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HomeMy WebLinkAboutMinutes - September 19, 2000 SSCITY OF LODI INFORMAL INFORMATIONAL MEETING "SHIRTSLEEVE" SESSION CARNEGIE FORUM, 305 WEST PINE STREET TUESDAY, SEPTEMBER 19, 2000 An Informal Informational Meeting ("Shirtsleeve" Session) of the Lodi City Council was held Tuesday, September 19, 2000 commencing at 7:05 a.m. A. ROLL CALL Present: Council Members — Hitchcock, Land, Nakanishi, and Pennino Absent: Council Members — Mayor Mann Also Present: City Manager Flynn, Deputy City Attorney Schwauber and City Clerk Blackston B. CITY COUNCIL CALENDAR UPDATE City Clerk Blackston reviewed the Mayor's and Council Member's Weekly Calendar (filed). C. TOPIC(S): "Wastewater Treatment Plant Master Plan" Public Works Director Prima recalled that a number of months ago staff advised Council the State had issued a revised permit that would significantly change how wastewater at the White Slough Water Pollution Control Facility would be managed. In response, a public advisory committee was formed. Mr. Prima reported that the plant is now 30 years old and improvements are needed. The new permit requires the City to go to tertiary treatment, which is an advanced form of filtration and a higher level of disinfection. Currently, secondary treatment is provided at the facility and surface discharge is done at Dreger Cut. Mr. Prima briefly reviewed possible alternatives. Bruce West, Project Manager with West Yost & Associates, explained that they only recently received information from the Regional Board about discharge requirements and other water studies which have impacted completion of their work. Mr. West submitted copies of the Wastewater Master Plan and overheads (filed). By the end of the 20 -year Master Plan (estimating a 1.5 percent growth rate) the population of Lodi will approach 80,000 and flows at the wastewater plant would be 8.5 million gallons per day (mgd). Mr. West reported that minimal growth is anticipated for industrial dischargers. The types of improvements to accommodate these flows would be relatively minor compared to the municipal improvements that are required at the plant and for disposal. He added that the major industrial dischargers are doing water conservation work. Council Member Hitchcock questioned the population estimate of 1.5 percent, noting that the City's average over a 30 -year period was determined to be 2 percent. Mr. Prima replied that if population increased 2 percent during the next twenty years, capacity at the plant would be reached in 2015 rather than 2020. Mr. West commented that in his experience with a recent $60 million project, connection fees were a significant part of financing. He explained that if growth occurs faster than anticipated, there will be more connection fee money to do the next expansion; and if growth is slower, it will delay the need for expansion. Mr. West stated that the current discharge location is at Dreger Cut, which extends from the edge of the City property out into the Delta and terminates at Bishop Cut. He reported that Bishop Cut has higher flows and better dilution. Rather than discharging into the Delta, Mr. West described an alternative of applying all or part of the wastewater Continued September 19, 2000 to land and percolating it into the ground. He noted that the land east of 1-5 has higher permeable soils. Rob Beggs, Project Engineer with West Yost & Associates, reported that with the new permit requirements, the City will not be able to discharge into Dreger Cut when the dissolved oxygen level drops below 5 milligrams per liter. He explained that this sometimes occurs independently of whether or not the City is discharging there. Data indicates that Bishop Cut maintains much higher levels of dissolved oxygen. Temperature change is also addressed in the new permit requirements. Discharging into Dreger Cut during the winter would increase the temperature more than the limit. Calfed is proposing to open some Delta channels to let more water flow from north to south through the Delta. If this is done, it will reduce some of the net flows through Bishop Cut. Mr. Beggs reviewed the subjective evaluation criteria, which was established with input from the public committee. He explained that benefits from the constructive wetlands option include storage, the reduction of temperature and nitrates, and the removal of heavy metals and trace toxic constituents. Mr. Beggs outlined improvements that need to be made. He explained that wastewater comes into the headworks at the treatment plant. There is need for improvement in the headworks, pumping, screening, and odor control. By the year 2020 the headworks will need to be replaced. Minor improvements in the septage handling facilities are also recommended. Currently, there are four basins for secondary treatment. Two additional basins are recommended in order to continue nitrifying, which is an implicit condition of the new permit. Clarified effluent now goes to chlorine contact tanks. It is recommended for safety reasons, that gaseous chlorine be changed to liquid chlorine. A third clarifier is recommended both for capacity and redundancy. Filters are required in the new permit requirements if discharge to Dreger Cut is continued. Secondary solids are thickened in dissolved air flotation thickeners. Currently, there is only one thickener, and two are being recommended for redundancy and capacity. A new digester is needed for digesting the solids. Converting one of the old aeration basins to a digested sludge storage basin is recommended. New odor collection, ducting, fans, and biofilter foul air treatment is needed. In response to Mayor Pro Tempore Nakanishi, Mr. Beggs explained that if the City goes to tertiary treatment, the water can be discharged into the river except when the dissolved oxygen level is too low. If discharge to land is done, tertiary treatment will probably not be required. The current permit requires tertiary treatment by 2004 if discharge to Dreger Cut is continued. For discharge to any other location, a new permit will be required. Mr. Prima added that tertiary treatment would likely be required for discharge to Bishop Cut as well. Mr. Beggs stated that Lodi has more zinc in its effluent than most other municipalities. The source has not been identified. He expressed confidence that the zinc requirement (limit of 100 micrograms per liter) could be met by tertiary treatment, or by use of wetlands which would remove it. To provide additional capacity to handle the peak flows at 8.5 mgd, improvements are needed to the following: domestic pumps, industrial pumping site, thickening for the waste activated sludge, sludge lagoon capacity, and a new anaerobic digester. Mr. Beggs explained that one of the most significant changes in the new regulations is in nitrification (converting ammonia to nitrate). Nitrates now must be removed, which will cut capacity from 8.5 mgd to approximately 6.5 mgd. Mr. Beggs reviewed the alternatives for effluent discharge, reuse and storage. He noted that complete land discharge is an attractive alternative from a regulatory perspective. Currently, there are about 790 net available acres. For alternatives that involve winter percolation and discharge to the Delta, 260 additional acres are needed. For complete land discharge, an additional 400 acres of sandy land is needed. The City currently has sufficient land for industrial wastewater, bio solids, and some municipal wastewater. Additional land is needed for municipal effluent, especially if wetlands and percolation basins are desired. OJ Continued September 19, 2000 In summary, Mr. Beggs reported that the three preferred alternatives and associated costs are: 1) Bishop Cut discharge with wetlands, which includes tertiary treatment — $33.8 million; 2) Bishop Cut partial discharge with wetlands, which does not include tertiary treatment — $30.7 million; and, 3) land discharge — $33.9 million. Mr. West explained that one of the assumptions related to land disposal deals with winter percolation rates and how much wastewater can be applied per acre. He recommended pilot testing of significant areas to test the rates of winter percolation. He also suggested submitting an application to the Regional Board to determine what the discharge permits would be for surface waters. Mr. West explained that regional permits come up for review every five years. He stated that today's presentation is the first of several public participation processes. Final recommendations will be determined at a later date. Mr. Prima reported that the issue of pilot testing would be brought back to Council for consideration. Council Member Pennino suggested that consideration also be given to economic development goals, as well as impacts of industrial and residential conservation. Mayor Pro Tempore Nakanishi requested a summary explaining why water cannot be discharged into the river after tertiary treatment and removal of chemicals. PUBLIC COMMENTS a) Wilbert Ruhl spoke in support of land discharge. He warned that regulations may soon prohibit discharging into the Delta. He urged the Council not to allow a sports complex to take up land that should be used for water disposal. D. COMMENTS BY THE PUBLIC ON NON -AGENDA ITEMS None. E. ADJOURNMENT No action was taken by the City Council. The meeting was adjourned at 8:20 a.m. ATTEST: Susan J. Blackston City Clerk OF <O O �P 4�COUNCIL COMMUNICATION JFORa AGENDA TITLE: Wastewater Treatment Plant Master Plan MEETING DATE: September 19, 2000 (Shirtsleeve Session) PREPARED BY: Public Works Director RECOMMENDED ACTION: None needed; direction on public participation and future Council discussions will be requested. BACKGROUND INFORMATION: City staff, our consultants - West Yost, and a public advisory committee have been working on a long range plan for meeting wastewater treatment requirements. We have looked beyond our current permit and attempted to assess long-term strategies. We have reached the point where public involvement is appropriate as we continue to evaluate options. We have two fundamentally different options — one is to provide advanced treatment through various sub -options and continue to discharge to the Delta at our present location — Dredger Cut — or at a new location — Bishop Cut. The second is to acquire additional land for percolation and total land discharge. These options are summarized on the attached chart. At the shirtsleeve session, staff and our consultants will review the options in more detail and respond to questions and comments. Following this, and additional public input, we will narrow the options and make a recommendation. Note that estimated costs are shown, and while they vary by a few million dollars, when considered on an annual basis, the difference is relatively small. Also, we are not prepared to discuss financing and rate impacts at this time. The possibility of obtaining grants and the potential impacts of the Pro -Style Sports Facility and the CalPine power plant could greatly reduce the cost. FUNDING: Wastewater Fund - none needed at this ti Richard C. Prima, Jr. Public Works Director RCP/lm Attachment cc: Fran Forkas, Water/Wastewater Superintendent Del Kerlin, Assistant Wastewater Treatment Superintendent West Yost Associates Advisory Panel APPROVED: H. Dixon Flynn -- City Manager Ss 09/13/00 City of Lodi - Wastewater Treatment Master Plan Summary of Major Alternatives t City of Lodi - Wastewater Treatment Master Plan Summary of Major Alternatives 1. Score is based on various criteria as described in the draft Master Plan. Cost is not a factor in the scoring. 2. Annualized cost is total of annual O&M plus 10% of capital cost based on assumed financing. 3. Tertiary treatment is additional filtration and disinfection. Treated water is then usable for food crop irrigation. 4. Secondary treatment is what is done currently. Treated water for irrigation is limited to use on animal feed crops. Altematives5ummary Cost of Alternatives Cost of Facility Alternative Description Major Components Additional Land Comments (All costs in million $) Improvement (all alts) Score Total Annualized s Capital Annual Capital Annual O&M O&M Cost 1. DC -D Discharge to Dredger Cut • Tertiary Treatment 3 • Project based on • 500 of Additional current permit 17.28 0.61 16.52 0.58 26 4.57 Storage (800 of total, 1 • No dilution in month storage) Dredger Cut • Source Control • May be unable to meet future requirements. 2. DC -W Discharge to Dredger Cut with . Tertiary Treatment . 130 ac west of . No dilution in wetlands for polishing . Wetlands W.S. Facility @ Dredger Cut 18.78 0.64 16.52 0.58 30.5 4.75 treatment and storage . 250 of Additional Bishop Cut Storage 3. BC -D Discharge to Bishop Cut • Outfall Pipeline (approx. • Easements for • Better dilution in through on outfall pipeline 1.3 miles) pipe Bishop Cut 16.66 0.59 16.52 0.58 32.5 4.49 Tertiary Treatment 3 • Source Control 4. BC -W Discharge to Bishop Cut . Outfall Wetlands • 100 ac west of . Better dilution in through an outfall wetlands . Tertiary Treatment 3 W.S. Facility @ Bishop Cut 17.18 0.62 16.52 0.58 37.5 4.57 Bishop Cut 5. BC -PD Partial discharge to Bishop Cut a Outfall Pipeline (approx. . 260 ac east of • Secondary through an outfall pipeline, 1.3 miles) Thornton Road Treatment 4 14.79 0.37 16.52 0.58 34.5 4.08 partial percolation disposal . Source Control • Easements for • Some crop potential • Denitrification pipe in percolation basins • Percolation Basins/Fields 6. BC -PW Partial discharge to Bishop Cut . Outfall Wetlands • 260 ac east of • Secondary through an ouffall pipeline, . Denitrification Thornton Road Treatment 4 14.24 0.34 16.52 0.58 37.5 4.00 partial percolation disposal . Percolation • 60 ac west of • Some crop potential Basins/Fields W.S. Facility @ in percolation basins Bishop Cut 7. LD Land discharge - complete . Percolation . 400 ac east of . Secondary effluent disposal through Basins/Fields Thornton Road Treatment ° 17.40 0.28 16.52 0.58 36.5 4.25 percolation and agricultural . Denitrification . Some crop potential irrigation reuse I I I in percolation basins 1. Score is based on various criteria as described in the draft Master Plan. Cost is not a factor in the scoring. 2. Annualized cost is total of annual O&M plus 10% of capital cost based on assumed financing. 3. Tertiary treatment is additional filtration and disinfection. Treated water is then usable for food crop irrigation. 4. Secondary treatment is what is done currently. Treated water for irrigation is limited to use on animal feed crops. Altematives5ummary CITY COUNCIL STEPHEN J. MANN, Mayor ALAN S. NAKANISHI Mayor Pro Tempore SUSAN HITCHCOCK KEITH LAND PHILLIP A. PENNINO CITY OF LODI PUBLIC WORKS DEPARTMENT CITY HALL, 221 WEST PINE STREET P.O. BOX 3006 LODI, CALIFORNIA 95241-1910 (209)333-6706 FAX (209) 333-6710 EMAIL pwdept@lodi.gov http:%kwww.lodi.gov September 15, 2000 Robert A. Beggs, P.E. Advisory Panel West Yost & Associates 1260 Lake Blvd., Ste. 240 Davis, CA 95616 SUBJECT: Wastewater Treatment Plant Master Plan H. DIXON FLYNN City Manager SUSAN J. BLACKSTON City Clerk RANDALL A. HAYS City Attorney RICHARD C. PRIMA, JR. Public Works Director We will be discussing the Wastewater Treatment Master Plan at the City Council's next informal Shirtsleeve Session. This meeting will be held Tuesday, September 19, 2000, at 7 a.m. in the City Council Chamber, Carnegie Forum, 305 West Pine Street. I hope you will be able to attend. We have included all of the options discussed to date (see enclosure), and, at this point, are not requesting the Council decide on an option. If you have any questions, please call me at (209) 333-6759. Sincerely, CY,G.1 U � \tlY1G�. Richard C. Prima, Jr. ANS' Public Works Director RCP/Im Enclosure / cc: City Clerk f NSS BOB ANDOSCA WADE BROUGHTON EXECUTIVE DIRECTOR SR ENVIRONMENTAL ENGINEER LIZ CAREY LODI CHAMBER OF COMMERCE GENERAL MILLS OPS INC P O BOX 2162 35 S SCHOOL ST P O BOX 3002 LODI CA 95241 LODI CA 95240 LODI CA 95241-1906 BILL FERRERO FIELD MANAGER CENTRAL VALLEY WASTE SRVCS 1333 E TURNER RD LODI CA 95240 JAMES L SCHWEICKARDT 2335 WOODLAKE CR LODI CA 95242 RICH FREITAS PLANT MGR PACIFIC COAST PRODUCERS P0BOX 880 LODI CA 95241-0880 LIZ CAkET Y c/o A+ SALON 325 W CKEFORD ST LODI 95241 KENN LA B DIRECTO -MANUFACTURING HOLZ RU 3BER COMPANY IN 1129 S SACRAMENT ST LODI CA 95240 MICHAE B DNER DIR OF JECT DEVELOPMENT ACRT- ST 730 BE KMAN RD STE A LODI CA 95240 JEAN THOMPSON 1311 CENTURY BLVD #50 LODI CA 95242 B ANL EX UTCTOR LODI CF COMMERCE 35 S SCLODI CA BILLJMA ZERO FIELAGE CENEY WASTE1333NER RDLOD5240 JAMES LPCHWEICKARDT 2335 WO DLAKE CR LODI CA 95242 RICH FR ITAS PLANT MGR PACIFIC OAST PRODUCERS 32 E TO AY ST LODI C 95240 KENN LAMB DIRECTOR -MANUFACTURING HOLZ RUBBER COMPANY INC 1129 S SACRAMENTO ST LODI CA 95240 MICHAEL B WEIDNER DIR OF PROJECT DEVELOPMENT ACRT-WEST P O BOX 1540 LODI CA 95241 WADE BR HTON SR E ONMENTAL ENGINEER ERAL MILLS OPS INC 2000 W TURNER RD LODI CA 95242 JEAN T4 OMPSON 1311 CE URY BLVD #50 LODI CA 9 42 -= �•l OF yr` ♦♦•• ya 0 • w w OINMP%7mod Ire w City of Lodi Wastewater Master Plan Imeas I I -or- ------ ---- r -------------- Wetlands $79 ------------------------- i or or -- --------- so C S""g, Control $Z4 M ......................... or - ---------------------------- Wetlands S&O M .......................... — or — -------------------------- pilsellno i $2.0 M i --------- ------- ------- 10.0 9.0 &0 7.0 &0 5.0. 3.0 2.0 1.0 0.0 Population and Wastewater Flow September 19, 2000 120,000 IN= 100,000 mow 50,000 70,000 6D.000 50.000 40.000 .30.000 .000 MOOD 0 1975 Iwo IM 1990 loss 2000 2005 2010 2015 2020 Y.Or West Yost & Associates 1 .............. Flow —4—HWtd..d Fl— ....... PrajdOddFlow - 2% G—th _PM1.06d Fl- -1.5% OMMh PI.Idd R- - 1% G.." Population F.Jeded PONWI. - 2% GMMh P Mi-d-P-PI"Ift - 1.5%G mroMh P lMod pw,. i. - 1% GMth PopLiation September 19, 2000 120,000 IN= 100,000 mow 50,000 70,000 6D.000 50.000 40.000 .30.000 .000 MOOD 0 1975 Iwo IM 1990 loss 2000 2005 2010 2015 2020 Y.Or West Yost & Associates 1 City of Lodi Wastewater Master Plan 1997-1999 and Projected Industrial Wastewater Flows ,50 September 19, 2000 Jen Feb Mkt AP, Mey Jun JW IW0 Se Da N. Dec MaM Discharge & Reuse Locations West Yost & Associates 2 City of Lodi Wastewater Master Plan Dredger Location West Yost & Associates Outfall Potential New Outfall Location in Bishop Cut September 19, 2000 City of Lodi Wastewater Master Plan Requirements Comparison ► Discharge Requirements Significantly More Difficult to Meet in Dredger Cut than Bishop Cut r t ler t per • Dissolved oxygen ,�P • Temperature - • Trace toxins - 17: uTTit•7i7 , Surface Discharge Alternatives September 19, 2000 ► Continuing to Discharge into Dredger Cut • Poor dilution • Discharge requirements difficult to meet ► Outfall to Bishop Cut • Improved dilution (still limited) • Easier to meet Waste Discharge Requirements West Yost & Associates 4 City of Lodi Wastewater Master Plan 25 20 1 15 Bishop Cut Dilution Mud. --7— EAsting —.—CalFed 2P -A r - CaIFad 28 • --A- CalFed 2P$3 Oct Nov Deo Jan Feb Mar Apr May Jun Jul Aug Sep Month September 19, 2000 West Yost & Associates 5 City of Lodi Wastewater Master Plan Wetlands Performance Characteristics ► Reduces Temperature ► Reduces Nitrates ► Reduces Toxicity ► Provides Storage September 19, 2000 West Yost & Associates 6 s f,� soc ( s Rj Rxw 1t•� w W: f West Yost & Associates 6 City of Lodi Wastewater Master Plan September 19, 2000 Treatment Plant Design and Operational Criteria ► Treatment Requirements ► Treatment Redundancy ► Staff and Public Safety ► Americans with Disabilities Act ► 100 -Year Flood Protection ► Power Backup and Control Redundancy ► Staffing Levels ► Operational Flexibility ► Control and Automation West Yost & Associates 7 S 804810096V V 490A ISOM a6aay3sia push :Q-1 , ino doysi8 of 961apsip puosees spugjeM :Md -Dg . ino doysi8 of e6mpsip soe}ins leuosees ioana :ad -09 . a6jay3sia aoapns Isuosaas ino doysi8 of e6jeyosip puelieM :M -O8 • ino doysi8 of 96jeyosip eoepns loam :Q -o8 . ino ja6paja of ebjeyosip puejlaM :M -Oa • ino ia6pajQ of a6aeyosip eoelans pejid :❑-0Q . 96aauosia eoa}ing punob-aeeA , aGe io;g T esnea loBjeyosla ;uenl jj3 JOI SOAl4euaa41d sepal spi ul pepnlou! IOU sen11ewe41e lenp!nlpu! 4i!M pale!oosse slsoo jue!d auatulml SeApaujo;fid ssa*oad SIV o; uowwoD s;uetusAoidLul OOOZ `64 aagwazdes ue1d aa}seyy J918MOISOM 1po-i ;o A110 City of Lodi Wastewater Master Pian September 19, 2000 Summaries & Conclusions ► City Has Sufficient Land for Industrial Wastewater and Biosolids ► More Land Needed for Municipal Effluent, Especially if Wetlands and Percolation Basins Are Desired ► Land Discharge Would Require Approximately 400 Net Additional Acres of Sandy Land ► Additional Nitrogen Removal Recommended with Percolation Basins ► Groundwater Level Control Measures May Be Needed for Winter Percolation Disposal West Yost & Associates 9 City of Lodi Wastewater Master Plan September 19, 2000 Costs for Major Alternatives * Includes tertiary filtration and disinfection I cost of additional treatment plant improvements not included which are common to all alternatives: $16A million West Yost & Associates 10 City of Lodi Wastewater Master Plan September 19, 2000 Comparison of Major Alternatives w.ph.dB.bi..dwFAnWo 22.0 2a0 2&0 2&0 30.0 32.0 34.0 38.0 38.0 40.0 42.0 10.0 12.0 14.0 18.0 S 18.0 c 20.0 .2 22.0 24.0 28.0 28.0 30.0 West Yost & Associates 11 + DC -D ♦ DC -W Mm DeBirahla i BC -0 ♦ BC -W X BC -PD X BC -PW • LD X ■ Preferred All-11— Less Desirebk West Yost & Associates 11 City of Lodi Wastewater Master Plan September 19, 2000 Recommendations ► Perform Pilot Testing of Winter Percolation Disposal ► Submit Application to Regional Water Quality Control Board for New Discharge Permit for Both Discharge to Bishop Cut and Winter Percolation ► Begin Discussions about Purchasing or Otherwise Obtaining Operating Control of Land Needed for Alternative Implementation ► Begin Public Participation Process West Yost & Associates 12 TABLE OF CONTENTS SECTION 1. EXECUTIVE SUMMARY................................................................................1-1 SECTION 2. INTRODUCTION.............................................................................................. 2-1 SECTION 3. FLOW AND LOADING PROJECTIONS....................................................... 3-1 POPULATIONPROJECTIONS................................................................................................. 3-1 LANDUSE.................................................................................................................................. 3-1 DOMESTIC WASTEWATER FLOW PROJECTIONS............................................................. 3-2 AverageFlow........................................................................................................................... 3-2 Wastewater Flow Peaking Factors........................................................................................... 3-3 Analysis of Inflow/Infiltration................................................................................................. 3-8 ProjectedFlows........................................................................................................................ 3-8 DOMESTIC WASTEWATER QUALITY AND LOADING PROJECTIONS ......................... 3-9 Concentrations of Major Constituents..................................................................................... 3-9 Loading Rates for Major Constituents..................................................................................... 3-9 INDUSTRIAL WASTEWATER FLOW AND LOADING PROJECTIONS .......................... 3-14 REFERENCE............................................................................................................................. 3-17 SECTION 4. ANTICIPATED DISCHARGE REQUIREMENTS AND ISSUES...............4-1 INTRODUCTION....................................................................................................................... 4-1 BACKGROUND......................................................................................................................... 4-1 Current Processes and Operations...........................................................................................4-1 ReceivingWaters.....................................................................................................................4-1 Current Discharge Requirements for Municipal Wastewater .................................................. 4-1 Reclamation Requirements...................................................................................................... 4-4 Solids Disposal/Reuse Discharge Requirements..................................................................... 4-4 Industrial Wastewater Discharge Requirements...................................................................... 4-5 Receiving Waters Modeling...................................................................................................4-5 POTENTIAL CHANGES TO DISCHARGE LOCATION AND BENEFICIAL USES ........... 4-5 Dischargeto Bishop Cut.......................................................................................................... 4-5 SportsComplex........................................................................................................................4-6 FUTURE DISCHARGE REQUIREMENTS.............................................................................. 4-6 General..................................................................................................................................... 4-6 Municipal Effluent Discharge to Dredger Cut......................................................................... 4-6 Municipal Effluent Discharge to Bishop Cut........................................................................... 4-9 Municipal Effluent Reuse—Unrestricted Irrigation................................................................ 4-9 Municipal Effluent Reuse—Animal Feed Crops..................................................................... 4-9 Industrial Effluent Irrigation Reuse....................................................................................... 4-11 Biosolids Disposal/Reuse....................................................................................................... 4-11 SUMMARY AND CONCLUSIONS........................................................................................ 4-12 REFERENCES..........................................................................................................................4-13 9/18/00 Draft i Wastewater Master Plan 213\wwmp SECTION 5. ALTERNATIVES FOR SATISFYING DISCHARGE REQUIREMENTS. 5-1 INTRODUCTION....................................................................................................................... 5-1 ALTERNATIVES FOR SATISFYING MUNICIPAL EFFLUENT DISCHARGE REQUIREMENTS....................................................................................................................... 5-1 Surface Discharge Alternatives................................................................................................ 5-1 WPCF Treatment Process Alternatives................................................................................... 5-3 Land Treatment and Reuse Alternatives................................................................................... 5-5 SourceControl......................................................................................................................... 5-5 Combinations of Alternatives to Satisfy Requirements........................................................... 5-6 SATISFYING OTHER DISCHARGE REQUIREMENTS........................................................ 5-7 Municipal Effluent – Animal Feed Crop Irrigation................................................................. 5-7 Municipal Effluent – Unrestricted Irrigation........................................................................... 5-7 Industrial Wastewater Discharge to Land................................................................................ 5-8 BiosolidsDisposal/Reuse......................................................................................................... 5-8 SECTION 6. EVALUATION CRITERIA.............................................................................. 6-1 ECONOMIC CRITERIA—COST............................................................................................... 6-1 SUBJECTIVECRITERIA........................................................................................................... 6-1 General..................................................................................................................................... 6-1 Compliance with Potential Future Discharge Standards......................................................... 6-1 Reliability................................................................................................................................. 6-1 Flexibility................................................................................................................................. 6-1 Ease of Operation and Maintenance........................................................................................ 6-2 Easeof Implementation .................... ....................................................................................... 6-2 Environmental Impacts or Benefits......................................................................................... 6-2 Safety....................................................................................................................................... 6-2 Potential Recreational/Open Space Benefits........................................................................... 6-2 Aesthetics................................................................................................................................. 6-2 Secondary Economic Benefits................................................................................................. 6-3 Resource Management Considerations.................................................................................... 6-3 RELATIVE WEIGHTINGS OF CRITERIA.............................................................................. 6-3 SECTION 7. WETLANDS TREATMENT............................................................................. 7-1 INTRODUCTION....................................................................................................................... 7-1 BACKGROUND......................................................................................................................... 7-1 AREA REQUIREMENTS FOR WETLANDS........................................................................... 7-1 WETLANDS PERFORMANCE CHARACTERISTICS............................................................ 7-1 WaterUse................................................................................................................................. 7-1 StorageCapacity...................................................................................................................... 7-3 TemperatureReduction............................................................................................................ 7-3 NitrateRemoval....................................................................................................................... 7-3 MetalsRemoval....................................................................................................................... 7-3 BOD and Suspended Solids Polishing..................................................................................... 7-4 PathogenRemoval................................................................................................................... 7-4 Dechlorination.......................................................................................................................... 7-4 9/18/00 Draft ii Wastewater Master Plan 213\wwmp WETLANDS SITE ALTERNATIVES....................................................................................... 7-4 Useof Existing DWR Wetlands.............................................................................................. 7-4 Constructed Wetlands North/East of the City's Current Irrigation ......................................... 7-5 Constructed Wetlands Immediately West of the Treatment Plant ........................................... 7-5 Outfall Wetlands Constructed South Of Dredger Cut On The Rio Blanco Site ...................... 7-5 COST OF CONSTRUCTED WETLANDS................................................................................ 7-5 Special Wetlands Funding Sources............................................................................:............ 7-7 ENVIRONMENTAL BENEFITS OF WETLANDS.................................................................. 7-7 WETLANDS MANAGEMENT ISSUES................................................................................... 7-7 CONCLUSIONS.......................................................................................................................... 7-7 REFERENCE............................................................................................................................... 7-8 SECTION 8. INDUSTRIAL WASTEWATER TREATMENT AND DISPOSAL/REUSE8-1 INDUSTRIALSOURCES........................................................................................................... 8-1 PACIFIC COAST PRODUCERS WASTEWATER SOURCES AND PRETREATMENT ..... 8-1 EXISTING INDUSTRIAL, WASTEWATER TREATMENT SYSTEM AT WHITE SLOUGH .... 8-3 ACREAGEREQUIRED............................................................................................................. 8-6 BODLoading........................................................................................................................... 8-6 HydraulicLoading................................................................................................................... 8-7 ALTERNATIVE IRRIGATION METHODS............................................................................. 8-7 TREATMENTALTERNATIVES.............................................................................................. 8-8 PRETREATMENT ALTERNATIVES AT PCP......................................................................... 8-8 RotaryDrum Screens............................................................................................................... 8-8 GravityDisk Screens............................................................................................................... 8-8 DissolvedAir Flotation............................................................................................................ 8-9 SUMMARY AND RECOMMENDATIONS................................................................................ -9 SECTION 9. BIOSOLIDS DISPOSAL/REUSE ALTERNATIVES .................................... 9-1 BACKGROUND......................................................................................................................... 9-1 BIOSOLIDSLOADINGS........................................................................................................... 9-1 Recent and Projected Loadings................................................................................................ 9-1 Comparison with Acceptable Loading Rates........................................................................... 9-3 BIOSOLIDS DISPOSAL/REUSE ALTERNATIVES................................................................ 9-3 ExistingSystem............................................................................................... Modified Surface Irrigation............................................................................. TankerInjection............................................................................................... Dewatered Biosolids Application.................................................................... Compost Biosolids to Provide Class A Material ............................................. THERMALTREATMENT................................................................................. SUMMARY..... REFERENCES ........................ 9-3 ........................ 9-3 ........................ 9-4 ........................ 9-4 ........................ 9-4 ........................ 9-5 ........................ 9-5 ........................................................................................................................ 9-6 SECTION 10. ALTERNATIVES FOR EFFLUENT LAND TREATMENT, REUSE, AND STORAGE................................................................................................................................10-3 9/18/00 Draft iii Wastewater Master Plan 213\wwmp INTRODUCTION..................................................................................................................... 10-3 OPERATIONALSCENARIOS................................................................................................10-3 STORAGERESERVOIRS........................................................................................................10-3 ................................................ Existing Storage ..................................................................... 10-3 Future Storage Reservoir Locations.......................................................................................10-3 DEDICATED PERCOLATION BASINS OR FIELDS............................................................ 10-3 CROPIRRIGATION.................................................................................................................10-3 Alfalfa....................................................................................................................................10-3 TurfGrass..............................................................................................................................10-3 AnnualCrops.........................................................................................................................10-3 CONSTRUCTEDWETLANDS...............................................................................................10-3 OTHER USES OF RECLAIMED WATER.............................................................................. 10-3 MosquitoFish Ponds............................................................................................................. 10-3 NCPAPower Plant Water......................................................................................................10-3 WATERBALANCES...............................................................................................................10-3 Complete Surface Discharge (Alternatives DC -D, DC -W, BC -D, BC -W) ........................... 10-3 Partial Discharge to Bishop Cut (Alternatives BC -PD, BC-PW)..........................................10-3 Land Discharge (Alternative LD)..........................................................................................10-3 Summary of Areas and Volumes Required for Water Balances............................................10-3 ALTERNATIVECROPS..........................................................................................................10-3 WoodTree Crops...................................................................................................................10-3 GreenchoppedCorn ................................................................................................:.............. 10-3 NITROGEN LOADING TO GROUNDWATER..................................................................... 10-3 CompleteSurface Discharge..................................................................................................10-3 Partial Discharge to Bishop Cut and Land Discharge........................................................... 10-3 GROUNDWATER LEVEL IMPACTS FOR PERCOLATION BASINS ............................... 10-3 SUMMARY AND CONCLUSIONS........................................................................................10-3 REFERENCES..........................................................................................................................10-3 SECTION 11. TREATMENT PLANT UPGRADE AND EXPANSION ALTERNATIVES11-1 INTRODUCTION.....................................................................................................................11-1 Existing Treatment Facilities ........................................... ...................................................... 11-1 FacilityReview Procedures...................................................................................................11-5 RatedCapacity....................................................................................................................... 11-5 DESIGN CRITERIA FOR UPGRADES...................................................................................11-5 General................................................................................................................................... 11-5 TreatmentRequirements........................................................................................................ 11-5 Redundancy............................................................................................................................ 11-8 Staff and Public Safety Criteria............................................................................................. 11-8 Americans With Disabilities Act (ADA)...............................................................................11-8 FloodProtection..................................................................................................................... 11-8 Power and Control Redundancy............................................................................................11-8 OPERATIONALCRITERIA.................................................................................................... 11-9 Staffing................................................................................................................................... 11-9 9/18/00 Draft iv Wastewater Master Plan 213\wwmp OperationalFlexibility........................................................................................................... 11-9 AutomationCriteria...............................................................................................................1l-9 Controland Data Acquisition.............................................................................................. 11-11 PRELIMINARYTREATMENT.............................................................................................11-12 Description of Existing Facilities......................................................................................... 11-12 Deficiencies and Alternative Improvements........................................................................11-13 OdorControl........................................................................................................................11-18 Summary of Recommended Facilities................................................................................. 11-18 PRIMARYTREATMENT...................................................................................................... 11-20 Description of Existing Facilities.........................................................................................11-20 Performance......................................................................................................................... 11-21 Summary of Recommended Facilities................................................................................. 11-22 SECONDARYTREATMENT................................................................................................11-22 Description of Existing Facilities......................................................................................... 11-22 Deficiencies and Alternative Improvements........................................................................ 11-24 Summary of Recommended Facilities ................ ................................................................. 11-29 EFFLUENTDISINFECTION................................................................................................. 11-29 Description of Existing Facilities......................................................................................... 11-30 Deficiencies............................. :............................................................................................ 11-30 General Chlorination Improvements.................................................................................... 11-31 AlternativeImprovements................................................................................................... 11-31 Screening of Disinfection Alternatives................................................................................ 11-35 EQUALIZATION PONDS AND EFFLUENT PUMPING .................................................... 11-41 EqualizationPond................................................................................................................ 11-41 Irrigation and Recirculation Pump Stations ..................... Aerated Lagoon and Skimming Pond.................................................................................. 11-42 Deficiencies and Recommended Improvements.................................................................. 11-42 STORAGEPONDS.................................................................................................................11-44 Description........................................................ ................................................................... 11-44 Deficiencies and Recommended Improvements..................................................... :............ 11-44 SOLIDSTHICKENING.......................................................................................................... 11-44 Description of Existing Facilities......................................................................................... 11-44 SolidsBalance...................................................................................................................... 11-45 Deficiencies and Alternative Improvements........................................................................11-46 Summary of Recommended Facilities................................................................................. 11-48 SOLIDSSTABILIZATION....................................................................................................11-48 Description of Existing Facilities......................................................................................... 11-48 Capacity...............................................................................................................................11-48 Deficiencies and Alternative Improvements........................................................................ 11-49 Summary of Recommended Facilities.................................................................................11-50 DIGESTEDSOLIDS HANDLING.........................................................................................11-50 Description of Existing Facilities......................................................................................... 11-50 Deficiencies and Alternative Improvements........................................................................ 11-51 Evaluation of Sludge Storage Alternatives.......................................................................... 11-51 Alternative Sludge Drying and Storage Methods................................................................ 11-52 9/18/00 Draft v Wastewater Master Plan 2l3\wwmp Biosolids Disposal/Reuse Alternatives................................................................................ 11-54 Summary of Recommended Facilities.................................................................................11-54 ADVANCED NUTRIENT REMOVAL TREATMENT.:...................................................... 11-55 General................................................................................................................................. 11-55 PhosphorusRemoval........................................................................................................... 11-56 NitrogenRemoval................................................................................................................ 11-56 Recommended Facilities Planning.......................................................... .-........................... 11-56 ADVANCED HEAVY METALS REMOVAL TREATMENT.............................................11-58 AdvancedSolids Removal................................................................................................... 