l E. IV + 2-22 Table 2-5 SOUTHERN MARIN SUBALTERNATIVES COST SUMMARY ($1,000) Suba1ternative Costs $l,OOOa SA-1 SA-2 I. SA-3 SA-4 SA-5 SA-6 ALT SM-2 Initial Capital Cost 16,970 16,170 15,970 16,630 16,780 16,740 Annual O&M (1980) 730 740 760 750 770 800 b Total Present Worth 23,270 22,670 22,550 23,130 23,500 23,770 . ALT S/CM-3 Initial Capital Cost Route TG 20,540 19,400 18,920 19,760 20,090 19,440 Route MV 20,290 18,920 19,060 19,200 19,770 19,330 Route HW 20,260 18,840 18,980 19,120 19,690 19,250 Annual O&M (1980) Route TG 550 560 540 530 550 520 Route MV 580 600 580 580 590 580 Route HW 560 570 560 550 570 550 b Total Present Worth Route TG 24,860 23,900 23,270 24,000 24,490 23,630 Route MV 24,960 23,860 23,850 23,990 24,610 24,040 Route HW 24,720 23,540 23,500 23,670 24,160 23,660 a . Dry weather treatment facilities only, ENR = 3800 b Present worth - 1977, 7 percent, 20 years 2-23 Nonmonetary Evaluation In order to further evaluate the six subalternatives and the three pipeline routes, various nonmonetary factors were evaluated as sum marized below. Environmental Impacts - Environmental impacts (of the subalternatives) would be primarily related to pipeline construction. Subalternatives SA-l and SA-5 would require the greatest amounts of pipeline construction, primarily along the Sausalito waterfront, while Subalternative SA- 3 would require the least pipeline construction. Route MV/ which passes through more developed areas, would have greater lmpact due to construction activities than the other routes which would utilize the railroad right-of-way much of the distance. Scarce Resources - Routes MV and HW, which would pump over higher elevations, would utilize greater amounts of power than Route TG which would pass through the abandoned railroad tunnel. Pumping requirements for the other subalternatives do not vary significantly. Ability to Implement - Subalternatives SA-I and SA-2 would be more easily implemented than the others, since there are existing agreements between the various wastewater agencies which would be connected together. The other subalternatives would require new agreements and cost arrangements between the various agencies. Flexibility and Reliability - Since the subalternatives involve the same number of pump stations and treatment plants, all of which will have standby power capability, the flexibility and reliability of the plants are equal. SUBALTERNATIVE SM-2A An additional refinement of subregional Alternative SM-2 would involve pumping flows from the Trestle Glen treatment plant to Mill Valley for treatment. Although higher capital costs would be incurred due to pipeline construction, annual operation and maintenance costs would be lower since one larger treatment plant would be operated and maintained. A 12-inch force main about three miles long would be necessary to pump the flows from the Trestle Glen plant to the Ricardo Road pump station. The pipeline from Ricardo Road to the Mill Valley plant would be increased from 14 to 21 inches in diameter to accommodate the increased flow. Additional treatment capacity for 0.21 mgd average dry weather flow would be provided at the 2.63 mgd Mill Valley plant. The 3D-inch effluent force main from Mill Valley to Raccoon Straits would remain the same size. Estimated capital and annual O&M costs are presented in Table 2-6. Capital cost for transporting Trestle Glen to Mill Valley would be 1.35 million dollars versus 415 thousand dollars for separate treatment. Annual operation and maintenance costs would be 120 , 2-24 Table 2-6 COST SUMMARY - SUBALTERNATIVE SM-2A ABANDON TRESTLE GLEN PLANT FOR TREATMENT AT MILL VALLEY Cost Trestle Glen Separate Treatment SM-2 upgrade Trestle Glen Plant $ 415,000 Annual Operation and Maintenance at Trestle Glen Plant 120,000 a Total Present Worth $ 1,575,000 Trestle Glen to Mill valley SM-2A Increased Capital Cost pipeline Trestle Glen to Ricardo Rd. PS 15,000 If 12-inch force main $ 780,000 Increase Pipe Size Ricardo Rd. to Mill Valley 5,500 If 21-inch vs 14-inch 143,000 Additional Treatment Plant Cost @ Mill Valley 0.21 mgd 315,000 Pump Station Modifications at Trestle Glen 110,000 Total Capital Cost $ 1,348,000 Annual Operation and Maintenance Costs Trestle Glen pumping $ 12,000 Pipeline Maintenance 3,000 Increased O&M at Mill Valley 20,000 Total Annual Cost $ 35,000 a Total Present Worth '. $ 1,606,000 a7 Percent Interest, 20-year period - '-, 2-25 .. \ i I I thousand dollars for separate treatment, while combined treatment \ is estimated to cost 35 thousand dollars, including pumping and I I pipeline maintenance costs. Total present worth for both alternatives, including 20 years of operation and maintenance costs, is nearly equal. Although greater impacts due to pipeline construction would be incurred with combined treatment, Subalternative SM-2A, it would eliminate one treatment plant. Reclamation potential for each of the alternatives would be equal since the effluent force main would pass next to the Trestle Glen plant in either case. Although Richardson Bay Sanitary District will be contracting with Mill Valley for treatment of flows from its Ricardo Road and Salt Works drainage areas, combined treatment Subalternative SM-2A would be more difficult to implement, since it would require abandoning an existing treatment facility. Although combined treatment would significantly reduce annual operation and maintenance costs, its higher capital costs offset the savings on a present worth basis. Since separate treatment would be easier to implement and would have a slightly lower total cost, it is retained in Alternative SM-2. PARADISE COVE SUBALTERNATIVES As discussed in Chapter 1, Sanitary District No. 5 currently operates and maintains a small package treatment plant at Paradise Cove on the north side of the Tiburon Peninsula. The plant, with a capacity of 25,000 gallons per day, was installed to serve a proposed subdivision near the Paradise Cove area which is over a mile from any existing sewer system; however, the subdivision has not been developed and the plant serves only three connections. Due to the present ban on water connections, additional flows to the treatment plant are not likely in the near future. The Paradise Cove plant provides extended aeration treatment with disposal through a 4-inch outfall extending 500 feet offshore into a minimum of 10 feet of water. The plant meets Regional water Quality Control Board requirements, except in regard to dechlorination. The plant is maintained during three visits per week by Sanitary District No.5 personnel. " Three subalternatives have been evaluated regarding the continued use of the Paradise Cove treatment plant. ALTERNATIVE PC-l would retain the plant in operation. Operation and maintenance costs, including power, are estimated at $5,000 per year, which has a present worth value of $50,000. ALTERNATIVE PC-2 would abandon the package plant and pump the untreated wastewater to the Richardson Bay Sanitary District over the ridge of Paradise Drive. The pipeline would be 7,500 feet long with a 2-26 mInImum size of 6 inches to allow for maintenance. Capital cost, including the pump station, would be $280,000 and annual maintenance costs would be an estimated $1,600. Total present worth of this alternative would be $278,000. ALTERNATIVE PC-3 would abandon the plant and transport the untreated wastewater to the main sewer system on the south end of the Tiburon Peninsula. This plan would also facilitate the connection of the Tiburon Oceanographic and wildlife Center located about two-thirds the distance to the main sewer line. The force main required would be 14,000 feet long. Capital cost for this alternative would be $516,000 and annual O&M $2,200. Total present worth of this alternative would be $503,000. Environmental effects of the discharge are likely to be negligible, since the effluent is of high quality, very low in volume, and receives good dilution. Short term impacts from constructing a force main to either the Richardson Bay or Sanitary District No.5 system would be significant, since 1.5 to 3 miles of force main would be required. Growth-inducing aspects of the 6-inch force main would also be significant since it would pass through much undeveloped area and would have more than a 25,000-gallon-per-day capacity. Due to the small number of connections and the high cost of connecting to either the Richardson Bay or Sanitary District No. 5 systems (five to ten times more costly on a present worth basis) it is recom mended that the Paradise Cove plant remain in service. Should future development dramatically increase the connections to the Paradise Cove area, or if existing sewer systems from either Corte Madera, Richardson Bay, or Sanitary District No.5 expand closer to the Paradise Cove area, then abandoning the package plant may be more feasible. In the meantime, if no additional connections are foreseen, annual operation and maintenance costs may be significantly lower if the three houses were served by septic tank or other small scale treatment systems and effluent disposed by subsurface leach fields. Subalternatives Evaluation Summary Based on the cost analysis and other relevant factors considered, Subalternative SA-3 is selected for further analysis in conjunction with both Alternatives SM-2 and S/CM-4. This subalternative is the least costly and would require the least amount of pipeline construction. Tamalpais Valley would continue to pump into the Sausali to-Mar in Ci ty system for treatment and ·,disposal. Ricardo Road and Salt Works pump stations would either be routed to Mill Valley for treatment or pumped to Sanitary District No.1. Only pump station modifications to the Sausalito system would be required to handle the peak wet weather flows from Tamalpais Valley. Route TG is the least costly route and would require the least amount of power. It is selected as the most viable routing for transport of southern Marin flows to central Marin in Alternative S/CM-4. Since this routing follows the abandoned railroad