11-58 Other Advanced Metals Removal Processes.......................................................................11-58 Recommended Heavy Metals Removal Treatment.............................................................11-58 EFFLUENT FILTRATION..................................................................................................... 11-59 Granular Media Filtration.................................................................................................... 11-60 Synthetic Media (Fuzzy) Filters........................................................................................... 11-60 Membrane Microfiltration..........................................:........................................................ 11-60 Evaluation of Filtration Alternatives and Recommended Alternative ................................. 11-60 PLANT SUPPORT SYSTEMS............................................................................................... 11-61 Administration Space and Personnel Spaces (Washrooms and Lockers) ............................ 11-61 Deficiencies.......................................................................................................................... 11-62 Recommended Improvements............................................................................................. 11-62 ElectricalService.................................................................................................................11-63 FloodProtection............................................................................................... ........... 11-65 SUMMARY OF TREATMENT PLANT IMPROVEMENT RECOMMENDATIONS........ 11-65 REFERENCES.............................................................................................................. ......11-70 SECTION12. ODOR CONTROL.........................................................................................12-1 INTRODUCTION..................................................................................................................... 12-1 OVERVIEW OF ODOR SOURCES.........................................................................................12-1 Influent Sewers/Headworks................................................................................................... 12-1 GritWashing and Storage...................................................................................................... 12-1 Primary Sedimentation Basins...............................................................................................12-1 SeptageDischarge.................................................................................................................. 12-1 Grease Truck Unloading and Scum Sump............................................................................. 12-1 Digesters................................................................................................................................12-2 Digester Gas Combustion...................................................................................................... 12-2 SludgeLagoon No. 2............................................................................................................. 12-2 Dissolved Air Flotation Thickener (DAFT)..........................................................................12-2 LandApplication Sites...........................................................................................................12-2 WASTEWATER ODORANTS................................................................................................. 12-3 PLANT INFLUENT CHARACTERISTICS AND HEADWORKS SITUATION .................. 12-4 CHEMICALADDITION.......................................................................................................... 12-5 Alternatives............................................................................................................................ 12-5 SEPTAGEHANDLING............................................................................................................ 12-7 HEADWORKS AREA FOUL AIR CONTAINMENT ............................................................ 12-7 ................................. InfluentSewers...................................................................................................................... 12-7 9/18/00 Draft vi Wastewater Master Plan 2131wwmp SeptageReceiving.................................................................................................................. 12-8 HeadworksRoom...................................................................................................................12-8 Grit Washing and Grit Storage/Loadout................................................................................ 12-8 Scum/Grease Sump................................................................................................................12-8 FOUL AIR TREATMENT FOR HEADWORKS AREA SOURCES......................................12-9 EVALUATION OF FOUL AIR TREATMENT ALTERNATIVES ........................................ 12-9 SUMMARY OF ODOR CONTROL RECOMMENDATIONS..............................................12-11 SECTION 13. EVALUATION OF COMBINED TREATMENT AND DISPOSAL/REUSE ALTERNATIVES....................................................................................................................13-1 DESCRIPTION OF ALTERNATIVES.................................................................................... 13-1 EVALUATION OF ALTERNATIVES FOR DENITRIFICATION ........................................ 13-1 COSTS OF COMBINED TREATMENT AND DISPOSAL/REUSE ALTERNATIVES ....... 13-2 Costsof Alternatives.............................................................................................................. 13-2 COSTS OF ALTERNATIVES WITH SPORTS COMPLEX ................................................... 13-4 SUBJECTIVE CRITERIA......................................................................................................... 13-5 Compliance with Future Discharge Requirements................................................................ 13-5 Reliability............................................................................................................................... 13-5 Flexibility............................................................................................................................... 13-5 Ease of Operation and Maintenance....................................................................................... 13-5 Easeof Implementation......................................................................................................... 13-7 Environmental Impacts..........................................................................................................13-7 Safety..................................................................................................................................... 13-7 Open Space/Recreational Benefits......................................................................................... 13-7 Aesthetics............................................................................................................................... 13-7 Secondary Economic Benefits................................................................................: .........13-7 Resource Management Considerations.................................................................................. 13-7 COMPARISON OF ALTERNATIVES.................................................................................... 13-7 RECOMMENDATIONS...........................................................................................................13-8 SECTION 14. RECOMMENDED WASTEWATER PROGRAM.....................................14-1 APPENDICES TO BE COMPLETED LIST OF FIGURES Figure 3-1. Population and Wastewater Flow.............................................................................. 3-2 Figure 3-2. Daily Influent Flows................................................................................................. 3-4 Figure 3-3. Wastewater Flow Factors by Month (8/94 — 1/99) ................................................... 3-5 Figure 3-4. Normalized Daily Flows Frequency Distribution..................................................... 3-6 Figure 3-5. Sustained Peak Flow Factors (8/94—1/99)............................................................... 3-7 Figure 3-6. Normalized Daily BOD Loading Frequency Distribution ...................................... 3-10 9/18/00 Draft vii Wastewater Master Plan 2l3\wwmp Figure 3-7. Sustained Peak BOD Loading Factors (8/94 –1 /99) .............................................. 3-11 Figure 3-8. Normalized Daily TSS Loading Frequency Distribution ........................................ 3-12 Figure 3-9. Sustained Peak TSS Loading Factors (8/94 – 1/99) ................................................ 3-13 Figure 3-10. 1997 –1999 and Projected Industrial Wastewater Flows ..................................... 3-16 Figure 4-1. Discharge and Reuse Locations................................................................................ 4-2 Figure 4-2. Delta Circulation Patterns......................................................................................... 4-3 Figure 5-1. Bishop Cut Outfall Pipeline Alternative................................................................... 5-4 Figure 7-1. Constructed Wetlands Schematic.............................................................................. 7-2 Figure 7-2. Wetlands Site Alternatives........................................................................................ 7-6 Figure 8-1. 1997 – 1999 and Projected Industrial Wastewater Flows ......................................... 8-2 Figure 8-2. Existing City -Owned Fields...................................................................................... 8-4 Figure 9-1. Projected Biosolids Nitrogen Loadings.................................................................... 9-2 Figure 10-1. Promising Areas for Percolation Disposal............................................................ 10-3 Figure 10-2. Partial Discharge to Bishop Cut............................................................................ 10 -9 - Figure 10-3. Land Discharge Alternative................................................................................ 10-12 Figure 11-1. Existing Site Plan .................................................................................................. 11-2 Figure 11-2. Existing Treatment Plant Flow Schematic............................................................ 11-3 Figure 11-3. Location of Treatment Plant and Ponds................................................................ 11-4 Figure 11-4. Master Plan Facilities.......................................................................................... 11-19 Figure 11-5. Aeration Basins—Two Parallel Processes Mode ................................................ 11-25 Figure 11-6. Aeration Basins—Three Parallel Processes Mode .............................................. 11-26 Figure 11-7. Location of Treatment Plant and Ponds.............................................................. 11-43 Figure 11-8. Basic Nutrient Removal Flow Schematic........................................................... 11-55 Figure 11-9. Aeration Basins with Nitrogen Removal Facilities ............................................. 11-57 Figure 11-10. Approximate Best Achievable Effluent Heavy Metal Concentrations for Lime and SulfidePrecipitation................................................................................................................. 11-59 Figure 11-11. Recommended Control Building Improvements..............................................11-64 Figure 13-1. Comparison of Major Alternatives........................................................................13-9 Figure 13-2. Alternative BC -PW Conceptual Layout.............................................................. 13-11 LIST OF TABLES Table 3-1. Peak Flow Rates and Peaking Factors........................................................................ 3-3 9/18/00 Draft viii Wastewater Master Plan 2131wwmp Table 3-2. Average Inflows During Storm Events (Averages for 1994 through 1998) .............. 3-8 Table 3-3. Projected Flows, Mgd.........................................................................:....................... 3-8 Table 3-4. Average Influent Concentrations of Major Constituents (1995 through 1998) ......... 3-9 Table 3-5. Projected Average and Sustained Peak Loading Rates in lbs/day .............................. 3-9 Table 3-6. Industries Contributing to the Lodi WWTP Industrial Stream ................................ 3-14 Table 3-7. Projected Industrial Flows and Loadings................................................................. 3-15 Table 4-1. Current Interim Requirements for Discharge of Treated Municipal Effluent – Major Parameters.................................................................................................................................... 4-4 Table 4-2. Current Interim, Year 2004, and Potential Future Discharge Requirements For Dischargeto Dredger Cut............................................................................................................ 4-7 Table 4-3. Anticipated and Potential Future Discharge Requirements For Discharge to Bishop Cut 4-10 Table 4-4. Anticipated Discharge Requirements for Unrestricted Irrigation ............................ 4-10 Table 4-5. Current and Potential Future Discharge Requirements For Irrigation of Animal Feed Crops.......................................................................................................................................... 4-11 Table 4-6. Current and Potential Future Discharge Requirements For Irrigation with Industrial Wastewater................................................................................................................................. 4-11 Table4-7. Biosolids Limits........................................................................................................ 4-12 Table 5-1. Altematives for Satisfying Municipal Effluent Discharge Requirements .................. 5-2 Table 5-2. Apparent Reasonable Combinations of Alternatives ................................................. 5-6 Table 6-1. Subjective Criteria Weightings................................................................................... 6-3 Table 7-1. Removal of Metals in Constructed Wetlands............................................................. 7-3 Table 8-1. Allowable BOD Loading Rates.................................................................................. 8-6 Table 9-1. Biosolids Production and Nitrogen Content............................................................... 9-2 Table 10-1. Water Balance for Land Application of Industrial Wastewater and Biosolids ......10-6 Table 10-2. Water Balance for Partial Discharge to Bishop Cut...............................................10-8 Table 10-3. Water Balance for Land Discharge......................................................................10-10 Table 10-4. Water Balance for Land Discharge – Average Year............................................10-11 Table 10-5. Area and Volume Requirements.......................................................................... 10-13 Table 10-6. Preliminary Estimated Costs of Alternatives— Land Treatment/Reuse and Discharge FacilitiesOnly..........................................................................................................................10-17 Table 11-1. Summary of Controlling Unit Process Design Criteria .......................................... 11-6 Table 11-2. Plant Automation Criteria..................................................................................... 11-10 Table 11-3. Summary of Operation and Control Design Criteria......... Table 11-4. Primary Sedimentation Performance ................................. ..................................11-10 .............11-21 9/18/00 Draft ix Wastewater Master Plan 213\wwmp Table 11-5. Costs and Subjective Comparison of Disinfection Alternatives .......................... 11-37 Table 11-6. Basis of Subjective Rankings for Disinfection Alternatives ................................ 11-38 Table 11-7. Projected Solids Production................................................................................. 11-46 Table 11-8. Costs of Sludge Drying Alternatives.................................................................... 11-54 Table 11-9. Cost of Additional Facilities for Advanced Conventional Nitrogen Removal.... 11-56 Table 11-10. Costs of Filtration Alternatives..........................................................................11-61 Table 11-11. Treatment Plant Improvement Alternatives....................................................... 11-66 Table 11-12. Summary of All Treatment Plant Improvement Recommendations .................. 11-67 Table 11-13. Estimated Costs of Treatment Plant Improvements Common to All Process Alternatives ..................................................................................................................................................11-69 Table 12-1. Common Odorous Compounds in Wastewater......................................................12-3 Table 12-2. Odor Control Alternatives Summary ......................................................................12-7 Table 12-3. Estimated Foul Air Characteristics (Headworks and Related Sources) .................12-9 Table 12-4. Advantages and Disadvantages of Foul Air Treatment Options (Lodi Headworks System)....................................................................................................................................12-10 Table 12-5. Odor Control Alternatives Summary ....................................................................12-11 Table 12-6. Recommended Improvements..............................................................................12-11 Table 13-1. Unique Components of Major Alternatives...........................................................13-1 Table 13-2. Comparison of Estimated Costs for Denitrification Alternatives ...........................13-2 Table 13-3. Costs of Unique Components for Combined Treatment and Disposal/Reuse Alternatives................................................................................................................................13-3 Table 13-4. Costs of Major Alternatives Assuming Sports Complex Funds 2.5 Mgd Tertiary TreatmentCapacity..................................................................................................................... 13-4 Table 13-5. Subjective Comparison of Alternatives..................................................................13-6 9/18/00 Draft x Wastewater Master Plan 213\wwmp SECTION 1. EXECUTIVE SUMMARY pending 7/10/00 Draft 1-1 Wastewater Master Plan 213\wwmp DRAFT SECTION 2. INTRODUCTION pending 7/10/00 Draft 2-1 Wastewater Master Plan 213\wwmp SECTION 3. FLOW AND LOADING PROJECTIONS This section quantifies existing wastewater flows and loadings, and presents projections for future flow rates and loadings through Year 2020. Flows affect the hydraulic design and sizing of pumps, pipes, and other system components. Loadings affect the biological treatment process components such as aeration basins and anaerobic digesters. Projections are presented for both domestic and industrial sewer wastewater flows. In addition, this section presents an initial analysis of infiltration and inflow (I/I) into the City's municipal wastewater collection system. POPULATION PROJECTIONS The City's most recent General Plan was completed in 1991. The target population through 2007, the end of the General Plan period, was 70,741. This represents a two percent annual growth rate from the 1987 population level of 45,794. According to the City's 1998 Residential Growth Management Schedule', the population of Lodi was 55,681 in January 1998. Population projections for San Joaquin County and its cities have been developed by the San Joaquin Council of Governments for Year 2020. Their projection for Lodi is that the City will grow to a population of 69,156 by 2020 — a growth rate of 0.99 percent. This is the lowest rate of the seven cities in the county. The total county growth rate was estimated to be 1.92 percent. At the General Plan target 2 percent growth rate, the population would be 86,000 by the year 2020. Population projections for 1 percent, 2 percent, and a mid- range value of 1.5 percent through 2020 are shown in Figure 3-1 LAND USE The ratios of future land uses are expected to remain relatively constant over the next 20 years 2. For residential units, the current proportions are projected to remain approximately constant for at least the next decade at 65 percent single family, 10 percent medium density, and 25 percent high density. If the land uses and residential mix stay constant as expected, wastewater flows should correlate well with projected population. DOMESTIC WASTEWATER FLOW PROJECTIONS Average Flow Historical wastewater flows (annual average) and projected wastewater flows for 1980 through 2020 are shown in Figure 3-1. Flows have generally correlated with population, except for a flow increase during the late 1980s and a flow decrease during the latter stages of the 1987 to 1992 drought. The increase during the late 1980's may be partly explained by calibration problems with the old flow meter around 1985 through 1987. A new flow meter was installed in mid -1988. The decrease in flow during 1991 and 1992 was probably due to water conservation efforts. Since the end of the drought, flows have been increasing slightly faster than population as water conservation efforts have probably lessened. This recent pattern has been evident in wastewater flow data for many municipalities in the area. 9/18/00 Draft 3-1 Wastewater Master Plan 213\wwmp FIGURE 3-1. POPULATION AND WASTEWATER FLOW 10.0 9.0 8.0 7.0 3.0 2]} 1.0 O.041975 — 1980 1985 1990 1995 2000 Year West Yost & Associates Lodi Wastewater Master Plan lodignowth.xls Charl:2 9/18/00 Flow 4, ---*—Historical Flow ------ Projected Flow - 2% Growth 7'' —Projected Flow - 1.5% Growth Population Projected Population - 2% Growth —Projected Population - 1.5% Growth Projected Population - 1% Growth O.041975 — 1980 1985 1990 1995 2000 Year West Yost & Associates Lodi Wastewater Master Plan lodignowth.xls Charl:2 9/18/00 DRAFT Based on the historical flows and population for 1980 through 1997, the average wastewater flow per resident was 116 gpd/capita. The wastewater flow rate per resident in 1997 was also 116 gpd/capita. These flows included all commercial customers and some industrial customers. New development in Lodi uses mandated low flow toilets and showerheads. This should reduce average flow per new resident to approximately 97 gpd/capita 3. Flow projections were developed using the 97 gpd/capita for new growth and 1 percent, 1.5 percent, and 2 percent annual population growth. As can be seen in Figure 3-1, the projected average flow range for 2020 is 7.7 to 9.4 million gallons per day (Mgd). The 1.5 percent growth rate curve (8.5 Mgd at Year 2020) used for planning purposes in this study. Faster growth or higher per capita flows would accelerate the treatment capacity expansion schedule. Wastewater Flow Peaking Factors Daily wastewater flows for mid 1994 through early 1999 are shown in Figure 3-2. It is interesting to note that Lodi's wastewater flows are higher in summer months than winter months, which is atypical for cities in the Central Valley. As discussed below, this is probably because Lodi's sewer system has much lower wintertime inflow and infiltration than most other cities' sewer systems. In addition, some of Lodi's businesses have greater activity in the summer months. Because of this pattern, the average annual flow is a better parameter to use for planning purposes than average dry weather flow. The average annual, peak month, peak day, and peak hour flow rates and peaking factors for the August 1994 through January 1999 period are shown in Table 3-1. These flow rates are based on influent flow meter readings. Seasonal wastewater flow variation is shown in Figure 3-3 along with the maximum monthly flow factors for the period. The daily wastewater flow frequency distribution for this period is shown in Figure 3-4. A graph showing sustained peak flow factors versus number of days is provided as Figure 3-5. The values from Figures 3-3 through 3-5 can be multiplied by projected future average flows for use in sizing treatment and disposal/reuse facilities. ' The peak hour flow rate for the period was observed for the storm event peaking on Tuesday, February 3, 1998. The peaking factors shown in Table 3-1 are relatively low compared to most municipal wastewater systems. Table 3-1. Peak Flow Rates and Peaking Factors (a) Daily rainfall less than 0.3 inches (b) Daily rainfall greater than 1.0 inches 9/18/00 Draft 3-3 Wastewater Master Plan 213\wwmp Flow, Mgd Peaking Factor Annual Average 6.2 1.0 Peak Month 7.0 1.13 Peak Day, dry�a) 7.3 1.18 Peak Day, wet(') 8.0 1.29 Peak Hour, dry 10.5 1.70 Peak Hour, wet 11.9 1.92 (a) Daily rainfall less than 0.3 inches (b) Daily rainfall greater than 1.0 inches 9/18/00 Draft 3-3 Wastewater Master Plan 213\wwmp 2� I O J LL I - Z W J LL Z } J Q N M W N ,D V LL co O LO CA N r N �U N T Q Ui O Lf� O U) O to O U7 O r v0 00 00 U] Co UJ LO '7 y P6W >- a 3 4;;j co Co V N 0 co Co C) CD C> 0 C) M01=1 OBeJGAV / mol.1 Alqluoyy O Z 16 0 CL O 73 c ca (D LL c cu n 0 O 0 R m 00/£/L SJO IN 01JAW SIX-SMOU110 ue{d JOISew 103ennalseM IPOI sEgBPOssy +g tso,k IsOM MOIJ a6eJand / MOIJ lenaad £' L 9Z' 6 Z' L 9l' L VI 90' 6 L 96'0 6'0 99*0 8'0 9L'O L'0 %0 %0 L %OZ Me 0 0 %Ob -i 3 r %09 N %09 d %OL %08 %06 %OO L Nounewisio ADN3no3u:j SM0i3 Dildo C13ZI IVWUON 'v-£ asno1-q C) t" Q� co ui w Q V Q LL 0- -i LL Y Q LU IL 0 w z Q N N M N N co T T T ,It N O co CO N O N N N T r r T T T T T T T T T MOj_q OBeJOAV / MOIJ pouie;sng P LO N O N G T K--- 0 _ N i0 d 7 V d 0 U 0 L. CD m E z Analysis of Inflow/Infiltration Direct inflow into wastewater collection systems is defined as surface flows into collection system structures, such as manhole lids. Infiltration is defined as groundwater entering the sewer system through joints and cracks in the system. The purpose of analyzing I/I is to determine whether there is excessive I/I that would be more effective to eliminate through collection system improvements rather than be included in treatment capacity planning. Groundwater levels are typically highest in late winter months at approximately 40 feet below ground surface. Based on the fact that the wastewater influent flows to the treatment plant are higher in the summer than the winter months (see Figure 3-2), there is no distinguishable infiltration into the Lodi wastewater collection system. During peak storm events, influent wastewater flows have increased. The average, maximum, and minimum flows during days with rainfall greater than 1.0 inches are compared with the average, maximum, and minimum flows for days with less than 0.3 inches of rainfall in Table 3-2. The peak storm event of February 3, 1998 had an inflow of approximately 2 million gallons over a 24-hour period. The amounts of inflow are very low compared to most wastewater collection systems in the Central Valley of California, and would definitely not be considered excessive. Table 3-2. Average Inflows During Storm Events (Averages for 1994 through 1998) Influent Flow During Dry Periods, Mgd Influent Flow During Rainstorms,(a) Mgd Calculated Inflow, gallons Average for 24 Hours 6.19 6.69 500,000 Average Maximum Hour 7.75 8.96 50,000 Average Minimum Hour 2.94 2.99 2,000 (a) Rainfall greater than 1.0 inch per day Projected Flows The average and peak projected flows for planning purposes are listed in Table 3-3. These were calculated using the projected average flows at a 1.5 percent growth rate (Figure 3-1) and the peaking factors from Table 3-1. The frequency distribution and sustained peak flow factors can be used to develop other peaking factors specific to some of the treatment processes. Table 3-3. Projected Flows, Mgd 9/18/00 Draft 3-8 Wastewater Master Plan 2131wwmp 2010 2020 Average 7.5 8.5 Peak Month 8.5 9.6 Peak Day 9.7 11.0 Peak Hour 14.4 16.3 Peak Day, dry weather 8.9 10.0 Peak Hour, dry weather 12.7 14.5 9/18/00 Draft 3-8 Wastewater Master Plan 2131wwmp DOMESTIC WASTEWATER QUALITY AND LOADING PROJECTIONS Concentrations of Major Constituents The concentrations of major constituents for wastewater entering the Lodi Water Pollution Control Plant are fairly typical of medium strength municipal wastewater. Average and projected concentrations for the major constituents are shown in Table 3-4. Concentrations of minor constituents are addressed in Section 4, Waste Discharge Requirements. Table 3-4. Average Influent Concentrations of Major Constituents (1995 through 1998) Item Units Historical Average Projected Year 2010 ProjectedTreatment Year 2020 Existing Plan Design Criteria Chemical Oxygen Demand (COD) mgt 537 554 565 N/A Biochemical Oxygen Demand (BOD) mg/L 265 274 279 220 Total Suspended Solids (TSS) mgt 235 243 248 240 Ammonia mg/L 17.3 17.9 18.2 — Total Kjeldahl Nitrogen mg/L 28.5 29.4 30.0 — Although the land uses and the mix of residential units are not expected to change significantly through Year 2020, new development should have a lower average flow rate per capita. This will result in an increase in the concentrations of major constituents for new development because the constituent loading rates per capita should remain essentially unchanged. This explains the slight increase in concentrations projected over time shown in Table 3-4. Loading Rates for Major Constituents Influent loading rates of BOD and TSS have been evaluated for 1994 through 1998. The daily BOD loading rate frequency distribution and sustained peak loading factors are shown in Figures 3-6 and 3-7, respectively. The daily TSS loading rate frequency distribution and sustained peak loading factors are shown in Figures 3-8 and 3-9, respectively. The projected loading rates of major constituents are shown in Table 3-5. Table 3-5. Projected Average and Sustained Peak Loading Rates in lbs/day Constituent 2010 2020 Sustained Peak Average 30 -Day Loading Average Sustained Peak 30 -Day Loading BOD 17,100 19,700 19,800 22,800 TSS 15,200 19,300 17,600 22,400 9/18/00 Draft 3-9 Wastewater Master Plan 213\wwmp 0 0 N e1 I I N r iT,N a a a r N X N O O r co ti � R 0 T O r � C R m L d d Ct i Q y V R y cn 0 N r O m m =o N 3 J r+ r V Q I O O O O O N N CD0 0 U) O OO O O O O O O O O Q O CD OM 07 00 r- O LOj N OT O °a r co O amen ueyl SSO-1 awil10 % } N N Q1 r v Li 0 U Q ILL. V z Q O J O m Y Q Lu a 0 Lu z QL 1- V! ti M W LL 0 N 0 0 N 0 r PeOI ao8 a6ejaAv / Peo-i aos peuie;sng 0 0 r 0 M N 0 N 0 T LO 99 O O T O OO OO O OOOMOi co �CO LO � ' amen UeU ssa-1 awil;o % N N T j N 0 N O T co r CO T 'Q R O J U) d CD L Q I M A O J N N U) H T R r+ V T Q I r. I!I I O T cq Q O to 6 Ui O O O O O O O N T N 1 r v LL O F- U Q W a _z D Q O J N N I - Y Q LU a 0 W z a F- U) D U) ci M W D C9 LL 0 0 U o L o N N .- PeOI SSl a6eaand / peO-1 SSS pouffe;snS O M N O N LO 0 INDUSTRIAL WASTEWATER FLOW AND LOADING PROJECTIONS The City has a separate 33 -inch sewer trunk line which serves the Pacific Coast Producers (PCP) cannery and several small industries. PCP processes primarily apricots during June, and tomatoes and peaches during June through October. PCP also produces sauces and processes other products, but the flows and loads from these operations are very minor. The smaller industries connected to the industrial sewer system include a cherry packer, metal finishers and several other industries. The combined annual total flow from these industries (other than PCP) is only approximately 14 million gallons versus the 300 to 440 million gallons annually from PCP. The industry names, types, and annual flows are listed in Table 3-6. Table 3-6. Industries Contributing to the Lodi WWTP Industrial Stream Industry Name Industry Type Discharge, MGy(a) Discharge Areas within Plant Interlake Metal finisher 0.12 Process wastewater Lodi Iron Works Iron -casting plant 0.4 Compressor cooling water M & R Packing Fruit packing 2.8 Cooling water, fruit wash Pacific Coast Producers Cannery 300 — 440 Fruit wash, boiler blow down, caustic peeling of fruit, factory washdown Pacific Coast Producers Can -making plant 0.25 Compressor cooling water RMT Holtz Inc. Industrial Rubber Products 3.3 Process wastewater, cooling water, autoclave blowdown Valley Industries Metal finisher 11 Process wastewater (') Million gallons per year. Monthly industrial wastewater flows for 1997, 1998, and a portion of 1999 'are shown in Figure 3-10. The 1998 and 1999 flows were much higher than 1997 flows. New equipment is being installed to reduce dilution water flows at PCP. PCP production may expand slightly in the future, but no new major production lines are planned. Based on discussions with PCP management and City staff, the projected flows and loadings were projected using averages for 1998 and 1999 values. Projected flows are shown in Table 3-7 and Figure 3-10. Future peak industrial sewer flow is projected to equal the August 26, 1999 peak of 9.7 mgd. This flow includes taihvater return. Projected loadings are shown in Table 3-7. 9/18/00 Draft 3-14 Wastewater Master Plan 213\wwmp DRAFT Table 3-7. Projected Industrial Flows and Loadings Month Flow, Mgal BOD, lbs BOD, mg/L TSS, lbs TSS, mg/L Jan 4.69 10,264 263 10,264 263 Feb 3.89 8,278 255 8,278 255 Mar 6.96 30,355 523 15,964 275 Apr 4.37 9,480 260 9,480 260 May 3.08 6,237 243 6,237 243 Jun 7.37 20,065 326 6,106 99 Jul 59.22 339,631 688 98,637 200 Aug 119.58 2,020,425 2,026 888,599 891 Sep 144.97 2,707,717 2,239 1,321,841 1,093 Oct 52.90 487,436 1,105 271,469 615 Nov 2.69 5,265 235 5,265 235 Dec 2.84 5,644 238 5,644 238 Totals412.56 5,650,797 N/A 2,647,784 N/A Note: PCP flows for Nov through May not sampled — 300 mg/L BOD and TSS assumed. BOD and TSS for other industries assumed to be an average 100 mg/L. 9/18/00 Draft 3-15 Wastewater Master Plan 2131wwmp 160 140 120 L C O E 100 m CL a c 0 80 c 0 E 60 3 0 LL 40 99 9 FIGURE 3-10.1997 -1999 AND. PROJECTED INDUSTRIAL WASTEWATER FLOWS Jan Feb Mar Apr May Jun Jul, Aug Sep Oct Nov Dec Month West Yost & Associates Lodi Wastewater Master Plan allflows indflows 5/8/00 REFERENCE City of Lodi Residential Growth Management Schedule 1998, adopted in accordance with Ordinance #1521 dated September 18, 1991. Personal phone conversation with Konradt Bartlam, March 1999. 3 Wastewater flow reduction values calculated from Wastewater Engineering, Treatment, Disposal, and Reuse. Tchobanoglous, G. and F.L. Burton. Metcalf and Eddy, Inc. Third Edition. 1991. 9/18/00 Draft 3-17 Wastewater Master Plan 2131wwmp SECTION 4. ANTICIPATED DISCHARGE REQUIREMENTS AND ISSUES INTRODUCTION The prime objective for the City of Lodi's (City) wastewater facilities is to reliably meet discharge requirements. The purpose of this task was to formulate a set of anticipated and potential future discharge requirements for use in the development and evaluation of upgrades to the City's treatment, reuse, and discharge facilities. BACKGROUND Current Processes and Operations The current treatment process includes primary clarification followed by conventional activated sludge secondary treatment and chlorine gas disinfection. Primary and secondary solids are further treated in anaerobic digesters and a biosolids lagoon. Most treated effluent is either discharged to surface waters or used for agricultural irrigation of animal feed crops. Small amounts of treated effluent are used for the Mosquito Abatement District fish ponds and the NCPA Power Plant. Biosolids are mixed with effluent and land applied on City owned property. Receiving Waters The City of Lodi discharges to Dredger Cut, which connects with White Slough and Bishop Cut in the Delta as shown in Figure 4-1. Dredger Cut is a manmade channel which was constructed in the early 1900s to provide drainage for agricultural lands in the area. Dredger Cut, White Slough, Bishop Cut, and other Delta channels are normally dominated by tidal flows. Water from Bishop Cut typically flows to the San Joaquin River and Stockton Deepwater Ship Channel through Disappointment Slough' as shown in Figure 4-2. During periods of no exports from the Delta, there is a net flow west from Disappointment Slough towards San Francisco Bay. During periods of high water exports from the Delta, there is a reverse net flow up the San Joaquin River to the confluence with Turner Cut. Current Discharge Requirements for Municipal Wastewater Lodi's current (adopted January 2000) discharge requirements for municipal effluent are applied at the discharge into a side slough of Dredger Cut (R-1). The current interim discharge requirements include secondary treatment and disinfection limits, biotoxicity requirements, dissolved oxygen limits, nitrogen loading limits for land application, and related* requirements. The most significant current interim discharge requirements related to treatment facility capacities and operation for municipal effluent are listed in Table 4-1. The interim requirements are set to expire in April 2004. The new requirements effective in 2004 are discussed later in the "Future Discharge Requirements" subsection. 9/18/00 Draft 4-1 Wastewater Master Plan 213\wwmp a I I Station s -_ I m: \\,+ A�� i-_ - - atii-`'iiR� I F - ... - I i y �? TREDWAY `•�S ROAD .- EFW\ \ , , y L .,- _ I \ ,+ 3 1 R A C T.>. �:� = _ _. �__ — a �:�_ w•ryl�� — 21 I d., ^ .i;-.1 i•':'-. ■ N;d7•'?. grin I- \` �•`` aerPolfifXI� t.-- ra;ontrol PrafR• .�;;; Nat �` , __ . 1 •,.'.1 r - - - �� r I` k\ Pumping i r s .N U . `-a, (r Pumping. �___------ ----- ------�.'�fJ Aga ��\ -PSP ng Well �� ..: - taGal \ g... 26 Z ' I Y ;\ I •, `! R `A 0 B L jA N 'C '0� 2� 1 .; CAD FILE: 1:/213/99-01/213f-4-2.dwg CFG FILE: WYA2500J-,,,-MRG DATE: 05-04-00 4:28pm + r- z IT T It t • CL Z aU) M IL b rn �g r kr Ell Q. z Z3. CL p--yx 10 w )RO A: r -M or - CL UP Zg- -no ca L OL 1p CD ZL 0 30 c A3 P: -n O r -nO Zz > 0 0 M A KX 'e( Ci) 0 r- �l , ro z ca o• s I 1* 4-0 0 ly, r+ CL CD c: .9 M X .7pp is 41 J9 0 m Mm --4 z all) N ca A < w 0 ta co /0 am CD Ai H bi DRAFT Table 4-1. Current Interim Requirements for Discharge of Treated Municipal Effluent — Major Parameters Constituent or Parameter Units Limit BOD mg/L 20/40/50(a) TSS mg/L 20/40/50(x) Total Coliform MPN/100 mL 23 Acute Toxicity Survival one/three 700/o/90% Chronic Toxicity TUc11 1 Dissolved Oxygen mg/L 5.0 minimum (a) Monthly average/weekly average/daily maximum. Effluent from the Water Pollution Control Facility (WPCF) consistently complied with the previous discharge requirements for BOD, TSS, and toxicity. There were three instances in 1996 and one instance in 1999 when individual biotoxicity test results were outside the allowable survival rate, but the adverse results did not occur in consecutive tests so as to cause a violation of the permit requirements. The suspected cause for the instances of toxicity in 1996 was excessive use of sulfur dioxide for dechlorination. Reclamation Requirements The City irrigates animal feed crops on its own land surrounding the treatment plant using a mixture of non -disinfected secondary effluent, digested biosolids, and industrial (mostly cannery) wastewater. The current discharge requirements for the secondary effluent are 40 mg/L BOD and 0.2 mL/L settable matter (SM) (monthly averages). The current discharge requirements also contain other operational restrictions derived from Title 22, Division 4 Reclamation Requirements or Department of Health Services guidelines. The reclamation requirements state that nutrient loading of the reclamation area shall not exceed the crop demand. The City's nitrogen loading rates have been consistently below agronomic use rates. However, nitrate concentrations in several of the shallow groundwater monitoring wells have exceeded the 10 mg/L drinking water standard. The causes of the relatively high nitrate levels have not been determined. Solids Disposal/Reuse Discharge Requirements Biosolids disposal and reuse practices are required to conform with Section 405(d) of the Federal Clean Water Act. In addition, nitrogen loading rates from biosolids are included in the total reported nitrogen loadings for the City's land. Total nitrogen loading rates are not allowed to exceed crop uptake and denitrification rates in order to protect groundwater quality. 9/18/00 Draft 4-4 Wastewater Master Plan 2131wwmp j + . Industrial Wastewater Discharge Requirements Because the industrial wastewater is applied directly to the land, there are no specific effluent quality requirements. The main requirements are related to the prevention of odors and groundwater impacts. Receiving Waters Modeling A dilution study of White Slough and Bishop Cut receiving waters was performed by Whitley Burchett & Associates in 1994. The average dilution ratio over the tidal cycle at the confluence of White Slough and Bishop Cut (monitoring point R-2, see Figure 4-1) was estimated to be approximately 8:1 for an effluent flow of approximately 6 Mgd. A more detailed model of Dredger Cut, White Slough, and Bishop Cut was completed in 1998 by Dr. Gary Litton and Jason Nikaido at the University of the Pacific.2 The average dilution in Dredger Cut was estimated to be 2:1 for an 8.5 Mgd effluent flow rate. The average dilution at the east side of the confluence of Dredger Cut and White Slough (R-2) was estimated to be 4:1. Sampling and modeling dissolved oxygen concentrations within Dredger Cut were the main focus of the Litton study. One of the most significant results was that dissolved oxygen (D.O.) levels in Dredger Cut dropped below 5 mg/L on several occasions during the testing period even when the treatment plant was not discharging, indicating impacts from other non -point sources of pollution. The dissolved oxygen model predicted that treatment plant effluent with 20 mg/L BOD would cause D.O. levels in Dredger Cut to drop below 5 mg/L at low slack tides. At an effluent BOD concentration of 10 mg/L, the D.O. concentration was predicted to remain above 5 mg/L at low slack tides assuming inputs from non -point pollutions sources were not severe. Subsequent to the Dredger Cut study, Dr. Litton performed modeling of net flows in White Slough and Bishop Cut using models from the Department of Water Resources and CALFED3. The model results showed that for an 8.5 Mgd discharge, the average annual dilution in Bishop Cut would be 12:1. The highest dilutions would be in December through March, with at least 20:1 dilution in half the years and at least 10:1 dilution in about 96 percent of the years. The lowest dilutions would occur in May through July, with an average dilution of only 6:1. Some of the potential future modifications to Delta channels proposed by CALFED would reduce dilutions by 20 to 70 percent. See Appendix ■ for more details. POTENTIAL CHANGES TO DISCHARGE LOCATION AND BENEFICIAL USES Discharge to Bishop Cut Construction of an outfall pipeline or channel to Bishop Cut immediately south of the confluence with White Slough is a potential alternative for providing improved effluent dilution flows. Water quality objectives for the receiving water would be easier to meet with more dilution. A diffuser across the most active portion of the channel would provide an estimated dilution of over 20:1 during most winter months, but only about 6:1 during summer months. 9/18/00 Draft 4-5 Wastewater Master Plan 213\wwmp Sports Complex A sports complex has been proposed for 400 acres in the southeastern portion. of the City's property. This complex would include a significant portion of grass fields which would need irrigation. The current project concept calls for peak summertime use of up to 2.5 Mgd of treated effluent meeting Title 22, Division 4 Reclamation Requirements for unrestricted irrigation as the irrigation water source for the fields. FUTURE DISCHARGE REQUIREMENTS General New waste discharge requirements will be enforced when the interim requirements expire in April 2004. For discussion purposes, these anticipated new waste discharge requirements are referred to in this report as "Year 2004 discharge requirements". The City would have to apply for new discharge requirements if the point of discharge were changed. Probable requirements resulting from an application for a new point of discharge are referred to as "anticipated discharge requirements". Requirements which may be imposed in future permits are referred to as "potential future discharge requirements". Anticipated and potential future discharge requirements presented in this report were developed from discussions with Regional Board staff, current discharge requirements, and the review of relevant research and guidelines. Municipal Effluent Discharge to Dredger Cut Discharge to Dredger Cut will need to satisfy current, Year 2004, and future discharge requirements mandated by the EPA and Regional Water Quality Control Board. The most significant new requirements are related to trace toxins, dissolved oxygen objectives, disinfection, and biosolids reuse. Current interim, Year 2004, and potential future discharge requirements are listed in Table 4-2 along with average and peak values from the last 5 to 10 years for comparison purposes. The anticipated and future discharge requirements include no dilution in Dredger Cut for water quality objectives. The enlarged bold values are those likely to be difficult to meet with current facilities. Complete results from the City's trace toxins sampling program since December 1992 are shown in Appendix E. Discharge requirements shown in Table 4-2 are based on meeting Delta water quality objectives at Location R-1 in Dredger Cut. BOD requirements are effectively dictated by the D.O. objective for Dredger Cut. As discussed previously, modeling indicates that the 5 mg/L D.O. requirement cannot be reliably met for effluent with BOD above 10 mg/L. Contact recreation and agricultural irrigation are listed in the Basin Plan as beneficial uses of the Delta. The Year 2004 and potential future disinfection requirements incorporate the general recommendation from the Department of Health Services (DHS) that discharges to streams with little dilution should be tertiary treated to the same levels as required for unrestricted irrigation water as per wastewater reclamation requirements contained in Title 22, Division 4 of the California Water Code. This includes coagulation, sedimentation, and filtration or a DHS - approved direct filtration alternative process. Previous DHS guidelines have not recommended tertiary treatment when dilution in the receiving waters was above 20:1. 9/18/00 Draft 4-6 Wastewater Master Plan 213%wwmp DR FT Table 4-2. Current Interim, Year 2004, and Potential Future Discharge Requirements For Discharge to Dredger Cut(a) Constituent or Parameter Units Current Interim Year 2004 Potential Future Historical Average Historical Peak BOD mg/L (30 day) 20 10 10 8.4 16 TSS mg/L (30 day) 20 10 10 10.0 24 D.O. mg/L (receiving water) 5 5(6) 5(b) 5.2 0.6 (min) Temperature A°F (receiving water) 5 4(6) 4(6) 9.3 21.6 Chlorine Residual mg/L 0.01 0.01 0.01 <0.1 4.6 Coliform MPN/100 mL 23 2.2 filtered(`) 2.2 filtered(`) 2 13(d) Lead µg/L n/a 3.7 3.7 <5 (total) 10 (total) Zinc µg/L n/a 101 100(6) 105 (total) 160 (total) Cyanide nll- n/a 5.2 5.2 <10 49 Mercury µg/L n/a TML 0.050(e) & TML <0.2 0.63 Bis -2 ethyhexyl phthalate µg/L n/a n/a 11,8(e) <15 (median) 190 Chloroform µg/L n/a n/a 10.4(e) 21 102 Lindane pg/L n/a n.d. 0.02 n.d. 0.01 (median) 0.051 Chronic Toxicity TUc 10 1 1 1 (median) >16 Acute Toxicity % survival 70/90 70/90 70/90 99.2 85 (min) Ammonia mg/L n/a n/a 3,2() 1.2 6.5 Total Nitrogen mg/L n/a n/a TML(g) 9.4 — Total Phosphorous mg/L n/a n/a TML(9) 0.21 1 — (') All limits are for average concentrations, typically a 30 -day averaging period. ts1 Basin Plan. (Limits for metals expressed as dissolved concentrations.) (`) Proposed DHS/Regional Board guidelines, may be incorporated into future Basin Plan. (d) Monthly median, 9 days have exceeded 500 MPN/100mL since Jan 1994. EPA California Toxics Rule, metals limits expressed as dissolved concentrations. to EPA Ambient Water Quality Criteria, no dilution assumed for chronic criteria. cs> No specific requirements pending, Total Mass Loads (TML) may be applied in the future. 9/18/00 Draft 4-7 Wastewater Master Plan 213\wwmp The potential for nutrient mass limits in the future is based on the fact that Total Mass Daily Loadings are being proposed for Stockton and other dischargers who may contribute to the dissolved oxygen sag in the Stockton Deepwater Ship Channel. The current proposals only address BOD limits, but excess nutrients are recognized as contributors to the problem. Lodi's discharge only appears to impact the lowermost reach of the Deepwater Ship Channel under high export conditions. This reach below (northwest of) Turner Cut does not experience dissolved oxygen sags which violate Delta water quality objectives (see Figure 4-2). However, it would be prudent to begin considering the possibility of nutrient limitations in long term planning. Compliance with Year 2004 Requirements. The treatment plant was designed to produce an effluent with a BOD concentration of 20 mg/L at 8.5 Mgd without nitrification. The WPCF has historically produced effluent with an average BOD of less than 10 mg/L and essentially all ammonia converted to nitrate (full nitrification). There have been a few recent instances when the City had difficulty achieving full nitrification, so it appears that the plant reached its original nitrification capacity limit at approximately 6.0 Mgd. Disinfection and biotoxicity test results could be adversely affected if the treatment plant cannot fully nitrify. Reliably achieving 10 mg/L BOD could also become more difficult as the plant approaches its 8.5 Mgd original design capacity. Since the treatment process does not currently include filters and a chlorine contact tank sized for tertiary treatment, meeting Title 22, Division 4 treatment and disinfection requirements would not be possible without additional facilities. Some anticipated discharge requirements related to trace toxins may be difficult to consistently meet. The plant effluent has contained concentrations of zinc ranging up to 160 mg/L (as total recoverable metal). This would be in excess of the Year 2004 discharge limits for zinc, although the effective limit could be reduced, depending upon the relationship between total and dissolved zinc for the treatment plant effluent. The plant effluent contained cyanide in excess of the anticipated limit on two occasions in 1995 and one occasion in 1996. The new lead requirement could be exceeded on occasion. During winter months, the plant effluent is considerably warmer than the water in Dredger Cut. Permit requirements specify that the surface water temperature cannot be raised by more than 4°F at any location. While it is unlikely that aquatic life is adversely affected by the warmer water temperature near the discharge, there could be a technical violation of the temperature requirement. Compliance with Potential Future Requirements. The potential future requirements in Table 4-2 which are more restrictive than the anticipated discharge requirements are the requirements for ammonia, mercury, chloroform, and nutrients. Although there has been only one sampling result which contained detectable mercury, the detection limit for mercury (0.20 µg/L) was higher than EPA ambient water quality criteria for chronic toxicity (0.012 pg/L). Based on effluent quality measurements to date, meeting potential future requirements for mercury, zinc, and nitrogen would not be possible with existing treatment facilities. Based on limited data, the secondary treatment process as it is currently operated produces effluent with unusually low levels of phosphorus, which would probably satisfy future TMLs. Chloroform and other trihalomethanes are formed as byproducts of chlorine disinfection. There are no established diversions for drinking water use in the northwestern portion of the Delta. It is unclear what mixing zone and dilution would be allowed for this water quality objective since it 9/18/00 Draft 4-8 Wastewater Master Plan 2131wwmp is intended to protect sources of drinking water rather than aquatic life. Assuming no dilution in Dredger Cut, this potential requirement would be very difficult to meet with existing facilities. If dilution beyond Dredger Cut were allowed to be considered, the chloroform objective could probably be satisfied. Municipal Effluent Discharge to Bishop Cut As discussed previously, one of the obvious alternatives for the City is to construct an outfall to Bishop Cut. This would provide more dilution for meeting receiving water quality objectives. In addition, water at R-3 in Bishop Cut (see Figure 4-1) has always contained dissolved oxygen substantially above the 5.0 mg/L water quality objective for the Delta based on monitoring by the City. Taking the greater available dilution into account, the near-term anticipated and potential future discharge requirements are listed in Table 4-3. Anticipated and potential future effluent limits shown for trace toxins are based on either an assumed 5:1 average dilution and continuous concentration criteria or maximum concentration criteria, whichever is more restrictive. Values shown in enlarged bold are those likely to be difficult to meet with current facilities. Diurnal storage of effluent could be required so that discharge does not occur at low dilution ratios during slack portions of the tidal cycle. Compliance with Anticipated Requirements. For treated effluent discharged directly to Bishop Cut during times when dilution exceeds 20:1, effluent quality similar to that achieved historically should be adequate to satisfy anticipated discharge requirements, except possibly for zinc concentrations. However, during most of the year, the more stringent BOD, TSS, and disinfection requirements could not be met without new tertiary treatment facilities. Tertiary treatment may or may not be required for Winter months at less than 20:1 dilution, depending upon the interpretation of law, policies, and site-specific conditions. There may be some difficulty achieving consistent disinfection results as flows increase, especially if nitrification cannot be assured throughout the year. Compliance with Potential Future Requirements. Disinfection requirements could become more stringent in the future depending upon actual dilution ratios in Bishop Cut. Total mass limits could be adopted for BOD, mercury, and nutrients in the future. Municipal Effluent Reuse—Unrestricted Irrigation The anticipated discharge requirements for unrestricted irrigation of fields at the proposed Sports Complex or food crops are shown in Table 4-4. These requirements generally reflect standard Reclamation Requirements from Title 22, Division 4 of the Water Code. New tertiary filtration treatment facilities would be required to satisfy these requirements. Municipal Effluent Reuse—Animal Feed Crops Discharge requirements for irrigation of animal feed crops are not anticipated to change substantially in the future. These are shown in Table 4-5. The anticipated and future potential requirements for animal feed crop irrigation should be easy to satisfy with existing treatment processes. Effluent disinfection could potentially be required to satisfy future site specific concerns regarding potential public or farm worker contact with the effluent. 9/18/00 Draft 4-9 Wastewater Master Plan 2131wwmp DRAFT Table 4-3. Anticipated and Potential Future Discharge Requirements For Discharge to Bishop Cut Constituent or Parameter Units Near Term Anticipated Potential Future Historical Average Historical Peak BOD mg/L (30 -day) 10(') TML 8.4 16 TSS mg/L (30 -day) 10(') 10(') 10.0 24 D.O. - mg/L (receiving) 5(b1 5(b1 9.3 2.9 (min) Temperature 0°F (receiving) 4(1) 4(1) 9.3 21.6 Chlorine Residual mg/L 0.0101 0.01(`) <0.1 4.6 Coliform MPN/100 mL 2.2(2,d) filtered 2.2(d)filtered 2 13 Zinc gg/L (receiving) 100(1) 100(1) 105 (total) 160 (total) Zinc µg/L (effluent) 101@1 1011b1 105 (total) 160 (total) Cyanide gg/L (receiving) 10(1) 10(b1 <10 49 Cyanide µg/L (effluent) 22(`) 22(`) <10 49 Mercury gg/L (receiving) 0.050(e) TML <0.2 0.63 Mercury gg/L (effluent) 1.4(`) 1.4(`) <0.2 0.63 Bis -2 ethyhexyl phthalate gg/L n/a 118(`) <15 (median) 190 Chloroform µg/L n/a 29(el 21 102 Lindane µg/L (receiving) 0.02 n.d. 0.01 (effluent) 0.051 (effluent) Chronic Toxicity TUC 5(1� 5(1) 1 (median) >16 Acute Toxicity % survival 70/90 70/90 99.2 85 (min.) Ammonia mg/L n/a 6 1.2 6.5 Total Nitrogen mg/L n/a TMO) 9.4 — Total Phosphorous mg/L n/a TML( 0.21 — BOD and TSS limits of 30 mg/L, coliform limit of 23 MPN/100mL may be allowed during Winter months and/or when dilution exceeds 20:1. (b> Basin Plan. (Limits for metals expressed as dissolved concentrations.) (`) EPA Ambient Water Quality Criteria (imposed through Basin Plan narrative toxicity requirements). (d) Proposed DHS/Regional Board guidelines, may be incorporated into future Basin Plan. California Toxics Rule. (fl No specific requirements pending, future Total Mass Limits may apply. Table 44. Anticipated Discharge Requirements for Unrestricted Irrigation Constituent or Parameter Units Antici ated BOD m 10 TSS m 10 Turbidity NTU 2 Coliform MPN/100 mL 2.2 filtered Ammonia + Nitrate lbs/ac/yr Agronomic use 9/18/00 Draft 4-10 Wastewater Master Plan 2131wwmp Table 4-5. Current and Potential Future Discharge Requirements For Irrigation of Animal Feed Crops Constituent or Parameter Units Current Potential Future BOD mg/L 40 30 SM ml/L 0.2 0.1 Coliform MPN/100 mL Secondary 23 Ammonia.+ Nitrate lbs/ac/yr Agronomic useAgronomic use Industrial Effluent Irrigation Reuse The industrial wastewater is principally from the Pacific Coast Producers (PCP) cannery. The main discharge requirements for industrial wastewater involve the prevention of nuisance odors and adverse impacts to groundwater. Current, anticipated, and potential future requirements are listed in Table 4-6. Table 4-6. Current and Potential Future Discharge Requirements For Irrigation with Industrial Wastewater Constituent or Parameter Units Anticipated Potential Future BOD lbs/ac/da n/a 200 Hydrogen Sulfide mg/L n/a 1.0 Dissolved Oxygen m n/a 1.0 minimum Salinity lbs/ac/yr No significant impacts No significant impacts Ammonia + Nitrate lbs/ac/E Agronomic use A onomic use Distribution facilities may need some improvements to minimize the potential for sulfide generation and odors from industrial wastewater irrigation. Average fixed mineral TDS for the industrial effluent is approximately 800 mg/L vs. 400 to 500 mg/L for the municipal effluent. The industrial wastewater would be considered good quality for irrigation and should not cause significant impacts to groundwater. A zero degradation objective applied to major mineral constituents is a future possibility. It would be nearly impossible to meet if strictly interpreted and applied to shallow groundwater directly under the irrigation fields. Biosolids Disposal/Reuse The City currently produces approximately 320 metric tons (dry weight basis) of biosolids annually. The existing anaerobic digesters and lagoon produce Class `B" biosolids under the new Federal 40 CFR Part 503 regulations. The biosolids are mixed with the irrigation water and applied via surface irrigation to land designated for annual row crops (approximately 300 acres 9/18/00 Draft 4-11 Wastewater Master Plan 2131wwmp irrigation in any one year). A total of 600 acres (243 ha) is used for biosolids application on a multi-year rotation. The discharge requirements for biosolids are derived from the Federal Part 503 regulations and the proposed General Biosolids Permit authored by the State Water Resources Control Board. These requirements generally address maximum concentrations and loading rates for heavy metals and operational procedures to prevent pathogen transmission. The maximum concentrations and loading rates for metals and other constituents under the Part 503 regulations are included in Table 4-7. The proposed General Biosolids Permit is not applicable to areas in the statutory Delta, but many of the operational requirements from the General Biosolids Permit will undoubtedly be applied to Lodi's site specific permit. Table 4-7. Biosolids Limits Constituent Ceiling Concentration, mg/kg Max. Cumulative Loading, kg/ha Historical Concentration, mg/kg Average Loading, kg/ha/yr Life of Existing Site, years Arsenic 75 41 7.8 0.01 4,100 Cadmium 85 39 5.6 0.007 5,600 Chromium 3,000 3,000 22 0.029 10,400 Copper 2,500 1,500 246.0 0.32 4,700 Lead 350 300 30.5 0.04 7,500 Mercury 57 17 5.5 0.007 2,400 Molybdenum 75 18 11.1 0.014 — Nickel 420 420 15.0 0.019 22,000 Selenium 100 100 1.2 0.002 50,000 Zinc 7,500 2,800 604.0 0.80 3,500 Total N (lbs/ac/yr) Agronomic use Agronomic use — — — Compliance with Biosolids Limits. The biosolids limits should be reasonably easy to comply with as long as sufficient land continues to be available for biosolids application. The distribution uniformity of biosolids may have to be improved to effectively utilize all available land. SUMMARY AND CONCLUSIONS Discharge to Dredger Cut will require more highly treated effluent than is reliably obtainable with current facilities. Compliance with dissolved oxygen, disinfection, and zinc requirements will be problematic. Potential future requirements for other trace toxins and nutrients may also be impossible to meet with current facilities. Requirements for discharge to Bishop Cut could possibly be satisfied during Winter months using existing treatment processes with the addition of capacity for full nitrification and a 9/18/00 Draft 4-12 Wastewater Master Plan 213\wwmp reduction in peak zinc concentrations. Tertiary treatment will probably be required for discharge to Bishop Cut during Spring through mid -Fall months. Delta channel modifications by CALFED could necessitate year-round tertiary treatment. Land application and irrigation reuse of effluent on animal feed crops would have the least restrictive treatment requirements. Landscape irrigation or irrigation of food crops would require compliance with Title 22 Reclamation requirements, including tertiary filtration and disinfection. Dilution flows and dissolved oxygen impacts in Bishop Cut should continue to be evaluated in greater detail for a discharge into the west portion of Bishop Cut immediately south of the confluence with White Slough. The potential impacts of BOD in downstream Delta channels should also be evaluated. REFERENCES I State Water Resources Control Board. Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary. Pub. # 954WR, May 1995. 2 Litton, G.M. and J. Nikaido. Water Quality Impact Report White Slough Water Pollution Control Facility. Draft, University of the Pacific, Department of Civil Engineering, October 1998. 3 Litton, G.M.. Draft City of Lodi Outfall Relocation Study. May 9, 2000. Jones and Stokes Associates. Potential Solutions for Achieving the San Joaquin River Dissolved Oxygen Objectives. Prepared for DeCuir and Somach and the City of Stockton. June 1998. 9118/00 Draft 4-13 Wastewater Master Plan 213\wwmp SECTION 5. ALTERNATIVES FOR SATISFYING DISCHARGE REQUIREMENTS INTRODUCTION The purpose of this section is to identify general alternatives for satisfying the anticipated and potential future discharge requirements. These are broad process or disposal/reuse alternatives targeted to discharge requirements listed in Section 4 as difficult to meet with existing facilities. The alternatives identified in this section will be evaluated in detail in later sections. ALTERNATIVES FOR SATISFYING MUNICIPAL EFFLUENT DISCHARGE REQUIREMENTS There are a number of discharge, treatment process, and land treatment or reuse alternatives which could partially or fully enable the City to meet the anticipated and potential future discharge requirements. The most plausible alternatives and their anticipated effectiveness in meeting requirements are discussed in this section. The discharge requirements listed in Table 5-1 are those which will be difficult or impossible to meet with existing facilities. The relative effectiveness of the alternatives at meeting the requirements is indicated by 0 through 3 stars as described in the table legend. The effectiveness of combinations of alternatives is generally additive. Surface Discharge Alternatives Continued Discharge to Dredger Cut. The City could continue to discharge to Dredger Cut as it currently does. The lack of net dilution in Dredger Cut effectively subjects the City to stringent discharge requirements for most constituents and parameters. Factors outside the City's control, such as low dissolved oxygen levels, would prohibit discharge at some times. Bishop Cut Outfall Pipeline. Flows in Bishop Cut are strongly influenced by tidal cycles. Water flows east up White Slough and south down Bishop Cut during a rising tide. Flows reverse during an ebbing tide. Peak instantaneous flows over a tidal cycle are about 600 cfs. In addition, there is a net flow south in Bishop Cut which coincides with the general north -south net flows across the Delta to the major diversions in the South Delta. The net flow averages about 160 cfs. Net flows are lower in summer months and are low when the State Water Project and Central Valley Project pumps are shut down for a couple weeks in Spring due to the fish migrations. Estimated net flows during these periods are about 50 to 100 cfs. Future modifications to Delta channels could also reduce net flows to Bishop Cut. Additional details are contained in the City of Lodi Outfall Relocation Study completed in May 2000 (Appendix W. Construction of a 1.3 -mile pipeline, as shown in Figure 5-1, to move the discharge to the north end of Bishop Cut would provide an estimated dilution of between 5:1 and 40:1 for the treated effluent. In combination with full nitrification treatment, this should allow the City to meet 9/18/00 Draft 5-1 Wastewater Master Plan 2131wwmp Table 5-1. Alternatives for Satisfying Municipal Effluent Discharge Requirements(a) Alternative Discharge Requirements Type of Alternative Year 2004 and Anticipated Possible Future WPCF Process Discharge Land Trt. Or Reuse DO(b) BOD Temp. Bact. Zinc NH3 Hg N P Bishop Cut Outfall Pipeline * * * * * * * * * * ✓ Bishop Cut Outfall Wetlands * * * * * * * * * * * * * * * ✓ ✓ Nitrification * * * * ✓ Tertiary Filtration and Disinfection * * * * * * ✓ Biological N Removal * * ✓ Biological P Removal * * ✓ Chemical P & Heavy Metals Removal ✓ Other Treatment Wetlands * * * * * * * * * ✓ Winter Percolation *** *** *** *** �k*yt ** ****,k , ✓ Winter Well Injection * * * * * * * * * ✓ Additional Storage * * * ✓ Source Control (a) Legend: * Helps meet anticipated and future requirements. * * Meets anticipated requirements and probably meets future requirements. * * * Reliably meets anticipated and future requirements. (b) DO (dissolved oxygen) refers to the DO of receiving waters. Discharge requirements prohibit discharge when receiving water DO is below 5 mg/L. This occurs in Dredge Cut even when the WPCF is not discharging. 9/18/00 Draft 5-2 Wastewater Master Plan 213\wwmp anticipated discharge requirements for all parameters except zinc when dilution is over 20:1. When dilution is under 20:1, tertiary filtration and disinfection are likely to be required. The extra dilution would help the City meet potential future mercury concentration limits, but potential future mass loading limits for nutrients, mercury, or BOD could be problematic. The discharge requirements specify a maximum temperature differential of 20 degrees Fahrenheit, a maximum surface water temperature change of 4 degrees Fahrenheit, and a maximum discharge zone temperature change of 1 degree Fahrenheit over 25 percent of the channel. The maximum temperature differential between treated effluent and Bishop Cut has been 22 degrees Fahrenheit. If effluent is briefly stored in the storage ponds and discharged through a well-designed diffuser when flows in Bishop Cut are over 100 cfs, the temperature requirements should be achievable. The city's existing storage ponds could be used to provide short-term storage during the slack phases of tidal cycles. Bishop Cut Outfall Wetlands. This alternative combines the benefits of extra dilution from Bishop Cut discharge with polishing treatment from a constructed wetlands. For this alternative, wetlands would be constructed between the existing discharge into Dredger Cut and a new discharge point at the north end of Bishop Cut, thereby eliminating the need for an outfall pipeline. The wetlands would provide better temperature equalization and removal of some zinc, mercury, nitrate, and any chlorine residual. The wetlands would also provide a significant amount of storage and effluent disposal/reuse capacity. Wetlands provide some pathogen removal, but tertiary treatment would probably still be required when dilution is less than 20:1. WPCF Treatment Process Alternatives Nitrification (Ammonia Removal). The treatment plant was not designed to provide ammonia removal, however it has proven to be capable of reliably removing ammonia up to a flow rate of about 6 Mgd. With recently implemented changes to the air diffusion system, the capacity of the treatment plant at full nitrification is approximately 7 Mgd. Providing treatment capacity for the conversion of essentially all ammonia to nitrate at the 8.5 Mgd Master Plan flow rate would help satisfy biotoxicity discharge requirements. Nitrification also helps to reduce dissolved oxygen uptake in the receiving waters and improve the reliability of chlorine disinfection. If direct ammonia limits are imposed in the future, nitrification would be mandatory. Tertiary Filtration and Disinfection. Coagulation, sedimentation, and filtration (or DHS - approved equivalent) followed by enhanced disinfection is required for discharge to Dredger Cut in the new Waste Discharge Requirements. Tertiary filtration and disinfection would probably also be required for discharge to Bishop Cut during at least the warm months of the year. Along with satisfying tertiary treatment requirements, filters would make it much easier to reliably meet a 10 mg/L BOD effluent discharge requirement. Filters would also help reduce TSS and heavy metals, especially if used in conjunction with the addition of aluminum or iron salts to aid coagulation. Biological Nitrogen Removal. Nitrate can be converted to nitrogen gas when there is adequate carbon in an anoxic zone in the treatment process or in percolation basin soils. This would help satisfy potential future loading limits on nitrogen discharged to surface waters. It would also help satisfy limitations on nitrate loading to groundwater under fields or percolation basins. 9/18/00 Draft 5-3 Wastewater Master Plan 2131wwmp 0 toxo " 4000 N WALE IN FEET Figure 5-1 City of Lodi Wastewater Master Plan W $ 8 T Bishop Cut Outfall Ybm Pipeline Alternative & Tm O' •�` O. :,--, III al .1 - L 14 1 +: .S w. -ice KINGDON BM 4 c'•' , Umping Station R a J �• � � ♦ilk` : � •- 1.. �'' g �1\ .: �4 t •. 23 T R A C T<` controI PAMC ' \ � "•�` '?, \,, �. `• ...__ . tom- .. __r:y " ` t �1 � Pum m Pumping•,,, Station ��, � Mdsting I -�" _ _C. .1G - - Discharge" M:'.'.,�`.. Location ' outSOLU IPipeline '- Aeration 0, 26 _ . .. y . z i • ; Discharge RA 0 'a B I. '•.A N C O'.� . 1 :< =a 3=_- � .- =-d eve d_'J3 �3' •t-, as____r_ _____�� mping •�tanon T M. A•. C s, -. ...� i ---- -_ , ,r: BM -3 _ .J PGmpmg �otida ; - --- I L it[. 1Stet-0ngr----------- n. 1 m I l• 0 toxo " 4000 N WALE IN FEET Figure 5-1 City of Lodi Wastewater Master Plan W $ 8 T Bishop Cut Outfall Ybm Pipeline Alternative & Tm Biological Phosphorous Removal. Biological uptake of phosphorous is an unintended feature of the current secondary treatment process of the WWTP through the use of an anaerobic selector zone. The successful operation of an anaerobic selector may need to be continued to help satisfy potential future loading limits on phosphorous. Chemical Phosphorous and Heavy Metals Removal. The addition of aluminum or iron salts into or after the secondary process would remove phosphorous and particulate associated heavy metals through precipitation and enhanced removal of suspended solids. Land Treatment and Reuse Alternatives Wetlands Treatment. Wetlands could be constructed on land near the treatment plant. Wetlands could provide polishing treatment for secondary effluent from the treatment plant, including temperature equalization and removal of zinc, mercury, nitrate, and chlorine residual. The wetlands would also provide additional storage and effluent disposal/reuse capacity. Winter Percolation Disposal. Some of the soils in the area are relatively sandy with moderately high permeability. It may be possible to utilize fields with little or no slope for percolation disposal of effluent during late autumn and winter months. Improvements in field leveling, groundwater level control, runoff -return systems, and/or containment berms would be required for this alternative. If successful, this alternative would eliminate discharge to surface waters and all the associated discharge requirements. The major remaining concern would be a potential increase in nitrate loadings to groundwater. This could be minimized through percolation disposal operational techniques and/or treatment process modifications. Additional land would need'to be purchased or leased with this alternative. Winter Well Injection/Saltwater Intrusion Barrier. Another alternative for winter disposal could be well injection of tertiary treated effluent to prevent saltwater infusion from the west. This is currently being practiced in Orange County. Significant geological and funding issues would need to be addressed before this alternative could be compared with other alternatives. Additional Storage. If the surface water discharge point continues to be in Dredger Cut, all effluent will have to be stored or reused during periods of time when the dissolved oxygen level in Dredger Cut falls near or below 5.0 mg/L. Storage ponds could also reduce the temperature of effluent during winter months so that temperature related discharge requirements could be satisfied. Some additional effluent storage may be desirable to provide flexibility for properly managing irrigation reuse operations. Source Control Source control will need to be an element of the City's wastewater management program regardless of the final disposal location chosen for the effluent. Current water quality control legislation requires that dischargers take all reasonable measures to reduce the concentrations of trace toxins regardless of whether or not an actual problem has been observed. Since the concentrations of these constituents are so low, end of pipe treatment systems are costly and often of little effectiveness. For purposes of this report, however, efforts substantially beyond traditional source control measures are listed as "source control" for the reduction of zinc concentrations. It may be possible to identify some of the sources of zinc and other heavy metals 9/18/00 Draft 5-5 Wastewater Master Plan 2 Mwwmp through upstream sampling programs. There is some preliminary data indicating that elevated levels of zinc may be coming from older areas of town (galvanized water pipes) and from industrial sources. If the sources can be positively identified, the concentrations of zinc and other metals could be reduced through changes at industrial sources or water system operational changes. Water system operational changes could include minimizing the run time of the wells which produce the most aggressive water as measured by the Langlier Index. Other potential changes could include adding calcium or phosphate compounds at wellheads to reduce corrosion of galvanized pipes. Mercury levels may be reduced as a result of the source identification and reduction program recently initiated by the City. Current levels may be reduced through the installation of amalgam recovery systems in district offices and florescent tube and thermometer collection program. Combinations of Alternatives to Satisfy Requirements Combinations of discharge, process, and/or land treatment alternatives will be needed to satisfy all the anticipated and potential future discharge requirements listed in Table 5-1. The apparent reasonable combinations of alternatives are listed in Table 5-2. Table 5-2. Apparent Reasonable Combinations of Alternatives 9/18/00 Draft 5-6 Wastewater Master Plan 213\wwmp Discharge Facilities Needed for Possible Facilities Needed for Combination Point Anticipated Requirements Potential Future Requirements(' DC -D Dredger Cut — Additional Storage Biological N Removal Direct Nitrification Biological P Removal Tertiary Treatment Metal Salts Addition Source Control DC -W Dredger Cut — Additional Storage Biological P Removal Wetlands Nitrification Tertiary Treatment Wetlands BC -D Bishop Cut — Outfall Pipeline Biological N Removal Direct Nitrification Biological P Removal Tertiary Treatment Metal Salts Addition Source Control BC -W Bishop Cut— Outfall Wetlands Biological P Removal Wetlands Nitrification Tertiary Treatment BC -PD Bishop Cut — Percolation Basins and Fields Biological P Removal Partial Discharge Nitrification Metal Salts Addition Biological N Removal(') Source Control BC -PW Bishop Cut— Percolation Basins and Fields Biological P Removal Partial Discharge Nitrification with Wetlands Biological N Removal(') 9/18/00 Draft 5-6 Wastewater Master Plan 213\wwmp LD Land Discharge Percolation Basins and Fields Nitrification(`) Biological N Removal(b) ca) The existing plant already has excellent biological P removal even though it was not specifically designed for P removal. This process feature may be useful for satisfying future requirements and should be specifically considered in capacity expansion alternatives. (b) Wetlands could be substituted for biological denitrification in treatment process tanks. Some denitri- fication can occur in the percolation basin soils. Nitrification may not be mandatory depending upon percolation basin design and operation. Alternatives for seasonal discharge of secondary treated effluent to Dredger Cut were also considered and evaluated in some detail. However, the original assumption behind these alternatives was that only a secondary level of treatment would be required during months when contact recreation and agricultural irrigation using water from Dredger Cut were considered unlikely. After extensive discussions with Regional Board staff, it was apparent that long term discharge of any secondary treated effluent to Dredger Cut would not be allowed under the new permit. These alternatives also would have required large amounts of additional land and storage. Therefore these alternatives were dropped from further consideration. Construction of the Sports Complex does not significantly affect the combinations of alternatives required to meet municipal effluent discharge requirements because the majority'of the treated wastewater will still have to be discharged or reused somewhere else. If the Sports Complex covers the cost of tertiary filtration and disinfection for a portion of the flow, it could affect the net costs to the City for some of the combinations of alternatives. This will be addressed later in Section 13—Evaluation of Treatment and Disposal/Reuse Alternative Combinations. SATISFYING OTHER DISCHARGE REQUIREMENTS Municipal Effluent – Animal Feed Crop Irrigation The anticipated and potential future requirements for animal feed crop irrigation can be reliably met with existing treatment processes. Municipal Effluent — Unrestricted Irrigation Unrestricted irrigation reuse of municipal effluent for the proposed sports complex or other uses will require tertiary filtration and enhanced disinfection. The reasonable filtration alternatives are: • Sand filters • Membrane filters • Synthetic compressible medium (fuzzy) filters Disinfection alternatives include: • Gas chlorination • Liquid chlorination (hypochlorite) • Ultraviolet disinfection 9/18/00 Draft 5-7 Wastewater Master Plan 213%wwmp These filtration and disinfection alternatives are discussed in greater detail in Sections 11 and 13. Industrial Wastewater Discharge to Land Since all industrial wastewater (which is primarily cannery waste) is land applied, the discharge requirements are related to the prevention of nuisance odors and adverse impacts to groundwater. The anticipated discharge requirements can be met with some changes in cropping patterns and assuming no loss of land to the Sports Complex. Additional land and better distribution facilities would improve operations and enable potential future requirements to be more easily satisfied. Additional solids removal prior to land application, using screens or dissolved air flotation, could also reduce the potential for nuisance odors. Improvements to industrial wastewater disposal/ reuse facilities are discussed in greater detail in Section 8. Biosolids Disposal/Reuse Current and anticipated biosolids discharge requirements can be satisfied with existing facilities. The loss of land to the Sports Complex could limit flexibility in future biosolids disposal/reuse operations. Improvements in mixing with municipal and industrial effluent and/or distribution improvements would help satisfy potential future discharge requirements for land application of Class B biosolids on City -owned property. These improvements are discussed in Section 9. 9/18/00 Draft 5-8 Wastewater Master Plan 213\wwmp SECTION 6. EVALUATION CRITERIA This section presents the criteria which were developed for the evaluation of treatment and disposal/reuse alternatives. These criteria were developed together with Lodi City staff and the Public Advisory Committee to be representative of a wide spectrum of interests. ECONOMIC CRITERIA—COST Life cycle costs are typically one of the most important considerations when comparing alternatives. Life cycle costs include the capital cost of improvements plus the present worth of future operations, maintenance, and other recurring costs. A discount rate of 7 percent for a 20 -year period was selected for life cycle cost calculations in the wastewater master plan evaluations. SUBJECTIVE CRITERIA General Subjective criteria are criteria which cannot be easily quantified in terms of direct or indirect costs, yet have a significant effect on the overall success of an alternative. These criteria will be evaluated subjectively for each alternative where they are relevant. The results of the evaluation of subjective criteria will then be used to choose from alternatives which are similar in terms of life cycle costs. Compliance with Potential Future Discharge Standards Compliance with current and anticipated discharge standards is mandatory. This requirement has already been used to screen alternatives in Section 5. The ability to satisfy potentially more stringent future standards is a desirable feature for an alternative and was used as a subjective evaluation criterion in this study. Reliability Reliability refers to the anticipated reliability of major equipment and processes. Reliability is important not only for minimizing operations and maintenance costs, but for assuring that discharge requirements will not be violated. Processes that have a proven track record are generally considered more reliable than new or experimental treatment methods. Processes or combinations of processes which provide redundant capacity or storage will also contribute to better reliability. Flexibility Flexibility refers to the ability to meet future conditions that are now undefined and may change over time. For example, if influent concentrations of key constituents change significantly or if discharge requirements change in an unexpected manner, flexibility refers to how easily those 9/18/00 Draft 6-1 Wastewater Master Plan 213\wwmp changes could be handled using the proposed facilities or through minor modifications. The ability to increase capacity through simple, inexpensive modifications also indicates a high degree of flexibility. In addition, flexibility refers to how well major equipment or processes would perform during temporary downtime of related equipment or processes. Ease of Operation and Maintenance Ease of operation refers both to the operation and maintenance of individual equipment or processes as well as the coordination of multiple related processes. Processes which are conceptually simple, more stable, and/or require less operator intervention will generally be rated higher in terms of ease of operation and maintenance. Ease of Implementation Ease of implementation can sometimes be partially quantified in the estimated capital cost of alternatives. However, it is very difficult to estimate the extra management and overhead costs associated with alternatives which are difficult to implement. The ability of a given alternative to be completed in a timely manner and begin operation will be evaluated in regard to potential political constraints, requirements to negotiate agreements, land purchase, construction concerns, difficulties in implementing new technology, and any other similar factors which could affect its successful completion. Environmental Impacts or Benefits This criteria includes any significant negative impacts or positive benefits that could result from the implementation of each process alternative. This generally refers to factors beyond those addressed in the anticipated discharge requirements such as wildlife habitat benefits, improvements over background water quality, reductions in dust, etc. Safety The relative safety of an alternative is related to its potential to cause serious injury in the event of an equipment failure or operational error. Safety applies both to risks to treatment plant staff and to the general public who may be near the treatment plant. Potential Recreational/Open Space Benefits This criteria refers to any benefits that could be realized by the public as incidental aspects of project implementation. This could include bird watching features, educational features, community recreational areas, and other benefits. Aesthetics Aesthetics include considerations such as visual appeal, odors, noise, and traffic impacts. Aesthetics will be used to apply to new physical facilities so as not to be confused with Recreational/Open Space Benefits. 9/18/00 Draft 6-2 Wastewater Master Plan 2131wwmp DRAFT Secondary Economic Benefits There are secondary economic benefits or impacts to some of the potential alternatives for effluent disposal/reuse. This could include factors such as additional farm income in the area or additional employment opportunities or taxes from businesses using reclaimed water. Resource Management Considerations This criteria refers to the overall best use of resources managed by the wastewater treatment department. This would include the use of fresh water, treated effluent, biosolids, energy, and land. RELATIVE WEIGHTINGS OF CRITERIA The relative weightings of the evaluation criteria were discussed in meetings with.City staff and the Advisory Panel. The consensus relative weightings developed in these meetings were as shown in Table 6-1. Table 6-1. Subjective Criteria Weightings Criteria Relative Weighting Compliance with Potential Future Discharge Standards 1.5 Reliability 1.5 Flexibility 1.5 Ease of Operation and Maintenance 1.0 Ease of Implementation 1.0 Environmental Impacts 1.0 Safety 1.0 Potential Recreational/Open Space Benefits 0.5 Aesthetics 0.5 Secondary Economic Benefits 0.5 Resource Management Considerations 0.5 The weightings shown in Table 6-1 will be used in the evaluation of alternatives for later Sections of this Master Plan Report. It should be noted that not all criteria will necessarily be applicable to every set of alternatives. While there is no firm standard for evaluation criteria or the weightings of criteria, these relative weightings are reasonable in comparison to criteria and weightings used for other similar projects. 9/18/00 Draft 6-3 Wastewater Master Plan 213\wwmp SECTION 7. WETLANDS TREATMENT INTRODUCTION Constructed wetlands offer the potential to provide polishing treatment, effluent reuse, and storage. The purpose of this section is to provide an initial evaluation of the appropriateness of wetlands for the Lodi wastewater system. Hydraulic loading and balancing issues are discussed subsequently in Section 8. The combined treatment and disposal/reuse train alternatives are evaluated in Section 13—Evaluation of Treatment and Disposal/Reuse Process Train Alternatives. BACKGROUND Constructed wetlands consist of horizontal flow treatment units with treatment occurring as the wastewater passes slowly through emergent vegetation. Free water surface (FWS) wetlands with water levels ranging from 1 to 2 feet deep are the most common type of constructed wetland and the most appropriate for the City of Lodi. FWS wetlands can be designed for removal of BOD, TSS, nitrogen, heavy metals, or for temperature reduction. FWS wetlands can also serve to dechlorinate an effluent that has been chlorinated for pathogen destruction. A schematic of a FWS constructed wetlands that includes open water zones is shown in Figure 7-1. The advantages of constructed wetlands are their low cost of operation, their ability to accept a range of peak flows and variations in loadings, and their attribute as wildlife habitat. Constructed wetlands can provide relatively high water use, nitrate -nitrogen removal treatment, heavy metals removal treatment, and temporary water storage. The water level in wetlands can fluctuate from 0.5 to 3 feet to provide storage capacity. The primary disadvantages of wetlands are relatively high initial cost and no crop revenue. Other disadvantages include limited nitrification potential and the need to manage the propagation of mosquitoes. The effluent from constructed wetlands is often low in dissolved oxygen as a result of the reducing conditions in the wetlands. AREA REQUIREMENTS FOR WETLANDS Each of the treatment objectives discussed in Section 5 – metals removal, temperature reduction, and nitrate reduction – require different detention times. Metals removal requires the longest detention time, which determines the land area required. Based on a flow of 8.5 mgd, the area required is 130 acres for roughly a 50 percent removal of zinc. For nitrate reduction, as preliminary treatment prior to irrigation or recharge, an area of 65 acres would be sufficient. Area for berms, roads, and setbacks should be added to the field area calculated. WETLANDS PERFORMANCE CHARACTERISTICS Water Use Constructed wetlands consist of a combination of open water (20 to 30 percent) and dense emergent vegetation (70 to 80 percent). As a result, the water use or consumption of a 9/18/00 Draft 7-1 Wastewater Master Plan 2l3%wwmp OZ ' :x BODf r•{.1'J� HZO Wind ••-� �. ,1 meqq; ''-} I�� -- . c Open Water Zone Emergent r j,:f 024-. NZ. ' Atgoe DeposRion NMA - � A POLE ,,,- constructed wetlands can be estimated by using an open water evaporation rate. Assuming a net evaporation of 3 ft/yr, the 130 -acre constructed wetland would use 390 acre-ft/yr. Storage Capacity Constructed wetlands typically operate at a depth of 1 to 1.5 feet. Shallower depths require more land for the same detention time and deeper depths will affect the emergent vegetation. During the winter months (say November through March) or for shorter durations other times, the bulrush can tolerate periodic inundations of up to 2.5 to 3 ft deep. The dormant season storage can then be expected to be 1.5 acre-ft/acre of wetlands. Temperature Reduction Wetlands can reduce the temperature of the wastewater by a combination of shading and atmospheric cooling. The effluent cooling effects are greatest in the winter when the difference between average ambient air temperature and the wastewater temperature is the greatest. At Sacramento County's Demonstration Wetlands, the winter temperature loss through the wetlands averaged 107. During summer months the difference dropped to 2.2°F. An initial gradient of temperature loss of —3°F per 100 ft was reported for the pilot wetlands configuration of the Sacramento Regional Wastewater Treatment Plant. For the 5 -day detention time wetland in Lodi, a reduction of 8 to 10°F can be expected in the winter months and a 2 to 3°F drop in the summer temperature can be expected. This would allow the temperature differential requirements to be met for discharge to Dredger Cut. Nitrate Removal Nitrate removal by denitrification can be achieved through constructed wetlands with detention times of from 2 to 3 days. The nitrate levels created by in -plant nitrification can be reduced in the wetlands because of the anoxic conditions prevalent in free water surface constructed wetlands. Metals Removal Metals are removed in constructed wetlands by a combination of plant uptake and burial in the root zone, precipitation, adsorption, and complexationt. The removal of metals in free water surface wetlands was studied over five years at the Sacramento Regional CSD Demonstration Constructed Wetlands project in Elk Grove. The removals of six key metals are summarized in Table 7-1. Table 7-1. Removal of Metals in Constructed Wetl2nds2 Metal Influent, ppb Effluent, ppb Percent Removal Cadmium 0.25 0.03 87 Copper 7.44 3.17 57 Mercury 10.77 ppt 4.01 ppt 63 Lead 1.14 0.23 80 Nickel 5.80 6.84 -18 Zinc 35.8 6.74 81 9/18/00 Draft 7-3 Wastewater Master Plan 2131wwmp 1t The removals presented were obtained using secondary effluent with a detention time of 7 to 10 days. The only major metal that resisted removal was nickel, which was 80 percent in the dissolved form and not readily removable. BOD and Suspended Solids Polishing BOD and TSS removal in constructed wetlands can be achieved in relatively short detention times. Secondary effluent can be polished down to the 10 to 15 mg/L level. Plant upsets can be absorbed by the wetlands without adverse effects on the wetlands effluent. Pathogen Removal Typical removal of influent pathogens and indicator organisms in constructed wetlands is one to two logs. Die -off and predation occur in wetlands at rates similar to facultative ponds. Fecal coliform removals at Arcata ranged from 80 percent in the winter to 95 percent in the summer. At Listowel and Iselin, 99.9 percent removal of fecal coliforms were reported'. Wildlife in wetlands contributes a baseline level of coliform bacteria which is not easily distinguished from human pathogens in the standard tests. So although wetlands remove human pathogens from wastewater, this removal is not easily measured or given numeric credit by regulatory authorities. Disinfection prior to or after wetlands is usually required to meet California standards for discharge or reuse. If disinfection is prior to the wetlands, the point of compliance for disinfection standards can be applied at the outlet of the disinfection facilities. Dechlorination Established wetlands have substantial amounts of available carbon. Free chlorine residual is readily removed from the water column by reaction with available carbon. Wetlands can serve as an effective buffer to assure complete dechlorination after conventional dechlorination with sulfur dioxide or sodium bisulfite. This would allow conventional dechlorination to be performed without worrying about maintaining an excess of dechlorinating agent and with a greatly reduced risk of receiving water impacts in the event of equipment or control system failure. WETLANDS SITE ALTERNATIVES Wetlands alternatives were developed for combined polishing treatment, effluent disposal/reuse, and storage. The wetlands site alternatives are: • Use of the existing DWR wetlands • Construction of new wetlands north or east of the City's current irrigation area • Constructed wetlands immediately west of the treatment plant • Outfall wetlands constructed south of Dredger Cut on the Rio Blanco site Use of Existing DWR Wetlands An existing wetlands site northwest of the treatment plant has been considered for potential use as a wastewater treatment option. The site is parallel to the High Line Canal and the alignment of 9/18/00 Draft 7-4 Wastewater Master Plan 2131wwmp the Peripheral Canal and Highway I-5. The California Department of Water Resources (DWR) controls the land. Dave Brown from DWR indicated that the site is earmarked for either water conveyance (canal) or for mitigation. Neither use seems compatible with Lodi's wastewater treatment goals. The wetlands are considered waters of the state and therefore would require that effluent water quality be similar to that in a surface water discharge. Constructed Wetlands North/East of the City's Current Irrigation The farmland to the east of the DWR wetlands could be converted into a constructed wetland for wastewater treatment. The benefits of this site would be compatibility (sharing of edges) with the existing DWR wetlands, treatment capability for denitrification, temperature reduction, and metals reduction. The site would be converted to a free water surface constructed wetland by creating berms, open water areas and deep water (>3 ft) areas. For treatment of 8.5 mgd, the net wetland treatment requirement would be approximately 130 acres assuming that zinc removal is the most restrictive factor. Treated effluent from the wetlands could be discharged or used for irrigation or aquifer recharge/recovery. Constructed Wetlands Immediately West of the Treatment Plant A small (50 — 100 acres) wetland could be constructed immediately west of the treatment plant on land currently irrigated with reclaimed water. This location would be easy to accommodate hydraulically because it could be gravity -fed from the treatment plant. Effluent' from a constructed wetland at this location could be easily returned to the storage ponds for subsequent conveyance to percolation basins or fields. A small wetlands would still provide adequate denitrification, but would provide proportionately less zinc removal and temperature equalization than a 130 -acre wetland. Outfall Wetlands Constructed South Of Dredger Cut On The Rio Blanco Site The use of constructed wetlands at this site would allow a surface discharge into Bishop cut without the cost of an extended outfall. The influent to the wetlands would flow into the eastern edge of the wetlands, as shown in Figure 7-2, and treatment would occur as the water moved westward through the wetlands, ending up at a lift station next to Bishop Cut. Reaeration would be provided by pumping the effluent over a cascade aeration system. COST OF CONSTRUCTED WETLANDS Typical costs per acre of FWS constructed wetlands can range from $20,000 to $40,000/acre depending on the site work, need for liners, interior berm spacing, and planting density. The three sites are relatively level so that site work would not be extraordinary. With the application of secondary effluent, there should not be a need for artificial liners. To minimize the planting costs it is recommended that the wetlands be planted in strips perpendicular to the flow path, with unplanted and open water zones in between the planted areas. The planting would consist of cattail seeding and a moderate amount of transplanted bulrush. The shallow unplanted areas will be readily colonized by the bulrush that are transplanted. For the Rio Blanco site the cost should be about $20,000 to $25,000/acre without land costs. 