right-of-way most of its distance, adverse impacts due to traffic disruption are minimized. Subalternative SM-2A, which would route flows from the Richardson Bay Sanitary District's Trestle Glen plant to the City of Mill Valley for treatment, does not result in savings on a present worth basis and would be more difficult to implement; therefore, SM-2A is not considered further. Due to its small flows and long distances to alternate treatment facilities, Paradise Cove will continue in operation and discharge offshore. SUMMARY This chapter has presented the screening of alternatives for the southern Marin subregion, as well as combined south and central Marin alternatives. Based on these studies, two subregional alternatives, SM-2 and S/CM-4, have been identified for further detailed evaluation in Chapter 4. Plan SM-2, the least costly plan for separate southern Marin facilities, would upgrade the four existing treatment facilities with a common outfall for Mill Valley, Richardson Bay Sanitary District, and Sanitary District No. 5 to Raccoon Straits. Sausalito would discharge in a separate outfall at its present location at Yellow Bluff. Plan S/CM-4, the least costly combined southern-central Marin alter native, would abandon treatment facilities at Mill Valley and Richardson Bay Sanitary District and pump raw wastewater to central Marin for treatment and disposal near San Quentin. Treatment facilities at Sanitary District No. 5 and Sausalito would be upgraded to provide secondary treatment with separate discharges to deeper bay waters at Raccoon Straits and Yellow Bluff respectively. In addition to the two major subregional alternatives, various subalter native combinations of the smaller sanitary districts within the southern Marin area have been analyzed. It was determined that subalternative SA-3, which retains Tamalpais Valley Sanitary District with Sausalito-Marin City and reroutes the Salt Works and Ricardo Road areas of Richardson Bay Sanitary District t6 Mill Valley or central Marin, is the most cost effective. The small Paradise Cove plant, serving only three connections, will remain in service. Chapter 6 APPARENT BEST ALTERNATIVE INTRODUCTION Evaluations reviewed in Chapter 4 indicated that Alternative SM-2 is the apparent best subregional alternative for the southern Marin area. Under this plan, the four existing treatment facilities would be upgraded and continue in operation. Secondary effluent from the Mill Valley and Richardson Bay Sanitary District, which is pre sently discharged into Richardson Bay, would be transported to deeper waters of San Francisco Bay at the end of the Tiburon peninsula. The Sausalito-Marin City and Sanitary District No.5 treatment facilities would be upgraded to provide secondary treatment, with each dis- charging into San Francisco Bay offshore of the treatment facilities. SUMMARY COMPARISON OF MAJOR SOUTH MARIN ALTERNATIVES The purpose of this section is to review and summarize the comparison of South Marin Alternatives as developed in prior chapters. It should be noted that the alternatives analysis summarized in Chapter 4 did not include any costs for treating wet weather flows, which were developed in Chapter 5. In addition, as a result of subsequent local discussions and environmental considerations additional miti gation measures are deemed necessary for any treatment plants located in Central Marin under Plan S/CM-4 because of their proximity to populated areas. The final alternatives which were evaluated are summarized below: Alternative SM-2 involves upgrading treatment facilities at Sanitary District No. 5 in Tiburon, Mill Valley, and Richardson Bay Sanitary District with a combined outfall from Mill Valley to Raccoon Straits. Sausalito-Marin Ci,;ty would upgrade to secondary treatment and have a separate discharge offshore of Yellow Bluff. Alternative S/CM-4 involves upgrading sanitary District No. 5 in Tiburon and Sausalito-Marin City to secondary treatment with independent outfalls to deep waters of San Francisco Bay. Mill Valley and Richardson Bay would pump to Sanitary District No. 1 in Central Marin for treatment and disposal. 6-1 Monetary Comparison of Alternatives The monetary comparison of the two alternatives is summarized in Tables 6-1 and 6-2. The cost estimates include the cost of wet weather treatment to meet Maintenance Level B conditions and the cost of miscellaneous improvements at Sanitary District No. 1 which will be required in order to assure that the plant is compatible with adjacent land uses. A summary comparison of alternatives is shown in Table 6-3. Based on the comparison of alternatives developed in prior chapters and summarized above, Alternative SM-2 has been selected as the apparent best alternative for Southern Marin. Alternative SM-2 has been chosen because it is the least costly alternative having a lower present worth and initial capital cost. Implementation of Alternative SM-2 would be significantly easier since existing treatment facilities and local agencies would be utilized and additional land for treatment at Central Marin would not be required. Due to the long length of force main carrying treated wastewater from Mill Valley to Tiburon, local reclamation opportunities would be enhanced. Studies summarized in Chapter 5 conclude that it is more economical for the Southern Marin agencies to treat high wet weather flows rather than have extensive sewer rehabilitation projects to decrease infil I tration and inflow. Therefore, the systems are not subject to excessive infiltration/inflow and, with the exception of the City of Belvedere, do not require sewer system evaluation surveys. .1 1 This chapter provides a detailed description of the apparent best I subregional alternative including the local treatment facilities at Sausalito-Marin City, Sanitary District No.5, Mill Valley, j and Richardson Bay Sanitary District which are incorporated into I the subregional plan. Also presented are cost estimates including wet weather facilities, and plan for project implementation, financing j I and operation. I I DETAILED DESCRIPTION OF PROPOSED PROJECT The major feature of apparent best subregional alternative is the i six mile long 30-inch diameter outfall line from ,the Mill Valley treatment plant to Raccoon Straits offshore of Tiburon. As shown in Figure 6-1, the outfall would cross under Highway 101 at the north end of Strawberry Point to the Richardson Bay Sanitary District Trestle Glen treatment plant. Treated effluent from the Trestle Glen plant would be pumped into the force main which would be routed along the existing bicycle path on the southern edge of the Tiburon peninsula much of the distance to Point Tiburon. Secondary effluent from the upgraded Sanitary District No. 5 plant would be connected 6-2 -f'» =,-~.~,~~--------------------=~----'="? "'f lv,' "'!""~"-d 'I'·'oe' f' IOU"" "'-~ Table 6-1 COST SUMMARY ALTERNATIVE SM-2, $1,000 Annual Operation and Maintlinance Item Capital Cost Cost Present 1978 1988 1978/88 1988/98 Worth - Sausalito-Marin City Treatment 3,300 215 218 5,588 wet weather facilities (ML-B) - - - - - Sanitary District No. 5 - Tiburon 2,590 - 170 173 4,402 - wet weather facilities (ML-B) 50 50 Mill Valley Treatment Facilities 5,760 - 318 323 9,147 <J'\ wet weather facilities (ML-B) 1,620 - - - 1,620 I w Richardson Bay S.D. - Trestle Glen 460 50 123 126 1,799 - - wet weather facilities (ML-B) 40 - 40 '. f\. Force main ext. Salt Works to Ricardo Rd. 185 Main and Locust,.Street Pump Stations 100 Salt Works Pump Station 120 20 21 5,371 Ricardo Road Pump Station 90 Equalization at Mill Valley 150 Force Main Ricardo Road to Mill Valley 385 Force Main Mill Valley to Raccoon Strait 4,126 TOTALS 18,976 50 846 861 28,017 _. - a1978 dollars, inflation not considered Table 6-2 COST SUMMARY ALTERNATIVE S/CM-4, $1,000 Annual Operation and Maintenance Item Capital Cost Cost Present 1978 1988 1978/88 1988/98 worth Sausalito-Marin City Treatment 3,300 215 218 5,588 wet weather facilities (ML-B) Tiburon Treatment 2,720 170 173 4,532 wet weather facilities (ML-B) 50 50 Sanitary District No. 1 (Ross Valley) 5,750 361 154 155 7,568 '" Treatment Facilities ..I. . wet weather facilities 1,700 40 40 2,124 misc. improvements 2,600 2,600 Main & Locust Street Pump Stations 100 Trestle Glen Pump Station 110 Salt Works Pump Station 150 t\. Ricardo Road Pump Station 90 Mill Valley Pump Station 2,000 94 95 9,860 Mill Valley Equalization 50 Force Main Mill Valley to Salt Works 2,003 Force Main Salt Works to SD #1 3,848 Force Main Trestle Glen to Salt Works 312 Force Main Ricardo Road Mill Valley F.M. 198 TOTALS 24,981 361 673 681 32,322 Table 6-3 SUMMARY COMPARISON OF MAJOR SOUTH MARIN ALTERNATIVES Factor SM-2 S/CM-4 Cost Effective Analysis ($1,000) Initial Capital Cost 18,976 24,981 O&M Cost, 1978 846 673 Present Worth Cost 28,017 32,322 Environmental Impact Good Good Social Impact Fair Fair Additional Considerations Scarce Resources Fair Fair Flexibility & Reliability Good Fair Ability to Implement Good Poor Compatibility with Local Fair Fair Planning Bypass Analysis Adequate Adequate Flood Protection Adequate Adequate Land Use Fair Fair Public Acceptabili ty Fair Poor .', I 6-5 Figure 6-1 APPARENT BEST ALTERNATIVE -SOUTHERN MARIN ill .1'',1 ,./ / iii ' ! ! " i! I! ! j 1/ ,/ ,, i \ /1 ;- i I ; i I ;f ,I ! i\,,\~~ j \\ C'i- f \.