9/18/00 Draft 7-5 Wastewater Master Plan 2131wwmp 0 a n c c v n a 3 L; LL L' L White Slough Wildlife Area (DWR) Northern Alternative Wetlands Site Rio Blanco Alternative ' Wetlands Sites Immediate West Alternative Wetlands .c;+ - Figure 7- 2 City of Lodi Wastewater Master Plan W E S T Wetlands Site Alternatives Ymm & AssocurIM iti2., �� 1 I I ' 1 .� � • i j• 1 : � ..fo.; iii - - - --- - -�•a== �- _ z J� I. _______-- --_ -- w �-, -" j ti 6 t V, • KINGDDN • d RGWD n I • � I : e1C� W s?% - �` is - - „•\ � - � \ i _. _. ---- - --I � ' T R A C T:\-' F - - -- �� 23 a• f � �.\ ,i\ _ '�i � • _ ,gyp 24 1 0 ' 1000 t 2000 WALE IN FEET t •.. a h Se Pumping \ t PumpY . ----- --- ----- — ego �.� ila, •' _ _ ,�, ! "' Constructed ` ,\ BM 7­r',l (jdjt..:..p'iijlljt. •'.`��'Alll[r.'.;,-:'.'. \ r w 4 . Aerati rj' ilk. • ..`... •�, z --_ ._._tilt - ... ......ri, .....:.... vs. .. �\ •'� ! Discharge3, ' °I I � ,'��•�f�� ... �, \l � ,,\ • ;� m I I. •�1� R : I 0 '' B L �A N y; umping i !IR I 25 .gtation T A C T. N k''. A i� ♦-f kill .�swiio! swellf8l PuMpiqg White Slough Wildlife Area (DWR) Northern Alternative Wetlands Site Rio Blanco Alternative ' Wetlands Sites Immediate West Alternative Wetlands .c;+ - Figure 7- 2 City of Lodi Wastewater Master Plan W E S T Wetlands Site Alternatives Ymm & AssocurIM Special Wetlands Funding Sources Special funding sources exist for the construction of wetlands to increase the acreage of habitat for wildlife. Agencies and organizations that have funding programs for the development of wetlands include the Natural Resources Conservation Service, U.S. Fish and Wildlife Service, the State Department of Fish and Game, and CALFED. Ducks Unlimited supports many wetlands development projects, but usually is fully consumed with large fresh -water wetlands projects. EPA has some wetlands grants available through the Association of Metropolitan Water Agencies (AMWA). Drinking water suppliers are eligible to receive the grants, which are to be used to establish new wetlands programs or refine existing ones. The USF&WS has a partners program that supports wetlands enhancement and development. ENVIRONMENTAL BENEFITS OF WETLANDS The environmental and community benefits that come with constructed wetlands include wildlife habitat, recreational benefits from bird watching and hiking, and educational benefits to school groups and community groups that can visit the wetlands. Wildlife habitat includes that for song birds, ducks, and geese. Audubon Societies are often the strongest supporters for the development of constructed wetlands. WETLANDS MANAGEMENT ISSUES To manage a constructed wetlands requires attention to the flow path (avoiding short-circuiting), attention to the vegetation and berms (controlling any burrowing animals or pests), and control of mosquito production. Mosquito control requires multiple management techniques and frequent sampling during the April through October time frame. Management techniques developed in the 5 -year demonstration wetlands at Sacramento County include introduction of mosquitofish, the use of BTI or other bacterial parasites, and encouragement of natural predators. Harvesting of vegetation is not generally required except as needed to allow mosquito control practices. CONCLUSIONS Constructed wetlands offer potentially significant benefits in the overall treatment and disposal/reuse system. The Rio Blanco site is the most promising in terms of benefits versus cost if treated effluent is to be discharged to Bishop Cut or Dredger Cut and 50 percent zinc removed is a design criteria. For the Land Discharge alternative, a wetland located immediately west or north of the existing treatment plant would provide denitrification, disposal, storage, and environmental enhancement benefits closer to the best irrigation reuse and percolation disposal areas. Combined treatment and disposal train alternatives which include wetlands alternatives are evaluated in Section 13. If the need for zinc removal is reduced through source control or tertiary treatment, a smaller wetland (65 acres) immediately west of the treatment plant or on the Rio Blanco site would be preferred. 9/18/00 Draft 7-7 Wastewater Master Plan 2 ] 3lwwmp DRAFT REFERENCE ' Crites, R.W. and G. Tchobanoglous. Small and Decentralized Wastewater Management Systems. McGraw-Hill. New York. 1998. 2 Nolte Associates, Executive Summary, Sacramento Constructed Wetlands Demonstration Project, Five -Year Summary Report, 1994-1998. January 2000. 9/18/00 Draft 7-8 Wastewater Master Plan 2131wwmp SECTION 8. INDUSTRIAL WASTEWATER TREATMENT AND DISPOSALIREUSE INDUSTRIAL SOURCES Some industries discharge to a segregated industrial wastewater line that enters the White Slough wastewater treatment facility adjacent to the domestic line. This wastewater is then pumped to the distribution system for direct application to farmlands. Approximately 95 percent of the industrial wastewater flow comes from Pacific Coast Producers (PCP). The remainder comes from M&R Packing and several small manufacturers. PCP processes apricots, peaches, and tomatoes for a variety of canned products. The processing season begins in early Summer with apricots, then peaches and tomatoes, with the peak flows generally occurring in August of each year. There is little or no wastewater flow during the remainder of the year. During 1998 and 1999, flow rates from PCP were higher than in past years. The flows during the last three years are shown on Figure 8-1 (identical to Figure 3-10). The 1999 increase was due to an expansion of tomato processing facilities and the corresponding increase in tomato processing wastewater flow. PCP plans to increase its recycled flows prior to the 2000 season in order to obtain a one million gallons per day (1 Mgd) reduction in wastewater flows. PACIFIC COAST PRODUCERS WASTEWATER SOURCES AND PRETREATMENT Pacific Coast Producers wastewater comes from the following sources: 1. Washwater from washing and transporting incoming fruit and vegetables 1. Boiler blow down wastewater 2. Wastewater from caustic peeling of apricots, peaches, and tomatoes 3. General factory washdown water The washwater from the incoming product area is treated in mud removal chambers to settle and remove some waste material. The collected mud is placed in a container for off-site disposal. This wastewater source is high in fine suspended solids. Boiler blow down wastewater is low in suspended solids and BOD but can be high in total dissolved solids (TDS). Wastewater from the peeling operation varies depending on the type of peeling operation employed. Apricots and peaches are peeled using a caustic peeling system. Tomatoes are peeled using either a caustic peeler or steam peeler. Both peeling operations produce a wastewater high in suspended solids and BOD. The caustic peeling operation produces a wastewater that also has high concentrations of both TDS and sodium. The average TDS, total fixed dissolved solids (TFDS), and pH values for the 1998 season were 1,369 mg/L, 717 mg/L, and 9.8, respectively. The mineral salinity as measured by TFDS is moderately elevated, and the pH is relatively high. TFDS and sodium are undesirable in land-based wastewater treatment systems where crops are grown. Sodium will cause infiltration rates in clay soils to become so low that water will not penetrate the soil surface. High TFDS levels in soils and 9/18/00 Draft 8-1 Wastewater Master Plan 2 l 3lwwmp 160 140 120 s r c 0 E 100 d a a c 0 m 80 c 0 E 60 3 0 LL 40 20 761 FIGURE 8-1.1997 -1999 AND PROJECTED INDUSTRIAL WASTEWATER FLOWS Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month West Yost & Associates Lodi Wastewater Master Plan allflows indflows 5/18/00 water will cause crop damage. No problems associated with elevated levels of TFDS and sodium have been observed to date. TDS is not an accurate measure of salinity for food processing wastewater because it includes organic compounds which break down when treated or applied to land. Pretreatment has historically consisted of parabolic screens (0.020 -inch openings) to remove solids. The parabolic screens were enlarged this past summer. During the 1999 processing period, abnormally large quantities of solids were observed in the wastewater from the tomato processing. It was later discovered that the new screen had slipped in its frame leaving a gap where solids discharged directly into the effluent channel. This problem was corrected by fixing the screen. Solids coming off the screens enter a conveyor system that discharges the solids into a container for off-site disposal. With the plant expansion this past summer the conveyor system was sometimes overloaded and solids fell into the effluent channel, thus defeating the purpose of the screening system. During the processing season (1999), PCP installed pH adjustment and recycling systems to handle wastewater from the caustic peeler for the tomato processing. These systems convert the peeler wastewater to a neutral water supply high in salt that is then used in canned tomatoes as a salt source. Installed late in the 1999 season, the operation of this system still requires some adjustment. Full utilization of this system will greatly reduce TFDS and sodium discharged to the City. The water supply/recycling system was modified to recycle approximately 1 Mgd of wastewater for washing incoming fruit and tomatoes. Fresh water and other recycle streams are all routed to a sump that has several pumps that deliver water to a variety of destinations. The modification made to recycle the additional 1 Mgd of wastewater did not work and has not been used. PCP is re -designing a new system to achieve the recycling goal. EXISTING INDUSTRIAL WASTEWATER TREATMENT SYSTEM AT WHITE SLOUGH The treatment and disposal system at the White Slough facility is the simplest, most economical system that could be employed to treat and dispose of cannery wastewater. The reason for this is that there are no mechanical treatment processes to operate and maintain. Cannery wastewater is not treated at White Slough other than by coarse screening to remove large solids. The wastewater is directly applied to the farmland owned by the City surrounding the White Slough facility. The individual field designations and sizes are shown on Figure 8-2. Alfalfa and feed corn are grown during the summer months with oats or small grains grown on the corn ground during the winter months. If not controlled, excessively high solids concentrations or high TDS levels will create problems for a system of this type. The high solids will results in odors in the fields and/or crop damage where the irrigation water first enters the fields. Effective screening systems at the cannery will be adequate to prevent this from occurring. As pointed out above, there were excessive solids found entering the system from PCP during the summer of 1999. The excessive solids were a result of a misaligned parabolic screen and spillage of solids from the conveyor system removing the solids from the 9/18/00 Draft 8-3 Wastewater Master Plan 2131wwmp E Q N 0 0 m v u a a u n z CL U CIL 0 In c 3 4 4 a i ,i �: '_--__��r-._�.s + OGARD St tin '� \ ' p D 1�AIE8 I W G CLX' �.. �� SANDY I Z ecu LOAttA, LOAM .. ice,3 RO --WAYL sic ROAD � 11ac 1A IS VAI 37ac _ I a E E 1D 55ac lac i EF Sac t i — i `4A 2423f aC 3A; ,,;t° 4B �I,. a n a i \ 5 [ 36ac ? 2A 3a. r.;;1 M:i, 4 22ac ( I ,e \ "� - -... i:..., r 4C - v a •$ t'. ) Q \ 16a S •i Q ',- 32ac ,`s ,t autl, 4D ` , v. C a I ,w \ , . . c 49ac To 20ac , Pumping AD" a mP g I . t tab 2C4E I ps�s rt i,' I i- Pumping c' t` Station ,;\ 37ac5aC t I V. , 43ac 430, % 45 c 45a 5ad 40aC �� II ' 35ac Z r. _ .�:. 'Neil 4. j' `;• f `. 35ac i Oa BA 6 6C 6D I ,6�. 6F Sac'. R ; I 0 B L .A N ,CYO' ''�. ', ` 5B 15'C 5D.� ,5E 5�5 6 ,StationTIR A L T y )n y `� : \� ;;j GUARD DEVRI1S°'ti, CLAY SANDa'ti 1 `' a LOAM LOAM j �> % V . it5.`it' � is � : SWPAn i "�• - —°- ...—.. io � Puh10.1n@ " 1~ dl Stdtl i ` , stat .., p 0 1000 2000 N SCALE IN FEET Figure 8-2 City of Lodi Wastewater Master Plan Existing City -Owned Fields W E 8 T bm y0 8 T r ANOCasa screening system. The miss -alignment was repaired. The conveyor system still needs modification. The problem can be solved by enlarging the conveyor and by covering the effluent channel so that spilled solids are routed to the pump sump rather than to the effluent channel. During the summer of 1999 alfalfa production was impacted due to too much water in the root zone causing root rot and other root damage. The damage was caused by extended periods of an anaerobic soil condition. The anaerobic condition was caused by excessive water in the root zone (alfalfa roots can be as deep as 6 feet and are very sensitive to extended periods of excessive moisture). This problem was due to a number of factors, one of which was over -irrigation when the farmers had to add treated wastewater to dilute the cannery wastewater. With the improved solids removal at the PCP facility, the wastewater should not require as much dilution, thus reducing the total amount of water applied to the crops. Direct application of cannery wastewater is a very efficient and cost effective means of treatment and disposal. Misapplication or over -application can result in development of odors and crop damage. To prevent these developments, application rates are set based on BOD loading. The loading rate is set to match soil type. The BOD limitation is based on the rate that oxygen can be transferred to satisfy the demand of the aerobic bacteria in the soil. If the oxygen transfer is limited, anaerobic conditions may develop leading to odors. The following oxygen diffusion model estimates the maximum oxygen diffusion rate to the soil for one day after waste application (Overcash and Pal, 1979). This equation can be used to calculate allowable BOD loading rates for land application of wastewater. where: N 02 = 2(C 02 - C p )[DT/ 7t ] 1/2 = 80 g/m2/d = 7141bs/ac/d Nox = the flux of oxygen crossing the soil surface, ML Coe = vapor phase 02 concentration above the soil surface = 300 ppm Cp = vapor phase 02 concentration required in the soil to prevent adverse yields or root growth = 140 ppm T = time over which diffusion is occurring, 1 day D = effective diffusion coefficient D = 0.6(S)(Do, ) where: S = air filled soil pore volume at field capacity Doe = oxygen diffusivity in air = 1.6m2/d 9/18/00 Draft 8-5 Wastewater Master Plan 2 Mwwmp There are two predominant soil types on the City -owned land surrounding the wastewater treatment facility. They are Devries sandy loam and Guard clay loam. Estimated allowable organic loading rates for these two soils calculated using the above equation are shown in Table 8-1. Table 8-1. Allowable BOD Loading Rates These loading rates are based on the assumption that the application is made with a number of days of rest in between applications. For tilled soils the application should be made with a minimum of three days rest between applications, and land should be disced after the soil has dried adequately to support tractor and tillage implements. Applications on the alfalfa or corn fields should be made with a 10-14 day rotation as is practiced in conventional agricultural operations. The allowable application rates determined by the above formula are the average amounts applied over the entire period. Instantaneous daily application rates will be much greater. Experience with other sites has shown a maximum 2,000 lb/ac/day on one day will not create odor conditions as long as the average value does not exceed the recommended one. It is also important to consider the effect of the BOD loading rates in conjunction with the hydraulic loading rates, especially for crops which are somewhat sensitive to suffocation such as alfalfa. This was evaluated during the 1999 season when the hydraulic application rate of combined industrial and domestic effluent exceeded the hydraulic capacity of the irrigated acres, resulting in some crop damage and odors. The loading rates in Table 8-1 are only appropriate for crops which are irrigated at rates which meet, not exceed, evapotranspiration requirements. With both soils the Natural Resource Conservation Service recommends in its soil survey that occasional soil ripping and/or drainage enhancement projects may be necessary to maintain adequate soil conditions for the system to work successfully. Areas mapped as the Devries soil can have hardpan at 15 inches to as much as 80 inches below the surface. The hardpan can be broken up mechanically by deep ripping between crop rotations. Re -leveling fields to prevent ponding will also minimize formation of cemented soils with the Guard series soils. ACREAGE REQUIRED BOD Loading In order for a direct land application system to work, the loading rates must be controlled based on the previously presented formula. The acreage required is determined by the acceptable loading rate. At the 1999 peak weekly flow, 142,000 lb/day of BOD from the cannery was applied to 790 acres (net) farmland. This equates to a daily application rate of 180 pounds 9/18/00 Draft 8-6 Wastewater Master Plan 213%wwmp Reaeration Allowable Soil Net Pore NO2, I Time Loading, Type Permeabili Space, S lb/ac/d Factor lbs BOD/ac/da Devries Sandy Loam Moderately rapid 0.27 825 .8 560 Guard Clay Loam Moderately slow 0.27 825 .6 420 These loading rates are based on the assumption that the application is made with a number of days of rest in between applications. For tilled soils the application should be made with a minimum of three days rest between applications, and land should be disced after the soil has dried adequately to support tractor and tillage implements. Applications on the alfalfa or corn fields should be made with a 10-14 day rotation as is practiced in conventional agricultural operations. The allowable application rates determined by the above formula are the average amounts applied over the entire period. Instantaneous daily application rates will be much greater. Experience with other sites has shown a maximum 2,000 lb/ac/day on one day will not create odor conditions as long as the average value does not exceed the recommended one. It is also important to consider the effect of the BOD loading rates in conjunction with the hydraulic loading rates, especially for crops which are somewhat sensitive to suffocation such as alfalfa. This was evaluated during the 1999 season when the hydraulic application rate of combined industrial and domestic effluent exceeded the hydraulic capacity of the irrigated acres, resulting in some crop damage and odors. The loading rates in Table 8-1 are only appropriate for crops which are irrigated at rates which meet, not exceed, evapotranspiration requirements. With both soils the Natural Resource Conservation Service recommends in its soil survey that occasional soil ripping and/or drainage enhancement projects may be necessary to maintain adequate soil conditions for the system to work successfully. Areas mapped as the Devries soil can have hardpan at 15 inches to as much as 80 inches below the surface. The hardpan can be broken up mechanically by deep ripping between crop rotations. Re -leveling fields to prevent ponding will also minimize formation of cemented soils with the Guard series soils. ACREAGE REQUIRED BOD Loading In order for a direct land application system to work, the loading rates must be controlled based on the previously presented formula. The acreage required is determined by the acceptable loading rate. At the 1999 peak weekly flow, 142,000 lb/day of BOD from the cannery was applied to 790 acres (net) farmland. This equates to a daily application rate of 180 pounds 9/18/00 Draft 8-6 Wastewater Master Plan 213%wwmp 1' � — —- BOD/acre/day. Using the lower number presented in Table 8-1 (420 lbs. BOD/ac/day), the ranch can accept more cannery wastewater. At 420 pounds BOD/ac/day, 338 acres would have been the minimum recommended area for disposing of the 1999 cannery flows. Using the projected cannery loading (from Section 3) of 2,700,000 pounds BOD/month and a maximum loading of 420 pounds BOD/ac/day, the theoretical minimum area recommended based on BOD loading criteria would be 210 acres. Because of crop rotation, harvest operations, and irrigation scheduling considerations, a realistic minimum area based on BOD loading would be about double the theoretical minimum, or 420 acres. Hydraulic Loading The maximum hydraulic loading for the 790 net acres available for irrigation is controlled by a combination of industrial effluent flows and treated domestic effluent flows. The cannery flows generally peak in mid- to late -August or early September. The projected industrial flows were shown in Figure 8-1. Assuming an evapotranspiration rate of 6.4 inches for the month of August, an irrigation efficiency of 75 percent, and a leaching fraction of 0.10, a conventional irrigation application rate would be 9.5 inches for the month. Applying the industrial effluent at. this conventional application rate would require a minimum of 600 acres of crops. Therefore hydraulic loading is more limiting than BOD loading for the industrial effluent. Additional irrigated area is required for disposal/reuse of the domestic municipal effluent. Less land can be used if soil and crop conditions allow irrigation in excess of conventional rates. The risks of adverse crop impacts and odors increase for irrigation at higher rates. Detailed water balances which include industrial effluent and domestic effluent for the various process train alternatives are shown in Section 10. ALTERNATIVE IRRIGATION METHODS Currently, irrigation is accomplished using furrows for corn and graded border check systems for alfalfa and small grains. The disadvantages of the furrow irrigation is mediocre distribution of solids and wastewater. The disadvantage of graded border check irrigation is poor solids distribution because of filtration and interception of solids by the crop stems. Poor solids distribution can cause an increase in effective organic loading at the upper end of the graded border check and can significantly reduce soil reaeration by blinding soil pores. This can cause crop damage at the upper end of the field. One alternative would be to use sprinklers for irrigation. Sprinklers would distribute wastewater moderately better than surface irrigation and would distribute solids substantially better than surface irrigation. However, this option would be very costly to install (approximately $400 to $2,000 per acre) and would require booster pumps to generate enough pressure for the system to work. Sprinklers have the additional disadvantages of clogging and spreading aerosols, which in turn could increase odors from the application site. The benefits from sprinkler irrigation are not sufficient to warrant the costs and other disadvantages at this time. Other alternatives would be to change the surface irrigation system employed. One possible modification would be conversion to a level basin system. This would provide a system with no 9/18/00 Draft 8-7 Wastewater Master Plan 2l3%wwmp tailwater to pump. An advantage of this type of system is that flows are generally much higher during irrigation, which would create greater velocities and spread solids further out into the fields. The major disadvantage of conversion to a level basin system is the extensive regrading to create smaller dead -level fields from the larger sloped fields which currently exist. A second variation for surface irrigation would be to install "surge" systems. These systems use gated pipe and valves to send the water down the furrows in pulses typically from 10 to 30 minutes apart. This type of system would also push solids further into the field by providing a greater instantaneous flow rate during application. Surge systems would distribute water and solids more uniformly. Surge systems would require the installation of a new network of underground supply pipelines to the fields along with the purchase of the gated pipe, surge valves, and controllers. The cost of a complete surge system would be on the order of $300 to $500 per acre. Surge systems are generally not used with graded border checks. TREATMENT ALTERNATIVES The direct land application alternative (as presently practiced) requires no treatment at the White Slough facility. In order for this process to work effectively without producing odors, effective solids removal is necessary by the industrial discharger prior to discharge. All the alternatives to direct land application include treatment for reduction of BOD and then land application or surface water discharge. Treatment could be provided with a fixed film reactor and/or an aerated pond system. Either alternative would require significant capital investment and power cost. Because adequate land is available based on BOD loading rates, conventional treatment of food processing wastewater is not economically justifiable. PRETREATMENT ALTERNATIVES AT PCP Completion of the projects mentioned previously for the PCP cannery will help reduce both suspended solids and TDS entering the sewer to White Slough. Assuming continuation of the existing direct land application of the cannery wastewater, efforts should be made to reduce suspended solids. Possible alternatives for a greater reduction in solids would include installation of finer screens or installation of a dissolved air flotation system to remove colloidal solids. Rotary Drum Screens The screens in use at the PCP cannery are relatively fine compared to most static screens. An incremental improvement in solids removal performance could be obtained through the use of rotary drum screens. Rotary drum screens tend to require less manual cleaning than static screens and have openings as small as 0.010 inches. The amount of additional solids captured by rotary drum screens with 0.010 inch openings would not justify the cost of switching from static screens with 0.020 inch openings. Gravity Disk Screens Gravity disk screens work on the filter precoat principal in which captured solids provide the filter mat for removing additional solids. Gravity disk screens provide very efficient solids removal down to particle sizes much smaller than are achievable with rotary drum screens. 9/18/00 Draft 8-8 Wastewater Master Plan 2l3\wwmp However, the flow capacity of individual gravity disk screen units is relatively low, and the resulting costs are much higher than for static or rotary drum screens. Gravity disk screens are usually employed on food processing waste streams where the recovered solids have a high market value. Therefore, gravity disk screens are not a recommended alternative unless PCP can derive a high value from its recovered solids or if land for reclamation/disposal becomes very limiting. Dissolved Air Flotation Dissolved air flotation is commonly used to remove solids from food processing wastewater. It removes approximately 70 to 90 percent of suspended solids, depending upon polymer usage. Dissolved air flotation is particularly attractive when the food processor is discharging to a municipal system or to a land treatment system with limited solids handling capacity. A 50 -foot circular dissolved air flotation tank would be required to treat the projected 4.5 Mgd peak cannery flow rate. A gravity belt filter or belt filter press would probably also be required to dewater the solids prior to disposal or reuse. The capital cost of new dissolved air flotation and solids dewatering facilities at PCP is estimated to be approximately $3 million including polymer feed, support facilities, engineering, and contingency. This would not include redundancy for either the dissolved air flotation tank or dewatering facilities. This also does not include the present worth of operational costs for disposal of dewatered solids. The main benefits to the City of Lodi from dissolved air flotation at PCP would be moderately improved wastewater infiltration rates and a lower potential for odors from the irrigated fields. These benefits are not sufficient to justify the costs of installing dissolved air flotation at PCP at this time. SUMMARY AND RECOMMENDATIONS The existing direct land application of industrial wastewater should be continued along with increased tracking of wastewater application at the White Slough Facility. Increased tracking should include recording of actual fields receiving wastewater so that the hydraulic and BOD loading rates are known for each day. Industrial wastewater should be preferentially applied by furrow irrigation to annual crops rather than by border irrigation. Improvements recommended for implementation at the PCP cannery include better removal of solids from the wastewater at PCP through redesigned solids conveyance systems and increased recycling to reduce BOD loading to farmland. For long-term viability of the land treatment system, the PCP facility should continue to develop means to minimize sodium loadings in effluent. 9/18/00 Draft 8-9 Wastewater Master Plan 213\wwmp SECTION 9. BIOSOLIDS DISPOSAL/REUSE ALTERNATIVES BACKGROUND Currently, biosolids are anaerobically digested and discharged into a concrete -lined lagoon. During the summer growing season, the suspended biosolids are pumped from the lagoon at a solids content of about 2 percent and discharged to the fields through the surface irrigation system. Biosolids are sometimes applied to fields before planting in late Spring or after harvest in the Fall. The biosolids lagoon is decanted back to the storage ponds. The supernatant from the lagoon is combined with treated effluent for irrigation. Biosofids from this facility have consistently met the requirements of the Federal Regulations (40CFR503). The surface irrigation methods used for biosolids application to fields include furrow irrigation and border check (graded basin) irrigation. The furrows typically have been constructed with multiple 90 -degree turns rather than straight. The purpose of the turns is to reduce tailwater runoff. The ability of this system to distribute solids and nitrogen has been questioned by the Regional Water Quality Control Board staff. Even though the solids are suspended in 98 percent water, it is likely that some solids are settling out near the head end of the field rather than being distributed throughout the length of the furrows, graded basins, or fallow fields. The same unequal distribution of the non -soluble portion of organic nitrogen is also likely. This phenomenon occurs with either furrow irrigation of row crops or border irrigation of alfalfa, although it is more pronounced with the border irrigation of alfalfa. During the summer months, applications are limited to the corn crop. This is due to the 30 -day limitation of no harvesting after the biosolids application to alfalfa. Late in the season, when alfalfa harvest is completed, applications are made to the alfalfa fields. This 30 -day limitation would be applicable even if alternative methods were adopted for biosolids distribution. According to plant staff, the land applied biosolids can be a brief source of minor odors during initial drying. Better distribution of solids would minimize the potential for odors. BIOSOLIDS LOADINGS Recent and Projected Loadings The biosolids production and nitrogen content values for recent years and for projected Year 2020 are shown in Table 9-1. Organic nitrogen compounds in biosolids must be first mineralized to ammonia by natural biochemical processes before the nitrogen becomes available for plant uptake or bacterial conversion to nitrate. Total available nitrogen is therefore defined as the total amount of ammonia and nitrate nitrogen. The total available nitrogen was determined by assuming that 50 percent of the ammonia is lost due to volatilization after application and that mineralization rates for organic nitrogen for the first ten years are as per the EPA Process Design Manual'. There can be some gradual mineralization after ten years, but it is usually considered to 9/18/00 Draft 9-1 Wastewater Master Plan 2131wwmp DRAFT Table 9-1. Biosolids Production and Nitrogen Content Year Volume,(') M al Solids,(b) % NH3, lbs Available NH3, lbs Organic N, lbs Available Organic N,(`) lbs Total N Available,(d) lbs 1997 5.8 3.0 42,180 21,100 18,340 8,250 29,600 1998 5.6 2.9 24,700' 12,400 20,260 9,120 21,500 1999 6.0 3.0 24,700 12,400 39,600 17,800 30,700 Average 5.8 2.9 30,500 15,300 26,100 11,700 27,300 Projected 7.6 3.0 40,000 20,000 34,200 15,400 35,800 (a) Measured by change in biosolids lagoon water level during the pumping of biosolids to fields. (b) Measured from grab samples of settled biosolids in the biosolids lagoon. (`) Available N during the first 10 years after biosolids application. (d) Total nitrogen available for plant uptake, includes small amounts of nitrate in biosolids lagoon influent. be negligible. The total amount of available organic nitrogen was estimated at 45 percent of applied organic nitrogen. The variability in loadings from year to year may have been partly due to the limited number of grab samples taken. The average loadings were used as the basis for future projections. Treatment plant staff estimate that about 40 percent of the liquid volume of digested biosolids sent to the biosolids lagoon is decanted to the irrigation storage ponds where it is blended with municipal and industrial effluent for irrigation, The remaining 60 percent is directly pumped and land applied through the surface irrigation system. Approximately 350 acres of the total 790 acres available are used for biosolids application each year. The fields receiving biosolids directly are rotated every year so that Fields 1 through 5 (610 acres, see Figure 8-2) receive about the same average loadings over time. There are normally three to seven applications of biosolids per year between late Spring and mid -Fall. Fields 6A through 6G east of Interstate 5 have not received biosolids. Figure 9-1 below schematically shows the fate of biosolids and the associated nitrogen assuming current available fields for irrigation and biosolids application. Figure 9-1. Projected Biosolids Nitrogen Loadings Decant 29.800 lbs N Total Ponds � _ Irrlgatlon on 790 aa. V14,.300lbsN vailable (18 Ibs/ac Available N from blasolids) 74,500 lbs N Total 44,700 lbs N Total Direct ' Digesters � Lagoons Applleatiom 21,500 lbs N on 810 ac. ' 35.800 lbs N Available (35lbs/ac Available Available N from biosolids) 9/18/00 Draft 9-2 Wastewater Master Plan 213\wwmp Comparison with Acceptable Loading Rates The typical nitrogen utilization rate for alfalfa is 480 pounds/acre and the rate for a corn/oats double crop rotation is 365 pounds/acre. The nitrogen loading rate and available nitrogen is calculated every year for every field. The annual reporting forms for 1998 and 1999 are contained in Appendix M. The projected available nitrogen loading of 53 pounds/acre (Figure 9-1) is substantially less than the potential nitrogen uptake of the crops. Additional discussion of nitrogen loading rates is presented in Section 10. The nitrogen loading rate calculations assume uniform application of nitrogen from the biosolids. Based on visual observations only, wastewater treatment plant staff estimate that roughly 25 percent of the solids are deposited in the first 10 percent of the furrows. This percentage is somewhat higher for applications to cut alfalfa. While the uniformity of application of solids and organic nitrogen may be marginal, the uniformity of application of dissolved ammonia is probably reasonably good. Since the projected available nitrogen loading rate for the organic nitrogen associated with the solids is only 30 pounds/acre, or 10 percent of average annual crop uptake, the mediocre solids distribution uniformity does not appear to be a large factor for overloading nitrogen at the upper ends of fields. BIOSOLIDS DISPOSALIREUSE ALTERNATIVES Biosolids disposal/reuse alternatives include continuing with the current system, modifying the existing system, tanker truck injection of liquid biosolids, dewatering and spreading dewatered biosolids, and composting or co -composting. Existing System This_ system has worked effectively for the City of Lodi, but with increased quantities the uneven solids distribution may need to be investigated in greater detail to satisfy regulatory agencies. Modified Surface Irrigation There are three alternatives to the existing method of applying biosolids. 1. One alternative would be to agitate and mix the solids with a greater amount of treated effluent. This would suspend the solids more thoroughly and provide greater application velocities to reduce the settling at the upper end of the field. 2. The second alternative would be to provide level basins for irrigation and apply the biosolids with the normal irrigations. The level basin irrigation alternative requires high flow rates and greater velocity than graded border or furrow irrigation, thus pushing the solids further out into the field and improving distribution of both solids and nitrates. 3. The third alternative would be to apply the biosolids in surge flow surface irrigation systems. This would provide greater instantaneous velocities for better application distribution. 9/18/00 Draft 9-3 Wastewater Master Plan 213\wwmp For alternatives which involve furrow irrigation, straight furrows would be preferred over furrows which have multiple turns. Tanker Injection Acquisition of a tanker truck for application of biosolids to the land would provide for the optimum in consistency of application rate for both solids and nitrogen compounds. The -track could be provided for liquid application or injection with no further treatment required for the biosolids from the lagoon. This alternative would provide uniform distribution of biosolids and would work effectively on alfalfa fields with the use of "grass shanks." These shanks inject the liquid biosolids with little damage to the alfalfa crop. A 3,100 -gallon unit can be acquired for about $200,000. This unit has a diesel engine that consumes fuel at a rate of 6 gallons/hour. The unit is equipped with high flotation tires that would minimize compaction of the soils. Additional associated facilities for loading, vehicle storage, etc., would add about $100,000 in capital cost. Approximately 1,500 trips per year would be required to dispose of the projected biosolids after decanting. At 30 minutes per trip, this would translate to about 0.5 additional staff for driving and about 0.2 staff for support. Total O&M costs are estimated at approximately $60,000 per year. This work could also be contracted to eliminate the capital cost while increasing the O&M costs. Dewatered Biosolids Application A conventional agricultural spreader truck could be purchased for application of dewatered solids. Applications would be limited to times when the fields are being tilled (spring and fall for the corn/oats rotation or fall for new alfalfa fields). A major disadvantage of this alternative is the added cost of dewatering the biosolids, which would be very substantial. For a single belt filter press operating 500 hours per year, the capital costs including support facilities would be on the order of $1.5 to $2.0 million based on costs at San Bernardino, Fresno, and Sacramento Regional wastewater plants. The total O&M costs would be approximately $40 to $50 per dry ton, or $250,000 per year. Sludge drying lagoons could be a lower cost dewatering alternative as is discussed later in Section 11, but the costs of dewatering would still be a substantial increase over current practices. Costs for actual spreading of dewatered solids would be somewhat less than for the tanker injection alternative, or about $40,000 per year. Compost Biosolids to Provide Class A Material For biosolids to receive a Class A designation, they must be treated by an approved process to significantly reduce pathogens such as composting or thermal pasteurization. The composting option provides a product that can be used by homeowners or landscapers for a variety of uses. The possible uses are: 0 Sell to wholesalers for use as a soil amendment, • Bag and sell to homeowners, and/or • Use as an onsite soil amendment on the sports complex fields and landscaped areas. The cost of composting varies, depending on the type of system used. The costs range from $20/ton to $50/ton of compost, not including the costs of biosolids dewatering. Dewatering would add another $15 per CY of compost for a 3:1 green waste:biosolids ratio. Composting 9/18/00 Draft 9-4 Wastewater Master Plan 2131wwmp f �l could utilize a combination of leaves collected by the City, garden waste collected as part of the City's contracted garbage services, and green waste from the City's own landscaped areas. The possible revenue from selling compost depends on the market and how the composted material is sold (bulk or bagged). Revenues vary from $2/CY to $12/CY. The major difficulty with this alternative is that land application of biosolids is prohibited in the unincorporated areas of San Joaquin County. A major advantage of this alternative is that biosolids can be co -composted with City -collected green waste. Co -composting has been implemented successfully by the City of Modesto as a more cost-effective means to dispose of their city-wide green waste collections than landfill disposal. THERMAL TREATMENT The Northern California Power Agency owns and operates a gas-fired power generation facility adjacent to the wastewater treatment facility. This facility has excess heat that could be used to dry biosolids and produce a Class A product that could be used for City parks and recreation facilities. Grant money may be available for both parties to design and operate a pilot facility that would produce a pelletized material that could be productively used by the City of Lodi. This pilot study could be completed while continuing with the City's current biosolids operation. In 1995, West Yost & Associates completed an evaluation of drying and disinfecting biosolids using heat from cogeneration 2. The analysis was for biosolids generated from the treatment of 7 Mgd of wastewater at the City of Vacaville's Easterly Wastewater Treatment Plant. The facilities required for the drying process included belt filter presses, an Envirex brand heated sludge dryer, a building, and associated facilities. The capital and O&M costs without the belt filter press were $1.6 million and $102,000 per year, respectively, in 1994 dollars. Translated to Year 2005 dollars for 8.5 Mgd, the costs would be $2.0 million capital and $130,000 annual O&M. Including belt filter press pre -drying would nearly double these costs. Unless grant funds became available, the thermal drying alternative would not be economically competitive with other alternatives. SUMMARY The City should continue with its existing procedure of applying biosolids within agronomic use rates in the furrows of the corn crop and on alfalfa fields after the last cutting of alfalfa in the fall. The costs of alternative biosolids distribution methods are not justifiable for the potential improvements in distribution uniformity based on an evaluation of nitrogen loading rates. However, some relatively low cost improvements should be made to the existing operations to improve uniformity. Application scheduling should be adjusted to match times when the fields have been harvested and are about to be tilled for the subsequent crop. Biosolids should be agitated and mixed with additional effluent to suspend the solids more thoroughly. Irrigation should be performed with straight furrows and higher flow rates per furrow or basin to "push" the solids further down the field. The result would be more even distribution of solids and nitrogen compounds. 9/18/00 Draft 9-5 Wastewater Master Plan 2 t3\wwmp REFERENCES U.S. EPA. Process Design Manual for Utilization of Municipal Wastewater Sludge on Land. EPA 625/1-83- 016, October 1983. 2 West Yost & Associates. Digester Biosolids Disinfection Study. Prepared for the City of Vacaville, June 6, 1995. 9/18/00 Draft 9-6 Wastewater Master Plan 2131wwmp DRAFT SECTION 10. ALTERNATIVES FOR EFFLUENT LAND TREATMENT, REUSE, AND STORAGE INTRODUCTION The purpose of this section is to present the further development and evaluation of alternatives for the disposal, reuse and/or storage of treated municipal effluent, industrial wastewater, and biosolids. The first evaluation presented in this section is for hydraulic loadings management, i.e. where to send all the effluent. Sizing criteria for the land treatment, reuse, and storage facilities are developed from the results of the hydraulic loading management evaluation. Other issues related to loading rates such as nitrogen loadings and groundwater mounding are then also evaluated to determine sizing criteria. The limiting sizing criteria are then used to develop initial cost estimates for the facilities. Combined treatment and disposal/reuse alternatives are evaluated in Section 13 EVALUATION OF TREATMENT AND DISPOSAL/REUSE PROCESS TRAIN ALTERNATIVES. Other issues related to industrial wastewater treatment and disposal/reuse, and biosolids disposal/ reuse were discussed previously in Sections 8 and 9. OPERATIONAL SCENARIOS There are three basic operational scenarios based on the anticipated discharge requirements and the combinations of alternatives developed in Section 5: 1. Complete surface discharge (Section 5, Alternative Combinations DC -D, DC -W, BC -D, BC -W) 2. Partial discharge to Bishop Cut (Section 5, Alternative Combination BC -PD) 3. Land discharge (Section 5, Alternative Combination LD) Operational Scenarios 2 and 3 involve issues and constraints related to farming operations and the potential Sports Complex. STORAGE RESERVOIRS To reduce or eliminate discharge to the Delta during portions of the year, it will be necessary to store or percolate dispose of excess effluent. Additional effluent storage reservoirs could be constructed on City -owned land to provide this additional storage capacity. Existing Storage When not discharging to Dredger Cut, treated effluent is conveyed to the 9 acre-feet (af) equalization pond by gravity flow and then either pumped to the irrigation system or into the effluent storage ponds until needed for irrigation. 9/18/00 Draft 10-1 Wastewater Master Plan 213\wwmp DRAFT There are four existing storage ponds located north of the treatment plant as shown on Figure 10-1. The combined area of these ponds is 41 acres. The combined volume is 370 af. The maximum water depth in the ponds is approximately 9 feet with a 1 -foot freeboard. Future Storage Reservoir Locations New storage reservoirs could be located west of the existing ponds and immediately north or south of the existing 48 -inch outfall pipeline to Dredger Cut. Reservoirs at these nearby locations would be easy to hydraulically interconnect with the existing ponds. New ponds adjacent to the existing ponds could share levee sections to save costs. DEDICATED PERCOLATION BASINS OR FIELDS Some of the soils north and east of the treatment plant are sandy loam texture, with relatively high percolation rates if deep ripped to break up the underlying hard pan. Relatively high amounts of effluent could be disposed of through percolation if properly managed. At a minimum, this would require that fields be fallow and have very flat slopes with intermediate berms or checks to maintain continued ponding for several days at a time. Surface drainage and runoff return facilities would also be required. Based on infiltration tests, soil borings, and proximity to the existing facilities, the most desirable areas for percolation basins are shown in Figure 10-1. City property and nearby land south of the areas shown on Figure 10-1 would not be suitable for winter percolation disposal of effluent. Classic rapid infiltration basins could be constructed at dead level slopes with containment berms to provide the greatest percolation disposal capacity, but at a relatively high initial cost. Dedicated percolation fields or basins could accept some industrial wastewater and biosolids, although the solids would reduce percolation rates and require more frequent disking. The major disadvantage of percolation fields or basins is that those areas would not be available for farming during much or all of the year, resulting in a loss of farming revenue. The typical design criteria is based on 2 to 4 percent of infiltration test resultsl, which translates to 0.8 to 1.7 inches per day for the 35 min/in average double ring test infiltration rate in the area shown in Figure 10-1 (see soils report, Appendix W. The planning level percolation rate assumed for the percolation fields or basins was 1 inch per day. This is within the acceptable design range based on soils information and is relatively low compared to the loading rate for most classical rapid infiltration systems. The operation of percolation basins can have an effect on the amount of nitrogen in percolate, groundwater mounding, mosquito control, maintenance, and availability for summer crops. The EPA has published recommendations for optimizing nitrogen removal in rapid infiltration basins2'3. With proper wetting and drying cycle durations and sufficient carbon, it should be possible to remove about 50 percent of the applied nitrogen. Excessively long ponding durations can create undesirable mosquito breeding conditions. Groundwater level considerations can dictate maximum allowable ponding durations and the availability of basins or fields for summer cropping. Hydraulic and nitrogen loading rates are discussed in greater detail later in this section. 9/18/00 Draft 10-2 Wastewater Master Plan 213\wwmp 0 CL c co ca EE c 0 as O J CES L Cl) 0 li +>'_ • W ri) U3 ca �. Q Co E 0 L a a 9 �rics � r�0il, (C �a,ti a°a.0 Q j ti C) � � U U 'UO to 0 CO m cua 5 a CROP IRRIGATION A total of 790 acres of land is currently capable of being irrigated with municipal effluent, industrial wastewater, and biosolids out of a total of 880 acres of irrigated farm land owned by the City. The 90 acres furthest east is not currently irrigated with effluent, but could be if new conveyance facilities were constructed. The proposed Sports Complex would reduce the amount of farmland to 480 acres and add approximately 250 acres of turf grass. Alfalfa Alfalfa is already grown on much of the City's existing land. It is a multi-year crop with a high water use rate, high nitrogen uptake rate, and value to the nearby dairies. As discussed in Sections 8 and 9, alfalfa is not an ideal crop for accepting biosolids or industrial wastewater, especially using border strip surface irrigation. With border strip irrigation, solids tend to be concentrated at the upper end of the field, resulting in a greater potential for odors, crop impacts, and groundwater impacts. Turf Grass If the sports complex is constructed, the grass fields will be irrigated with reclaimed water. The water and nitrogen use rates for Turf grass can be relatively high. Turf grass area is combined with alfalfa in water balance calculations because they have essentially the same crop evapotranspiration coefficient (1.0). Turf grass is not suitable for irrigation application of high solids content wastewater such as the industrial wastewater or biosolids. Annual Crops Many annual crops are grown in the area surrounding the wastewater treatment plant. The main annual crops grown on the land owned by the City are corn and oats. Corn has a high water use rate in mid -summer, but a decreasing water use rate as harvest time approaches in the fall. Oats are planted as a winter crop, so they only need irrigation after planting in the fall and possibly during a dry spring. The annual crops are important for the application of high solids content wastewater. With furrow irrigation, industrial wastewater or biosolids can be applied at a reasonable uniformity. Industrial wastewater and biosolids can also be readily land applied to fallow ground in the fall after the harvest of annual crops. CONSTRUCTED WETLANDS Constructed free water surface wetlands were discussed previously in Section 7. Constructed wetlands would use slightly more water than grass crops per unit area and would also provide some temporary storage capacity. OTHER USES OF RECLAIMED WATER Mosquito Fish Ponds The San Joaquin County Mosquito and Vector Control District maintains ponds just south of the treatment plant for raising mosquito fish (gambuzia). The ponds are supplied with effluent from 9/18/00 Draft 10-4 Wastewater Master Plan 2l3lwwmp 1AWk N the treatment plant. The monthly range of water usage during the last two years has been 0 to 333,000 gpd, with an average usage of 97,000 gpd. Due to their operations, the water usage does not appear to follow a seasonal pattern. NCPA Power Plant Water The Northern California Power Agency runs a natural gas-fired 49 -megawatt power plant west of the biosolids lagoon. The power plant is primarily run to satisfy peak electrical demands. The power plant receives treatment plant effluent, filters it, and uses it for cooling water. Water used for steam generation receives the same treatment plus reverse osmosis. The power plant returns most of the blowdown and reject water to the City's treatment plant. The power plant has recently began using a deep injection well to dispose of about 25 percent (100,000 gpd) of the wastewater on an intermittent basis. The monthly range of net water usage during the last two years has been 0 to 388,000 gpd, with an average usage of 167,000 gpd. The water usage is highly variable and does not appear to follow a seasonal pattern. There have been preliminary discussions regarding an expansion of the power plant, which would increase its water usage. WATER BALANCES Water balances were prepared using the flow projections from Section 3 for the operational scenarios presented earlier in this Section. The water balances conservatively assume a constant combined usage of 100,000 gpd by the mosquito fish ponds and power plant. The results of the water balances show the minimum required land areas for irrigation, percolation, and wetlands storage. They also show the required storage volumes where storage reservoirs are considered. A 1 in 100 -year annual rainfall proportioned by month was applied for all water balances unless indicated otherwise. Complete Surface Discharge (Alternatives DC -D, DC -W, BC -D, BC -W) For year-round surface discharge (Alternatives DC -D, DC -W, BC -D, BC -W from Section 5), only industrial wastewater and biosolids would have to be land applied. The biosolids were conservatively assumed to be diluted in an average 0.1 Mgd of effluent prior to application. The water balance for this scenario is presented in Table 10-1. This water balance assumed that biosolids and industrial wastewater are only applied between April and October. The values for annual crops area and percolation field area were derived by iteration based on maintaining complete land disposal/reuse for April through October. Reservoirs and wetlands were not considered for storing industrial wastewater because of potential odor problems. It should be noted that 30 days (approx. 800 af) of reservoir or wetlands storage for treated municipal effluent is needed with this scenario to accommodate times when the dissolved oxygen level in Dredger Cut falls below 5.0 mg/L or when dilution in Bishop Cut is low because of South Delta pumping restrictions. Assuming that most of the existing 300 of of storage could be used for this purpose, an additional 500 of of new storage would be required. The water balance shows that 350 acres of annual crops and 350 acres of low rate percolation fields are needed for industrial effluent and biosolids disposal. The fallow percolation fields are needed for times when annual crop irrigation demands are low. The water balance does not show any alfalfa because alfalfa cannot be loaded as heavily with cannery effluent as annual crops or 9/18/00 Draft 10-5 Wastewater Master Plan 2131wwmp Table 10-1. Water Balance for Land Application of Industrial Wastewater and Biosolids (Alternatives DC -D, DC -W, BC -D, BC -W) 1 in 100 Year Rainfall Totals 35.2 49.5 (in./yr) MAIN INPUT PARAMETERS 1 (2) (3) (4) 5 (6 7 (8) (9) 6.0 Evapotranspiration Coefficient: varies 1.00 Total Annual Crops Percolation Fields Diluted Biosolids Flow Rate (Mgd): 0.10 Evap. & Evap. & 100 Year Reference Industrial Wastewater Treatment Rainfall E.T. Inflow Inflow Rainfall Perc. Rainfall Perc. & Discharge Month (in./mo) in./mo) (ac-in./mo) (ac-in./mo) ac-in.lmo ac-in.lmo (ac -in. o) ac-in./mo) (ac -in.) Jan. 5.79 0.98 173 173 0 0 0 0 173 Feb. 5.44 1.54 143 143 0 0 0 0 143 Mar. 4.96 2.93 256 256 0 0 0 0 256 Apr. 2.72 4.72 161 272 0 0 0 (272) 0 May 1.90 6.22 113 227 664 (1,377) 0 0 0 June 0.46 7.32 272 382 161 (2,639) 0 0 0 July 0.44 8.06 2,181 2,295 155 (4,433) 0 0 0 Aug. 0.41 6.96 4,404 4,518 142 (3,680) 0 (981) 0 Sept. 1.48 5.31 5,158 5,268 518 (2,259) 0 (3,527) 0 Oct. 2.04 3.30 2,498 2,613 714 (1,050) 0 (2,276) 0 Nov. 4.37 1 A 61 61 0 0 0 0 61 Dec. 5.17 0.73 79 79 0 0 0 0 79 Totals 35.2 49.5 (in./yr) MAIN INPUT PARAMETERS Annual Perc. Crops Fields' Percolation Rates (in./mo.): 3.0 6.0 Evapotranspiration Coefficient: varies 1.00 Surface Areas (ac.): 350 350 Diluted Biosolids Flow Rate (Mgd): 0.10 Note: Indicates low rate percolation fields. (1) Rainfall data is from Lodi station, using 100 year monthly statistics normalized to 100 year annual total (from Western Reg. Climate Center). (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Diluted biosolids and industrial flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (annual crop area) ' (6) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rate)) x (annual crops area) (7) Col. 1 x (percloation field area). (8) - (Col. 2 x (evapotranspiration coefficient for perc. fields) + (field percolation rate)) x (percolation field area), up to the amount of water left. (9) Sum of columns 4 through 8 West Yost & Associates lodibai.xls 5123/00 E•. fallow percolation fields (see Appendix W. The 700 -acre net land requirement for hydraulic loading is greater than the 210 acres required for BOD loading for the industrial wastewater specified in Section 8. The 700 -acre requirement is less than the 790 acres currently available for irrigation. However, if the Sports Complex were to be constructed, only 480 acres would be available for application of industrial effluent and biosolids. Extra annual crop area above 350 acres would reduce the need for percolation fields by about one-half of the extra annual crop area. Partial Discharge to Bishop Cut (Alternatives BC -PD, BC -PV) These alternatives includes the discharge of effluent to Bishop Cut up to the maximum allowable flow rate permissible without tertiary treatment. As was discussed previously in Section 4, it is assumed that a 20:1 dilution in Bishop Cut would be necessary to prevent tertiary treatment requirements from being imposed. 20:1 dilution in Bishop Cut should be available during December through March with normal to wet climatic conditions. During other months of the year or during a dry winter, only a portion of the effluent could be discharged while maintaining a 20:1 dilution. The rest of the effluent would be disposed of in percolation basins and fields, or would be used for agricultural irrigation. For water balance calculations, it was assumed that half the effluent would be sent to Bishop Cut and half to percolation disposal during winter months. This is a reasonable assumption for the net flows in Bishop Cut as estimated in the modeling report contained in Appendix 0. During spring months, the amount of discharge to Bishop Cut would taper off. Essentially all the water would be used for crop irrigation in the summer. The water balance for this scenario is shown in Table 10-2 and Figure 10-2. Land Discharge (Alternative LD) For the land discharge scenario, all effluent would be land applied. Based on experience at other sites, providing sufficient reservoir storage for all late fall and winter months would not be a viable alternative because of excessive capital construction cost. Instead, all effluent not used for irrigation would be disposed in dedicated percolation fields or basins. The water balance for this scenario for 1 in 100 -year rainfall is shown in Table 10-3. The water balance for average year rainfall is shown in Table 10-4. The distribution of effluent by month is shown graphically in Figure 10-3. The minimum required areas shown in Table 10-3 were derived by iteration based on having a balance of crop types and no surface discharge. Summer basins refer to winter percolation basins which would have to remain fallow in the summer and fall to provide adequate effluent disposal capacity. The alfalfa area could vary somewhat from the 400 acres shown, but the annual crop area should not be reduced below about 400 acres because annual crop area is better suited to receiving biosolids and industrial wastewater. Some industrial wastewater can be applied to alfalfa if it is blended with municipal effluent and not hydraulically loaded in excess of agronomic rates. The 400 acres shown for percolation fields and basins would be new fields with high permeability soils located generally to the east of the City's current land holdings (Figure 10-1). If percolation basins are selected as an effluent disposal method, pilot testing of percolation disposal should be performed to confine the assumptions based on initial soils testing (Appendix N. 9/18/00 Draft 10-7 Wastewater Master Plan 213\wwmp 1,400 1,200 c� 1,000 Figure 10-2. Partial Discharge to Bishop Cut Effluent Loading by Reuse or Discharge Type (Average Rainfall, Year 2020) r - w 400 200 0 Jan 1,400 1,200 1,000 800 600 400 200 0 Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month West Yost & Associates Lodi Wastewater Master Plan lodibal.xls partialchart 9/18/00 Table 10-2. Water Balance for Partial Discharge to Bishop Cut (Alternatives BC -PD, BC -PW) Average Rainfall, Year 2020 Totals 17.6 49.5 (in./yr) MAIN INPUT PARAMETERS Alfalfa Max. Percolation Rates (in./mo.): 3.0 Evapotranspiration Coefficient: 1.0 Surface Areas (ac.): 400 Municipal Effluent Flow (Mgd): 8.50 Mosquitofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (in/mo) 25.69 Annual Winter Summer Crops Basins Basins 3.0 30.0 30.0 varies 1.0 1.0 400 200 260 (1) Rainfall data is from Lodi station. (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rate)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloation basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 (13) Maximum allowable discharge to maintain 20:1 dilution for more than 85% of the years in the Bishop Cul net flow modeling West Yost & Associates ludibal.xis partialdisch 618M (1) (2) (3) (4)5) 6 7 (8) (9) (10) 11 12 13 Alfalfa & Grass Annual Crops Percolation Fields & Basins r Max. Total Average Reference Industrial Wastewater Water Allowable Evap. & Evap. & Evap. & Rainfall E.T. Inflow Inflow Rainfall Perc. Rainfall Pere. Left Rainfall Pere. Discharge Discharge Month (in./mo) (in./mo) (ac-in./mo) (ac-in./mo) (ac-in./mo) (ac-in./mo) ac-in./m) ac-in./mo) (ac in./mo) (ac-in./mo) ac-in./mo)(ac-in.) (ac -in. Jan. 3.52 0.98 173 9,601 0 0 0 0 9,601 704 (6,195) 4,110 4,795 Feb. 2.85 1.54 143 8,445 0 0 0 0 8,445 570 (6,309) 2,707 4,331 Mar. 2.73 2.93 256 9,647 1,092 (2,372) 0 0 8,367 546 (6,586) 2,327 4,795 Apr. 1.34 4.72 161 9,154 536 (3,090) 0 0 6,600 348 (6,949) 0 3,315 May 0.50 6.22 113 9,680 200 (3,690) 200 (1,573) 4,816 130 (4,946) 0 2,968 June 0.14 7.32 272 9,702 56 (4,129) 56 (3,016) 2,668 36 (2,705) 0 2,873 July 0.05 8.06 2,181 12,056 20 (4,422) 20 (5,066) 2,607 13 (2,620) 0 2,968 Aug. 0.05 6.96 4,404 14,343 20 (3,983) 20 (4,205) 6,195 13 (6,208) 0 2,968 Sept. 0.32 5.31 5,158 14,644 128 (3,326) 128 (2,582) 8,992 83 (9,076) 0 2,873 Oct. 0.90 3.30 2,498 12,029 360 (2,518) 360 (1,200) 9,031 234 (8,657) 609 2,968 Nov. 2.29 1.42 61 9,106 0 0 0 0 9,106 458 (6,283) 3,280 3,867 Dec. 2.92 0.73 79 9,322 0 0 0 0 9,322 584 (6,146) 3,760 4,795 Totals 17.6 49.5 (in./yr) MAIN INPUT PARAMETERS Alfalfa Max. Percolation Rates (in./mo.): 3.0 Evapotranspiration Coefficient: 1.0 Surface Areas (ac.): 400 Municipal Effluent Flow (Mgd): 8.50 Mosquitofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (in/mo) 25.69 Annual Winter Summer Crops Basins Basins 3.0 30.0 30.0 varies 1.0 1.0 400 200 260 (1) Rainfall data is from Lodi station. (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rate)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloation basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 (13) Maximum allowable discharge to maintain 20:1 dilution for more than 85% of the years in the Bishop Cul net flow modeling West Yost & Associates ludibal.xis partialdisch 618M Table 10-3. Water Balance for Land Discharge (Alternative LD) 1 in 100 Year Rainfall, Year 2020 Totals 35.2 49.5 (in./yr) MAIN INPUT PARAMETERS Max. Percolation Rates (indmo.): Evapotranspiration Coefficient: Surface Areas (ac.): Municipal Effluent Flow (Mgd): 8.50 Mosquilofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (irUmo) 24.83 (1) (2) (3) {4j 5 6 7 (8 9 10 11 12 Alfalfa & Grass Annual Crops 1.0 Percolation Fields & Basins 1.0 1.0 400 400 400 Total Evap. & Evap. & Evap. & 100 Year Reference Industrial Wastewater Water Rainfall E.T. Inflow Inflow Rainfall Perc. Rainfall Perc. Left Rainfall Perc. Discharge Month (indmo) (in./mo ac-in./mo ac-in./mo ac-in./mo ac-in./mo ac-in./mo) ac-in./mo ac-in./mo ac-in./mo (ac-in./mo) (ac -in. Jan. 5.79 0.98 173 9,601 0 0 0 0 9,601 2,314 (11,916) 0 Feb. 5.44 1.54 143 8,445 0 0 0 0 8,445 2,175 (10,621) 0 Mar. 4.96 2.93 256 9,647 1,982 (2,372) 0 0 9,257 1,982 (11,239) 0 Apr. 2.72 4.72 161 9,154 1,089 (3,090) 0 0 7,153 871 (8,024) 0 May 1.90 6.22 113 9,680 759 (3,690) 759 (1,573) 5,934 607 (6,541) 0 June 0.46 7.32 272 9,702 184 (4,129) 184 (3,016) 2,924 147 (3,071) 0 July 0.44 8.06 2,181 12,056 177 (4,422) 177 (5,066) 2,921 141 (3,062) 0 Aug. 0.41 6.96 4,404 14,343 163 (3,983) 163 (4,205) 6,480 130 (6,610) 0 Sept. 1.48 5.31 5,158 14,644 592 (3,326) 592 (2,582) 9,919 473 (10,393) 0 Oct. 2.04 3.30 2,498 12,029 815 (2,518) 815 (1,200) 9,942 652 (10,595) 0 Nov. 4.37 1.42 61 9,106 0 0 0 0 9,106 1,749 (10,854) 0 Dec. 5.17 0.73 79 9,322 0 0 0 0 9,322 2,069 11,391 0 Totals 35.2 49.5 (in./yr) MAIN INPUT PARAMETERS Max. Percolation Rates (indmo.): Evapotranspiration Coefficient: Surface Areas (ac.): Municipal Effluent Flow (Mgd): 8.50 Mosquilofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (irUmo) 24.83 (1) Rainfall data is from Lodi station, using 100 year monthly statistics normalized to 100 year annual total (from Western Reg. Climate Center). (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rate)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloation basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 West Yost & Associates lodibal.xls zeroextended 9/18/00 Winter Summer Alfalfa Annual Basins Basins 3.0 3.0 30.0 30.0 1.0 varies 1.0 1.0 400 400 400 320 (1) Rainfall data is from Lodi station, using 100 year monthly statistics normalized to 100 year annual total (from Western Reg. Climate Center). (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rate)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloation basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 West Yost & Associates lodibal.xls zeroextended 9/18/00 Table 10-4. Water Balance for Land Discharge - Avg. Year (Alternative LEJ) Average Rainfall, Year 2020 Totals 17.6 49.5 (in./yr) MAIN INPUT PARAMETERS Max. Percolation Rates (in./mo.): Evapotranspiration Coefficient: Surface Areas (ac.): Municipal Effluent Flow (Mgd): 8.50 Mosquitofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (in/mo) 21.96 (1) (2) (3) (4) 5 6 7 (8) (9) (10) 1 (11) 12) Alfalfa & Grass Annual Crops varies Percolation Fields & Basins 400 400 400 320 Total Average Reference Industrial Wastewater Evap. & Evap. & Water Evap. & Rainfall E.T. Inflow I Inflow Rainfall Perc. Rainfall Perc. Left Rainfall Perc. Discharge Month (tn./mo) in./mo ac-in./mo ac-in./mo ac-in./mo ac-in./mo (ac-in./mo) (ac-in./mo) (ac-in./mo) ac-in./mo ac-in./mo) ac -in.) Jan. 3.52 0.98 173 9,601 0 0 0 0 9,601 1,408 (11,009) 0 Feb. 2.85 1.54 143 8,445 0 0 0 0 8,445 1,140 (9,585) 0 Mar. 2.73 2.93 256 9,647 1,092 (2,372) 0 0 8,367 1,092 (9,459) 0 Apr. 1.34 4.72 161 9,154 536 (3,090) 0 0 6,600 429 (7,029) 0 May 0.50 6.22 113 9,680 200 (3,690) 200 (1,573) 4,816 160 (4,976) 0 June 0.14 7.32 272 9,702 56 (4,129) 56 (3,016) 2,668 45 (2,713) 0 July 0.05 8.06 2,181 12,056 20 (4,422) 20 (5,066) 2,607 16 (2,623) 0 Aug. 0.05 6.96 4,404 14,343 20 (3,983) 20 (4,205) 6,195 16 (6,211) 0 Sept. 0.32 5.31 5,158 14,644 128 (3,326) 128 (2,582) 8,992 102 (9,095) 0 Oct. 0.90 3.30 2,498 12,029 360 (2,518) 360 (1,200) 9,031 288 (9,319) 0 Nov. 2.29 1.42 61 9,106 0 0 0 0 9,106 916 (10,022) 0 Dec. 2.92 0.73 79 9,322 0 0 0 0 9,322 1,168 10,490) 0 Totals 17.6 49.5 (in./yr) MAIN INPUT PARAMETERS Max. Percolation Rates (in./mo.): Evapotranspiration Coefficient: Surface Areas (ac.): Municipal Effluent Flow (Mgd): 8.50 Mosquitofish and Power Plant Usage (Mgd): 0.10 Average Hydraulic Loading (in/mo) 21.96 (i) Rainfall data is from Lodi station. (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rale)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloalion basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 West Yost & Associates lodibal.xls zcroavg 9/18/00 Annual Winter Summer Alfalfa Crops Basins Basins 3.0 3.0 30.0 30.0 1.0 varies 1.0 1.0 400 400 400 320 (i) Rainfall data is from Lodi station. (2) Reference evapotranspiration data is from "Irrigation with Reclaimed Municipal Wastewater - A Guidance Manual," by Pettygrove and Asano, 1985. (3) Projected industrial wastewater flow rate (4) (Wastewater flow rate in Mgd) x 36.83 x (number of days in the month) (5) Col. 1 x (alfalfa+grass area) (6) - (Col. 2 x (evapotranspiration coefficient for alfalfa) + (alfalfa area deep percolation rate)) x (alfalfa area) (7) Col. 1 x (annual crop area) (8) - (Col. 2 x (melded monthly evapotranspiration coefficient for annual crops) + (annual crops area percolation rale)) x (annual crops area) (9) Sum of Columns 4 through 8 (10) Col. 1 x (percloalion basins area). (11) - (Col. 2 x (evapotranspiration coefficient for perc. basins) + (basins percolation rate)) x (perc. basin area). (12) Sum of columns 9 through 11 West Yost & Associates lodibal.xls zcroavg 9/18/00 1,400 1,200 1,000 i6 0 800 v w 400 9� y Jan West Yost & Associates Figure 10-3.1and Discharge Alternative Effluent Loading by Field Type (1 in 100 Year Rainfall, Year 2020) l Y IS $ ' {N'7hF1 at �k -1t, 4 0 Perc. Basins & Fields (400 ac) rl Annual I . . . . . . . . . . . ■AlfalfaPoll INKS� t fit<M�tt.''�H�C _ }Y'tiM�3lla9 ij�$t�;y,��'�1 .. �iL t k MEN Feb Mar Apr May Jun Jul Aug Sep Month Lodi Wastewater Master Plan Oct Nov Dec lodibal.xls zerochart 9/18/00 DRAFT Summary of Areas and Volumes Required for Water Balances The areas and volumes required for the various alternatives to satisfy water balances and provide emergency storage or percolation disposal capacity are summarized in Table 10-5. The land areas shown in the water balances and Table 10-5 are net areas, not including roads, berms, or buildings. Table 10-5. Area -and Volume Requirements Alfalfa and Alt. Grass, ac Annual Crops, ac Winter Percolation, ac Summer/Fall Percolation, ac New Storage Reservoirs, ac New Storage Volume, of Wetlands, Total, ac ac DC -D 0 350 0 350 80 500 — 780 DC -W 0 350 0 350 40 250 130 870 BC -D 0 350 0 350 0 0 0 700 BC -W 0 350 0 350 0 0 130 830 BC -PD 400 400 200 260 1 0 0 Oros 1,060 LD 400 400 400 320(a) 1 0 0 1 0(b) 1,200 tai High rate dedicated fields or basins (up to 30 in/mo loading). (b) Could use wetlands for denitrification in lieu of conventional denitrification facilities. ALTERNATIVE CROPS Wood Tree Crops Poplar and eucalyptus trees are farmed commercially in the Central Valley of California for use in paper and wood products. These tree crops have a relatively high water and nutrient usage rate over a long season. Another advantage of these tree crops is that they are multi-year and require less management than annual crops or alfalfa. Tree crops can be furrow irrigated, allowing some biosolids and industrial wastewater to be applied. Tree crops would require about 10 percent less area than the combined alfalfa and annual crop areas shown in Table 10-5. Some tree crops may be sensitive to oxygen deprivation with high loadings of industrial wastewater. Greenchopped Corn The corn currently grown on the site is allowed to dry in the field and is then harvested as grain. There is little or no irrigation of the corn during this drying period. Alternatively, the corn could be harvested green in late August or early September and used for silage. This would allow effluent and biosolids to be applied to the harvested fields during the critical months of September and October. The net effect of this would be to increase the allowable September and October hydraulic loadings by about 5 inches per month for greenchopped corn fields which had already been harvested before September. This could reduce the amount of percolation field area by roughly half the amount of greenchopped corn area. For example, if 200 acres of greenchopped corn were planted, the amount of percolation fields shown in Table 10-1 could be 9/18/00 Draft 10-13 Wastewater Master Plan 213%wwmp DRAFT reduced by 100 acres. This could also reduce the amount of summer percolation basin area by about one sixth the amount of greenchopped corn area. Crops for Human Consumption If tertiary treatment facilities are constructed, essentially any crop could be irrigated with the treated effluent. Although other crops would not use any more water than alfalfa or tree crops, the City could potentially receive more revenue from its land and water because of the ability to grow higher value crops. Some of the higher value crops grown in the area include fresh market tomatoes, grapes, and vegetables. Tertiary treated effluent could also be used without restriction on land not owned by the City. This could provide additional flexibility in using the treated effluent. NITROGEN LOADING TO GROUNDWATER The application of sources of nitrogen to land can be a concern because of the potential for increasing the concentration of nitrate in groundwater. The primary maximum contaminant limit for nitrate -nitrogen is 10 mg/L as N. The background nitrate -nitrogen concentration has recently ranged from 5 to 40 mg/L in the monitoring wells. The concentration of nitrate in percolate would need to be kept below the drinking water limit of 10 mg/L (as N) and may even need to be several mg/L below 10 to satisfy possible future directives by the Regional Water Quality Control Board. Total nitrogen in treated secondary effluent is primarily nitrate (7.7 mg/L avg), with small amounts of ammonia (1.2 mg/L avg) and nitrite (avg 0.5 mg/L avg). At the 8.5 Mgd design flow rate, the total nitrogen loading rate would be slightly less than 700 lbs/d. Nitrate is a mobile ion in soil which can leach down to groundwater if it is not taken up by crop roots or denitrified. Nitrogen uptake varies by crop, but is generally in the range of 100 to 480 pounds per acre per year. Denitrification in soil is a function of the amount of carbonaceous matter available in the soil and the development of anoxic conditions. Biosolids typically contain ammonia and a high amount of organic nitrogen. A portion of the organic nitrogen is mineralized to ammonia over time, which in turn can be oxidized to nitrate. The total nitrogen loading in biosolids is projected to be 49,000 pounds per year, of which approximately 42 percent, or 21,000 net pounds per year, is estimated to be converted into plant available ammonia and nitrate in the soil (see Section 9). The industrial wastewater is primarily from fruit and tomato canning. This type of wastewater typically contains a very high amount of organic carbon in relation to nitrogen. In intermittently flooded conditions, almost all of the nitrogen will typically become immobilized or denitrified for carbon:nitrogen ratios over 20:1. Therefore the industrial wastewater poses little or no threat to groundwater nitrate concentrations. If blended with secondary effluent and/or biosolids, the industrial wastewater should actually reduce the total amount of available nitrate -nitrogen. The considerations for minimizing nitrate impacts to groundwater for the land discharge scenarios are discussed below. 9/18/00 Draft 10-14 Wastewater Master Plan 213\wwmp DRAFT Complete Surface Discharge For surface discharge of almost all treated effluent to either Dredger Cut or to Bishop Cut, the only sources of nitrogen to be applied to land would be from industrial wastewater and/or biosolids. Assuming 350 acres of annual crops, the average annual crop uptake of nitrogen would be approximately 100,000 lbs/year assuming a corn/oats double cropping. This is greatly in excess of the projected plant available nitrogen loading of 21,000 lbs/yr from the biosolids. With the denitrifying effect of the high carbon content of the industrial wastewater, the actual effective loading rate would probably be much less. Therefore there would be a nitrogen deficit for the annual crops, and supplemental fertilizer would need to be applied to achieve satisfactory crop yields. Even if some municipal effluent continues to be used for agricultural irrigation, the total nitrogen applied would be less than the crop uptake. Irrigation of 400 acres of alfalfa or grass with effluent during the months of March through October would result in a net plant available nitrogen loading rate of 115 pounds per acre per year. Irrigation of 400 acres of annual row crops with effluent and biosolids during May through October would result in a net plant available nitrogen loading rate of approximately 130 lbs/ac/yr. The loading rate to the fallow fields would be approximately 300 pounds per acre per year, with most occurring during April, May, September, and October. For both annual crops and for alfalfa, the projected loading rate to cropped fields is significantly less than the annual crop usage. The effluent directed to percolation basins should have a low enough nitrogen content or enough carbon such that the concentration of nitrate in deep percolate is below the 6 mg/L discussed previously. The methods for maintaining a low concentration of nitrate in percolate from percolation basins or percolation fields are discussed below under the land discharge alternative. Partial Discharge to Bishop Cut and Land Discharge For Alternatives BC -PD, BC -PW, and LD, effluent would have to be applied to percolation basins or fields. For the purposes of this Master Plan, the average concentration of nitrate in percolate is assumed to be 6 mg/L or less. There are four options for minimizing the nitrate concentration in percolate: 1. Conventional Denitrification 2. Denitrification in Wetlands 3. Blending with Industrial Wastewater 4. Operation of Percolation Fields to Maximize Denitrification With the historical average concentration of total nitrogen in the effluent of 9.3 mg/L, about one third of the nitrate in the effluent will need to be removed using one or more of the 4 options above. Option 4 alone would remove approximately 20 to 50 percent of total nitrogen. Nitrogen removal rates would tend to be higher in the summer months and lower in the winter months. Option 3 in combination with Option 4 would increase nitrogen removal substantially in late fall and winter months, but the solids from the industrial wastewater could reduce the infiltration capacity of the percolation basins. Option 2 would remove over 80 percent of the nitrate -nitrogen assuming 9/18/00 Draft 10-15 Wastewater Master Plan 2131wwmp 130 acres of wetlands. Even 65 acres of wetlands would remove about 50 percent of nitrate - nitrogen. Conventional denitrification (Option 1) can remove up to about 50 percent of nitrate without a supplemental carbon source. Option 4 should be marginally adequate. Depending upon actual field performance and future discharge requirements, a nitrate reduction of approximately 2 to 3 mg/L using either Option 1 or 2 may be necessary in addition to implementing Option 4. The costs and other considerations of Options 1 and 2 will be compared later in Section 13. Option 3 is appealing for its simplicity, but would need to be pilot tested to determine its viability in percolation basins or dedicated percolation fields. The effluent and biosolids applied to cropped fields would have essentially the same loading rates and nitrogen usage as with current effluent irrigation practices. Therefore there would be no adverse impacts to groundwater nitrate concentrations from effluent irrigation of crops for the Bishop Cut partial discharge or the land discharge alternative. GROUNDWATER LEVEL IMPACTS FOR PERCOLATION BASINS Depending upon the layout of percolation basins or fields, groundwater mounding may need to be controlled for the Bishop Cut partial discharge and the land discharge scenarios. The most likely area for percolation basins or fields for the land discharge scenario was shown in Figure 10-1. The characteristics of the soils are described in the soils report in Appendix =- The depth to groundwater in the spring for this area is about 10 to 15 feet below ground surface (bgs). Some of the borings show lenses of lower permeability soils, especially at around 10 feet bgs. The few available deeper well and boring logs show sandier strata below 10 feet. Groundwater mounding could develop above the lower permeability lenses due to the effluent percolation. The groundwater mound elevation could reach an equilibrium if the additional hydraulic head of the mound is enough to force the water through the lower permeability layers. Deep ripping of the basins could also be performed to fracture the lower permeability layers and increase vertical hydraulic conductivity. Any mounding would be less pronounced if the basins are laid out in a long, narrow fashion. Pilot testing and deeper borings will be necessary to confirm the magnitude of groundwater mounding and the effectiveness of these measures. If groundwater mound equilibrium cannot be achieved with the above measures, underdrains could be required to keep at least a 2 -foot unsaturated zone beneath the percolation basins. Theoretical underdrain spacing was evaluated using Hooghoudt's equation, a horizontal hydraulic conductivity of 10 feet/day in the permeable soil, and assuming only half of the applied water percolates through the lower permeability layers. The results indicate that widely spaced (200 to 300 feet) underdrains could control groundwater mounding if needed. Groundwater collected from underdrains would need to be discharged to the Delta. Although this water would probably be excellent quality except for salinity, some discharge requirements could be imposed. The most similar situation to this is the proposed groundwater level control system at the wastewater irrigation fields for the planned Mountain House community north of Tracy. The adopted permit for discharge of groundwater to Old River does not contain any limitations 9/18/00 Draft 10-16 Wastewater Master Plan 213\wwmp DRAFT beyond the standard groundwater quality objectives typically contained in most waste discharge permits (including Lodi's permit). COST ESTIMATES FOR LAND TREATMENT/REUSE AND DISCHARGE ALTERNATIVES Preliminary costs for the Land Treatment, Reuse, and Storage Alternatives are shown below in Table 10-6. These costs are based on typical unit costs from other similar facilities. These costs are for comparison purposes only. They include engineering and administrative costs at 20 percent of construction costs and modest contingencies at 40 percent of construction costs. The wetlands costs assume very basic features and only moderate initial planting density. Related improvements in treatment facilities and EIR costs are not included in the table. Costs related to improvements needed for the irrigation and tailwater pumping systems are discussed later in Section 11 because of their proximity to the treatment pond. Combined treatment and disposal/reuse costs are compared in Section 13. Table 10-6. Preliminary Estimated Costs of Alternatives— Land Treatment/Reuse and Discharge Facilities Only Alternative Facility Capital Costs Annual O&M Life Cycle(') DC -D 500 of Storage (b) 3,800,000 108,000 4,940,000 DC -W 130 ac Wetlands 250 of Storage(b) 3,900,000() 1,900,000 182,000 54,000 Total, DC -W 5,800,000 236,000 8,300,000 BC -D 7,500 ft Outfall Reaeration, Diffuser(d) 1,600,000 1,100,000 24,000 66,000 Total, BC -D 2,700,000 90,000 3,650,000 BC -W 100 ac Wetlands Reaeration, Diffuser (d) 3,000,000(°) 1,200,000 182,000 66,000 Total, BC -W 4,200,000 248,000 6,800,000 BC -PD 260 ac Percolation 7,500 ft Outfall Reaeration, Diffuser (d) 8,320,000(`) 1,600,000 1,100,000 117,000 24,000 66,000 Total, BC -PD 11,020,000 207,000 13,210,000 BC -PW 260 ac Percolation 60 ac Wetlands Reaeration, Diffuser (d) 8,320,000 1,800,000 1,100,000 117,000 90,000 66,000 Total, BC -PW 1 11,220,000 273,000 14,110,000 LD 1400 ac Percolation 1 12,800,000 180,000 14,710,000 (a) Assumes O&M costs converted to present worth costs using 7% interest for 20 years. (b) In addition to the 300 of of existing storage. (`) Includes land at $6,000 per acre. (d) Includes cascade reaeration prior to discharge to Bishop Cut through a submerged outfall diffuser. (°) Includes land at $8,000 per acre. 9/18/00 Draft 10-17 Wastewater Master Plan 213\wwmp - SUMMARY AND CONCLUSIONS The City currently owns sufficient land for disposal/reuse of industrial wastewater, biosolids, and some municipal wastewater. Additional land would be required for alternatives which include wetlands or percolation basins. The maximum land area requirement is for the land discharge alternative of approximately 1,200 net acres, assuming that additional land with favorable soil conditions and geology can be obtained. Alternative crops such as trees or greenchopped corn could reduce land area requirements slightly. Nitrogen from effluent and biosolids should not cause adverse impacts to groundwater nitrate concentrations on fields where crops are grown. Additional nitrogen removal is recommended through either conventional means, wetlands, or operational practices to insure acceptable nitrate concentrations under percolation disposal fields or basins. Costs for conventional treatment facilities associated with the alternatives are presented later in Section 11. The final evaluation of combined treatment and disposal/reuse alternatives is presented in Section 13. REFERENCES I S. C. Reed et al. Natural Systems for Wastewater Treatment. Water Pollution Control Federation Manual of Practice FD -16, 1990. 2 Crites, R.W., Meyer, E.L., and R.G. Smith. Process Design Manual—Land Treatment of Municipal Wastewater. EPA 625/1-81-013. October 1981. 3 S.C. Reed et al. Process Design Manual - Land Treatment of Municipal Wastewater—Supplement on Rapid Infiltration and Overland Flow. October 1984. ° Reed, S.C. and R.W. Crites. Handbook of Land Treatment Systems for Industrial and Municipal Wastes. Noyes -Publications, 1984. 9/18/00 Draft 10-18 Wastewater Master Plan 2131wwmp DRAFT SECTION 11. TREATMENT PLANT UPGRADE AND EXPANSION ALTERNATIVES The primary performance objective for the treatment plant processes is to achieve compliance with the waste discharge requirements at the design flows and loadings. Flow and loading projections were presented previously in Section 3. The current and anticipated discharge requirements were presented in Section 4. This section describes alternatives developed for addressing deficiencies, increasing treatment plant capacity, and increasing treatment levels to serve the needs of the community through the year 2020 and beyond. In addition, this section presents general facilities improvements which are desirable because of safety, operational, or reliability considerations. This section focuses on the domestic wastewater treatment facilities. All cost estimates listed in this section include escalation to ENR 7000, a 40 percent contingency, plus engineering and administrative costs. INTRODUCTION The City of Lodi constructed the White Slough Water Pollution Control Plant in 1967 and expanded the treatment facilities in 1976 and 1990. Figure 11-1 presents a site plan of the existing treatment plant which provides comminution of industrial wastewater and complete treatment of domestic wastewater. Figure 11-2 presents a flow diagram of the overall treatment and disposal facilities for domestic and industrial wastewater. Figure 11-3 shows the locations of the ponds and treatment plant relative to roads and other nearby facilities. Appendix A contains a list of design criteria and additional facility data. Existing Treatment Facilities The existing domestic treatment process consists of grinding, grit removal, primary sedimentation, conventional activated sludge secondary treatment, and chlorine gas disinfection. Primary and secondary solids are further treated in anaerobic digesters and sludge lagoons. Treated effluent is used for agricultural irrigation of animal feed crops, as process water for the Northern California Power Agency power generation facilities, and for the Mosquito Abatement District pond feed water. After the crop irrigation season, treated effluent is discharged to surface waters. Effluent storage ponds are used to store treated domestic wastewater for irrigation purposes or to store untreated wastewater in an emergency. Industrial wastewater passes through grinders within the domestic treatment plant headworks prior to lift pumps. After grinding, industrial wastewater is direct land applied for agricultural irrigation of animal feed crops during the growing season. The headworks facility also provides flow measurement and pumping. Industrial treatment and reuse are evaluated in Section 8 and discussed in this section only to the extent that common facilities are provided within the domestic treatment facilities. 9/18/00 Draft 11-1 Wastewater Master Plan 213\wwmp LAI) PILL: 1:/LI)1 vB-UI/ai-II-LJ�y we r wWaw.r�r_�..� - - ayrtl O :e 11 C4 m m x N� m cn m v w S A Figure 11-2 - City of Lodi Water Pollution Control Facility POND POND Existing Treatment Plant Flow Schematic FIELD IRRIGATION POND I POND 4 TNLWATER 5%LAMING AERATED EQUALIZATION POND 1A000N POND INFLUENT PARSHALL CO � CORS PONDS RECIRC. 80%ES FLUMES SCREENS PUMPS PUMP FROM w TRI CITY W Of UERETURN LOOI CRR I ,,—EFFLUENT IRRIGATION PUMPS (I �= REMOVAL PRIMARY WASTE MENTATION AERATION SECONDARI• BASINS CWtIFlERS CHLORINE EFRUENT (i TO WHITE SLOUGH CONTACT BYPASS I BAsINS I TANKS BOX l�I k BISHOP CUT f CRR GRIT I ` RETURN CU / _ SO, SEPTAGE SEPARATOR PUMPS I I I ACTIVATED 1 I � SLUDGE GRIT TO I I I AIR I SUPERNATANT ACTIVE S�LUDGEO I r--_—i----------� Lt—_ PLWTATION LANDFILL THICKENER SUBTHICNENER L SUBWUAM I RAW — PRIMARY SLUDGE L — —��— I WASTE NED I AC1MtTE0 HEATERS SLUDGE — �— — �— — J (A��-E WASTE CASI BURNER I SLUDGE— I DIGESTER I BIOSOUDS MAlGN$ yT TO MOT WATER BOILER CONTROLDIGESTER T1 I _ CIS T DECANT TO SCRUBBER INDUSTRIAL SOLIDS BUILDING GAS WASTE f J L AS TD wfLUTM Bax LAND FUEL. OIL SUPPLY W E S T Y 0 S T k AS.ATTS Facility Review Procedures Process unit treatment performances were determined by reviewing historical operational records, compliance reporting, and past studies and reports. This performance was compared with industry performance standards. Preliminary process models were used where applicable to estimate reliable capacities of existing treatment processes for current, anticipated, and potential future waste discharge requirements. Based on these analyses and input from plant staff, capacities and operational deficiencies of plant process units were determined. Rated Capacity The capacity of the overall plant is currently limited by certain key processes to about 6.5 to 7.0 Mgd — substantially less than the 8.5 Mgd minimal capacity for the 1990 expansion. Since the last expansion, however, regulatory changes have required the plant to nitrify or remove ammonia. This requirement has effectively increased demands on the entire secondary process, requiring it to be rated at a lower capacity than the original basis for design. Additionally, several facilities which would have been included in the last expansion to provide redundancy and reliability were not constructed due to lack of funds at that time. The most notable areas lacking redundancy in the existing plant are the secondary clarifiers, dissolved air flotation thickeners for waste activated sludge, anaerobic digesters, and biosolids storage lagoons. The following section presents a process evaluation and presents recommendations for "expanding" the plant capacity to 8.5 Mgd, to compensate for de -rating of process components to meet regulatory requirements while providing sufficient redundancy for outages of process components during required maintenance. DESIGN CRITERIA FOR UPGRADES General Detailed unit process design criteria which control the sizing and capacity rating of treatment units are listed in Table 11-1. These criteria are based on generally accepted industry values, specific analysis of anticipated conditions and the experience of the facilities planning team. These criteria were used for sizing of unit process for all alternatives considered. Treatment Requirements Domestic treatment capacity has been affected by the need to meet more stringent discharge requirements than planned for when the last expansion was constructed. The purpose of the treatment plant review was to identify those improvements necessary to meet existing, anticipated, and potential future discharge requirements at Year 2020 projected flows and loadings. A related purpose of this review was to identify those improvements necessary for potential effluent reuse or disposal alternatives such as the proposed Sports Complex. The potential discharge requirements and alternatives for satisfying them were discussed previously in Sections 4 and 5. The major potential additions to the processes at the treatment plant are nitrification, nutrient removal, heavy metals removal, and tertiary filtration. For continued discharge to Dredger Cut, tertiary treatment and full nitrification are mandatory. 9/18/00 Draft 11-5 Wastewater Master Plan 213\wwmp Table 11-1. Summary.of Controlling Unit Process Design Criteria Unit Process Design Loading Condition Process Criterion Process Performance Pretreatment Influent pumps Instantaneous peak hour Total pumping capacity at required head with one Pump all flow under all operating (Mgd) pump out of service. conditions. Mechanical screens Instantaneous peak hour One mechanical unit out of service and one fixed Screen all flow under all operating (Mgd) or mechanical screen as backup. conditions. Aerated grit removal Instantaneous peak hour Detention time >— 3 minutes at peak hour with one Treat all flow under all operating system (Mgd) unit out of service. conditions. Primary Treatment Primary Instantaneous peak hour Surface overflow rate less than 2,500 gpd/ft2 with Average BODS removal — 30%. sedimentation basins (Mgd) one unit out of service. Average suspended solids removal — Preferred maximum overflow rate less than 2,000 65%. gpd/sf for all units in service. Aeration Basins Aeration Basins Maximum month BOD and Design is based on nitrification with all units in Soluble effluent BOD consistently ammonia loading condition. service. below 15 mg/L. Aeration requirements matched to peak BOD/ Ammonia consistently below 2 mg/L ammonia loads. average and 7 mg/L peak. Secondary Clarifiers Secondary Clarifiers Peak sustained flow with all Capacity rating based on Flux Analysis using: Secondary Effluent BOD and SS units in service. . SVI =I 00 mL/g consistently below 30 mg/L. . RAS = 8.5 Mgd (total) . MLSS = 3,500 mg/L Maximum overflow rate less than 1,100 gpd/sf for all uniis in service. 9/18/00 Draft 11-6 Wastewater Master Plan 213\wwmp DRAFT Unit Process Design Loading Condition Process Criterion Process Performance Disinfection System Chlorination System Peak Hour Flow Chlorine dosage of 20 mg/L for planning Effluent coliform 2.2 MPN/100 mL. purposes. Chlorine Contact Peak Hour Flow 30 minute contact time. Effluent coliform 2.2 MPN/100 mL. Basins (advanced secondary) Chlorine Contact Peak Dry Weather Flow 90 minute modal contact time Effluent coliform 2.2 MPN/100 mL. Basins (tertiary) C*T> 450 mg-min/L. Dechlorination Peak Hour Flow Chlorine Residual 8 mg/L for planning purposes. Effluent chlorine residual < 0.01 mg/L. System Feed Rate = 1.46 lb sodium Bisulfite per lb chlorine residual. Solids Processing DAFTs Maximum month solids Loading rate for waste activated sludge < 0.5 Thickened sludge concentration of loading; largest unit in service. lb/ft2/hr. 3.5%. Digesters Maximum month loading with Loading less than 0.15 lb VS/ft'/day and detention Class B Sludge. 