-", ') ~ I I \ , \ I , \: C" " .fm - \ \ lli\ I \ .. I ) \~'~ ~, '\: , I r51\ , \ , / ) i 0, ( \ \ \ \ ; \ \ ~ .. <lNGEL. ISLANO ------ 6-6 to the outfall line in order to utilize a common outfall and dif fuser which would extend 300 feet offshore into Raccoon Straits and provide a minimum 30:1 initial dilution. A common dechlorination facility located at Tiburon would allow a chlorine residual to be maintained in the outfall between Mill valley and Tiburon. Maintaining a chlorine residual in the outfall would be necessary if the wastewater is to be reclaimed for irrigation along the route and would also help disinfection during high wet weather flows as well as prevent in-line slime growths. An analysis of various combinations of the sanitary districts and drainage areas within the Southern Marin subregion conducted in Chapter 2 determined that the most cost effective system would in volve removal of the Richardson Bay Sanitary District's Ricardo Road and Salt Works drainage areas from the Sausalito-Marin City system. These two areas would be rerouted to Mill Valley for treatment, while Tamalpais Valley would continue to be served by the Sausalito Marin City system. The force main from Salt Works pump station would be extended to the Ricardo Road pump station and a 14-inch line approximately one mile long would be constructed from Ricardo Road pump station to the Mill Valley plant. The Sausalito-Marin City treatment facilities would be upgraded to provide secondary treatment and a new separate outfall and diffuser would be constructed into San Francisco Bay just offshore of the treatment facilities. Design criteria used in the sizing of the transportation treatment and disposal facilities are presented in Table 6-4. Design criteria utilized in the development of the apparent best treatment alter natives for each of the four treatment facilities are presented later in the chapter. A preliminary hydraulic profile of the outfall line to Raccoon Straits is shown in Figure 6-2. Sausalito-Marin City Sanitary District Treatment plant Improvements The proposed project constituting the apparent best alternative at Sausalito-Marin City consists essentially of the following basic elements: Grit Removal Primary Treatment Backup Secondary Treatment Sludg,e Thickening Primary Digestion and Sludge Dewatering Chlorination/Dechlorination Facilities 6-7 1 I ........- --------- Table 6-4 DESIGN CRITERIA APPARENT BEST ALTERNATIVE - SOUTHERN MARIN a Treatment Facility and Subareas Sanitary Sausalito- District Marin City Mill Valley Trestle Glen No. 5 Item Year S+TV MV+RR+SW TG T Average dry weather flow, mgd 1988 1.49 2.62 0.21 0.91 1998 1.58 2.74 0.23 0.98 '" I BOD load, Ib/day 1988 3,010 5,460 470 1,580 co 1998 3,200 5,690 510 1,730 " Daily wet weather flow, mgd 1988 7.9 19.3 1.8 5.8 1998 8.2 19.7 1.8 6.0 it" Peak 3-hr wet w~ather flow, mgd 1988 11.9 29.0 2.7 8.7 (20-year recurrence level) 1998 12.3 29.6 2.7 9.0 - L-~ ___________ aSubarea abbreviations: S - Sausalito-Marin City TV - Tamalpais Valley MV - Mill Valley RR - Ricardo Road SW - Salt Works TG - Trestle Glen T - Sanitary District No. 5 - Tiburon I Figure 6-2 PREll MINARY HYDRAULIC PROFILE EFFLUENT OUTFALL ,MILL VALLEY TO RACOON STRAITS ,----~~~:=~---------------------- 250 NOTE: ADWF,mgd 0.9/9.0 = PWWF,mgd 200 150 '" I '~-' \D Hydraulic Profile @ .,~ 100 _______P eak Wet Weather Flow ~\. ~ '" ;:;:; 50 ~ - ----- ~t~ -It t ~ichardson s.o. I" (MSL) 0 Mill Valley Bay MSL Q2 /2.7 Sanitary 2.6/20 (equalized) . District No.5, Outfall & Diffuser Q9/90 rr----:Racoon Straits -5o~I-------r------.-----~------.------.-------.~----r-----~ o 5 10 15 20 25 30 35 40 Length, /000 ft. Standby Power Control Building Bay Outfall Line and Diffuser Miscellaneous Improvements In connection with the specific process elements of the proposed project, it should be recognized that governing factors of existing facilities and sites are of major significance. As previously discussed, the existing primary clarifier becomes somewhat oversized in respect to projected average dry weather flows. However, this existing condition mitigates against the problem of high loadings associated with a relatively high peak wet weather flow condition. Also, the existing digester, as previously discussed, is considered unsuited for use as a primary tank because of its I very shallow depth, which does not permit adequate mixing and heating. However, this tank utilized as a secondary digester with the high I theoretical detention time should provide good separation of solids I as part of the enlarged plant. The restricted site, both in respect to property lines and elevations, mandates a unique design in respect to integrating structures. I And in the case of the proposed new primay digester, the use of a tall, small diameter tank is commended as a means to conserve space, while at the same time take advantage of a tank configuration which allows for good mixing characteristics. I Access to the proposed plant enlargements can be accomplished through extension of the existing roadway around in front (Bayward) of the e.xisting structures by constructing a causeway in tidal waters. It is not considered feasible to approach the new facilities location directly from the land, inasmuch as the land at that point is virtually a sheer cliff. The resultant plant design, dictated in large part by site and existing plant conditions, will be unique in its demonstration of what can be accomplished in spite of significant limitations. The proposed treatment enlargements, in relationship to existing plant facilities, are shown graphically in Figure 6-3. A detailed description of the basic elements of che proposed project is provided as follows: Grit Removal - The necessary grit removal will be accomplished through furnishing and installing a cyclone type degritter, together with a classifier, to receive and degrit underflow from the existing I primary clarifier on a continuous basis, with pumping rate of 200 gpm. The degritted underflow will be resettled in the sludge thickeners. I I 6-10 i , Figure 6-3 SAUSALlTO- MARIN CITY SANITARY DISTRICT PROPOSED ENLARGEMENTS IN RELATION TO EXISTING WASTEWATER TREATMENT PLANT ---z'_ ___ 0510 20304050 ~ I SCALE IN FEET MACHINE SHOP LEGEND c=J EXISTING PLANT I-/»-j PROPOSED ENLARGEMENTS 6-11 I primary Treatment Backup - The necessary primary treatment backup will be provided by oversizing the proposed two secondarysedimentati~n tanks on the basis of operating each tank in series with 1,200 gpd/ft overflow rate. The tanks will be partially covered to support the fixed film reactors above and to provide access. The two tanks will be 16 ft width by 78 ft length by 11 ft SWD. Secondary Treatment - The necessary secondary treatment will be provided by two fixed film reactors, each 36 ft in diameter by 25.1 ft SWD. The plastic media will be contained in a steel and plastic enclosure, all located above the secondary sedimentation tanks, chlorine contact tank and pump room. Three feed pumps will be provided, one being a backup for either of the other two. Pumps will be variable speed, with maximum capacity to pump 1/2 normal peak dry weather flows of 2.3 mgd. Included as part of the secondary treatment process element will be the two secondary sedimentation tanks previously described as coincidentally providing the needed primary treatment backup. Sludge Thickener - The necessary sludge thickener will be constructed as a separate circular tank with thickener mechanism, scum baffle and skimmer. The tank will be 18 ft square by 10 ft SWD. The tank will be covered to support the grit removal system and to confine odors. Primary Digestion and Sludge Dewatering - The necessary primary sludge digester will be provided by a single digester tank, 20 ft diameter by 45 ft SWD. The silo configuration will most easily accommodate the integrated plant structure concept within limited available space. Adequate mixing will be provided through gas recircu lation and heating by means of external heat exchanger. Chlorination/Dechlorination Facilities - The necessary chlorination for disinfection will be provided through use of existing chlorinators, which will be relocated to a separate room of the new control house. Similarly, the existing dechlorination system, a sulfonator unit and appurtenances, will be relocated. A new chlorine contact tank will be constructed as part of the plant improvements, to insure 40-minutes contact time at average peak dry weather flows. Standby Power - Additional standby power will be provided through installation of an engine-generator unit utilizing diesel oil. The unit will be adequate to provide standby power for all necessary plant systems, probably 75 kw capacity. Control Building - within and upon the integrated plant structure, the necessary control house will be constructed. This building will house, in addition to the chlorination/dechlorination equipment, a control room, office, laboratory, locker room, lunch room and storage. As part of this improvement, a revision will be made of the electrical control system and instrumentation so that visual indicators, metering, and basic controls will be provided in the control room. 2" 6-12 Ba! Outfall Line and Diffuser - The necessary Bay outfall line for ef luent dIsposal will consist of approximately 300 ft length of 3D-inch diameter cast iron pipe with bell jOints, or welded steel line and coated pipe, together with a 100-ft diffuser section with ports designed to insure a minimum of 25:1 initial dilution. Miscellaneous Improvements - At the plant site there will be a need to construct some miscellaneous improvements, including connections to existing plant. A significant improvement will be a necessary new access road causeway to reach the new plant addition. Also, there is a specific need at the existing Main Street pumping plant which provides pumping of the entire incoming wastewater flow. Consistently relatively large size rocks cause damage to the comminutors. A sump ahead of the comminutors is proposed to collect rocks. Flow Diagram - A flow diagram of the enlarged wastewater treatment plant as proposed is as previously shown in Figure 4-1, utilizing the fixed film reactor alternative for secondary treatment. Basic design criteria of the enlarged wastewater treatment plant as proposed is shown in Table 6-5. Expected Effluent Quality - Expected effluent quality of the enlarged treatment plant as proposed is summarized in Table 6-6. Summary of Plant Operation - Operation of the enlarged Treat~ent wastewater treatment plant as proposed may be described in narrative form, as follows: All incoming flow will pass through the existing primary clarifier. During periods of peak wet weather flow and at any time when needed, chemical flocculants may be added through use of the existing polymer feed system at the treatment plant, preceded by the alum feed system at the existing Main Street pumping plant. Effluent from the primary clarifier will go to the new reactor feed lift station and thence to one of the two new fixed film reactors. Depending upon flow rate, a portion of the effluent from the reactors will be returned as recirculation to the reactors, while the effluent passes to one of the two new secondary sedimentation tanks. At such times as the primary clarifier is out of operation, incoming wastewater can be bypassed directly to the No. 1 secondary sedimentation tank, thence to the fixed film reactors and then to the No. 2 secondary sedimentation tank in series operation. From the secondary sedimentation tanks, flow will go to the new mixing chamber for mixing with chlorine solution, thence to the new chlorine contract tank, with sulfur dioxide being added for dechlorination just prior to discharge to deep water through the new effluent line and diffuser. 6-13 . < Table 6-5 SUMMARY OF LOADINGS AND DESIGN CRITERIA FOR PROPOSED SAUSALITO-MARIN CITY FACILITIES Item Value Average dry weather (ADWF), mgd 1. 49 Peak dry weather flow rate (PDWF), mgd (1.7:1) 2.50 Peak wet weather flow rate (PWWF), mgd (5.75:1) 8.60 Primary Clarifier (Existing) Diameter, ft 55 Depth, ft 9.5 2 Overflow rate at ADWF, 9pd/ft 627 Detention time at ADWF, hrs 2 2.7 Overflow rate at PWWF, gpd/ft 2,510 Detention time at PWWF, hrs 0.5 Fixed Film Reactor (New) Number reactors 2 Diameter reactors, ft 36 Depth reactor media, ft 25.1 Treatabili ty factor, "k" 0.5 2 Hydraulic loading (Q), gpm/ft 0.2 Recirculation (Re) at ADWF, gpm/ft.2 48 BOD loading, Ibs/l,OOO c.f./day 2 Secondary Sedimentation Tanks Number sed imen ta tion tanks 2 Length tanks, ft 78 Width tanks, ft 16 Depth tanks, ft 11 2 Overflow rate in parallel at ADWF, 9Pd/ft 600 Detention time in parallel at ADWF, hrs 3.3 Overflow rate in series at ADWF, gpd/ft.2 1,200 Detention time in series at ADWF, hrs 1.65 Chlorine Contact Tank " Number tanks with center baffle 1 Length tank, ft 85 Width tank, ft 11 Depth tank, ft 10 Detention time at PDWF, min. 40 6-14 ---,:---,- Table 6-5 SUMMARY OF LOADINGS AND DESIGN CRITERIA FOR PROPOSED SAUSALITO-MARIN CITY FACILITIES (continued) Item Value Sludge Thickener (New) Number thickeners 1 Diameter thickener, ft 18 2 Combined sludge solids loading, Ibs/day/ft 9 Primary Digester (New) Number primary digesters 1 Diameter digester, ft 20 Depth digester, ft 48 Volume digester, c.f. 15,070 Total solids loading, Ibs/c.f./day 0.15 Detention time (at 5% solids), days 20.5 Secondary Digester (Existing) Number secondary digesters 1 Diameter digester, ft 75 Depth digester, ft 13 Volume digester, c.f. 57,400 Detention time (at 5% solids), days 78 Sludge Dewatering Number vacuumfil ters 2 2 Size vacuum filters, ft 113 Design capacity, Ibs/hr D.S. (combined sludge) 395 Raw sludge will be pumped continuously from the primary clarifier for degritting ahead of resettling and thickening, together with a continuous return of secondary sludge from the secondary sedimentation tanks in the new sludge thickener. Combined, thickened sludge will be pumped to the new ?rimary di~ester on a time clock sequence from the sludge thlckener, wlth overflow to the existing secondary digester. Supernatant will be returned to incoming wastewater from the secondary digester, with digested sludge being pumped to the new and existing vacuum filters for dewatering and transport to final disposal as a soil conditioner, . or dump. 6-15 Table 6-6 SUMMARY OF EXPECTED EFFLUENT QUALITY 30-Day 7-Day Maximum Instantaneous Constituent Units Average Average Daily Maximum Settleable Matter ml/l/hr 0.1 0.2 BOD. (S-day) mg/l 30 45 60 Suspended Solids mg/l 30 45 60 Grease & Oil mg/l 10 20 Chlorine Residual mg/l 0.0 Coliform (mean) MPN/IOO 200 400 Toxicity survival test organisms in 96-hr bioassay 90% of not less than 50% survival City of Mill Valley Treatment Facilities The apparent best alternative for the City of Mill Valley consists of upgrading and enlarging the existing biofilter treatment facilities. This alternative was selected over biofilter-activated sludge or activated biofilter-activated sludge treatment because it is the least costly alternative in annual operating and maintenance costs as well as on a present worth basis. It also requires less power comsumption and is simpler to operate than the other processes. The major components of the proposed treatment facilities would consist of the following: New headworks and influent pump station Aerated grit removal Conversion of existing secondary clarifiers to primaries, including odor control '. Use of existing primaries for wet weather flow treatment One additional wet weather primary clarifier Chemical addition facilities for wet weather flow Enlargement and rehabilitation of existing biofilters New secondary clarifiers 6-16 I I Additional microstrainer I ,1 Filtration facilities for wet weather flows New chlorine contact facilities Rehabilitation of existing sludge digestion and dewatering facilities New effluent pump station A schematic flow diagram of the proposed treatment process and a preliminary site plan of the existing treatment plant and proposed additions are included in Figures 6-4 and 6-5, respectively. The existing influent pump station which is over 30 years old and is hydraulically insufficient would be abandoned and a new headworks and influent pump station with a 30 mgd peak wet weather flow capacity would be constructed. Flow would be pumped to an aerated grit removal system located adjacent to the existing clarifiers. The grit removal I ! system would be covered to provide odor control. After grit removal, the wastewater would be given primary treatment in the converted secondary clarifiers which would be rehabilitated and covered to provide odor control. The existing 6-foot deep rock biofilters would be rehabilitated and enlarged by replacing the rock with a J 10-foot depth of plastic or horizontal redwood media. The existing walls would also be increased in height and the biofilter mechanisms replaced. New feed and recirculation pumping would be provided to operate the biofilters in series. Flow recirculation would be provided as required during low flow periods to maintain minimum wetting rates. Biofilter effluent would be clarified in the new secondary clarifiers and then micros trained in order to insure that suspended solids and BOD requirements are not exceeded. A new larger micros trainer would be added along with the two existing units in order to provide standby capability in case one microstrainer is out of service. After microstraining, the treated effluent would be disinfected in a new chlorine contact basin and then pumped through the 6-mile long 30-inch outfall to Raccoon Straits just offshore of Tiburon. Sludge from the primary and secondary clarifiers would be pumped to the rehabilitated existing anaerobic digesters. The existing secondary digester will be provided with standby mixing capability. Digested sludge would be mechanically dewatered and disposed of at a landfill site. A new control building containing office space, laboratory, lunchroom, and locker room facilities would be constructed. The City's existing corporation yard would be relocated to the abandoned sludge drying bed area in order to provide room for the new pumping station and clarifiers. 6-17 Figure 6-4 SCHEMATIC FLOW DIAGRAM APPARENT BEST TREATMENT ALTERNATIVE CITY OF MILL VALLEY AERATED GRIT REMOVAL RAW EXISTING WASTE PRIMARY CLARIFIERS INFLUENT ( 2) INFLUENT PUMP RECIRCULATION STATION I I POLYMER ,.L WET WEATHER r PRIMARY CLARIFIERS SECONDARY 1-- --r--{ CLARIFIERS I f- - - - - - ,_--._--' WET WEATHER I I EQUALIZATION WET WEATHER AND BASIN RECLAIMED WATER : I FLOWS I I MIXED MEDIA I I FILTERS I I wi I §I -' wi g "I I ,.I u!1 CHLORINE WET WEATHER !:ll FLOW ~I I CHLORINE I CONTACT I BASIN I I EFFLUENT SULFUR PUMPS I DIOXIDE OUTFALL I TO TIBURON ... '. DEWATERING .....J L __ 2:'_-. L ~IL_-.-JI LANDFILL 6-18 .~ Figure 6-5 SITE PLAN-CITY OF MILL VALLEY APPARENT BEST TREATMENT ALTERNATIVE j ._-- l N W. P. R. R. "'/ ., . . . . - I ---"'-~-"'--- , I SLuJ, DRYI" I"DS eZ- r- (TO BE ABANDONED) 1 PARK il I I DEPT I o 30 6,0 90 BLDG ! ! : LRELOCATED '---- i SCALE IN FecT CORPORATION YARe; i I I '~ 'I -'--'--'--'--'-- I • BJOFIL TER 810FILTER x NO. I NO.2 (TO BE MODIFIED) I I x :i L DECHLORINATION ~I I OIG N E O S .2 T ER G jk EN DG ER j ATOR AERA G T R E I D T , B O LDG D C CO H N LO TA R C J T N E B ASIN REMOVAL (TO BE ABANDONED) SA7 l STORMWATER PRIMARY 8 C D O IG N E T S R T O E L R INFLUENT CLARIFIERS M1CRO• EOUAU'AT"N x PUMP STRAINERS BLDG. STATION WET WEATHER PRIMARY MICRO I :1 CLARIFI ERS STRAINER [ (TO BE ABANDONED) x DIGESTER SECON DARY NO.1 CLARIFIERS, t il D x rr 0 OP S R Y E S S T S E U M R E 'NFLU' NT e- E PU FF M L P U ENT! PUMP CHLORINE STATION ~I STATIO N B CO NTACT BASIN HEAOW ORKS ., :ONTROL GARAGE, SHOPS a STORA [~~ (TO BE RE LOCATED TO DRYI NG BEDS AREAl I _=_:_:_::_ ' 0--.--.--.--.--.--,--, --.--,--, --.