50% Volatile Solids all units in service. time greater than 15 days. Destruction. Average month loading with one unit out of service Digested Sludge Average digested solids Minimum 120 day storage. Storage prior to land application Storage loading. without odors. Tertiary Filtration (required for most discharge alternatives) I Media Filtration Peak Tertiary Flow Max. 5 gpm/ft2. 2 NTU max. daily average, 5 NTU max. 5% of time, 10 NTU max. peak. Microfiltration Peak Tertiary Flow Varies by manufacturer. 0.2 NTU max. 5% of time, 0.5 NTU max. peak. 9/18/00 Draft 11-7 Wastewater Master Plan 213\wwmp Nitrification. Ammonia removal through biological nitrification is required for all alternatives which include discharge to Dredger Cut or Bishop Cut. Nutrient and Heavy Metals Removal. Additional treatment evaluated for the Master Plan includes nitrogen removal through biological denitrification, phosphorous removal through biological uptake, and additional heavy metal removal through chemical addition and enhanced effluent filtration. These alternatives are presented only to the extent that the Master Plan facilities provide flexibility to accommodate these and other facilities as they are required. Tertiary Filtration and Disinfection. Tertiary filtration and disinfection of the secondary effluent are required for most of the surface waters discharge alternatives and for the reclamation of effluent for the Sports Complex or other unrestricted irrigation uses. Redundancy Process equipment should have sufficient redundancy or reserve capacity to handle incoming flows and continue to meet discharge requirements if one equipment item is out of service for maintenance or repair. For example, pump stations should have sufficient capacity to handle peak flows with one pump of the set out of service. Where units of different capacity are installed, the process should accommodate peak flow with one of the largest units out of service. Staff and Public Safety Criteria All applicable safety related codes and regulations must be satisfied when the treatment plant facilities are modified or upgraded. Safety regulations by Federal OSHA, Cal OSHA, and other regulatory agencies will be followed. Other safety related codes to be followed include the Fire Code and Uniform Building Code. Americans With Disabilities Act (ADA) The ADA and other related governmental requirements for handicapped access will need to be satisfied in the modification of existing buildings and construction of new buildings. Flood Protection 100 -year flood protection must continue to be provided for the treatment plant. This is a requirement in the waste discharge requirements and will probably be a requirement for any governmental loan or grant monies used for treatment plant upgrades. Power and Control Redundancy Electrical power backup and control redundancy will be provided in any upgrades or modifications to prevent spills or overflow of undisinfected effluent in the event of a power outage. 9/18/00 Draft 11-8 Wastewater Master Plan 213\wwmp OPERATIONAL CRITERIA Operational criteria refers to items related to operational strategies and philosophies rather than mandated design criteria. Operational criteria includes staffing levels, operational flexibility, control, and automation. Staffing The plant is currently fully staffed 5 days per week from 7:00 a.m. to 3:30 p.m. One operator is on duty from 3:30 p.m. until 11:00 p.m. weekdays and from 7:00 a.m. to 11:00 p.m. on weekends. This level of staffing has proved adequate in the past and should be adequate for the near future. As treatment processes are added and the treatment requirements become more stringent, plant operation may be increased to 24-hour staffing. The need for additional staffing will depend on the timing and extent of the improvements made with the next plant expansion or upgrade project. Operational Flexibility The current flexibility of plant operation should be maintained by the upgrade so that unit processes can be operated in different modes and with varying loading so as to optimize overall plant performance. Existing deficiencies which limit flexibility should be eliminated where feasible. Upgrades should also provide enough flexibility to allow for periodic maintenance of any unit process without undue disruption of the remaining processes necessary to achieve compliance with discharge requirements. Automation Criteria Existing control systems are limited to data recording and alarm of critical plant components. After hours alarm notification is made with an autodial to service, which calls out plant staff. The existing system can be described as a programmable logic controller (PLC) system with main and local control panels. The PLC system consists of AB PLC 5/40 hot redundant standby processors inside the main control panel with remote PLC located in local control panel LCP-C which communicates over data highway cabling. Alarm, monitoring, and display functions are provided on the main control panel using conventional indicating lights, annunciator, vertical analog meters, and horizontal strip chart recorders. The PLC system as configured is SCADA ready, meaning that a SCADA graphic PC based system could be installed with minimum effort and expense now or during any phase of upgrades. In general, the next plant improvement project should incorporate instrumentation and control features which increase plant automation if such automation will result in improvements in one or more of the following areas: 1. Safety 2. Treatment reliability 3. Reduced operator workload 4. Reduced operating cost 9/18/00 Draft 11-9 Wastewater Master Plan 213\wwmp 5. Convenient alarm notification 6. Offsite data access As a minimum, new or updated process control equipment should be capable of automation as shown in Table I1-2. Table 11-2. Plant Automation Criteria Control Function Recommended Level Of Automation Aeration Blower Control Full automatic control Disinfection Chemical Dosing Full automatic control Dechlorination Chemical Dosing Full automatic control Digester Heating Full automatic control Influent Pumping Capable of upgrade to full automatic control Primary Sludge Pumping Capable of upgrade to full automatic control RAS/WAS Pumping Full automatic control Full automatic control implies computer control with redundant instrumentation. A fully automatic system can be started, stopped, and adjusted based on programmed process set points, time of day, or other pre-programmed criteria. Instrumentation must provide reliable control feedback and alarm capabilities. Automatic control provides two potential advantages. First, power and chemical use can be optimized through continuous monitoring and adjustments. Second, full plant automation can reduce operator workload so that more time can be devoted to preventative maintenance, or the need for 24-hour staffing can be delayed. The recommended operational and control criteria that should be provided with any plant expansion are summarized in Table 11-3. Additional criteria details are discussed below. Table 11-3. Summary of Operation and Control Design Criteria Plant Equipment or Area Design Criteria Desired Results Alarm Systems PC based auto dialer with prioritization Better communication, information, and and individual addressing. Laptop dial- response in to remotely access plant graphic screens Equipment or Local control, remote monitoring for all Increased process monitoring and centralized Process Control treatment equipment; full SCADA on control capabilities; improved automation major process control (Aeration Basin capabilities; increased process efficiency to DO, RAS, WAS, Disinfection/ reduce power and chemical costs Dechlorination, Digester Heating) Control Zone Loops PLC Control Simplicity, enable local or SCADA manual control 9/18/00 Draft 11-10 Wastewater Master Plan 213\wwmp Plant Equipment or Area Design Criteria Desired Results Control Zone Color graphics, on-screen Quick, easy comprehension to shorten Operator's Interface response time and reduce potential for errors Zone Computers: CPU Hardware High quality standard PC Lower cost, ease of upgrade and change - ability compared to conventional hardwired control panels Display PC Screen Lower cost, ease of upgrade Power System 15 to 30 minute uninterruptible power Reliability supply with conditioning Supervisory Control PC Based Availability of add-ons or upgrades, ease of and Data Acquisition programming, flexible data management and Software reporting to improve analytical capabilities and reduce workload Third party SCADA software: Setup and support available from many Wonderware, Intellution or similar. sources. Allen Bradley communication protocol Compatibility with existing City systems PLCs Allen-Bradley with Ethernet connection Compatibility with existing equipment, to PCs. similarity of replacement parts, leverage staff knowledge and reduce training costs Communication Link Fiber Optics Noise immunity and ground loop isolation Control and Data Acquisition Equipment and processes at the plant could be divided into control zones linked by a plant -wide supervisory control and data acquisition (SCADA) system. All control and instrumentation for any one process can be tied to a single zone; however, multiple processes may be controlled by a single zone for plant redundancy. The control zone concept could extend to auxiliary systems such as plant water, intrusion monitoring system, HVAC, etc. Each zone control center may consist of a programmable logic controller (PLC), and a networked zone computer with a standard color graphic CRT display. Motor control centers should have few or no switches and indicator lights; all remote control may be operated via the zone computer, or over the SCADA system from another zone control computer. Use of local control panels will be minimized. Each computer should have a standard CRT display and mouse which will serve as the operator interface. Manual override control of equipment should be provided through local switches and speed control (where appropriate) located adjacent to the equipment. These local control stations will include limited digital indicators providing the minimum necessary status information. Controls should be standardized as much as possible throughout the plant and should be easily adjustable or programmable by treatment plant staff. Communications and PLC hardware will be based on the Allen Bradley specifications for compatibility with existing control equipment. Any control system should provide adequate control redundancy through dedicated analog indicators 9/18/00 Draft 11-11 Wastewater Master Plan 213\wwmp and indicating lights in each control zone, or redundant PLC should be provided for each control zone. Data acquisition should be performed at a central computer in the operations building receiving signals from each of the control zones by way of the central PLC. The existing main control panel may no longer be necessary with existing functions such as trending, status and alarm indication done in graphics. The data acquisition hardware should utilize widely accepted industry standards and be non-proprietary to the greatest extent possible. The SCADA software should be graphical, easy to use, and based on a non-proprietary operating system with multi - sources of support. Operator training must be available and similarity to the existing data acquisition software will reduce training and start-up costs. PRELIMINARY TREATMENT The Water Pollution Control Plant headworks facility provides preliminary treatment consisting of flow measurement, comminuting, grit removal, and pumping. Description of Existing Facilities The headworks facility is a below grade structure. The pump room sets below an electric panel room and a sludge heater room. Inlet air blowers and exhaust fans provide fresh air and purge odors. The air blowers and exhaust were recently upgraded. Exhaust air is discharged at the headworks roof. No odor scrubbing is provided. Raw wastewater enters the plant headworks influent boxes from the east in a 48 -inch domestic waste sewer and a 33 -inch industrial waste sewer. Hydraulically operated sluice gates at the influent box automatically close upon a plant power failure preventing wastewater from entering the plant. Upon gate closure raw sewage backs up into the influent sewers. Raw sewage may then be diverted around the treatment plant and dumped into the effluent equalization pond. However, the equalization pond water level must be lowered sufficiently to allow for this plant bypass to occur. The domestic and industrial waste streams are treated separately through the headworks. The domestic waste flow is measured in an 18 -inch Parshall flume (expandable to 24 -inch), passed through a comminutor, treated for grit removal, and pumped to the domestic wastewater treatment facilities. The industrial waste flow is measured in a 12 -inch Parshall flume (expandable to 18 -inch), passed through a comminutor, and pumped directly to land for crop irrigation and/or direct land treatment. The existing Parshall flumes are adequate for projected flows within the Master Plan planning period. Septage is dumped into the domestic sewer upstream of the headworks. A septage receiving station and 4,000 -gallon holding tank (added in 1975) are not used because the holding tank has proved to be too small, and the holding tank piping is subject to plugging. An estimated 720,000 gallons of septage was received in 1998. Grease from local haulers within the City limits is dumped into the primary scum pits and pumped directly into the anaerobic digesters. An estimated 230,000 gallons of grease was received in 1998. 9/18/00 Draft 11-12 Wastewater Master Plan 213\wwmp The domestic wastewater grit removal system consists of two 16 -foot diameter settling tanks referred to as a detritus tanks. Collected grit is pumped through a cyclone/classifier grit dewatering system and then deposited into a dumpster and periodically hauled to a landfill. As much as 15 cubic yards of grit is removed every 2 to 3 weeks. Influent pumps consist of three domestic pumps and two industrial pumps. Pumps are powered by variable frequency drives. The drives are outdated and difficult to repair. Plant staff have begun a program to .replace all variable frequency drives with new equipment. Each influent pump is fed from an individual 4 -foot by 7 -foot wet well. Flow is directed to the wet wells through several manually operated slide gates from a single cross channel. All pumps discharge to a pump discharge channel ahead of the primary sedimentation basins. The industrial waste discharge line begins at the pump discharge channel. Flow is directed to the industrial discharge line or to the primary sedimentation basins through several manually operated slide gates. Deficiencies and Alternative Improvements The headworks is in need of rehabilitation. Existing equipment is outdated and parts of the structure are showing significant corrosion. Except for the influent pumps, all existing headworks components have sufficient capacity through the Master Plan planning period. Expansion will be required to handle flows beyond 8.5 Mgd. Headworks Structure. The existing headworks structure is a below grade structure that is difficult to expand or modify to accommodate improved equipment and higher capacities. In general the headworks concrete surfaces are partially deteriorated at floor level and in the wastewater channels. The concrete at the floor of the headworks structure appears to be superficially corroded. Concrete in the flow channels has experienced corrosion and has required repairs in the past. All concrete surfaces should be cleaned, inspected, and refinished as required. Existing channel grates which deflect and move under foot should be replaced with new aluminum grating. The alternative of constructing a new headworks is discussed later in this sub- section. Control Gates. The hydraulic pump for powering hydraulic equipment is located in a deep pit making access difficult and should be relocated. Most of the manually operated slide gates at the cross channel ahead of the pump wet wells and the slide gates in the pump discharge channel are not operable. The slide gates should be replaced and/or rehabilitated as required to restore full operation. Gate operators should be added to facilitate operation of critical slide gates that need to be operated in an emergency condition such as the gates at the cross channel ahead of the pump wet wells. These gates may be used to direct industrial flow to one of the domestic pumps during failure of an industrial influent pump. Removal of Large Solids. Comminuting is not in wide use for wastewater treatment. Comminuting grinds rags and other debris into smaller pieces but does not remove this objectionable material which is clogging downstream treatment systems and filling the digesters with debris. The preferred approach is to remove the rags and other coarse material from the flow stream with self-cleaning screens. 9/18/00 Draft 11-13 Wastewater Master Plan 213\wwmp DRAFT There are three general types of screens that can be used for the influent screening application: 1. Mechanically cleaned bar screens 2. Continuous self-cleaning bar/filter screens 3. Spiral basket screens Mechanically cleaned bar screens consist of fixed bars in a channel that collect debris and a motorized rake mechanism that cleans the debris off the front of the screen, and lifts the debris to a discharge point some distance above the channel. The only moving part of the screen that is submerged is the rake. Theses units require high overhead clearance and are not suitable for fine screening. Continuous self-cleaning bar/filter screens consist of a continuous belt of plastic or stainless steel mounted horizontally and vertically on a series of parallel shafts that collect, convey, and discharge all solids greater than a mesh size from 1/ inch to 3/4 inch. This type of screen is often selected over mechanically cleaned bar screens where greater capture is required and high continuous loading is expected. Collected screenings can be washed, dewatered, and compacted in separate units. Continuous self-cleaning bar/filter screens do not need to operate 24 hours per day. Adjustable timers are used to,match daily flow variations. Selection of the screening system should be based to a great degree upon the ability of the system the minimize head loss and reduce impacts to the Parshall flume. As a general rule, the maximum allowable flume submergence for a flume one foot wide or greater is 70 percent (ratio of downstream flow depth to upstream flow depth) before free flow conditions are interrupted and flow measurement is hindered. Preliminary review of the headworks hydraulic profile and head loss data provided by one screen supplier indicates that new screens may be inserted into the 32 -inch communitor channels with minimal impact to Parshall flume operation. This is based on no more than a 30 percent blocked screen and an approach velocity of about 2 feet per second. Some minor modifications to the channel bottoms and walls would be required. Actual screen head loss data for continuous filter screens should be collected at design flow conditions at a similar facility before screens are installed at Lodi. However, one screen would not treat all flow during peak flow conditions should a screen be out of service. It would be necessary to provide an overflow weir to the existing bypass channel to prevent Parshall flume submergence during high flow conditions with one screen out of service. This would still be a significant improvement over existing conditions. Spiral basket screens consist of a %a -inch screen basket and brush located in the flow channel, screenings washing agitator, shaftless spiral conveyor assembly, transport tube, and discharge chute. Spiral screens combine screening, screenings washing, dewatering, and compaction into one unit. The spiral screens are compact and ideally suited for low flows. Their primary disadvantage is that their rated capacity is limited to 7 Mgd each. Two units would have a maximum theoretical capacity of 14 Mgd at peak flow. The actual capacity will vary with the quantity of screenings and amount of basket plugging. With severe plugging the units will back up the water surface into the Parshall flume and overflow the top of the basket screen. The existing bypass channel could be fitted with a third screening unit or an overflow weir could be placed in the bypass channel to prevent Parshall flume submergence during high flow conditions or basket plugging. In this case a portion of the flow would not be screened. The other 9/18/00 Draft 11-14 Wastewater Master Plan 2131wwmp disadvantage of the basket screens is that the washing mechanisms at the bottom of the channel are not effective at water depths greater than 22 to 24 inches. As the flows increase and the screens begin to plug the water depth will rise. This will lead to diminished washing effectiveness, more plugging, and deterioration of screenings quality. For this reason it is important that the units not be overloaded. Actual screen headloss data for basket screens should be collected at flow conditions near 7 Mgd at a similar facility before screens are installed at Lodi. In addition, alternative designs recently on the market should be reviewed where the screen capacity is not limited to 7 Mgd. Continuous self cleaning bar screens are the recommended alternative at this time. The cost of self-cleaning screens is similar to spiral basket screens and only slightly greater than for mechanical bar screens. Spiral basket screens are not recommended because their capacity would be limited given the existing channel geometry. Spiral basket screens are still evolving rapidly and should be reevaluated during the predesign phase of the next treatment plant upgrade. The use of mechanically cleaned bar screens is not recommended because of the overhead clearance requirement and the fact that mechanically cleaned bar screens are not suitable for fine screening. The cost of two new continuous, self-cleaning screens including installation, channel modifica- tions, and electrical power is estimated at about $500,000. The total cost with a screw conveyor system is estimated at about $600,000. The actual cost will depend on the final screen selection and the number of screens purchased. Compacted screenings could be discharged to garbage barrels or small dumpsters and lifted out of the headworks each day through a roof access hatch. Alternatively, a hydraulic ram press or a screw conveyor could be used to lift the compacted screenings out of the headworks through a new roof opening and deposit the material directly into a dumpster located at ground level. Grit Removal. Detritus tanks are not in wide use for wastewater treatment. These tanks do not provide consistent grit removal during varying plant flow conditions. At low flows excessive organic material is removed and during high flows grit is washed downstream. However, the grit washing and dewatering system is designed to remove excessive organics which overcomes some of the deficiencies of the existing grit removal system. The existing grit removal hopper and piping is subject to plugging during peak inflow events or during a pump failure. The space for grit removal pumps and piping is very limited and makes pump repair work difficult and there are no redundant pumping units to operate during a pump failure. The existing grit removal tanks are not amendable to modification or expansion due to the confined space within the headworks. Aerated grit tanks are relatively small rectangular structures with steep -walled grit hoppers. Coarse -bubble aeration creates a rolling action in the tank, which keeps lighter organic material in suspension. Screw augers or recessed impeller pumps remove the collected grit from the grit hopper. Aerated grit tanks offer the added benefit of preaeration of the raw sewage. Preaeration can help prevent septic conditions in the primary clarifiers and remove corrosive or odor -causing compounds. 9/18/00 Draft 11-15 Wastewater Master Plan 213\wwmp A vortex grit removal system consists of relatively small circular structures with a center grit collection hopper. Incoming wastewater and small propeller blades above the grit hopper produce a spiraling vortex action that tends to lift lighter organic particles. Recessed impeller pumps remove the grit for further washing and dewatering. Vortex grit removal systems use less energy than aerated grit tanks. The principle disadvantages of this system are relatively greater potential for grit collection hopper plugging and the fact that the wastewater does not receive any aeration prior to primary treatment. New domestic wastewater grit removal facilities are recommended to replace the existing grit tanks. The aerated grit removal system is the preferred alternative at this time. A new grit removal system will require construction of new facilities outside the existing headworks. The most likely site for new facilities is the open area located to the southwest of the existing headworks. The existing oil storage room and waste gas burner would be relocated to allow room for the new facilities. Grit removal would occur after influent pumping so that the grit removal facilities could be built at a higher elevation for lower cost and better accessibility. Existing pump discharge piping would be extended to the new grit removal facilities. After grit removal, all flow would be returned to the existing pump discharge channel ahead of the primary sedimentation basins. The estimated construction cost of a new grit removal facility is over one million dollars. This expenditure of funds is not justifiable within the Master Plan planning period. However, in the long-term the grit removal system should be replaced with a new structure because it will become impractical to expand the existing structure when average flows exceed 8.5 Mgd. The need for new grit removal facilities is far enough into the future that vortex grit removal systems should be reconsidered prior to design. Septage. The existing septage receiving station consists of a removal lid centered in a small wash down area where waste haulers park and discharge their truck contents into a small holding tank. The tank contents can be discharged to either the industrial or domestic influent sewers. The existing septage holding tank can only hold the contents of one large septage hauling truck. When there is more than one truck, the holding tank is not effective. The existing station is not used because the holding tank has proved to be too small to be of much value and the holding tank piping is subject to plugging. As a result, the holding tank is out of service and waste haulers dump their waste directly into a manhole on the domestic influent sewer adjacent to the septage receiving station. This waste can sometimes contain large debris that can cause problems in the treatment plant headworks. Undiluted septage dumps are undesirable. The rapid dumping of 3,000 gallons or more of odorous septage into the plant influent flow stream creates a shock odor condition. Additional septage storage capacity is required. A new septage receiving station could be installed which provides storage for holding the peak daily volume of septage. The required tank storage volume is estimated at 20,000 gallons total with two tanks based on as many as 8 trucks a day with a septage volume of 2,000 to 3,000 gallons per truck. The station should be equipped with a large, hard -surfaced wash down area, wash down water, coarse bar screening, spray water, and foul air withdrawal and odor scrubbing. Facility design should include the ability to pump septage directly to the digesters. Additional features such as water flushing system inside the storage tank, flow metering, pH monitoring, or controlled access through a card -lock system could also be provided. A separate receiving station will require construction of new facilities outside the 9/18/00 Draft 11-16 Wastewater Master Plan 213\wwmp existing fenced treatment plant site. The most likely site for new facilities is the open area located to the east of the existing South Electrical/Polymer/Storage Building. One alternative would be to construct a new septage receiving facility at an estimated cost of approximately $400,000. A second alternative would be to reconstruct the existing septage receiving facilities to provide a hard-surfaced wash down area, coarse bar screen, and an unobstructed discharge to the domestic influent sewer. The cost of reconstruction of the septage receiving facility is estimated at approximately $60,000. New septage facilities are ultimately needed, but may be delayed for several years while sufficient funds are accumulated for the new facilities. Plant performance impacts do not justify such an expenditure of funds within the Master Plan Planning Period. New septage facilities should be constructed when a new headworks is constructed in the next expansion after the end of the Master Plan planning period. Influent Pumps. Influent pump capacity is inadequate to meet projected peak hour demand of 16.3 Mgd with one unit out of service. All domestic pumps will be required to operate during projected peak flow conditions, and all industrial pumps are required to operate during peak flow conditions. The existing cross channel in front of the individual pump wet wells allows pumps to be used interchangeably for domestic or industrial waste. However, most of the manually operated slide gates at the cross channel ahead of the pump wet wells and the slide gates in the pump discharge channel are not operable. In addition, it would be very awkward to make the channel and valve changes necessary to switch the industrial pumps to handle domestic wastewater during peak conditions. Therefore, the gates and channels should be replaced and/or rehabilitated. The cross channel would only be used for emergency operation. Domestic influent pump capacity should be increased to pump peak flows with the largest unit out of service. The two existing pumps (7.2 Mgd, 50 hp) should either be sped up or replaced with larger pumps with a capacity of about 5,900 gallons per minute each (8.5 Mgd, 60 hp). Industrial influent pump capacity should be increased to pump peak flows with the largest unit out of service. The problem with only increasing the capacity of the existing pumps is that during the non-canning season the pumps would be too large and would be cycling off and on too frequently. Therefore a third industrial influent pump should be installed to handle the non- canning season flows. The smaller of the two existing two pumps (4.7 Mgd, 30 hp) should be replaced with a pump which has a capacity of 7.2 Mgd to match the existing larger pump. Although this would not provide full redundancy, it would handle the peak day industrial flow assuming peak hour flow could be allowed to back up into the sewer trunk. One of the domestic wastewater pumps can be also used as additional backup for the industrial pumps through the use of the cross-channel gates. The third industrial wastewater pump should have a variable speed drive and a capacity of approximately 300 gpm (0.43 Mgd). This pump could operate at low speed to pump non-canning season industrial flows. The existing influent pump room is not designed for a third full sized industrial influent pump. A small pump could probably be installed south of Industrial Waste Pump No. 1. It would need a separate suction pipe installed into the wet well through the separating wall. It would discharge into the Industrial Waste Pump No. 1 discharge piping. A 9/18/00 Draft 11-17 Wastewater Master Plan 2 i 3lwwmp new check valve would need to be installed on the Industrial Waste Pump No. 1 discharge line to prevent backflow. New Headworks. A new headworks could be constructed either in the next few years or around Year 2020 when the capacity of the existing headworks is close to being exceeded. New headworks would include new channels, flow meters, screens, and influent pumps. The influent pumps would be located ahead of the other headworks processes in order to raise the headworks out of the ground. This would allow gravity flow through the headworks to the grit removal tanks and primary clarifiers. Grit removal tanks would be located immediately downstream of the screens. The location and general layout of new headworks are shown in Figure 11-4. The cost of a new headworks structure with a new influent pump structure, flow measurement, continuously cleaned screens, and aerated grit removal is estimated at about $4,000,000. This is about double the estimated cost of modifying the existing headworks. The benefit in plant operation or process performance is not sufficient to justify the cost of a new headworks at flows up to the capacity of the existing headworks. However, expenditures made in the existing headworks will ultimately be thrown away, as a new facility will ultimately be required. The headworks must be replaced with a new structure when the treatment plant capacity is increased beyond 8.5 Mgd because it will be impractical to expand the existing structure. Alternatively, the City may opt to replace the headworks now to provide facilities which would be suitable for the next several decades. Odor Control The White Slough Water Pollution Control Facility has no odor control facilities. Odor control will become more of an issue as proposed facilities near the treatment plant are developed. The headworks and preliminary treatment facilities are significant sources of odor. ' Odor control measures are described and evaluated later in Section 12. Summary of Recommended Facilities Recommendations for new facilities associated with preliminary treatment are summarized as follows: • Rehabilitate the headworks structure. All concrete surfaces should be cleaned, inspected, and refinished as required. Replace deteriorated grates with new aluminum grating. Relocate the hydraulic pump for powering hydraulic equipment. Replaced and/or rehabilitate all channel gates as required to restore full operation and add gate operators to facilitate operation of critical gates. Replace the existing domestic comminutors with self-cleaning screens at the next treatment plant upgrade. A continuous cleaning bar screen appears to be the best alternative at this time, but final selection of a screen type or manufacturer should be made during predesign based on headloss and operating data from units operating 9/18/00 Draft 11-18 Wastewater Master Plan 213\wwmp z25� �g|Z [ ] T]�§` | }■■■■@@� ■. \| / ° /� r : ! u . ©r—1 F -I L_l E: �121 \, \§� - E ------a \ @« , .. � re \ Ea Ll CD EAA ®2 0 0x E� . ' & § / � / 0 o a -n \�` r " / � 7E -- ■ E 23 07 -n , K §a . 7 under similar conditions. The self-cleaning screens should provide screening washing and compaction. This recommendation does not apply to industrial wastewater. There is no significant advantage to screening the industrial wastewater. Therefore, retain the existing industrial comminutors and or replace them with new grinders when the existing units are no longer serviceable. + When treatment plant capacity is expanded beyond 8.5 Mgd, the detritus tanks should be replaced with new aerated grit tanks. The open area located to the southwest of the existing headworks should be retained for future grit removal facilities. No action is required during the Master Plan planning period. During the next treatment plant upgrade the existing septage receiving station should be modified to provide a hard -surfaced wash down area, coarse bar screens, and a discharge to the domestic influent sewer. After these modifications, the existing septage receiving station should be restored to full operating status. Within approximately 10 to 15 years, new septage facilities should be constructed in the open area located to the east of the existing South Electrical/Polymer/Storage Building. • Replace the smaller existing domestic influent pumps or increase their capacities to 5,900 gallons per minute each (8.5 Mgd). • Replace the smaller existing industrial influent pumps with a larger pump with a capacity of at least 5,000 gallons per minute each (7.2 Mgd). Install a third pump with a capacity of approximately 2.5 Mgd for non -canning season pumping and peak period backup capacity. • When treatment plant capacity is expanded beyond 8.5 Mgd, the headworks should be replaced with a new structure. • As an alternative, the City may wish to invest in a new headworks facility that will serve beyond the 8.5 Mgd master plan design capacity. PRIMARY TREATMENT There are five primary clarifiers (sedimentation basins). The five basins remove readily settleable solids and floating material from the flow stream, constituting primary treatment. Description of Existing Facilities The primary sedimentation basins are 90 feet long, 20 feet wide, and 8 feet deep. The basins are located immediately north of the headworks as shown in Figure 11-1. Settleable sludge accumulates at the bottom of the basins and is then removed via a chain and flight system and sludge pumps. City staff have replaced all chain and flight systems with plastic components. Plastic has proved to be less durable than metal components, but plastic is much easier to service and repair. The sludge is pumped to the primary digesters periodically, which means that sludge is stored and thickened in the bottom of the basin. Grease, oil, scum, and other floatable materials are skimmed from the water surface by water sprays and helical skimmers. The 9/18/00 Draft 11-20 Wastewater Master Plan 213\wwmp skimmed materials (scum) are pumped directly to the primary digesters. Effluent flows over V -notch weirs at the end of each basin. Primary effluent flow from all basins is combined in an aerated channel which delivers flow to the aeration basins. The primary sludge pump room houses ten progressive cavity pumps, five for primary sludge and five for scum. Pumps are direct driven through a belt and pulley system. Mechanical variable speed drive units originally used for sludge pumping before 1989 have been replaced with direct drives. Sludge pumps added in 1990 with the construction of primary sedimentation basins No. 4 and 5 have proved to be over -sized with capacities as much as 175 gallons per minute, but staff are able to use all units by reducing the operating time. The older sludge pumps have an estimated capacity of 80 to 120 gallons per minute. In the last few years, City staff have replaced all old sludge pumps installed before 1990. Performance Primary clarifiers should remove 60 to 70 percent of the influent total suspended solids (TSS) and 25 to 40 percent of the influent biochemical oxygen demand (BODS). Table 11-4 presents the combined primary clarifier performance for percent removal of TSS and BODS. The removal percentages are monthly average values. Based on historical data, the performance of the existing primary clarifiers has averaged 29 percent BODS removal and 65 percent TSS removal. Table 11-4. Primary Sedimentation Performance Parameter Range Average BOD Influent, mg/1 232 to 324 272 Effluent, mg/l 163 to 226 192 Removal, % 17 to 45 29 TSS Influent, mg/l 199 to 331 244 Effluent, mg/l 61 to 118 85 Removal, % 51 to 75 65 Note: Based on monthly averages, Aug 1994 to Jan 1999. Design detention time of 1.5 hours and peak hour surface loading rates of about 1,800 gallons per day per square foot at 8.5 Mgd are within unit process design criteria previously presented in Table 11-1. The primary clarifiers are, therefore, rated with a firm capacity of at least 8.5 Mgd based on average flow conditions. The existing primary clarifiers have adequate capacity for the Master Plan planning period with no modifications. Additional primary clarifiers will be needed when flows exceed approximately 9.5 Mgd ADWF. 9/18/00 Draft 11-21 Wastewater Master Plan 2131wwmp DRAFT Summary of Recommended Facilities The existing primary sedimentation basins are adequate with no modification for projected flows within the Master Plan planning period. The open area to the west of the existing basins (see Figure 11-4) should be retained for future expansion. SECONDARY TREATMENT Secondary treatment is provided through an aerobic suspended -growth biological system consisting of aeration basins and secondary clarifiers. The aeration basins provide a rich environment for accelerated biological growth which converts biodegradable, organic waste material into cell mass which can be removed through settling. Mixed liquor flows from the aeration basins to the secondary clarifiers where the solids are settled out of the wastewater stream. The settled solids are either pumped back to the aeration basins as return activated sludge (RAS), or to the sludge thickeners as waste activated sludge (WAS). Description of Existing Facilities Aeration Basins. Each of the four aeration basins is 137 feet long by 30 feet wide and 15 feet deep. The basins are located immediately north of the primary clarifiers as shown in Figure 11-1. At a water depth of 15 feet, the volume of each basin is about 0.46 million gallons. Primary effluent flows from the primary sedimentation basins to the north end of Aeration Basin 4 (the western most aeration basin). At this point return activated sludge (RAS) from the secondary clarifiers discharges into the primary effluent flow stream as it enters the aeration basin. The aeration basins are operated in series (4-3-2-1), and thus the mixed liquor flows through each basin. From the north end of Aeration Basin 1, the mixed liquor leaves the aeration basins through a 60 -inch pipe to the secondary clarifier influent distribution box. The basins are provided with alternative primary effluent and RAS feed points and may be operated in series, parallel or divided into two independent aeration system. Aeration is supplied to the mixed liquor through a series of headers with membrane tube diffusers. The air supply provides the required oxygen and keeps the aeration basins mixed. The existing diffusers are evenly distributed between four basins. Each basin contains five headers which feed 120 diffusers for a total of 600 diffusers per basin. The original Wyss Flex -A -Tube diffusers in three basins were recently retrofitted with F1exLine fine bubble diffuser membranes by EnviroQuip. The F1exLine diffuser membranes are reported to have a higher efficiency and are considered to be more durable than the Wyss diffuser membranes. The air supply has normally been turned off at the first two diffuser headers at the north end of Aeration Basin 4 where primary effluent and RAS first enter the aeration basins. The intent has been to create an unbaffled anaerobic zone within the first 40 percent of the aeration basin and thereby create conditions favorable for improved settleability of the mixed liquor. The secondary treatment system is normally operated to provide full nitrification to prevent ammonia toxicity in the effluent. In order to maintain nitrification, the mixed liquor suspended solid concentration is maintained at 3,000 mg/1 or greater to achieve a sludge age of 6 to 8 days. During the Winter months the sludge age must be increased to as much as 10 days to maintain 9/18/00 Draft 11-22 Wastewater Master Plan 213\wwmp • nitrification because of cooler temperatures and slower reaction rates. As the mixed liquor suspended solids concentration is increased, the aeration system is unable to maintain dissolved oxygen levels consistently through out the basin. Under such operating conditions, filamentous organisms may predominate which leads to foaming on the surface of the aeration basins and effluent channels. Foaming in such cases is controlled through the use of chlorine solution surface sprays. The purpose of the aeration basins is to convert the waste into biological cell mass, which can later be settled out of the water in the secondary clarifiers. The concentration of soluble BODS and ammonia in the secondary clarifier effluent is a measure of the performance of the aeration basins. Effluent ammonia levels are maintained below 2 mg/1 under most operating conditions. Effluent BODS levels are generally maintained below 10 mg/1 on a monthly average condition. The existing aeration basins are not capable of reliably maintaining these treatment levels during periods of peak demand in Winter months. Secondary Clarifiers. Each of the two circular clarifiers is 100 feet in diameter with a side water depth of 16 ft. The total volume of the basins is about 1,880,000 gallons, and the total surface area is 15,700 ft2. Secondary Clarifiers 1 and 2 are identical, incorporating a flocculator center well, sludge collection mechanism, scum skimmer, and an outside weir and effluent launder. Chlorine solution is applied near the overflow weirs to control algal growth. It is important to note that the need to consistently achieve full nitrification requires that the concentration of solids in the mixed liquor from the aeration basins (MLSS) is relatively high. The MLSS concentration as flow enters the clarifiers is between 3,500 and 4,500 mg/L during late Fall and Winter months. This concentration is much higher than would be necessary if full nitrification were not required, and is outside the original design parameters of the two clarifiers. The RAS and WAS pumping system is located in the Secondary Sludge Pumping Station Iocated between the two clarifiers. RAS pumping consists of three 75 hp pumps with a capacity of 3,000 gpm @ 57 ft TDH each. WAS/Scum pumping consists of four 5 hp pumps with a capacity of 160 gpm @ 39 ft TDH each. Two pumps are dedicated for WAS pumping and two pumps are dedicated for scum pumping. Pumps can be interchanged between WAS and scum pumping as needed. All RAS and WAS pumps are equipped with variable frequency drives. Air Supply. The aeration basins are supplied air from four 150 hp multiple -stage centrifugal blowers located in the Control Building Blower Room. The blowers are rated at 3,000 standard cubic feet per minute (scfin) each. Air is delivered through piping ranging from 6 to 24 inches in diameter to the 5 headers for each basin which feed the diffusers. The Control Building Blower Room houses the four aeration basin blowers and a 15 hp blower for channel aeration. The channel aeration system is out of operation because the aeration systems in the flow channels need rehabilitation. The Blower Room is designed for a total of six aeration basin blowers. The existing blower inlet header is 30 -inch. The existing blower outlet header is 24 -inch. Normally, two blowers are adequate to meet aeration requirements in the Summer months. During late Fall and Winter as the solids concentration in the aeration basins is increased, three blowers are operated. When solids concentrations exceed 3,500 mg/l, the aeration system has been unable to maintain dissolved oxygen levels in the first two aeration basins. Until recent modifications discussed below, the fourth blower could not be operated 9/18/00 Draft 11-23 Wastewater Master Plan 213\wwmp DRAFT because the discharge pressure would exceed the operating limits of the tube diffusers. The existing control system is primarily manual; individual blowers are started depending on oxygen demands as determined by the operator. Blowers are stopped by electronic timers when aeration requirement are minimal based on operating experience. Deficiencies and Alternative Improvements The secondary system was not designed for nitrification and needs several improvements to restore treatment capacity while providing for nitrification. Aeration Basins. As of Fall 1999 when the aeration system was initially evaluated for this Master Plan study, air diffusion capacity in the aeration basins had been inadequate to maintain nitrifying conditions during Winter months. While air diffusion improvements may allow reliable operation with nitrification during the next few years, capacity will soon become limited by the minimum hydraulic detention time criteria during peak hour conditions and the limits of the secondary system to sustain an inventory of biomass necessary to provide nitrification. As of Fall 1999, the existing aeration system was in need of immediate upgrade. The aeration system had proven to be inadequate in the Winter months with average dry weather flows in the range of 6.1 to 6.3 Mgd. The existing diffusers are evenly distributed between four basins. As a rule, the first half of the aeration basins in a series configuration requires 60 to 65 percent of the total oxygen demand. Sometimes this can be accomplished by adjusting the air flow to each basin or each header within the basin. This is possible where sufficient diffusers are in place to accommodate the increased air flow in a particular basin. Pushing excess air through an individual diffuser increases head loss and decreases oxygen transfer efficiency. Based on the initial review of the aeration requirements of the existing operation as part of the Master Plan study, it appeared that the diffuser system at Lodi was inadequate to provide the required distribution of air. The major deficiency was related to the diffuser system and not blower capacity, which is adequate for most existing operating conditions. The simplest solution was to replace the existing 24 -inch diffusers with 36 -inch diffusers in Aeration Basins No. 2, 3 and 4. A detailed description of the recommended changing of diffusers was contained in a summary report entitled Interim Aeration System Improvements dated October 21, 1999. A copy of this report is contained in Appendix E. This recommendation was implemented in December 1999 and has proven to be effective at current flow rates. Additional aeration basins are required to maintain nitrification through the Master Plan planning period. The recommended upgrade is to construct two additional basins to provide capacity for full nitrification at 8.5 Mgd at an MLSS of 3,500 mg/L. The basins could be operated either as two parallel processes with three basins (Figure 11-5) each or as three parallel processes with two basins each (Figure 11-6). The beginning portion of one basin in each parallel process would be baffled off to serve as an anaerobic selector. Primary effluent and RAS is currently discharged into the aeration basins in a zone which lacks any significant agitation or mixing. The aeration is turned off in this area to provide an anaerobic selector. As an interim measure, the aeration system could be operated at low output to provide a minimal level of mixing without adding significant oxygen. Mechanical mixing should be installed in the anaerobic selector zones when additional aeration basins are constructed. 