~~==::I=:x:: '. o o EXISTING FACILITIES PROPOSED FACILITIES 6-19 _\. ._ ___________________ ______ _______ _ ~ ~na' As develped in Chapter 5, requirements for wet weather Maintenance Level B would be achieved by diverting flows in excess of 5.2 mgd (two times average dry weather flow) to wet weather primary clarifiers. Chemicals would be added to allow higher overflow rates through these primary clarifiers which would operate only during high wet weather flows. In order to achieve secondary effluent requirements for a two year storm as specified under Maintenance Level B, the flow through the secondary treatment process would be filtered prior to blending with the diverted primary effluent. The microstrainers will decrease the sOlids loading on the filters allowing the filters to be reduced in size. In addition to high wet weather flows, the media filters could be utilized during dry weather periods to produce reclaimed water which may have to meet stringent disinfection and turbidity requirements. In addition to the wet weather clarifiers and filters, 1.2 million gallons of equalization volume is necessary in order to equalize the projected 3-hour peak wet weather flows of 30 mgd to the daily wet weather flows estimated at 20 mgd. This equalization volume allows the effluent pumping station and the 6-mile outfall to Raccoon straits to be sized for 10 mgd less capacity providing a significant cost savings. This storage would be utilized only during high wet weather flows. wet weather flows would be stored for a short period generally less than six hours and then returned to the influent pump station. The most economical means of constructing this storage would be in a shallow earthen pond located adjacent to the treatment facilities. Due to the bay mud prevailing on much of the site, the maximum levee height would be 5 feet with a 3-foot maximum water depth. Design criteria for the proposed additions are presented in Table 6-7. The treatment facilities have been sized for projected 1988 flows and loadings. Since flows are expected to increase only 4 percent from 1988 to 1998, the facilities are expected to have sufficient operating flexibility to accommodate the projected increase without major additions or modifications. A summary of expected effluent quality is presented in Table 6-8. Richardson Bay Sanitary District Trestle Glen Treatment Plant Improvements As concluded in the studies summarized in the pr~vious chapters, it is proposed that the existing Trestle Glen treatment plant be maintained to provide secondary treatment for the Trestle Glen watershed of the Tiburon peninsula and that the treated effluent be discharged through a common outfall off Raccoon Straits. With the continued use of the Trestle Glen treatment plant, it was determined that the plant needs are related to improvement of the 6-20 i I ] Table 6-7 SUMMARY OF LOADINGS AND DESIGN CRITERIA FOR THE APPARENT BEST ALTERNATIVE PROJECT - CITY OF MILL VALLEY DESIGN LOADINGS, 1988 Average dry weather flow, ADWF mgd 2.63 Peak dry weather flow, PDWF mgd 4.2 Peak wet weather flow, PWWF mgd 30 (20 year return level) Daily wet weather flow, DWWF, mgd 20 (20 year return level) Biochemical Oxygen Demand, Ibs/day 5,460 Suspended Solids, Ibs/day 5,190 PRIMARY CLARIFIERS (Existing) (2) Size each, ft. 2 16 x 82 Total surface area ft. 2,600 Side water depth, ft. 2 10 Overflow rate ADWF, gal/ft /day 1,000 2 PWWF gal/ft. /day 2,000 Capacity ADWF, mgd 2.6 PWWF, mgd 5.2 Detention time, @ 2.6 mgd, hrs. 1.8 @ 5.2 mgd, hrs. 0.9 WET WEATHER PRIMARY CLARIFIERS (2-Existing) (I-New) Size each, ft. (Exist) 16 x 82 (New) 2 20 x 95 Total surface area, ft. 4,500 Side water depth, ft. 2 10 Overflow rate, PWWF, gal/ft. /day 2,000 Capacity, PWWF, mgd 9.0 Detention time, PWWF, hrs. 0.9 WET WEATHER EQUALIZATION BASIN Volume, MG 1. 25 Depth, ft~ 3 Area, ft. 56,000 BIOFILTERS (2) MODIFIED Diameter each, ft. 80 Height ft. 10 each~ Volume, ft. 100,000 Treatability factor, "K" 3 0.055 Hydraulic loading series opera tion, gpm~f.t. 0.39 Hydraulic loading inc. recycle, gpm/ft.' 0.75 BOD loading Ib/day/lOOO ft. 3 40 6-21 Table 6-7 SUMMARY OF LOADINGS AND DESIGN CRITERIA FOR THE APPARENT BEST ALTERNATIVE PROJECT - CITY OF MILL VALLEY, Continued SECONDARY CLARIFIERS (3) 2 Overflow rate, ADWF, gal/day/ft 700 PWWF 1,200 Surface area, ft2 3,800 Size each, ft 16 x 82 Side water depth, ft 10 Detention time @ ADWF, hrs 2.6 @ PDWF, hrs 1.6 MICROSTRAINERS (2-Existing) (I-New) Size, exist, diameter x width, ft 7.5 x 5 new, diameter x width, ft 10 x 10 Total Surface area, ft2 2 550 Hydraulic loading, gpm/ft 5.0 WET WEATHER MIXED MEDIA FILTERS Design flow rate, mgd 5.2 Loading rate, gpm/ft2 6.0 Surface area, ft2 600 CHLORINE CONTACT BASIN Contact time, ADWF, minutes 60 PDWF, minutes 40 3 Volume ft 15,000 EFFLUENT PUMP STATION Capacity, mgd 20 ANAEROBIC DIGESTERS, EXisting 3 Primary digester, Volume, ft 52,100 3 Loading rate, Ibs volatile solidS/ft /day 0.15 Capacity, Ibs volatile solids~day 7,800 Secondary digester volume, ft 31,000 SLUDGE DEWATERING Capacity Ibs/hour 500 Capacity, gpm 30 .', 6-22 Table 6-8 SUMMARY OF EXPECTED EFFLUENT QUALITY - MILL VALLEY 30-Day 7-Day Maximum Constituent Units Average Average Daily Raccoon Straits Discharge Settleable matter ml/l/hr 0.1 0.2 BOD (5-day) mg/l 30 45 60 Suspended solids mg/l 30 45 60 Grease and oil mg/l 10 20 Chlorine residual mg/l Coliform (mean) MPN/IOO ml 200 400 Toxicity - survival test organisms in 96-hour bioassay 90% of not less than 50% survival Reclaimed Water for Landscape Irrigation BOD 15 25 35 Suspended solids 15 25 35 Coli form (mean) MPN/IOO ml 2.2 23 aAt Raccoon Straits. 6-23 plant's solids handling capabilities, aeration capability, chlorination and dechlorination facilities, and odor control measures. In respect to the treatment of wet weather flows, it was determined that for a Raccoon Straits discharge, achievement of Maintenance Level B would provide adequate protection of the receiving water. The only plant modification necessary for Maintenance Level C would involve the construction of chemical addition facilities and a pipe connection between the primary clarifier and plant outfall to allow the blending of primary effluent with the effluent from the secondary process when the wet weather flow rate exceeds twice the dry weather flow rate. It was also determined in Chapter 3 that there is a significant potential for using reclaimed wastewater from the Trestle Glen plant to irrigate nearby landscaped areas. The City of Tiburon McKegney Field is now being irrigated with over 10,000 gallons per day of effluent from the Trestle Glen plant. In order to provide effective and reliable disinfection and a consistent quality product water, it is recommended that media filters be provided at the Trestle Glen plant to filter essentially all of the effluent produced. Also included in the proposed plant improvements will be the construction of an effluent pumping station which will pump effluent through the proposed outfall to Raccoon Straits to be used in common with Mill Valley and Sanitary District No.5. It should be noted that proposed improvements to the Trestle Glen treatment plant will utilize most of the existing plant facilities and will not increase the treatment capacity beyond the present design capacity of 0.3 mgd. The following specific elements of the proposed Trestle Glen treatment plant improvements are proposed: Headworks Improvements Aeration Equipment Sludge Digestion System Improvements Process Units Covering Chlorination-Dechlorination Improvements Standby Power Piping Revisions Media Filters Effluent Pumping Station Miscellaneous Improvements " The proposed improvements are described in more detail below. Headworks Improvements - The plant headworks piping will be reconstructed to provide a single influent box and allow sampling of the plant influent at one point. 6-24 Aeration Equipment - Surface aerators over air diffusers will be installed in the two aeration basins in order to maintain a dissolved oxygen level of 4.0 mg/l in the mixed liquor. Sludge Digestion Im1rovements - It is proposed that the existing sludge digester wil be recommissioned, and the existing sludge incinerator will be abandoned. The existing sludge incinerator was installed in 1967 in order to reduce odors at the plant. However, approximately 270,000 cu. ft. of natural gas is utilized per month in the incineration of sludge at a cost of $450 per month. with the recommissioning of the existing sludge digester, this resource and cost will be saved, and methane gas will be produced. In order to recommission the existing digester, a boiler and heat exchanger will be added, and a sludge mixing pump will be provided. The existing digester is currently being used to store reclaimed water, and thus, an alternative water storage should be provided. Digested sludge will be dewatered with the centrifuge, which is now being used for the sludge incinerator. The dewatered sludge will be hauled to a legal disposal site for final disposal. Process units Covering - In order to further reduce odors, it is proposed that the primary clarifier, superate filter, and aeration tanks be enclosed. The enclosures will be ventilated, and the exhaust air will be scrubbed to reduce odors. Chlorination-Dechlorination Imrrovements - The existing chlorination and dechlorination equipment w 11 be moved to an enclosed building, and a residual chlorine analyzer will be added for more reliable process control. Standby Power - Standby power will be provided for the plant facilities in the form of an engine generator set. The engine generator set I will have a rating of 150 kw. Piping Revisions - In order to properly handle peak wet weather flows, piping will be provided to allow the blending of effluent from the primary clarifier with secondary effluent. Media Filters - Two media filters will be provided to polish the effluent which is to be used for landscape irrigation. Each of the two filters will be 6 feet in diameter with a media depth of 3 feet. Effluent to be discharged to Raccoon Straits will not need to be filtered. ' i Effluent pumping Station - An effluent pumping station will be provided I which will pump effluent through the common outfall off Raccoon Straits. I Miscellaneous Improvements - As a part of the proposed plant improvements, I certain specific improvements will be included which are necessary ! 6-25 to complete the installation and make a properly functioning system. These miscellaneous improvements will consist primarily of construction of an enlargement to the control building to provide space for an office, employee changing, and a lunchroom. Plant Layout - The proposed plant layout in relation to the existing structures is shown in Figure 6-6. Flow Diagram - The proposed plant flow diagram is shown in Figure 6-7. Design Criteria - The basic design criteria for the proposed improved treatment plant is summarized in Table 6-9. Expected Effluent Quality - The expected effluent quality from the improved Trestle Glen treatment plant is summarized in Table 6-10 for both the Raccoon Straits discharge and for the reclaimed water. 1 I During wet weather the blended effluent quality will meet Federal Secondary Treatment Standards as necessary to achieve receiving water Maintenance Level C conditions. Summary of Treatment Plant Operation - Operation of the improved Trestle Glen treatment plant as proposed may be described in narrative form as follows: Flows from the Reedlands and Belveron Gardens areas will be pumped at the plant pumping station, and the remaining sewage flows from Little Reed Heights, Del Mar, and Hawthorne Terrace enter the primary I clarifier by gravity. All incoming flow will be ground up by two separate barminutors prior to entering the primary clarifier. During periods of peak wet weather flows, a portion of the effluent I from the primary clarifier will flow directly to the chlorine contact chamber, while the remainder of the flow will enter the secondary I treatment process. Recirculation pumps will recirculate the sewage over the superate biofilter and thence to the two aeration tanks, each of which will also be equipped with surface aerators. Effluent from the aeration tanks will flow to the secondary clarifier. Activated sludge from the secondary clarifier will be returned to the aeration system, and a portion will be wasted from the system. Grit will be removed from the underflow from the primary clarifier by pumping it through a cyclonic degritter and grit washer. The degritted primary sludge and waste activated sludge will be resettled in the I sludge thickener, and the thickened sludge will be pumped to the sludge digester. Digested sludge will be dewatered by means of I a sludge centrifuge and hauled to a legal disposal site. I i I Effluent from the secondary clarifier will be disinfected with the , injection of chlorine. Effluent to be reclaimed for landscape I irrigation use will be pumped through the media filters prior to distribution for use. The remaining effluent will be pumped by , ~ means of the effluent pumping facilities to the cornmon outfall off ¥ Raccoon Straits. I J •~ I 6-26 I H • L ~ Figure 6-6 RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT PLANT LAYOUT ~ , \ MIXING TANK , \ PUMPING SUPERATE PIT BIOFILTER \ I/. I , I/. I SECONDARY CLARIFIER TANK \ , \ , SLUDGE \ DIGESTER (Reactivate) -:jg PROPOSED \ MEDIA FILTERS mSJ ~: \ l",:' .. I BUILDING I \ I I '. MARSH ASH / PLOT POND \ I 1 ~ Note: Additional marsh plots located southeast of plant. 1_ ___ - - - - - - . - 6-27 - < : ! ' - _ LANDSCAPE IRRIGATION SUPERATE FILTER MANAGED CHEMICAL ADDITION WETLANDS (Wet Weather Flows) 5°2 I t t I-...... ~ I REelRe I-4fl----j 1 ! _ICHLORINE TO COMMON • PUMPS CONTACT OUTFALL TO RACCOON STRAITS WET WEATHER FLOWS SLUDGE en I '" OJ TO LANDFILL , DEGRITTER SLUDGE SWDGE i;\ THICKENER DIGESTER .- Figure 6-7 RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT PROPOSED PROCESS FLOW DIAGRAM Table 6-9 DESIGN CRITERIA FOR THE PROPOSED IMPROVEMENTS TO THE RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT Item Value Basic Data - 1988 Design Year Design Population (Existing Plant) 4,000 Average Dry weather Flow (ADWF), mgd 0.30 Peak Dry Weather Flow (PDWF), mgd 0.45 Peak Daily Wet Weather Flow (DWWF), (0-5-yr Return), mgd 1.0 Peak 3-hr Wet Weather Flow (PWWF), (0.5-yr Return), mgd 1.5 BOD, 5 day, Ibs/day 680 Suspended Solids, Ibs/day 680 Headworks (Existing) Barminu tor s 2 Maximum Capacity, mgd 1.7 Plant Pumping Units 3 Capacity, each, gpm 100 Primary Clarifier (Existing) Number 1 Diameter, ft 30 Side Wall Depth, ft 7.5 Surface Area, sq ft 707 Volume, gal 2 39,770 Overflow rate at avg dwf, gpd/ft 424 Detention time at avg dwf, hrs 3.2 . Aeration Tanks (Existing) Number 2 Diameter, ft 26 Depth,ft 6 Total Volume, 1,000 cf 6.37 BOD applied, Ibs/day 476 BOD removed, Ibs/day 426 MLSS, mg/l 2,000 F:M ratio 0.53 MCRT, days 4 BOD loadings, Ibs/day/l,OOO cf 75 Detention time at avg dwf, hrs 3.8 6-29 Table 6-9 DESIGN CRITERIA FOR THE PROPOSED IMPROVEMENTS TO THE j RICHARDSON BAY SANITORY DISTRICT TRESTLE GLEN TREATMENT PLANT (Continued) .1 I Item Value I I Aerators Superate Filter (Existing) Diameter, ft Surface Aerators Capacity, each, scfm Secondary Clarifier (Existing) Number Diameter, ft Side Wall Depth, ft Surface Area, sq ft Volume, gal 2 Overflow rate at avg dwf, gpd/ft Detention time at avg dwf, hrs Sludge Thickener (Existing) Number Diameter, ft Side Water Depth, ft Surface Area, sq ft Volume, gal Solids loading, Ibs/day/sq ft Sludge Digester (Existing--to be recommissioned for service) Number 1 Diameter, ft 30 Side Wall Depth, ft 15 Volume, cu ft 10,600 Solids loading, Ibs/cu ft/day 0.058 Detention time, days 43 Sludge Dewatering Sludge centrifuge, number 1 Capacity, Ibs dry sOlids/hr 85 6-30 Table 6-9 DESIGN CRITERIA FOR THE PROPOSED IMPROVEMENTS TO THE RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT (Continued) Item Value Chlor ina tion-Dechlor ina tio.n (new ar rangemen t) Number of Chlorinators 2 Chlorinator Capacity, each, Ibs/day 500 Chlorine Contact time at avg dwf, hrs 0.7 Number of Sulfonators 1 Sulfonator Capacity, Ibs/day 30 Media Filters (0.3 mgd capacity) Number 2 Diameter, each, ft 6 Media depth, ft 3 2 Hydraulic application rate, gpm/ft 4 Effluent Pumps Number 3 Combined capacity, mgd 2.7 '. 6-31 Table 6-10 SUMMARY OF EXPECTED EFFLUENT QUALITY FROM THE TRESTLE GLEN TREATMENT PLANT 30-Day 7-Day Daily Constituent and units Average Average Maximum Raccoon Straits Discharge Biochemical Oxygen Demand, BOD, mg/l 30 45 60 Suspended Solids, mg/l 30 45 60 Settleable Solids, ml/l 0.1 0.1 0.2 Grease and Oil, mg/l 10 20 Coliform Bacteria, MPN/IOO ml 23 240 10,000 Reclaimed Water for LandscaEe Irri9ation Biochemical Oxygen Demand, BOD, mg/l 15 25 35 Suspended Solids, mg/l 15 25 35 Coliform Bacteria, MPN/IOO ml 2.2 23 240 Sanitary District No. 5 Treatment Plant Improvements The apparent best treatment alternative for Sanitary District No. 5 consists of air activated sludge treatment. This alternative was selected because it is the least costly treatment process on a capital cost and present worth basis and would be more reliable in meeting discharge requirements as well as possible future changes in treatment requirements. The major components of the proposed project would consist of the following: Diffused air aeration basins and blowers Secondary clarifiers and return sludge pumps Primary anaerobic digester Sludge dewatering modifications '. Standby power generator Control building additions A schematic flow diagram of the proposed treatment process is shown in Figure 6-8. The existing influent pumping and primary treatment facilities would be fully utilized in the proposed project. Following primary treatment, flow would be piped to the secondary treatment structure located adjacent to the existing plant as shown in Figure 6-9. f , 6-32 Figure 6-9 SITE PLAN -SANITARY DISTRICT NO.5 APPARENT BEST TREATMENT ALTERNATIVE NEW RETAINING INLET CHANNEL WALL [~ AERATION AERATION OEXIST SECONDARY BASIN BASIN • .---D-IG-ES.T-E-R ---.------.----- PIPING SECONDARY SECONDARY 5 CLARIFIER CLARIFIER SLUDGE (BLOWER a SLUDGE PUMPING DEWATERING ROOMS BELOW) EXISTING PRIMARY CHLORINE CONTACT BASIN CLARIFIER aUILOING 150' EXIST.RETAINING WALL MAR WE'S r \ " , . " SCALE IN FEET " 6-34 primary effluent would enter the activated sludge aeration basins which would provide a 6-hour detention time with oxygen supply and mixing accomplished by diffused air. The activated sludge organisms would be separated in the secondary clarifiers and returned to the aeration basins. Clarified secondary effluent would be disinfected in the chlorine contact basin and discharged through the combined outfall along with effluent from Mill Valley and Richardson Bay Sanitary District into Raccoon Straits about 200 feet offshore of Point Tiburon. During high wet weather flows, chemicals would be added to the primary clarifiers to increase removal of BOD and suspended solids. In order to meet Maintenance Level B requirements of secondary effluent for 2 year recurrence level storms, the secondary treatment facilities would be operated at twice the average daily flow rate and primary and secondary effluent blended to meet the effluent standards. Sludge from the primary clarifiers along with waste activated sludge from the secondary clarifier underflow would be anaerobically digested in the existing primary digester. Digested sludge would be allowed to thicken in the new secondary digester before being mechanically dewatered and trucked to a landfill site. The expansion site owned by the Sanitary District is only 50 feet by 150 feet in size and consists of steeply sloped land. In order to fit the secondary treatment additions on this site, extensive excavation and retaining wall construction will be necessary. The secondary treatment structure, as shown in Figure 6-9, would have common wall construction for the aeration basins, secondary clarifiers, and chlorine contact basin. The sludge pumping and transfer piping would be located within the treatment structure along with air blowers and sludge dewatering facilities which would be constructed under one of the secondary clarifiers. A new anaerobic digester will be constructed in order to provide secondary digester capacity and provide additional operating flexibility. The digester will be 25 feet in diameter and 34 feet high and provided with standby mixing capability. Additional office space, lunchroom, and locker room facilities will be constructed above the existing board meeting room, while the laboratory facilities would remain at their present location under the primary clarifier. A standby generator will be provided to maintain essential plant operations in the _,event of a power failure. Design criteria for the proposed additions are presented in Table 6-11. The treatment facilities have been sized for projected 1988 flows. Since 1998 flows are expected to increase only 8 percent from the 1988 flows, the treatment facilities are expected to have sufficient operating flexibility to accommodate the increase without major additions or modifications. A summary of expected effluent quality is presented in Table 6-12. 