9/18/00 Draft 11-24 Wastewater Master Plan 213\wwmp E 0 F r, r---------------------- -- -� No. 9 --------------------------- 0 --------------------- — o zs so 1 i No. 8 SCALE IN FEET L ---------------------- I - - - - J ---------------------- ----- No. 7 -------------------------- PRIMARY SEDIMENTATION.:, : j .,�P H BASINS � M. mim t --------------------- Q AERATION BASINS No. 5 W i No. 4. I No. 3 W :==► No. 3 No. 2 CL No. 2 l I No. 1 E — J DISTRIBUTION f BOX (PROPOSED)—/ CONTROL: B" i Legend: Figure 11-5 Existing Facility ---Baffle Master Plan Facility -f— Flow Direction City of Lodi MPlan Plus Denitrification Water Pollution Control Facility "' E s T Plus Anaerobic Zone 7Lona—term Facilitv AERATION BASINS Y o 3 T TWO PARALLEL PROCESSES MODE & AMCIAM E 8 0 r---------------------- I -- —� No. 9 ---------------------- ---- ---------------------------- 5a --- --------------5 No. 8 I � SCALE IN FEET L---------------------- ----� r----------------------------- I No. 7 L-------------------------- J, PRIMARY SEDIMENTATION BASINS No. 7 No. 6 1z 1Q U No. 5 No. 4 UJ No. 3 r No. 2 Cr No. 1 I I i f CONTROLBUILDING -- —AERATION BASINS_ �� .EXTENDED K1 A f COLLECTION l::.i►; i CHANNEL ► No. 3 CHLORINE =i CONTACT TANKS I No. 2:.: ' ; SECONDARY CLARIFIE� s No 4' No. 1 DISTRIBUTION BOX (PROPOSED)—/ Legend: Figure 11-6 Existing Facility — —Baffle l Master Plan Facility Flow Direction Master Plan City of Lodi Plus Denitrification Water Pollution Control Facility w E s T Anaerobic Zone Long—term Facility AERATION BASINS Y o s T THREE PARALLEL PROCESSES MODE x ASSWUrM In conjunction with the construction of additional aeration basins, new primary effluent conveyance piping and channel modification will be required. Air Supply. Air supply capacity is a critical component of secondary process capacity. At an ADWF of 8.5 Mgd, the maximum day air demand is estimated at about 10,000 scfin. The peak hour air demand is estimated at about 14,000 scfm. The existing firm air capacity is rated at 9,000 scfin with one blower out of servicf,, so existing blower capacity is not adequate to meet projected Year 2020 aeration and nitrification needs. The recommended project is to add two additional blowers at the same time new aeration basins are added. The air diffusion system in the new aeration basins should be consistent with blower capacity and oxygen requirements at Master Plan flow and loading conditions. As the aeration basins and air supply are expanded, an automated control system using air manifold throttling valves controlled by dissolved oxygen concentration in the aeration basins would decrease future energy use by more closely matching the number of blowers operating to actual oxygen demands. The blowers would. be controlled independently of the air manifold throttling valves, employing either variable speed drives or inlet throttling valves to maintain a preset outlet manifold pressure. Operating costs can and should be reduced through the use of increased blower control and higher efficiency blowers. Secondary Clarifiers and Storage Ponds. With both clarifiers online, design peak hour surface loading rates of about 1,000 gallons per day per square foot at 8.5 Mgd are within the unit process design criteria previously presented in Table 11-1 (1,100 gpd/ft2 Max). The secondary clarifiers, therefore, have a capacity of at least 8.5 Mgd based on overflow rate. The capacity rating may be limited if the secondary clarifiers cannot accommodate the flow and solids loading delivered from the aeration basins. The entire secondary process (aeration basins, secondary clarifiers, and return activated sludge pumping) must therefore be evaluated as a whole. The current secondary clarifiers lack redundancy. Although peak hour surface loading rates of about 1,000 gallons per day per square foot at 8.5 Mgd are within unit process design criteria, peak loadings will exceed 2,000 gallons per day per square foot, and solids loading would substantially exceed the system capacity with one unit out of service. Effluent quality at this loading will deteriorate to a significant degree, and sustained operation with one clarifier would likely "wash out" the secondary active cell mass. Alternate solutions are to construct a third clarifier, provide additional emergency effluent storage, or provide chemically enhanced clarification during operation with one clarifier. Addition of a third clarifier is the only viable option. The best apparent site for construction of a new clarifier is east of the existing chlorine contact tank as shown in Figure 11-4. This site is not accessible to the existing clarifier influent distribution box, and the influent distribution box is designed for only two clarifiers. Therefore a new distribution box and new clarifier inlet piping are required for this alternative. Relocation of the chlorine contact tank would be required to accommodate construction of a fourth secondary clarifier as shown in the figure. -The cost of a new clarifier and related improvements is estimated to be about $3,000,000. 9/18/00 Draft 11-27 Wastewater Master Plan 213\wwmp Emergency effluent storage can be provided using the existing storage ponds. Clarifier effluent can be directed into a bypass pipeline and then conveyed into the ponds. The effluent can be returned through the equalization pond, irrigation pump station, and effluent return pipeline for treatment and disinfection after the emergency clarifier repairs had been performed. This could only be accomplished in the Winter months when the storage ponds were not being used for irrigation storage. It would be difficult to use the ponds in this manner without advance planning. There would be little or no direct cost associated with this alternative. Chemically enhanced clarification could be provided with rehabilitation of the exiting polymer feed facilities and additional chemical feed facilities for metal salts. The capital cost of these facilities is estimated to be in the range of $100,000 to $200,000. A chemical feed system for enhanced clarification should be installed as soon as possible as a short term means to provide emergency capacity. An operations plan should also be developed for the use of emergency storage should one clarifier need to be taken out of service for repair or maintenance. A third clarifier is really the only viable long-term option. The third clarifier should be constructed in conjunction with the construction of additional aeration basins. RAS Pumping. The three RAS pumps can return a total of 8.6 Mgd, which is more than adequate for the Master Plan planning period. The most significant operating problems with the RAS pumping system are the lack of turn down capability and the inability to measure the rate of RAS withdrawal from each individual clarifier. The inlets to the RAS pumps are on a common manifold from the clarifiers with valves which allows either one pump to be used for both clarifiers or a separate pump to be used for each clarifier. The RAS meter is located downstream of the RAS pumps on the common RAS line discharging to the aeration basins. In the past, treatment plant staff have tried to use one RAS pump for both clarifiers because one pump operating at normal speed provides the correct RAS flow rate. Unfortunately, the RAS header for one individual clarifier would tend to become partially clogged, and the RAS withdrawal from the other clarifier would then gradually increase. This condition allowed solids to accumulate in one clarifier. The current operating practice is to run a dedicated pump at low speed for each clarifier. Although this has provided satisfactory performance, the RAS pump curves should be evaluated to determine if trimming the impellers would provide better energy efficiency for this mode of operation. Installing a flow meter on the RAS line from each clarifier would allow the plant operations staff to obtain better data for control of RAS return rates and the operation of each clarifier. New individual flow meters should be installed on each clarifier RAS pipeline in conjunction with the next major improvements to the aeration basins and clarifiers. WAS Pumping. Waste activated sludge is pumped to the DAFT thickener each day for a period of about 10 hours. Thickened sludge is pumped to the digesters during thickener operation. Thickener performance could be improved by continuous operation 24 hours per day. Generally, biological systems are more stable when operated at a continuous solids withdrawal, and the DAFT thickener is a mechanical process which functions best if the feed and air dissolution systems are run continuously. Maximum thickener performance will become more critical as the 9/18/00 Draft 11-28 Wastewater Master Plan 213\wwmp volume of waste activated sludge increases in future years and the digester detention times are affected by the increased volume of waste solids. Each WAS pump is rated at 160 gpm, which is excessive for continuous WAS withdrawal. Even at lower speeds, the pump performance is not suitable for continuous WAS withdrawal. WAS pumps should be downsized to allow continuous waste activated sludge withdrawal. Two of the four pumps should have their impellers trimmed or should be replaced with smaller units. Summary of Recommended Facilities Recommendations for new facilities associated with secondary treatment are summarized below: • Replace the existing diffusers in Aeration Basins No. 2, 3, and 4 with 36 -inch diffusers as soon as possible, (completed 12/99). • Install flow meters on the RAS pipelines from each clarifier. • Downsize two WAS pumps to allow continuous waste activated sludge withdrawal. • Expand the aeration basins as required for projected increased loads and reliable nitrification. Two new basins are recommended. • Provide a baffled anaerobic selector zone in the aeration basins. Remove existing aeration diffusers in this portion of the tank and install a slow speed mixing system to keep the solids in suspension. • Add an automated blower control system using air manifold throttling valves controlled by dissolved oxygen concentration in the individual aeration basins. • Construct a third clarifier as soon as possible. Advanced treatment processes such as nutrient removal may require additional hydraulic improvements and more treatment tankage than the two additional aeration basins recommended above. The additional facilities for advanced treatment alternatives are discussed later in this section. EFFLUENT DISINFECTION The disinfection system uses chlorine to inactivate potential disease causing organisms remaining in the treated wastewater. The chlorine residual is converted to chloride ions through the addition of sulfur dioxide before the effluent is discharged to White Slough. The design criteria for chlorine disinfection were shown previously in Table 11-1. Effluent disinfection limits were discussed in Section 4. Description of Existing Facilities The disinfection system consists of a chlorination system, chlorine contact chamber, and a dechlorination system. The chlorination system includes chlorine gas storage, liquid and gas 9/18/00 Draft 11-29 Wastewater Master Plan 213\wwmp piping, chlorinators, injectors, and diffusers. The dechlorination system includes sulfur dioxide gas storage, liquid and gas piping, sulfonators, injectors, and diffusers. Chlorine and sulfur dioxide are stored outside in 2,700 -gallon steel vessels.. The five chlorine contact basins are converted secondary sedimentation basins partitioned with redwood baffle walls to create a serpentine contact chamber. Basins are 80 feet long, 18 feet wide, and 8.2 feet deep with two baffle walls placed the length of each basin. Each basin volume is about 88,000 gallons. In a test performed in October 1999, average modal contact time with all basins in service was determined to be 93 minutes at 7.5 Mgd. This would translate to 82 minutes at the design flow of 8.5 Mgd. Peak hour contact time at Master Plan design flow of 16.3 Mgd is slightly over 40 minutes, which is adequate for secondary disinfection. Assuming equalization storage to reduce diurnal peak flows, a tertiary level of disinfection would require 90 minutes modal contact time at peak day dry weather design flow. Modal contact time, at the projected peak day dry weather flow of 10.0 Mgd is 70 minutes, which would not be adequate for tertiary treatment. An additional 130,000 gallons of tankage would be required to meet tertiary disinfection criteria. There are two 2,000 lbs/day chlorinators for effluent disinfection and one 500 lbs/day chlorinator for filament, algae, and foam control. Total chlorine feed has ranged from 500 to 800 lbs/day during discharge to Dredger Cut. Chlorine feed has been less than 200 lbs/day during discharge to land. Chlorine residuals are normally maintained at between 3 and 4 mg/1. The sulfur dioxide system includes two 1,000 lbs/day sulfonators. The existing disinfection capacity is based on a firm chlorinator feed capacity of 2,000 lbs/day, assuming one 2,000 lbs/day chlorinator is out of service. Dosages of up to 10 mg/L of chlorine are recommended for disinfection of activated sludge effluents. With a firm chlorination capacity of 2,000 lbs/day and a maximum dosage of 10 mg/L, the peak disinfection capacity is 24 Mgd. The system's firm capacity is, therefore, adequate to accommodate projected peak flow conditions for the Master Plan planning period. At a theoretical dose of 0.9 parts of sulfur dioxide per part of chlorine, the firm dechlorination capacity of 1,000 lbs/day is also adequate to accommodate the projected flow conditions. Deficiencies Chlorine doses in the 15 to 20 mg/L range may be required as a result of ammonia breakthrough due to incomplete nitrification in the secondary process. If secondary treatment capacity improvements are not implemented, it will be increasingly difficult to maintain adequate chlorination capacity. When ammonia breakthrough occurs, the initial chlorine demand (while the chlorination system attempts to maintain a free chlorine residual) could approach the chlorination system capacity or exceed it if one of the two chlorinators is out of service. The existing chlorine contact basins provide adequate capacity at up to 11 Mgd ADWF for secondary disinfection. The basins would be inadequate to provide tertiary disinfection during the master planning period which requires 90 minutes modal contact time at peak day dry weather flow. 9/18/00 Draft 11-30 Wastewater Master Plan 213\wwmp DRAFT The disinfection performance of the current chlorination system has generally been satisfactory. Recent research indicates that disinfection performance and reliability can be improved by keeping chlorine contact tanks cleaned more frequently and by using microstrainers to remove any remaining large particles or flocs in secondary effluent prior to chlorination. Both of these measures serve to minimize solids in the chlorine contact tank which can shield bacteria from the chlorine disinfectant. Several legislative or code requirements affect the manner in which chlorine and sulfur dioxide gas are stored and handled. This most significant code requirement is contained in the Uniform Fire Code (UFC). This is a model code produced by the International Conference of Building Officials. The UFC has no force of effect unless it has been adopted by a local agency. Section 80 of the UFC governs toxic gases stored under pressure, and applies to both chlorine and sulfur dioxide gas. Although the UFC has not been adopted by the local agency, compliance may be necessary to protect public safety and major revisions would be required to comply with the UFC, if chlorine gas and sulfur dioxide gas continue to be used. General Chlorination Improvements If chlorination continues to be the recommended method of wastewater disinfection, there are several improvements common to all the chlorination alternatives. These are as follows: • Install valves, gates, and mixing enhancements to allow easier, more frequent flushing and cleaning of chlorine contact tanks. • Expand contact tank volume by 130,000 gallons to provide 90 minutes modal contact time at PDWF for tertiary treatment (unless effluent discharge/disposal alternative without tertiary treatment is implemented). This assumes that equalization storage will be provided to eliminate hourly dry weather flow peaks. The costs of these improvements will be added to the estimated costs of chlorination alternatives where appropriate. Alternative Improvements Given the restrictions imposed on the continued use chlorine gas and sulfur dioxide gas, a preliminary review was conducted of alternative means of providing effluent disinfection. The four alternatives that were evaluated included: 1. Improvements to the gaseous chemical based systems (chlorine & sulfur dioxide) 2. Liquid Chemical based systems (sodium hypochlorite & sodium bisulfite) 3. On-site generation of liquid chemicals 4. UV Disinfection Chlorine Gas/Sulfur Dioxide Facilities Improvements. The treatment plant is currently equipped with a chlorine gas/sulfur dioxide disinfection system. This alternative would improve the existing system and include modifications and upgrades to enhance safety and reliability. 9/18/00 Draft 11-31 Wastewater Master Plan 213\wwmp In order to comply with the Uniform Fire Code, the storage vessels must be enclosed and the new building must contain a treatment system to treat (scrub) air exhausted from the building in the event of the rupture of either a chlorine or sulfur dioxide cylinder. The treatment system must be sized to accommodate the largest storage vessel. In this case, the treatment system would have to accommodate 2,700 gallons of chlorine. It is assumed that a gas leak occurs at the point of connection at the top of the tank and that a catastrophic failure of the vessel does not occur. Alternatively, one ton cylinders could be used in place of one large vessel. Assuming that adequate space should be available for 30 days of chlorine and sulfur dioxide at average flow conditions and average dose, the required storage capacity would be as much as 10 1 -ton cylinders. This would reduce the required scrubber capacity to a manageable size, but would require more space and more frequent handling of gas cylinders. Sodium Hypochlorite/Sodium Bisulfite. In this alternative, the existing chlorination/ dechlorination equipment would be taken out of service and replaced with sodium hypochlorite and sodium bisulfite feed equipment. The sodium hypochlorite would provide disinfection in the contact tank while sodium bisulfite would be injected after disinfection to remove any toxic chlorine residual. Suppliers located in Stockton and Tracy produce sodium hypochlorite from chlorine gas and caustic. The sodium hypochlorite system would be sized to provide the same firm capacity as the chlorine gas system — 2,000 lbs/day. Municipal -grade sodium hypochlorite is typically purchased as a 12'h percent solution. At this strength, there is 1 pound of chlorine in a gallon of solution. Approximately 2,000 gpd of sodium hypochlorite solution would be needed at peak design conditions. Sodium hypochlorite decomposes over time. A 12%z percent solution loses half its strength in about 45 days. Therefore, in sizing hypochlorite storage facilities, a balance between maintaining an adequate reserve for peak demands and emergencies and minimizing the loss of chemicals through decomposition must be reached. Two new 10,000 -gallon sodium hypochlorite storage tanks would be installed in the existing bulk storage area. The existing chlorine gas storage area could be split in half to provide enough space for each of the new tanks. At average design conditions, these tanks would contain 30 days worth of hypochlorite. Sodium bisulfate functions as an equivalent to sulfur dioxide gas dissolved in water. The principles of dechlorination with sodium bisulfite are identical to those of sulfur dioxide. One pound of chlorine residual is removed by approximately 0.64 gallons of a 25 percent solution of sodium bisulfite. The feed system would be sized to eliminate 5 mg/L of chlorine at the peak flow of 16.3 Mgd — a bisulfate solution feed rate of approximately 500 gallons per day (gpd). Unlike sodium hypochlorite, sodium bisulfite solution can be stored for extended periods without significant chemical degradation. The storage tanks only need to be large enough to accommodate potential interruptions in delivery schedules. Two new 3,500 -gallon sodium bisulfite storage tanks would be installed the existing bulk storage area. The tanks would have heat tape and insulation to prevent chemical precipitation. At average design conditions, the tanks would hold enough bisulfite solution for 30 days of operation. All chemical storage tanks would be equipped with secondary containment to prevent spills. Metering pumps or eductors would withdraw hypochlorite and bisulfite solution from the storage 9/18/00 Draft 11-32 Wastewater Master Plan 2131wwmp DRAFT tanks and inject it into carrier water. The carrier water streams would convey the hypochlorite and bisulfite to injection diffusers at the upstream and downstream ends of the chlorine contact basin, respectively. The control system would be similar to that of the other chlorination/ dechlorination alternatives except that the analyzers would control metering pumps or motorized valves rather than chlorinators and sulfonators. Operating tasks -would be similar to those of the chlorine gas. The primary difference would be the increase in chemical handling. On a weight basis, approximately 10 times more disinfectant would be needed. However, the sodium hypochlorite would be delivered in tank trucks and pumped directly to the storage tanks. Use of a sulfur dioxide storage vessel and maintenance of sulfonators would be replaced with filling sodium bisulfite storage tanks and maintaining metering pumps or eductors. Because chlorine gas and sulfur dioxide would be replaced with sodium hypochlorite and sodium bisulfite solutions, the use of hazardous gases would be eliminated. This offers significant safety advantages. Secondary containment would prevent spills from creating a safety hazard. On -Site Generation. In this alternative, sodium hypochlorite is produced on site from salt, water, and electricity. Softened water and salt are mixed to produce a concentrated brine solution. The solution is then diluted and passed through an electrolytic cell where electrolysis converts the sodium chloride to sodium hypochlorite. The final product contains approximately 8,000 mg/1 of sodium hypochlorite (0.8% solution). Byproducts include hydrogen gas and unreacted salt at a concentration reported by one manufacturer to be 20,000 mg/1. This is slightly greater than purchased liquid sodium hypochlorite. Hydrogen gas is constantly vented to avoid buildup. On-site generation facilities have the advantage of producing a relatively stable product on as -needed basis, and it eliminates the hauling and transfer of liquid chlorine. On-site generation facilities are becoming popular for small water facilities in the range of 100 pounds per day. Larger generating facilities up to a few thousand pounds per day of chlorine are more common in the southeast and in southern California. The City of Folsom recently constructed and started operation of a 6001bs/day on-site generation facility at the Folsom Water Treatment Plant. Preliminary results have been favorable. The facility is too new to have any experience with actual operating costs. In other aspects this on-site generation of sodium hypochlorite is similar to the sodium hypochlorite/sodium bisulfate alternative in such aspects as chemical storage, chemical feed, and dechlorination with sodium bisulfite The sodium hypochlorite generating system could be sized to provide the average chlorine demand with peak demands provided from storage. Proposed generating capacity is 1,200 lbs/day in two or more units. Peak feed capacity would be the same firm capacity as the chlorine gas system — 2,000 lbs/day. Sodium hypochlorite could be purchased as a backup supply of chlorine. The primary difference to the liquid sodium hypochlorite alternative would be the decrease in chemical handling. On a weight basis, approximately 3.5 pounds of salt is required to produce one pound of chlorine as compared to 8.4 pounds of liquid sodium hypochlorite to provide one pound of chlorine. Dry salt is delivered in tank trucks and blown into the brine tanks. A new 9/18/00 Draft 11-33 Wastewater Master Plan 213\wwmp DRAFT building would be required with room for the brine tanks, bisulfite tanks, and three generators on 6 -foot by 12 -foot pads. UV Disinfection. UV light with a wavelength of 254 nanometers penetrates the cell walls of microorganisms and prevents reproduction by altering the structure of the microorganism's DNA. UV is well suited to activated sludge treatment plants with relatively long mean cell residence times (MCRT) such as are used at Lodi. The long MCRT breaks down particle associated coliform bacteria, which are the most difficult ones to reach with IJV light. A delivered LTV dosage of approximately 100 mJoules/cm2 at peak day flow is needed for either secondary (23 MPN/100 mL) or filtered tertiary (2.2 MPN/100 mL) disinfection. Conventional UV disinfection systems use low-pressure, low -intensity mercury vapor lamps, which are similar to the fluorescent lamps commonly used for commercial lighting. While low- pressure lamps are efficient at producing germicidal light, they are rated for relatively low power use — about 40 watts. Therefore, relatively large numbers of lamps are required to disinfect a given effluent flow rate --on the order of 50 lamps per Mgd of peak flow depending on effluent quality and disinfection requirements. With the advent of medium -pressure, high-intensity lamps, UV disinfection is becoming a more attractive alternative at large WWTPs. While medium -pressure lamps are less efficient than their low-pressure counterparts, their higher power use (approximately 2 kilowatts), greatly reduces the total number of lamps needed to treat a given flow rate. Medium -pressure systems typically have one-tenth to one -fifteenth as many lamps as low-pressure systems of the same capacity. Modern medium -pressure systems are normally equipped with automatic lamp cleaning devices, further reducing maintenance requirements. However, medium -pressure systems do have several drawbacks. In addition to lower efficiency, medium -pressure lamps cost more and last less than half as long as low-pressure lamps. Despite these disadvantages, most new UV disinfection systems designed and constructed at medium and large plants are medium -pressure due to the reduced maintenance requirements and smaller system footprint. A third UV disinfection option is the recently developed low-pressure, high-intensity Iamp. These lamps have the high efficiency and long lamp life associated with low-pressure, low - intensity lamps; however, their higher output results in system designs that require only one-third as many lamps as conventional low-pressure, low -intensity systems. In addition, much like medium -pressure systems, low-pressure, high-intensity systems are equipped with automatic lamp sleeve cleaning systems to reduce labor costs. A new UV disinfection system would consist of the following components: • Channel structure. At least two channels are needed so that half the system can be taken out of service for maintenance. The channels could be located indoors or outdoors, or constructed within the existing chlorine contact basin. Control system. The control system can be located in panels rated for outdoor installation or be installed indoors to simplify maintenance during inclement weather. 9/18/00 Draft 11-34 Wastewater Master Plan 213\wwmp • Lamp modules. Several lamps would be located on a single module. Each module can be removed from the channel independently. Lamp ballasts are located directly above the modules. • Automatic lamp cleaning mechanism. The efficiency of the UV system deteriorates as deposits build up on the lamp sleeves. Automatic wiper mechanisms typically use a chemical solution to help remove deposits on the lamp sleeves. • Level control gates. A level control gate would be installed in the downstream end of each channel. The gates control water level and velocity. It should be noted that medium -pressure UV systems create over 2 feet of head loss, so a detailed plant hydraulic evaluation is critical. • Sodium hypochlorite system. A small liquid hypochlorite feed system would be needed for other miscellaneous chlorine needs at the plant. Operation and Maintenance associated with UV disinfection systems include: • Lamp replacement. Medium -pressure lamps have an expected life of 5,000 hours. However, as with other lights, the useful life of UV lamps is also affected by the number of on/off cycles. Lamp ballasts also must be replaced periodically; however, this cost is small relative to that of lamp replacement. Maintenance of the automatic wiper mechanism. The cleaning solution reservoir must be refilled regularly. The lamp sleeve wiper mechanism must be periodically realigned to prevent binding. • Periodic manual lamp sleeve cleaning. The lamp sleeves may have to be cleaned manually on occasion. The need for manual cleaning is related to the performance of the WWTP. For example, manual cleaning probably would be necessary after a major plant upset. Screening of Disinfection Alternatives Disinfection alternatives are compared on relative cost differences and on a non -economic evaluation. Chlorine Gas/Sulfur Dioxide Improvements Costs. Construction of new gaseous chlorine facilities would be less costly than UV disinfection but more costly than the use of liquid sodium hypochlorite and sodium bisulfite. As the area around the treatment plant develops, the need to contain an accidental release of chlorine will become more critical. Already, risk associated with exposure to traffic along I-5 is significant. The cost of conversion to 1 -ton cylinders and containment and treatment systems is estimated at approximately $1.4 million. Additional chlorine contact tank capacity for tertiary treatment would add another $1.1 million for a total of $2.5 million. 9/18/00 Draft 11-35 Wastewater Master Plan 213\wwmp Sodium Hypochlorite/Sodium Bisulfite Facilities Costs. The costs of sodium hypochlorite/ sodium bisulfite feed facilities and additional chlorine contact tanks are - estimated at approximately $1.3 million, which is less than comparable gas containment facilities or UV disinfection. Purchase of liquid chlorine or on-site generation costs are similar over the long tern. Liquid chlorine feed facilities are less expensive to construct, but liquid chlorine costs more to purchase. On-site generation facilities are more expensive to construct, but the cost of chlorine production is less than liquid chlorine hauled to the treatment plant site. On-site generation appears very attractive in areas remote from sodium hypochlorite supply outlets or on sites where bulk storage of liquid sodium hypochlorite is undesirable. These conditions do not currently exist in the Lodi area where liquid sodium hypochlorite is produced both in Stockton and Tracy. The addition of sodium hypochlorite to effluent tends to increase pH slightly while the addition of chlorine gas tends to decrease pH slightly. The treatment plant has had a few occasions of effluent pH below the minimum specified in the discharge permit (6.5). The use of sodium hypochlorite would have a beneficial effect in ameliorating low effluent pH when compared to the continued use of chlorine gas for disinfection. On -Site Liquid Chemical Generation Costs. The estimated cost of producing one pound of chlorine from 3.5 pounds of salt and 2.5 kW hours of electricity per pound of chlorine is about 42 cents based on salt at 4 cents per pound and electricity at 11 cents per kWh. This costs does not account for electrolytic cell replacement or maintenance which one supplier estimated at 3 cents per pound of chlorine produced. The facilities required for delivered liquid sodium hypochlorite and on-site generated sodium hypochlorite are similar regarding storage tanks, feed pumps, and dechlorination. On-site generation in addition to these facilities requires two generators about 6 by 12 feet in dimension and two 10 -foot diameter brine tanks. The additional cost of these facilities, above and beyond the cost of liquid sodium hypochlorite facilities common to both alternatives, is estimated at about $700,000 including additional building space. This equates to about 20 cents additional cost per pound of chlorine produced over 15 years at a 6 percent discount rate assuming chlorine demand at about 850 pounds per day and continuous over the life of the generator. Therefore, for a relative comparison of costs the on-site generation of chlorine costs about 67 cents per pound of chlorine. This includes the cost of materials, energy, and additional generating facilities not required for liquid sodium hypochlorite or sodium bisulfite dechlorination. This is not a total cost but the material cost and incremental cost increase for on-site generation facilities. The material cost of one gallon of liquid sodium hypochlorite which provides about one pound of chlorine is 50 to 75 cents per gallon delivered in bulk. Chemical suppliers would not provide a firm estimate. The actual cost will depend on the quantities ordered, market conditions at the time of bidding, and other conditions of the purchase. Overall, on-site generation of chlorine may cost about the same as liquid sodium hypochlorite. Based a preliminary cost review of alternatives, on-site generation of chlorine compares favorably to liquid sodium hypochlorite over the life of the project. The differences is that on-site generation of chlorine involves unknown operation and maintenance costs and reliability issues whereas liquid sodium hypochlorite involves unknown cost increases that may be passed on to the City from the supplier as a result of future market conditions. 9/18/00 Draft 11-36 Wastewater Master Plan 213\wwmp UV Irradiation System Costs. Based on other studies, the capital cost of UV disinfection facilities is two to three times the cost of other alternatives. This is especially true where the existing facility already has a chlorine contact chamber associated with other disinfection alternatives. This cost is somewhat offset because there is no need to buy chlorine or other products. This advantage is somewhat less significant at Lodi where disinfection is not provided for land application of effluent during the Summer. Filters may be needed for the UV system to comply with even a 23 MPN/100 mL disinfection limit. The estimated cost for IJV disinfection for Lodi is over $4,000,000. Overall, the cost of UV disinfection makes this alternative uneconomical at this time. UV disinfection systems are still evolving and may be a desirable disinfection in the future, especially if complete effluent filtration is installed, and the existing chlorine contact tanks need to be replaced with new, larger capacity tanks. Costs and Subjective Evaluation Criteria Comparison. Selection of a disinfection alternative will depend to a great extent on non -economic considerations. The costs and relative rankings of subjective evaluation criteria are shown in Table 11-5. The estimated costs shown in Table 11-5 are preliminary and for comparison purposes only. The costs include engineering, administration, contingency, and escalation to ENR 7000. Rationale for the rankings are summarized in Table 11-6. The non -economic evaluation factors were presented and explained in Section 6. Table 11-5. Costs and Subjective Comparison of Disinfection Alternatives Subjective Criteria Weightings Alternatives Gas Chlorination Liquid Chlorination On -Site Generation UV Compliance with Future Discharge Requirements 1.5 3 3 3 4 Reliability 1.5 4 3 2 3 Flexibility 1.5 3 4 3 3 Ease of O&M 1 4 5 3 3 Ease of Implementation 1 3 4 3 2 Environmental Impacts 1 1 2 2 4 Safety 1 1 3 4 4 Aesthetics 0.5 2 3 3 4 Totals 21 27 23 26 Totals (weighted) 24 29 24 28 Capital Cost (secondary) $1,400,000 $260,000 $960,000 $4,800,000 Capital Cost (tertiary) $2,500,000 $1,300,000 $2,000,000 $4,800,000 Annual O&M (tertiary) $141,000 $305,000 $270,000 $275,000 Life Cycle Cost (tertiary) $4,000,000 $4,500,000 $4,900,000 $7,700,000 Note: Present worth of O&M costs calculated at a discount rate of 7% for 20 years. 9/18/00 Draft 11-37 Wastewater Master Plan 213%wwmp Table 11-6. Basis of Subjective Rankings for Disinfection Alternatives 9/18/00 Draft 11-38 Wastewater Master Plan 213\wwmp ' Environmental �L:Alternative Safety Reliability Flexibility Ease of Operation Impacts Implementation 1. Chlorine • Hazardous gases used - Proven process . Multiple units permits Identical to existing • Toxic chemicals are Gas scrubbing system Gas/Sulfur Dioxide - Scrubber/containment • Residual allows confirm- maintenance during low system used must be added, including system contains leaks in ation of disinfection flows Potential for conversion to l -ton building • Can comply with . Chlorine can be used for discharge of toxic cylinders • Safety concerns during disinfection standards process and odor control residuals transport and handling during process upsets by • Can comply with • Potential for of cylinders increasing doses reclaimed water formation of • Ammonia and nitrites can disinfection standards toxic/carcinogenic significantly increase byproducts chlorine demand and • Low energy use impair operation 2. Sodium • Hazardous liquids used - Proven process - Multiple units permits Relatively simple • Toxic chemicals are • Existing equipment Hypochlorite/ • Spill containment • Residual allows confirm- maintenance during low control system used abandoned Sodium Bisulfite required ation of disinfection flows . Potential for - Chlorine contact basin • Safety concems during - Sodium hypochlorite - Chlorine can be used for discharge of toxic has large footprint transport and handling decomposes over time process and odor control residuals • Multiple equipment of chemicals • Can comply with • Can comply with Potential for manufacturers and • Ventilation required to disinfection standards reclaimed water formation of chemical suppliers remove fumes during process upsets by disinfection standards toxic/carcinogenic increases competition increasing doses byproducts and lowers cost • Ammonia and nitrites can • Low energy use • No scrubbing/gas significantly increase containment needed chlorine demand and impair operation 3. Sodium • Hazardous liquids used • Proven process but more - Multiple units permits Relatively complex • Toxic chemicals are • Existing equipment Hypochlorite/ • Spill containment complex operation maintenance during low system used abandoned Sodium required - Residual allows flows - Potential for - Chlorine contact basin - Ventilation required to confirmation of - Chlorine can be used for discharge of toxic has large footprint remove fumes disinfection process and odor control residuals - Limited number of • Sodium hypochlorite does - Can comply with • Potential for large systems in not decompose over time reclaimed water formation of California - Can comply with disinfection standards toxic/careinogTic • No scrubbing/gas disinfection standards byproducts containment needed during process upsets by • Medium energy use increasing doses - Ammonia and nitrites can significantly increase chlorine demand and impair operation 9/18/00 Draft 11-38 Wastewater Master Plan 213\wwmp DRAFT Table 11-6. Basis of Subjective Rankings for Disinfection Alternatives cont'd Alternative Safety Reliability Flexibility Ease of Operation Environmental Impacts Implementation 4. UV Irradiation - No hazardous - Relatively new process - Dual channels permit - Relatively complex - No toxic chemicals - Existing chlorination chemicals used - No measurable residual to maintenance during low control system used system would be - Exposed UV lights can confirm disinfection flows - Automatic lamp - High energy use abandoned impair vision - High effluent solids impairs - Parallel channels can be cleaning device may - No toxic residuals - Small system footprint performance added to increase capacity require significant - No toxic/carcino- - Only one manufacturer - Process unaffected by - Must have separate maintenance genic byproducts of large systems Lack ammonia and nitrites hypochlorite system for - Operators unfamiliar formed of competition may other chlorine needs with system - Effluent frltratipn increase costs - Major upgrade may be - Effluent filtration system would reduce - Existing chlorine needed to comply with system required BOD and TSS building can be used for reclaimed water discharges equipment and disinfection standards materials storage 9/18/00 Draft 11-39 Wastewater Master Plan 213\wwmp Recommended Secondary Disinfection Facilities. For either tertiary or secondary treatment, the liquid sodium hypochlorite and sodium bisulfite based system is recommended for the following reasons: 1. The hypochlorite/bisulfite option had the highest subjective ranking and was close to the lowest life cycle cost. 2. Serious safety concerns are involved with chlorine gas use and handling. 3. A liquid sodium hypochlorite and sodium bisulfite system is less expensive and less labor intensive to maintain than LTV disinfection and less expensive than construction of new gas chlorine handling facilities. The low capital costs required for a liquid chemical system would allow future conversion to LTV or other disinfection tech- nology without requiring the abandonment of expensive fixed facilities. 4. A liquid sodium hypochlorite and sodium bisulfite system is less complex than on- site generation of sodium hypochlorite, and there are less labor and maintenance costs associated with liquid sodium hypochlorite. Sodium hypochlorite facilities should be constructed to replace the existing gaseous chlorine facilities. Sodium bisulfite facilities should be constructed to replace the existing gaseous sulfur dioxide facilities. The sodium hypochlorite will be used as a source of chlorine for effluent disinfection, clarifier weir maintenance, foam control, return sludge chlorination for bulking control, and for pre -chlorination of the influent wastewater at the influent junction box to control odors. At least 30 days of on-site storage should be provided for each chemical. Tanks for the sodium bisulfite are anticipated to be of cross-linked high density polyethylene construction. Tanks for sodium hypochlorite should be high density linear polyethylene construction. All tanks should be located in the bulk storage area with secondary containment walls. Separate chemical metering pump feed systems should be provided for each chemical and housed in an adjacent building. New facilities should provide for easy future conversion to on-site generation of sodium hypochlorite or LTV disinfection. EQUALIZATION PONDS AND EFFLUENT PUMPING Treated effluent is currently either discharged to Dredger Cut or is applied to City owned land for irrigation of animal feed and fodder crops. Treated effluent for irrigation flows through one or more ponds prior to application to land. The storage and equalization ponds are described in this section. Equalization Pond When not discharging to Dredger Cut, treated effluent is conveyed to the 3.5 million gallon equalization pond by gravity flow and then either pumped to the irrigation system by the irrigation pumps or pumped into the effluent storage ponds by the recirculation pumps until needed for irrigation. The irrigation pumps may also be used to return stored effluent directly to 9/18/00 Draft 11-40 Wastewater Master Plan 213\wwmp the wastewater treatment process. A schematic diagram of the pond system was included in Figure 11-2. The pond layout was shown previously in Figure 11-3. The equalization pond may also be used to collect untreated wastewater for emergency storage by lowering the equalization pond water level and opening the bypass gate at the Water Pollution Control Facility headworks. Untreated wastewater will then flow by gravity to the equalization pond and may be pumped to the effluent storage ponds as required. The equalization pond serves as a large wet well for the irrigation pump system. Irrigation and Recirculation Pump Stations The irrigation pump station consists of three 3,500 gpm vertical turbine pumps and one smaller vertical turbine pump mounted on a concrete structure located over the equalization pond water surface. The recirculation pump station consists of two vertical turbine pumps for transferring treated effluent from the equalization pond to the storage ponds. The recirculation pump station also includes a submersible pump for pumping irrigation tailwater to the storage ponds. Irrigation tailwater flows by gravity from the effluent irrigation area to the recirculation pump station. The tailwater is combined municipal and industrial effluent runoff from the irrigated fields. Aerated Lagoon and Skimming Pond Two of the storage ponds located adjacent to and west of the equalization pond were originally referred as the Aerated Pond and the Skimming Pond. These were originally used for industrial wastewater treatment prior to storage. When used for industrial wastewater treatment, the ponds became overloaded and filled with wastewater solids. These ponds were taken out of service several years ago. Industrial wastewater is now applied directly to land without pond treatment or storage. Deficiencies and Recommended Improvements Modification of the pond system is required to accommodate construction of a tertiary filtration system and eventually new chlorination tanks. At a minimum, this construction would require relocation of the equalization pond south berm. The costs of tertiary filtration will include the costs for relocating the equalization pond south berm. Another area of needed improvement is associated with the tailwater return system. The tailwater is typically anaerobic by the time it flows to the pump station and as a result can cause odor problems in the storage ponds. The preferred method for tailwater return is to construct a new tailwater return pump station west of the Water Pollution Control Facility at the collection point for the effluent irrigation area runoff (see Figure 11-7). Collected runoff would then be returned to the storage ponds in a small force main. This would eliminate the gravity return pipeline and the need to pump tailwater at the recirculation pump station. This would help with odor problems associated with the tailwater. Further reductions in the volume of tailwater would also be helpful. 