6-35 Table 6-11 SUMMARY OF LOADINGS AND DESIGN CRITERIA APPARENT BEST ALTERNATIVE PROJECT _ SANITARY DISTRICT NO. 5 DESIGN LOADINGS - 1988 Average dry weather flow ADWF mgd Peak dry weather flow, PDWF mgd 0.91 Peak wet weather flow, PWWF (5 year 2.1 return level) mgd 6.9 Daily wet weather flow, DWWF (5 year return level) mgd 4.6 Biochemical Oxygen Demand Ibs/day Suspended Solids, Ibs/day 1,580 1,580 PRIMARY CLARIFIERS (Existing) - (2) , Size each, ft 2 Total surface area, ft 2 14 x 56 1,570 Overflow rate @ ADWF gal/ft /day 580 @ DWWF 2,900 Detention time @ ADWF, hrs 3.2 @ DWWF, hrs .63 AERATION BASINS (2) Food to microorganism ratio (F:M) MLVSS, mg/l 0.35 2,000 Detention time, ADWF, hrs 6.4 SRT, days 3 8 Volume, ft 32,500 SECONDARY CLARIFIERS (2) 2 Overflow Rate, ADWF, 9Pd/f~ 520 PDWF gpd/ft 1,200 Surface Area, ft 2 1,750 Solids loading, ADWF, Ibs/ft /day 17 CHLORINE CONTACT BASIN Detention Time @ ADWF, min 60 @ PDWF, min 3 27 Volume, ft 5,100 PRIMARY DIGESTERS (Existing) Size, diameter x height Volume, ft3 3 25 x 34 16,800 Total Solids loading Ibs/ft /day 0.15 Detention time (@3% solids), days 15 6-36 Table 6-11 SUMMARY OF LOADINGS AND DESIGN CRITERIA APPARENT BEST ALTERNATIVE PROJECT - SANITARY DISTRICT NO.5, Continued SECONDARY DIGESTER Size, diameter x height 25 x 34 Volume 16,800 Detention time (@ 3% solids) days 15 SLUDGE DEWATERING 2 Vacuum filter - design loading, Ibs/hr/ft 4.0 Surface Area, ft2 100 Table 6-12 SUMMARY OF EXPECTED EFFLUENT QUALITY 30-Day 7-Day Maximum Instantaneous Constituent Units Average Average Daily Maximum Settleable matter ml/l/hr 0.1 0.2 BOD (5-day) mg/l 30 45 60 Suspended solids mg/l 30 45 60 Grease and oil mg/l 10 20 Chlorine residual mg/l 0.0 Coliform (mean) MPN/IOO 200 400 '. Toxici ty - survival test organisms in 96-hour bioassay 90% of not less than 50% survival 6-37 l DETAILED ESTIMATE OF COST FOR PROPOSED PROJECT A summary of estimated costs for the Southern Marin subregion are 1 , presented in Table 6-13. Additional costs for wet weather treatment facilities required under Maintenance Level B, as developed in I, Chapter 5, are included in the table. Capital costs of additional 1 facilities required for Maintennce Level A would be 4.54 million dollars additional or about 25 percent of the entire project. The additional costs required by Maintenance Level A provide for treatment of large storm flows which occur only infrequently. Since the outfall locations in Southern Marin provide excellent dilution capability, infrequent bypassing of diluted wet weather flows allowed under Maintenance Level B should not be detrimental to the water quality of San Francisco Bay. Detailed project costs for the four treatment facilities are presented in the following tables. Costs are estimated on the basis of 1978 dollar value and costs escalated to assumed 1979 construction year on the basis of a 10 percent increase. project Costs Versus Local Funding Needs State and Federal grant regulations restrict grant funding to that project capacity needed to serve populations as projected by the State Department of Finance Series 0-100 curves. For wastewater treatment plant construction, grant eligible costs are further limited to capacities to meet 10-year projected needs. The subaggregation of DOF Series 0-100 projections for the Southern Marin service area in comparison with project design population capacity is summarized in Table 6-18. Grant regulations are such that the cost for increased capacity beyond that needed for the State Department of Finance (DOF) Series 0-100 projections will be borne by the local sewering agencies on the basis of 100 percent of the incremental increase in project costs. It will not be possible to determine the cost for wastewater treatment plants having a capacity to serve the DOF Series 0-100 projected 1988 population. This determination could only be made on the basis of actual design and obtaining of construction bids for two plants with corresponding capacities, as noted above. However, an estimate can be made on the assumption that capital costs increase at a rate of 0.7 power of capacity, which is represented by the slope of generally accepted cost curves for this type of work. It should be noted that actual incremental cost increases will be determined from final estimates of each individual process unit, as'.agreed upon with State Water Resources Control Board Staff. For preliminary planning purposes, the factor for computing the fraction of costs eligible for grant participation is presented in Table 6-18. An example calculation for the City of Mill Valley; DOF D-100 0.7 19,401 0.7 Eligible cost factor =(Design Popul.) = (21,000) = 0.95 Using the factors presented in Table 6-18, the estimated grant participation and local funding needs are summarized in Table 6-19. ... . , 6-38 Table 6-13 SOUTHERN MARIN SUBREGION ESTIMATED PROJECT COSTa Item Size Cost 1978 Construction Sausalito-Marin City treatment and outfall b 1.5 mgd $ 3,300,000 Wet weather facilities Maintenance Level B -0- Mill Valley treatment expansion 2.6 mgd 5,760,000 Wet weather facilities Maintenance Level B 1,620,000 Trestle Glen treatment 0.2 mgd 460,000 ~ Wet weather facili ties Maintenance Level B 40,000 Sanitary District No. 5 treatment 0.9 mgd 2,590,000 Wet weather facilities Maintenance Level B 50,000 Main and Locust pump station modification 100,000 Salt Works pump station modification 120,000 Ricardo Road pump station modification 90,000 Equalization at Mill Valley 150,000 Force main extension Salt Works to Ricardo Road 12 inch 185,000 Force main Ricardo Road to Mill Valley 14 inch 385,000 Force main and outfall Mill Valley to Raccoon Straits 30 inch 4,126,000 TOTAL 1978 CONSTRUCTION $18,976,000 1988 Construction I Trestle Glen treatment modification $ 50,000 = aENR 3800. Includes contingency and engineering bWet weather treatment costs for Maintenance Level B San Francisco Bay Basin Plan - Costs for Maintenance Levels A&C presented in Chapter 5 " 6-39 Table 6-14 PRELIMINARY CONSTRUCTION COST ESTIMATE PROPOSED PROJECT SAUSALITO-MARIN CITY TREATMENT FACILITIES Estimated Access causeway $ 250,000 Estimated Site protection during construction 175,000 Estimated Foundation preparation 50,000 350 c.y. Foundation concrete 52,000 1,400 c.y. Structural concrete, in place 490,000 2 only Secondary sedimentation tank mechanisms 80,000 3 only Reactor feed pumps 15,000 2 only Reactor mechanisms 40,000 51,000 c.L Reactor media 140,000 3 only Secondary sludge pumps 12,000 1 only Sludge thickener mechanism 25,000 2 only Sludge pumps 10,000 1 lot Sludge degritting system 10,000 1 lot Digester heating & mixing systems 50,000 1 only Digester sludge dewatering filter 30,000 Estimated Process pipework 270,000 Estimated Standby power additions 50,000 1 lot Miscellaneous ironwork 36,000 Estimated Chlorination/dechlorination system modification 80,000 Estimated Control house, laboratory and appurtenances 90,000 Estimated Connections and revisions to existing work 85,000 Estimated Electrical work & instrumentation 200,000 300 L.F. 30-inch outfall 100,000 300 L.F. 30-inch diffuser section 40,000 Sub-total, Construction Costs $2,540,000 Escalation to Construction Year (1979) 250,000 Technical Services 250,000 Legal & Fiscal 10,000 Administrative 5,000 Project Contingencies 245,000 ESTIMATED PROJECT COSTS $3,300,000 " 6-40 , Table 6-15 PRELIMINARY CONSTRUCTION COST ESTIMATE PROPOSED RICHARDSON BAY SANITARY DISTRICT TRESTLE GLEN TREATMENT PLANT Plant Improvements 1 lot Headworks equipment $ 10,000 1 lot Aeration equipment 10,000 1 lot Digester heating and mlxlng equipment 40,000 1 lot Sludge dewatering equipment 50,000 1 lot Piping and misc. ironwork 20,000 1 lot Odor control equipment 50,000 1 lot Wet weather chemical feed equipment 15,000 Estimated Control building enlargement 40,000 Estimated Emergency power 20,000 Estimated Electrical work 25,000 Estimated Painting 15,000 Estimated Media filters 45,000 Subtotal $340,000 Effluent Pumping Station Estimated Effluent pumping Station Complete 40,000 Subtotal Construction Cost $380,000 Escalation to Construction Year (1979) 40,000 Technical Services 40,000 Legal & Fiscal 3,000 Administrative 2,000 Project Contingencies 35,000 ESTIMATED TOTAL PROJECT COST $500,000 " I I I 6-41 I Table 6-16 PRELIMINARY CONSTRUCTION COST ESTIMATE PROPOSED PROJECT a CITY OF MILL VALLEY TREATMENT FACILITIES Item Cost Headworks and pumping $1,650,000 Aerated grit removal 150,000 Control building and laboratory 260,000 Primary sedimentation modifications including odor control 195,000 Wet weather clarifier modification and additions 270,000 Chemical addition equipment 115,000 Biofilter and recirculation pumping 775,000 Secondary clarifiers 650,000 Microstrainer additions 200,000 Wet weather equalization basin 115,000 Digester and dewatering modifications 230,000 Chlorination-dechlorination 240,000 Wet weather filtration facilities 510,000 Effluent pump station 380,000 Site work and landscaping 50,000 SUBTOTAL CONSTRUCTION COST $5,790,000 Escalation to Construction Year 1979 580,000 Technical Services 580,000 Legal Fiscal 5,000 & Administrative 5,000 Project Contingencies 570,000 TOTAL CAPITAL COST $7,530,000 = aENR 3800 includes wet weather facilities for Maintenance Level B '. 6-42 .",. Table 6-17 PRELIMINARY CONSTRUCTION COST ESTIMATE PROPOSED SANITARY DISTRICT NO. 5 TREATMENT FACILITIES Item Costs Excavation and retaining wall $ 300,000 Aeration and clarifier structure 575,000 Aeration basin mechanical 95,000 Secondary clarifier--mechanical 100,000 Return sludge pumping 65,000 Blower room mechanical 50,000 Chlorine contact basin and feed equipment 105,000 Wet weather chemical feed equipment 40,000 Anaerobic digester 155,000 Sludge dewatering modifications 65,000 Standby power 50,000 Modification to existing plant 30,000 Control building additions 50,000 Painting and sitework 50,000 Piping 150,000 Electrical and instrumentation 150,000 SUBTOTAL CONSTRUCTION COST $2,030,000 Escalation to Construction Year 1979 200,000 Technical Services 200,000 Legal & Fiscal 5,000 Administrative 5,000 Project Contingencies 200,000 TOTAL CAPITAL COST $2,640,000 aWet weather Maintenance Level B '. 6-43 Table 6-18 COMPARISON OF DEPARTMENT OF FINANCE SERIES D-IOO POPULATION PROJECTIONS AND PROPOSED DESIGN CAPACITY PROJECTIONS FOR SOUTH MARIN For Design Year 1988 DOF Design Grant Series D-IOO Capacity Elig ibili ty Service Area Projections Projections Factor Richard son Bay SD 10,427 9,900 1. 00 Mill Valley 19,401 21,000 0.95 Sausalito-Tam. Valley 15,980 18,250 0.91 Tiburon 6,645 8,750 0.82 2 Combined outfal1 36,473 39,650 0.94 Totals 88,926 97,550 O 7 7 IFormula a • /bO. =c a = D-IOO population projection b = local agency population projection c = grant eligibility factor 2Mill Valley, Tiburon, and Richardson Bay. '. 6-44 , -;-"'+--'";-.;M:-,it\i;~,;fV;;"",;h';;'!'\li!fJ,*"h Table 6-19 SUMMARY OF LOCAL FUNDING NEEDS FOR SOUTHERN MARIN a WASTEWATER MANAGEMENT PROGRAM Grant Total Elig ib\,e Grant Local C Project Cost Amount Amount Cost Sausalito-Marin City SD Treatment plant $ 3,300,000 $ 3,000,000 $ 2,625,000 $ 675,000 Main and Locust pump station 100,000 91,000 80,000 20,000 Sanitary District No. 5 2,640,000 2,164,000 1,894,000 746,000 Mill Valley Treatment plant 7,380,000 7,011,000 6,135,000 1,245,000 Equalization storage 150,000 143,000 125,000 25,000 '" ..,. I Richardson Bay Sanitary District 1JI Trestle Glen treatment plant 500,000 500,000 438,000 62,000 " Salt Works pump station 120,000 120,000 105,000 15,000 Ricardo Road pump station 90,000 90,000 79,000 11,000 i:\ Force main-Ricardo Rd. to Mill Valley 385,000 385,000 337,000 48,000 Force main ex{:ension Salt Works to Ricardo Road 185,000 185,000 162,000 23,000 Force main and outfall-Mill Valley to Tiburon 4,126,000 3,892,000 3,405,000 721,000 Total $18,976,000 $17,581,000 $15,385,000 $3,591,000 ~ENR 3800 mid-1979 dollars, the construction mid-point Based upon grant eligibility factors developed in Table 6-12 c87•5% of grant eligible costs IMPLEMENTATION SCHEDULE The present studies, together with the separate Environmental Impact Report/Statement, as well as Financing/Administration Study, constitutes the required facilities planning, Step 1, pursuant to the state and federal grant regulations. Implementation of the proposed project will be carried forward in accordance with a time schedule to be modified, approved, and included in the revised NPDES Permit for waste discharge. A list of suggested implementation steps for preliminary planning purposes is set forth in Table 6-20. In connection with the implementation steps shown in Table 6-20, it should be noted that numerous institutional agreements and approvals, in addition to those related to the two major participating agencies, will be required. These approvals begin with the San Francisco Bay Conservation and Development Commission (BCDC), and U. S. Corps of Engineers, as well as Regional Water Quality Control Board, Association of Bay Area Governments (ABAG), State Lands Commission, and numerous other agencies, whose approval of various elements of the project must be obtained. INSTITUTIONAL MEANS OF CONSTRUCTING AND OPERATING PROPOSED PROJECT The recommended institution arrangements in South Marin are discussed in the attached Financing Plan. OPERATION AND MAINTENANCE PROGRAM The financing plan following this chapter has recommended that a Joint Powers Authority (JPA) construct, operate, and administer the regional sewerage project. The utilization of a JPA could allow for more efficient operation of the four treatment facilities. One function of the JPA could be a jointly owned wastewater testing laboratory. Presently each of the four agencies operating treatment facilities contract with private laboratories to perform many of their required tests. Each agency currently performs simpler tests such as settleable matter, turbidity, plant and dissolved oxygen, while only Mill Valley and Sanitary District No. 5 perform BOD tests. Based on the current types and numbers of tests. required of the I four agencies and average testing costs for private labs, an estimate of private lab costs are presented in Table 6-21. In addition, costs incurred by the agencies for sample collection, transporting I I and reporting are estimated at $50,000 per year, for a total private lab estimate of $100,000. I I I I 6-46 j I I t I Table 6-20 SUGGESTED IMPLEMENTATION STEPS FOR PROPOSED SOUTHERN MARIN PROJECT I I Step Work To Be Done 1 Receive revised NPDES Permit. 2 Complete and submit for SWRCB approval, Project Report, including EIR/EIS, together with Step 2 grant application. 3 Receive SWRCB Step 2 grant offer and approval 4 Complete institutional arrangements necessary to implement project. 5 Authorize commencement of final engineering Step 2 contract. 6 Submit all necessary construction permit applications to local, state and federal agencies. 7 Complete financing arrangement for project, including any necessary bond issues 8 Complete work of Step 2, final engineering, submit to SWRCB for final approval. 9 Receive SWRCB approval, authorize advertise ment for project construction bids. 10 Receive all necessary local, state and federal construction permits. 11 Receive construction bids, commence construction. 12 Complete project construction. 13 Meet all NPDES Permit requirements. • I I 6-47 Annual cost estimates for a jointly owned lab are also presented in Table 6-21. Based on one full-time and 2 part-time employees who would also pick up the samples and use a computerized reporting system, the jointly owned lab is estimated to cost $67,900 or two thirds of using the private labs. Therefore, the jOintly owned lab appears to be cost effective and should be included as part of the apparent best alternative project. The lab would likely be centrally located in either the Strawberry Shopping center or Shelter Bay areas. Estimated Operation and Maintenance Costs Estimated annual operation and maintenance costs for the four treatment facilities and the outfall from Mill Valley to Raccoon Straits are shown in Table 6-22. Staffing Requirements Based on analysis of the federal Environmental Protection Agency Manual, "Estimating Staffing for Municipal Wastewater Treatment Facilities," staffing requirements for the various facilities have been estimated. If the joint lab concept is fully utilized, these staffing estimates may be adjusted downward. Sausalito-Marin City - Treatment facilities are estimated to require 6,500 hours per year or 4.4 persons based on 1,500 hours per person per year. The 4.4 persons are in addition to those assigned to maintenance and operation of the Districts trunk sewers and lift stations. It appears that the existing five District employees could be supplemented by one additional staff member with maintenance capabili ties. The Clean Water Grant Regulations will require the plant superintendent to hold a Class III State Certification and all remaining plant operators to hold at least a Class I. City of Mill Valley - Treatment plant expansion requires approximately 9,000 hours per year for operation, maintenance, laboratory, and supervision. Based on 1,500 hours per person per year, 6 operators would be required to operate the plant. Therefore, it would be necessary to add one additional operator when the new facilities are put into operation. Recommended staffing patterns would have the plant attended 16 hours per day during weekdays and 8 hours a day during weekends. " The Clean Water Grant Regulations classify the existing plant and the proposed expanded plant as a Class III facility and, therefore, the plant superintendent must hold a Grade III certificate and all other operators at least a Grade I, Richardson Bay District - Trestle Glen plant would be upgraded Sanitar~ while remaining essentlally the same size. Therefore, it is estimated that the existing staff size will be adequate for the proposed project. The plant is currently attended 8 hours per day 7 days a week. 6-48 Table 6-21 ANNUAL COST SUMMARY SOUTHERN MARIN JOINT LABORATORY FACILITY Jointly Private Owned Laboratory Laboratory Collecting, transporting and reporting - $ 50,000 by local agencies Annual testing costs 50,000 Total Annual Cost $100,000 Wages and benefits: 1 lab technician $ 15,000 2 part-time assistants 10,000 Employee benefits 6,000 Office expenses & supplies, computer 9,800 Building rent and maintenance 8,000 Lab equipment annual cost - 7%-10 yrs. 5,100 Automotive & reserve 8,000 Lab supplies 6,000 Total Annual Cost $ 67,900 '. 6-49 Table 6-22 SUMMARY OF ESTIMATED OPERATION AND MAINTENANCE COSTS FOR THE a PROPOSED SOUTH MARIN WASTEWATER MANAGEMENT PROGRAM FOR 1978/88 Sanitary District No.5 - Treatment facilities are currently operated by a staff of five persons including a Grade IV superintendent. These personnel also maintain the collection system and its 21 pump stations. The 1976-77 budget estimates that the treatment plant operation and maintenance accounts for 65 percent of the total staff time, or about 3.25 persons. The plant is currently attended 14 hours per day during weekdays and 8 hours per day on weekends. Based on an analysis of the federal Environmental Protection Agency Manual, "Estimating Staffing for Municipal Wastewater Treatment Facilities," the proposed treatment additions would require approximately 6,500 hours per year for operation, maintenance, laboratory, and supervision. Based on 1,500 hours per person per year, 4.4 people would be necessary to operate the plant. Therefore, it would be necessary to add one additional operator when the new facilities are put into operation. The existing shift schedule will be adequate for the new facilities. The new facilities will be classified as activated sludge 5 mgd or less and will require the plant superintendent to hold a Class III State Certification and the remaining operators a Class I • • 6-51