9/18/00 Draft 11-41 Wastewater Master Plan 213\wwmp Nom mm .11 14 CAO FILE: 1:/213/99-01/213-11-7.dwg CFC FILE: WYA2500.PCP_MRC DATE- nA-11-nn o•n—.., 0 U Z O z m 1 / ' I � I z 1 �zrrl v J i / I/ $O 2� z I o z /I / / I / I / 1 I G I 1 I 00 wz v i r* 0 0 ((D .-r 900 0 C C7 -n 0 � �, m CD o o .;L � o na y -n 0 r -t Nom mm .11 14 CAO FILE: 1:/213/99-01/213-11-7.dwg CFC FILE: WYA2500.PCP_MRC DATE- nA-11-nn o•n—.., 0 U Z O z m 1 / ' I � I z 1 �zrrl v J i / I/ $O 2� z I o z /I / / I / I / 1 I G I 1 I 00 wz v i STORAGE PONDS Description There are four storage ponds north of the treatment plant used for the storage of treated effluent (see Figure 11-2). These ponds are used during the growing season to equalize the effluent flows with irrigation demands. The ponds are used during the Winter to store tailwater runoff and to provide some effluent pH and temperature moderation. Deficiencies and Recommended Improvements The storage pond control piping constructed in 1990 is working properly and provides sufficiently flexibility for all current modes of operation. If the ponds were to be used for emergency effluent storage when one of the two existing secondary clarifiers was temporarily out of service, some valving improvements would be recommended to be able to more easily return water to the chlorine contact tank. The dissolved oxygen level in the ponds can drop below 1.0 mg/L when there is a relatively high amount of industrial effluent or tailwater from irrigation with industrial effluent entering the ponds. Floating brush style aerators are recommended for the storage ponds to maintain higher dissolved oxygen levels and help prevent odors from the ponds. Although it is difficult to predict the tailwater BOD and therefore the required aeration horsepower, approximately two 15 hp aerators per pond should generally provide sufficient aeration to keep the dissolved oxygen in the upper portion of the ponds above 1.0 mg/L. SOLIDS THICKENING Solids residuals removed from the liquid wastewater stream are treated by anaerobic digestion prior to disposal. Primary sludge is thickened in the primary sedimentation basins as previously described. Waste activated sludge (WAS) from the secondary process is thickened in a separate process facility to remove excess water before being pumped to the digesters. Description of Existing Facilities WAS is thickened in a rectangular dissolved air flotation thickener (DAFT) where particles attach to microscopic air bubbles and float to the surface for removal by skimming. Heavier particles settle to the bottom of the thickener tank. Sludge removed by flotation or settling is pumped to the digesters, and the remaining effluent (subnatant) is returned to the industrial influent flow in the plant headworks channel. No effluent is returned to the domestic treatment plant. WAS thickening can be expected to increase the solids concentration to between 3 and 4 percent. No actual data are collected at Lodi. The solids recovery rate is typically in the range of 85 to 95 percent without the use of polymer. Polymer can increase the recovery rate, but the polymer feed facilities added in 1976 for sludge dewatering are no longer in service. DAFT No. 1 was constructed in 1976 with a surface area of about 300 square feet. DAFT No. 2 was constructed in 1990 with a surface area of about 600 square feet. Under the current 9/18/00 Draft 11-43 Wastewater Master Plan 2 (3\wwmp ' f � operation, WAS is thickened in DAFT No. 2 only for a period of about 10 hours per day. DAFT No. 1 is out of service. DAFT operation is intermittent because the WAS pumps are oversized and do not allow 24-hour per day pumping. Typical DAFT loading rates for WAS are 10 to 30 lb/sf/d (if polymer is used). Based on 12 lb/sf/d, the capacity of DAFT No. 2 is about 7,200 lb/day. WAS solids production is projected to average 10,500 lb/day depending on influent BOD concentrations and actual solids yield. The existing loading on DAFT No. 2 probably exceeds the equivalent of 24 lb/sf/d for the 10 hour per day operation. Solids Balance An estimate of the solids production from the liquid stream process units and the subsequent loadings on the solids handling processes was made in order to determine the design loadings on the solids handling units. The estimates were made based upon typical (or actual, if available) process performance and solids characteristics assumptions as follows: 1. The primary sedimentation basins remove approximately 65 percent of the influent suspended solids from the main plant flow stream and thicken it to an average concentration of 5 percent prior to pumping to the digesters. This solids stream was assumed to contain a volatile fraction of 70 percent. 2. The primary sedimentation basins remove approximately 30 percent of the influent BOD from the main plant flow stream before discharge to the secondary system. Solids production estimates from the secondary treatment systems were made by scaling the output of a Biowin model for a nearly identical process under design for the City of Vacaville. The model assumed full nitrification, a mean cell residence time of 9.5 days and a MLSS concentration of 3500 mg/L. 3. The secondary solids were assumed to contain a volatile fraction of 80 percent. The concentration of this flow stream used in this analysis assumed that solids will be obtained from the return sludge piping from the secondary clarifiers at concentrations around 0.8 percent solids. 4. Solids capture in the dissolved air flotation thickeners (DAFTs) was assumed to be 95 percent of the solids they receive. Thickened solids concentration was projected to be 3.5 percent. 5. Primary and thickened waste activated sludges are combined and placed in the anaerobic digesters for stabilization and solids destruction. The digesters are expected to achieve a 50 percent rate of destruction of the volatile solids fraction. 6. Digested solids are then sent to the sludge storage lagoons. Volatile solids destruction in the storage lagoon was assumed to be 30 percent. The resulting flow, total suspended solids, and volatile solids loadings on the main plant components at average annual and maximum month influent loading conditions for Year 2020 are shown in Table 11-7. The detailed solids balance is shown in Appendix ®. 9/18/00 Draft 11-44 Wastewater Master Plan 213\wwmp Table 11-7. Projected Solids Production Parameter Average Max Month Plant Loadings BOD, lbs/day 19,800 22,800 TSS, lbs/day 17,600 22,400 Primary Solids Total Solids, lbs/day 11,300 14,400 VSS @ 70%, lbs/day 7,900 10,100 Total Flow @ 5%, gpd 27,200 34,600 Secondary Solids Total Solids, lbs/day 10,500 12,100 Thickened Solids, lbs/day 10,000 11,500 VSS @ 80%, lbs/day 8,600 9,300 Thickened Sludge Flow @ 3.5%, gpd 34,200 39,500 Digester Feed Total Solids, lbs/day 21,300 25,900 VSS, lbs/day 16,500 19,400 Total Flow, gpd 61,400 74,000 Digested Solids Total Solids, lbs/day 13,000 16,200 Total Solids, tons/year 2,370 — Total Flow, @ 2.6%, gpd 61,400 74,000 It should be noted that the primary sludge flow as measured by the sludge flow meters does not match the primary sludge flow calculated from TSS removal and measured percent solids. Despite several tests of the sludge flow meters, the cause of this discrepancy has not been discovered. The result is that the projected solids production values used in this section are significantly higher than the measured and reported quantities of biosolids used for calculations in Section 9. Deficiencies and Alternative Improvements Alternative solids thickening deficiencies and alternative improvements are described below. Continuous Operation. The most significant operating deficiency with the WAS thickeners is the inability to operate 24 hours per day. Operation should be changed to 24 hours per day after the capacities of the WAS pumps are reduced. Continuous operation will reduce the solids loading and should improve thickener performance. 9/18/00 Draft 11-45 Wastewater Master Plan 2131wwmp Capacity. DAFT No. 2 for WAS thickening is currently operating at double the recommended loading rate for less than half of each day. It will be moderately overloaded at the projected master plan WAS solids production and has no operational redundancy. If the DAFT No. 2 is taken out of service, either a primary clarifier must be temporarily converted to WAS thickening or the digesters must accommodate a diluted sludge flow for several days. Available alternatives are to either rehabilitate DAFT No. 1 or construct a new thickener. The preferred alternative is to replace unit No. 1 with a new thickener equal in capacity to Unit No. 2. This alternative would provide two similar units and improve reliability. Co -Thickening of Primary Sludge and WAS. Co -thickening of these sludges has been successfully practiced at other wastewater treatment plants. For co -thickening, primary sludge is removed from the primary clarifiers continuously at a relatively low solids concentration (approximately 1 percent). This primary sludge is combined with WAS before thickening in the DAFTs. The reported benefits are: • A thicker sludge float • Better primary BOD removal • Better primary TSS removal at high flows These benefits can translate into slightly lower capacity requirements for primary clarification, secondary aeration, and anaerobic digestion. Co -thickening does not require any increase in DAFT sizing, but does require more than doubling the pressurized recycle and air flows to maintain a high air:solids ratio. A co -thickening trial was run at the City of Vacaville Easterly plant in 1998. The performance results were generally favorable, but operation was substantially more difficult and odorous than with WAS alone. The projected energy costs for co -thickening were approximately $70,000 per year greater than the costs for treating the expected 5 percent higher BOD loads to the secondary treatment system if co -thickening were not practiced. Co -thickening will require covers, foul air collection, and odor scrubber. Based on the trial run and projected operating costs, it was determined that co -thickening would not be cost-effective unless anaerobic digestion capacity or secondary aeration capacity became limiting. The elimination of thickening in the primary clarifiers may also reduce the concentrations of volatile fatty acids in primary effluent, which in turn could reduce the secondary solids settleability and phosphorus removal. In the case of Lodi, expansion of the anaerobic digestion capacity and secondary aeration capacity are required regardless of any benefits achieved by co -thickening. As a result, co -thickening is not recommended for Lodi. Effluent Return. The DAFT effluent (subnatant) from the WAS thickener is returned to the industrial influent flow at the plant headworks channel. Irrigation of animal feed crops with DAFT subnatant may be allowed at the present, but it does increase the risk of pathogen transfer to farm workers and may not be allowed under future reclamation requirements. New piping should be installed to return all DAFT subnatant to the treatment plant headworks. Polymer addition may be provided to improve solids capture and reduce the amount of solids returned to the treatment system. 9/18/00 Draft 11-46 Wastewater Master Plan 2l3\wwmp Summary of Recommended Facilities Recommendations for new facilities associated with WAS thickening are summarized below: • Operate the WAS thickener continuously for 24 hours per day. • Construct a second DAFT similar in capacity to DAFT No. 2. • Continue to thicken primary sludge in -the primary clarifiers. • Return all DAFT subnatant to the treatment plant headworks. • Restore the DAFT polymer feed system. SOLIDS STABILIZATION Solids from the primary clarifiers and DAFTs are anaerobically stabilized to reduce pathogens and convert the solids to a stable product suitable for storage and direct land application. Description of Existing Facilities Primary sludge, thickened waste activated sludge, and scum is pumped alternately to Primary Digester Nos. 1, 2 and 3 on an hourly basis. Waste haulers periodically deliver grease from grease traps within the City and pump the grease into the digesters. Approximately 230,000 gallons of grease was delivered to the treatment plant in 1998. The primary digesters are mesophilic anaerobic digesters, one with a fixed steel cover and two with floating covers. The floating cover digesters were constructed in 1967. The fixed cover digester was constructed in 1990 and the floating cover digesters were rehabilitated at the same time. The digesters are 45 feet in diameter with a 25 -foot side wall depth. The total working volume of the primary digesters with all three in service is 120,000 cubic feet. Mixing is accomplished through confined gas •lifting with compressed digester gas and draft tubes. Heating is provided by external heat exchangers. Digester gas is used to produce hot water for digester and control building heating. Excess gas is flared in a waste gas burner. The digesters have not been cleaned since 1990. Digester gas compressors have had excessive maintenance problems. Equipment suppliers believe that the problem is caused by poor water removal through existing water/gas separators. Plant staff plans to install new water/gas separators. Capacity Typical solids loading criteria for anaerobic digestion is 100 to 200 pounds of volatile suspended solids (VSS) per 1,000 ft3 per day for heated and mixed digesters. A loading rate of 150 pounds of VSS per day per 1,000 cubic feet was used to estimate digester capacity. Total digester capacity at 120,000 cubic feet (all 3 primary digesters in service) is 18,000 pounds of VSS per day based on this criteria. This assumes that all digesters are in service and all digester space is active. Digester capacity is 12,000 pounds of VSS per day with one digester out of service. Projected master plan total solids production ranges from 16,000 lb/day VSS during average loading conditions to 19,000 lb/day VSS during peak 30 -day loading conditions. Based on solids production, the digester volume is inadequate for projected master plan solids production. 9/18/00 Draft 11-47 Wastewater Master Plan 213\wwmp II ' Digestion capacity is also determined by hydraulic detention time. Minimum hydraulic detention time required for anaerobic digestion is 15 days. Total digester capacity (all 3 primary digesters in service) is about 60,000 gallons per day based on this criteria. Projected master plan total sludge production ranges from 61,000 gallons per day during average loading conditions to 74,000 gallons per day during peak 30 -day loading conditions. The actual volume will depend on the thickening performance in the primary sedimentation basins and the DAFT unit. A value of 5 percent was assumed for primary solids and 3.5 percent for WAS. These loadings ignore grease which is about 1 percent of the total digester feed. Based on hydraulic detention time, the digester volume is inadequate for projected master plan solids production. Deficiencies and Alternative Improvements Digestion Capacity. The solids digestion system is inadequate for projected master plan solids production. A preliminary review of alternative means of providing digestion capacity was conducted. Improved sludge thickening was not evaluated because thickening would increase the hydraulic detention time but would not reduce the solids loading, which is above the recommended operating criteria. Available digestion alternatives are continued use of mesophilic digestion with construction of a fourth digester or conversion to thermophilic digestion using extra digester gas and/or waste steam from the Northern California Power Agency power generation facilities. The existing anaerobic digesters operate under mesophilic temperature conditions of between 97 and 102°F. Thermophilic digestion at approximately 135°F has been reported to provide improved solids dewatering, increased pathogen destruction, and increased scum digestion. In addition, hydraulic detention time may be reduced by a few days in some cases. The disadvantages of thermophilic digestion included higher operating costs, lower process stability, more stringent digester structural and insulation requirements, and additional facilities to provide digester heating. Part of the disadvantages could be overcome by use of waste heat from the adjacent Nor -them California Power Agency. The facility generally operates continuously during the Summer when peak electrical power is required, but operation may be intermittent during the Winter when electrical power requirements are not at their peak. Given the nature of facility operation, digester heating equipment would be sized to operate without waste heat from the electrical generating facility. Waste heat would reduce the cost of supplemental fuel when the generating facility was operating. Overall, the advantages of using waste heat from the electrical generating facility are not significant given the other disadvantages and cost associated with reconstruction of the digesters and adding digester heating facilities. For these reasons, continued mesophilic digestion is recommended. A fourth digester is needed to provide the required digestion capacity and allow one digester to be taken out of service during off peak periods for maintenance and cleaning. Digester Feed System. Existing digesters are operated as single -stage units in parallel. With the addition of a fourth digester two-stage operation may provide additional solids stabilization. In a two-stage operation the first three digesters would be operated in parallel and discharge to the fourth digester. The fourth digester would also be heated and mixed to promote digestion but would not be used for gas storage or solids separation as provided for in conventional two-stage 9/18/00 Draft 11-48 Wastewater Master Plan 213\wwmp digestion. Two-stage digestion as proposed reduces the potential for short circuiting of solids in one digester and can improve volatile solids reduction. Digester feed is presently switched between digesters automatically. Operational experience with anaerobic sludge digestion systems has shown that optimal performance (e.g. volatile solids destruction and gas production) and process stability is obtained when raw sludge is fed to the process continuously and uniformly. An alternative to the present feed system that could provide continuous feed of sludge to the digesters is to use a blending tank for DAFT thickened and primary sludges followed by dedicated feed pumps for each digester. Each digester would then receive an equal proportion of primary and secondary sludge and grease on a continuous basis. The advantages of this alternative are that the process is continuous and relatively simple. The disadvantages are the costs of a blending tank and its mixer, odor control, additional piping, and pumping. The cost of a new blending tank facility is estimated at approximately $700,000. The continuous feed alternative provides the best process results, but the benefits in plant operation and process would be minor within the Master Plan planning period. Based on cost considerations, the current digester feed scheme should be continued. For a major expansion after Year 2020, continuous feed should be strongly considered as the optimum method of digester feed. Sludge Grinder. The existing digester piping includes an inline grinder on the lagoon discharge line after digestion. This grinder probably is of little benefit and should be moved to the digester recirculation line. Alternatively, an inline screen may be used to remove rags and other debris from the digester. This would be important if new influent screens were not added to the plant headworks. Assuming new headworks screens are provided then an inline sludge screen is not recommended. Summary of Recommended Facilities Recommendations for new facilities associated with sludge stabilization are summarized below: Add a fourth anaerobic digester. Operate the digesters in a two-stage mode for enhanced solids stabilization. Move the existing inline grinder to the sludge recirculation line. The grinder may not be necessary if headworks screening is added. DIGESTED SOLIDS HANDLING Description of Existing Facilities The overflow from the anaerobic digesters is discharged to Sludge Lagoon No. 2, which is a concrete lined open basin 440 feet long, 110 feet wide, and 9 feet deep. The purpose of this sludge lagoon is to provide sludge storage for periods when application to the land is not possible due to weather, crop management, or other site restrictions. The lagoon also provides additional sludge stabilization. The available storage volume with 2 feet of freeboard is approximately 2.25 million gallons. At a projected Master Plan production of 61,000 gallons of digested sludge per day, the average sludge storage capacity is about 37 days. The actual detention of the sludge 9/18/00 Draft 11-49 Wastewater Master Plan 2131wwmp is much greater because the solids tend to concentrate at one end of the lagoon as the liquid is pumped from the other end of the lagoon. In addition, lagoon supernatant is pumped to the treated domestic wastewater storage ponds during the Winter to increase lagoon solids storage capacity and detention. Lagoon contents are periodically applied to the land by pumping to the head of the effluent irrigation system. No portion of the lagoon contents is returned to the main treatment plant processes. A pontoon mounted sludge withdrawal system installed in 1990 was abandoned after operation proved difficult and labor intensive. Once every few years the lagoon water level is lowered sufficiently to allow large equipment to enter the lagoon and push the majority of accumulated sludge toward the pump inlet for removal and application to land. Sludge Lagoon No. 1 is an unlined earthen basin which is out of service. All digested sludge is discharged to Sludge Lagoon No. 2. There are no bypass provisions and no means to remove Sludge Lagoon No. 2 from service. The 1976 improvement project included the addition of a belt filter press for digested solids dewatering. The lagoons at that time were intended for emergency storage. The 1990 improvement project lined Sludge Lagoon No. 2 and converted the sludge dewatering building to contain the South Electrical Room and provide miscellaneous storage space. The polymer facilities originally used for sludge dewatering were retained in the building but have been out of service for many years. Deficiencies and Alternative Improvements The most significant operating deficiency is the lack of long-term storage capacity and the inability to bypass Sludge Lagoon No. 2 for cleaning. The apparent alternatives are: 1. Pump digested sludge directly to land and bypass Sludge Lagoon No. 2 for a couple of weeks. The digested biosolids could be applied to corn fields, but not to alfalfa. 2. Line Sludge Lagoon No. 1 and place into service. 3. Construct an additional sludge lagoon west of Sludge Lagoon No. 2. 4. Convert the Aerated Pond to a sludge lagoon. Evaluation of Sludge Storage Alternatives Bypass Sludge Lagoons When Necessary. Bypass of the sludge lagoon is possible in an emergency, but it is not recommended due to the constraints which would be imposed on the crop irrigation system and farm management. Alternatives which provide additional storage capacity to allow bypass of Sludge Lagoon No. 2 and allow additional storage of solids during the Winter months are preferable. Sludge Lagoon Expansion. Sludge Lagoon No. 1 could be placed in service with the addition of a concrete liner similar in design to Sludge Lagoon No. 2. Alternative designs include synthetic liners, soil cement, or shotcrete. A second operating lagoon would increase total storage capacity and allow either lagoon to be taken out of service as needed for cleaning or maintenance. The area of Sludge Lagoon No. 1 is about 75 percent of that of Sludge Lagoon No. 1 because of the 9/18/00 Draft 11-50 Wastewater Master Plan 213\wwmp DRAFT space taken from Sludge Lagoon No. 1 by the 1990 construction of new secondary clarifiers. The volume of Sludge Lagoon No. 1 after lining is estimated at 1.72 million gallons. The total volume of both lagoons would be slightly over 4 million gallons which would increase the average liquid sludge storage capacity to about 66 days at Master Plan projected conditions. If a liquid decant rate of 30 percent is assumed, this would equal about 94 days of storage capacity. This capacity is less than the recommended process criteria of 120 days. The other problem with improving Sludge Lagoon No. 1 is that it is located in the area needed for long-term expansion of the treatment plant facilities. New Sludge Lagoon. A new sludge lagoon could be located immediately west of existing Sludge Lagoon No. 2 on land which was previously earmarked for power plant use, but has not been purchased by NCPA. Unlined Sludge Lagoon No. 1 would be abandoned and replaced with a new lined basin with at least 2.8 million gallons storage capacity. This would bring the total storage capacity to approximately 5.2 Mgal. This amount of storage could hold all sludge for 120 days with 30 percent liquid decant. Small surface aerators could be used to dissipate scum and help maintain aerobic conditions at the lagoon surface. The advantage of a new lagoon at this site would be easier integration and operation in conjunction with Sludge Lagoon No. 2. The main disadvantage of this alternative is that future expansion of sludge lagoon capacity and power generation would be limited. Convert Aerated Pond to Sludge Lagoon. This alternative would include converting the Aerated Pond to a sludge lagoon and abandoning unlined Sludge Lagoon No. 1. The Aerated Pond would provide 4.2 million gallons of additional sludge storage. The Aerated Pond currently contains a buildup of industrial solids and biosolids from previous operation. It is not currently in use. It has an operating depth of 8 feet, which is greater than the existing sludge lagoons. The advantages of converting the Aerated Pond to a sludge storage pond include lower costs, aeration facilities in place, more volume, and better access to feed biosolids into the irrigation system. The main disadvantages of using the Aerated Lagoon are a slight reduction in total available effluent storage and that biosolids may have to be pumped into the pond rather than allowed to flow by gravity. Future expansion of sludge lagoon capacity could be accomplished by converting the Skimming Pond to a sludge lagoon when needed. Recommended Sludge Lagoon Alternative. Based on operational and future expansion considerations, the recommended alternative is to convert the Aerated Pond to a Sludge Lagoon. This will involve cleaning out the pond, constructing an access ramp, and installing a lining. Alternative Sludge Drying and Storage Methods A significant long-term issue is whether the current practice of direct application of liquid sludge to land will be allowed in future discharge requirements. Therefore, alternative dewatering and sludge handling methods are presented as contingencies to the current process. Belt filter press and thermal drying alternatives were discussed in Section'9 and are included again in this discussion of alternatives following paragraphs. Drying Lagoons. Sludge drying lagoons are a simple variation on the operation of sludge lagoons as practiced at Lodi. A sludge drying lagoon receives digested sludge for a period of approximately 2 years. After the two year period, liquid is decanted off the lagoon and the sludge 9/18/00 Draft 11-51 Wastewater Master Plan 213\wwmp in the lagoon is allowed to dry. Drying may take one year during dry years or two years during years with relatively high rainfall. The drying sludge is normally turned over several times and then pushed into piles using a front end loader to enhance drying. The cost of drying lagoons may be increased by the need to keep groundwater out of the lagoons through the installation of a lining and/or underdrains. Drying lagoons would be approximately 8 feet deep and occupy approximately 12 acres of land. Groundwater level control facilities would probably also be required to maintain separation between the basin bottoms and groundwater; Drying Beds. Open drying beds provide dewatering by the process of drainage and evaporation. Sand drying beds historically have been the most common form of this method of dewatering. Other methods include paved beds, wedge wire, and vacuum assisted drying beds. Paved drying beds were selected for comparison to sludge lagoons and mechanical dewatering because they represent an easy to operate, low end technology, and low energy use dewatering method for comparison to mechanical dewatering alternatives. The principle advantages of paved drying beds over sand drying beds are reduced labor and maintenance costs. Front-end loaders can easily turn the solids to enhance drying and remove dewatered solids from the paved surface. In addition, there is no need to replace sand removed with the biosolids from sand drying beds. The principle disadvantage of paved beds is the lack of an underdrain system for solids draining, although significant drainage may occur with sloped beds and the use of properly designed drain outlets. Solids drying occurs primarily during the warmer months between April and October. At other times storage space is required to hold the biosolids within the paved basin or in the storage lagoons. Approximately 10 acres of paved drying beds would be required at Master Plan design loadings. Mechanical Dewatering. The three most common mechanical dewatering methods are centrifuges, belt filter presses, and pressure filter presses. Centrifugation applies centrifugal force for. the separation of the liquid and solid fractions. The process provides both clarification and compaction. Belt filter presses have moving belts to dewater sludge continuously through a combination of gravity drainage and compression. Pressure filter presses pump sludge through recessed filter plates operated as a batch process which leaves a concentrated sludge cake trapped between the filter plates. All processes have been improved in the last several years and have been the subject of numerous studies. While the selection of a dewatering method is generally site specific and often requires pilot testing, belt filter presses are commonly used for small to medium facilities and would be suitable for Lodi as a mechanical sludge dewatering alternative to drying basins. Evaluation Of Sludge Drying Alternatives. Drying beds and mechanical dewatering alternatives would need separate liquid sludge storage lagoons for operating flexibility and control of odors. In addition, open drying basins would be needed for the mechanical dewatering alternative to provide dewatered sludge storage for additional drying and storage until final disposal. The estimated costs of sludge drying alternatives are shown in Table. 11-8. The capital cost of mechanical dewatering is lowest followed by drying lagoons. The capitil costs of paved drying beds are significantly higher than the other alternatives. The operating costs of mechanical dewatering are much greater than the operating cost of drying lagoons or paved drying beds because the drying beds and lagoons require no chemical conditioning, less operational labor, and no special equipment other than a front end loader. From a cost and ease 9/18/00 Draft 11-52 Wastewater Master Plan 213\wwmp Mai of operation standpoint sludge drying lagoons are the preferred alternative.. The primary disadvantage of drying lagoons is the large land area they would require. Table 11-8. Costs of Sludge Drying Alternatives Alternative - Capital Cost, dollars Annual O&M, dollars Life Cycle Cost, dollars Drying Lagoons 4,300,000 18,000 4,500,000 Paved Drying Beds 5,000,000 141,000 6,500,000 Mechanical Dewatering 2,700,000 240,000 5,300,000 Biosolids Disposal/Reuse Alternatives Land application of biosolids is the preferred management alternative assuming that there are no regulatory restrictions imposed on future disposal operations. The potential costs of landfill disposal are presented to demonstrate the impact of eliminating land application of biosolids on City -owned property. The nearest landfill available for sludge disposal is located between Stockton and Manteca east of Highway 99. This is a Class 2 landfill operated by Forward Inc., a division of Allied Waste Inc. Forward will accept sludge with a solids content of at least 50 percent and not classified as hazardous or restricted material as demonstrated by laboratory testing. Cost of disposal is $28 per ton not including haul costs. Forward estimates haul costs at about $18 per ton based on costs of handling a 20 -yard bin. The total cost of disposal is $46 per ton. As much as 2,300 dry tons of solids will be produced per year at projected Master Plan loading conditions. At a solids content of around 60 percent the total weight is 3,900 tons and the cost of disposal is about $180,000 per year. These costs do not include the cost of dewatering which must be operated to produce a dry cake suitable for hauling and disposal. Mechanically dewatered solids must be stockpiled to allow additional drying. On-site land application of biosolids is the preferred disposal/reuse alternative. Landfill disposal is a backup alternative should land application become prohibited. Summary of Recommended Facilities Recommendations for new facilities associated with digested sludge handling are summarized below: • Relocate the sludge storage facilities away from the existing treatment facilities. Provide a total of three one -acre lined basins. Use the existing sludge storage lagoon and construct two additional lagoons at a site removed from the treatment plant facilities. 9/18/00 Draft 11-53 Wastewater Master Plan 213\wwmp 0 Continue the practice of land -applying biosolids with irrigation water, with distribution improvements as discussed in Section 9. If liquid application of biosolids directly to land becomes no longer feasible or allowed by waste discharge permits, provide sludge dewatering in drying lagoons. ADVANCED NUTRIENT REMOVAL TREATMENT General Beyond a standard secondary level of treatment with ammonia removal through biological nitrification, additional treatment alternatives include nitrogen and phosphorous removal. These alternatives are presented only to the extent that the master plan facilities provide flexibility to accommodate these and other facilities in the future should they become necessary. The costs of these facilities are compared with other non -conventional treatment or disposal alternatives for meeting potential future discharge requirements later in Section 13. Nutrient removal processes include a variety of physical/chemical and biological treatment systems. Biological treatment systems are generally less expensive to operate than physical/chemical systems. Integrated systems employ both biological and physical/chemical treatment systems to achieve a greater level of nutrient removal (especially phosphorous) where the physical/chemical treatment systems provide additional removal or backup to the biological systems. Biological nutrient removal systems are an extension of the conventional activated sludge process for carbonaceous BOD removal. These systems may be adapted for nitrogen or phosphorous removal or both. A basic nutrient removal flow schematic is shown in Figure 11-8. Many flow schemes have been developed for combined nitrogen and phosphorous removal including some patented processes. The final selection of a particular process will depend on the desired level of nutrient removal, current practices at the time of design, and the experience of the process designer. PHOSPHORUS RELEASE SOLUBLE BOD UPTAKE ORGANISM SELECTION PRI EFF (o) Figure 11-8. Basic Nutrient Removal Flow DENITRIFICATION NITRIFICATION 800 REMOVALPHOSPHORUS EFF WASTE ACTIVATED SLUDGE (WAS) 9/18/00 Draft 11-54 Wastewater Master Plan 213\wwmp (l ' R The nutrient removal performance of the existing wastewater treatment process is already substantially better than would be expected because of the fact that decant from the biosolids treatment processes is not returned to the liquid stream treatment process. Phosphorus Removal Phosphorous removal occurs through accumulation of phosphorous compounds in micro- organisms at rates 3 to 4 rimes that of conventional activated 'sludge systems. An anaerobic selector zone at the beginning of the process usually favors the enhanced removal of phosphorous. This selector zone is typically approximately 10 percent of the total process volume. Phosphorous absorbed by microorganisms is removed by normal sludge wasting. The effectiveness of phosphorous removal will also be dependent on a properly designed and operating final clarifier. Clarifier loading rates may have to be reduced to improve solids capture. Chemical addition to the clarifier or effluent filtration is sometimes required to meet low phosphorous effluent limits. The existing plant is already operating in a mode which accomplishes very good phosphorous removal. Nitrogen Removal Nitrogen removal occurs through conversion of nitrate to insoluble nitrogen gas in anoxic conditions. This is usually accomplished by having a high amount of RAS recycled to an anoxic zone near the beginning of the process. Nitrogen removal typically requires an increase in tankage volume of 20 to 30 percent compared to the tankage needed for just carbon and ammonia removal. This equates to two additional basins for nitrogen removal assuming six basins are required for carbon oxidation, ammonia nitrification, and incidental biological phosphorous removal at Master Plan projected loading conditions. The partitioning and flow paths for the secondary treatment basins with nitrogen removal are shown in Figure 11-9. Recommended Facilities Planning Because the phosphorus removal efficiency is already high, only the facilities required for advanced nitrogen removal need to be addressed at this time. The facilities required to reduce effluent nitrogen concentrations to about 5 mg/L and the estimated costs are listed in Table 11-9. The costs and subjective considerations related to these facilities are compared with the wetlands alternative for denitrification in Section 13—Evaluation of Combined Treatment and Disposal Alternatives. Table 11-9. Cost of Additional Facilities for Advanced Conventional Nitrogen Removal Capital Cost, _ dollars Operation and Maintenance, dollars Life Cycle, dollars 5,800,000 100,000 6,900,000 9/18/00 Draft 11-55 Wastewater Master Plan 2131wwmp r---------------------- -- -� ---------------------- ---- 0 25 50 SCALE IN FEET �-1;vC.OCC AERATION BASINS M DISTRIBUTION s BOX (PROPOSED) JC\VIV V['tR CLARIFIER No: 2 ' :sl COLLECTION CHANNEL CHORINE RINE r //TANKS SECONDAR CLARIFIE r' L,� IVIU9LCF rlan Iwlxea LIquur Plus Denitrificotion CP Recycle Pump Figure 11-9 >>^ = Anoxic Zone City of Lodi Anaerobic Zone F7 Lona -term Facilitv Water Pollution Control Facility AERATION BASINS WITH NITROGEN REMOVAL FACILITIES PRIMARY SEDIMENTATION BASINS il�I�+I; ------------------- U� r EE No. 7 N -------------------'{ W :. z No N No. 6 Z. SI c = U 8 No. 5 z W No. 4 � w No. 3 No. 3 > No. 2 Fr No. 2 No. 1 CIO .1 ] I I � No. 1 �-1;vC.OCC AERATION BASINS M DISTRIBUTION s BOX (PROPOSED) JC\VIV V['tR CLARIFIER No: 2 ' :sl COLLECTION CHANNEL CHORINE RINE r //TANKS SECONDAR CLARIFIE r' L,� IVIU9LCF rlan Iwlxea LIquur Plus Denitrificotion CP Recycle Pump Figure 11-9 >>^ = Anoxic Zone City of Lodi Anaerobic Zone F7 Lona -term Facilitv Water Pollution Control Facility AERATION BASINS WITH NITROGEN REMOVAL FACILITIES ADVANCED HEAVY METALS REMOVAL TREATMENT Advanced Solids Removal Some of the total recoverable metals are bound with particulates in secondary effluent. Removal of particulate bound metals can help assure compliance with discharge requirements since the discharge requirements currently are applied to total metals with a translator factor to conservatively estimate maximum dissolved metals. Advanced solids removal using tertiary treatment (coagulation and effluent filtration) could remove over half the effluent TSS and associated metals. This would not be as effective as treatment technologies which remove dissolved metals, but it may be sufficient to meet discharge requirements. Costs associated with tertiary treatment are presented in the next sub -section of this report. Chemical Precipitation is sometimes used to remove dissolved metals from industrial wastewater . The major disadvantages of metals removal through chemical precipitation are the ongoing costs of the chemicals and the treatment and disposal of additional sludge. Hydroxide and sulfide are used for direct precipitation, while alum or iron flocs are effective at coprecipitating some metals. Metals removal as a function of pH is shown in Figure 11.10. As can be seen in the figure, the best zinc removal at an optimal pH would leave a concentration of about 100 Mg/L with hydroxide precipitation. This is almost the same as the discharge limit, so it would not be reliable enough as a process. Sulfide precipitation would produce low enough metals concentration to meet discharge limits as long as the pH could be maintained above about 5. Sulfide precipitation occurs naturally to a degree in the influent sewer line and primary treatment because of the presence of hydrogen sulfide. This may reduce dissolved zinc and lead, leaving most of the remaining metals in the particulate form leaving the primary clarifier. Some of the metals could possibly resolubilize in the secondary treatment process. The addition of sulfide to the secondary clarifiers for final treatment would again remove soluble metals. However, this would leave excess sulfide in the effluent prior to chlorination and would dramatically increase chlorine usage. It would also require special odor and corrosion control measures. Because of these issues, sulfide precipitation is not practiced on secondary effluent at any known treatment plant. Therefore, removal of dissolved metals by sulfide precipitation is not recommended as a viable alternative for Lodi. Other Advanced Metals Removal Processes There are other processes for advanced metals removal including ion exchange and reverse osmosis. These other alternatives are more expensive than chemical precipitation and would only be worth consideration if there were no other alternatives for satisfying metals standards in discharge requirements. Recommended Heavy Metals Removal Treatment If metals removed must be performed using conventional treatment processes, coagulation and effluent filtration are recommended. Pilot testing should be performed to determine if adequate 9/18/00 Draft 11-57 Wastewater Master Plan 213\wwmp Figure 11-10. Approximate Best Achievable Effluent heavy Metal Concentrations for Lime and Sulfide Precipitation) 10. 10. PH removal can be achieved. Effluent filtration is compared with wetlands for metals removal in Section 13 EFFLUENT FILTRATION Effluent coagulation and filtration are required for most of the surface discharge alternatives. It would provide enhanced BOD removal and may provide additional removal of some heavy metals. If constructed, the proposed Sports Complex would be irrigated with reclaimed water. In a previous study prepared by HYA Consulting Engineers in 1995, a tertiary filtration and disinfection capacity of 2.5 Mgd was recommended to meet irrigation needs. The water reclamation plant was proposed for a location east of the existing chlorine contact tank 9/18/00 Draft 11-58 Wastewater Master Plan 213\wwmp 00=00 SEEMME 0111 NNEWIMMIMERM NEMESES, ON MEMEMENSOMEME NOMMEM&WIM-6sm NEENNEMEM-1-01 0000136,000MEMEN MEMENNO moms MEMENNEEMEMEN NOMEMENKNEMN ENEENNEMMEMON NEEEENNNEEN� PH removal can be achieved. Effluent filtration is compared with wetlands for metals removal in Section 13 EFFLUENT FILTRATION Effluent coagulation and filtration are required for most of the surface discharge alternatives. It would provide enhanced BOD removal and may provide additional removal of some heavy metals. If constructed, the proposed Sports Complex would be irrigated with reclaimed water. In a previous study prepared by HYA Consulting Engineers in 1995, a tertiary filtration and disinfection capacity of 2.5 Mgd was recommended to meet irrigation needs. The water reclamation plant was proposed for a location east of the existing chlorine contact tank 9/18/00 Draft 11-58 Wastewater Master Plan 213\wwmp 1 A% approximately where the third secondary clarifier is proposed in this report. A copy of the HYA report is contained in Appendix M. There are several types of filtration systems that can be used for the effluent filtration application. The three systems evaluated for master planning purposes were: 1. Granular Media Filtration 2. Synthetic Media (Fuzzy) Filters 3. Membrane Filtration Granular Media Filtration Granular media filtration has been the industry standard filtration technology for several decades. Granular media filters have been improved to provide greater effective use of the entire media bed depth to trap and hold particles. Two of the most popular designs have been pulsed bed (ex. Hydroclear) and continuous cleaned upflow filters (i.e. Parkson Dynasand). The typical design hydraulic loading rate for advanced granular media filters is 5 gpm/sq ft for tertiary reclamation treatment. Synthetic Media (Fuzzy) Filters Fuzzy Filters are a depth filter like a granular media filter, but with a special compressible filament media bed. The Fuzzy Filter media has much greater void space than granular media filters, allowing design unit area loading rates to be in the range of 20 to 25 gpm/sq ft The media compression can be adjusted to provide the desired performance. Fuzzy Filters also require much less backwash water than pulsed bed or some of the other granular media filters. There is currently only one small commercial Fuzzy Filter installation in California producing tertiary reclaimed water. The California Department of Health Services has yet to fully approve of the use of Fuzzy Filters operated at high hydraulic loading rates for producing reclaimed water. Membrane Microfiltration Membrane microfiltration technology has been improving rapidly to the point where it is becoming more competitive with granular media filtration. One of the advantages of membrane microfiltration is that it provides better direct removal of bacteria, viruses, and free swimming parasites than granular filtration. The main disadvantages for membrane filters are that costs are significantly higher than for granular media filters and there are few installations in California for producing tertiary reclaimed water. Membrane microfiltration has proven to be a cost effective pretreatment step prior to reverse osmosis of effluent. Performance requirements in terms of turbidity are over 10 times more stringent for membrane filters than for granular media filters (0.5 NTU max. versus 10.0 NTU max., respectively). Evaluation of Filtration Alternatives and Recommended Alternative Cost estimates for the filtration alternatives are shown in Table 11-10. It should be noted that the costs shown are for the filters only and do not include the costs of related facilities required for tertiary treatment. The costs of the Fuzzy Filter facilities and the membrane filters were partially 9/18/00 Draft 11-59 Wastewater Master Plan 2131wwmp based on a study performed for Dublin -San Ramon Services District. Because of the lower costs and proven track record for granular media filtration, it is the recommended alternative at this time. The proposed location for effluent filters was shown on Figure 11-4. The cost of media for the Fuzzy Filters is expected to gradually drop over the next few years due to manufacturing efficiency improvements. Membrane filter costs are also expected to become more competitive in the future. Both fuzzy filters and membrane filters should be reevaluated in any future predesign of tertiary filtration facilities. The costs of complete tertiary filtration and disinfection facilities are compared with other non -conventional treatment or disposal alternatives for meeting potential future discharge requirements later in Section 13. The impact of constructing tertiary treatment facilities for only 2.5 Mgd for the proposed sports complex is also addressed in Section 13. Table 11-10. Costs of Filtration Alternatives(a) Alternative Capital Cost, Annual O&M, dollars dollars Life Cycle Cost, dollars Granular Media 7,500,000 170,000 9,300,000 Synthetic Medium 6,500,000 170,000 8,300,000 Membrane Microfiltration 17,000,000 1,000,000 27,800,000 (a) Costs of filtration facilities only, not complete tertiary treatment facilities. PLANT SUPPORT SYSTEMS Other general facilities improvements which are desirable because of safety, operational, or reliability considerations have also been evaluated, including existing buildings, electrical service, and control and monitoring systems. Administration Space and Personnel Spaces (Washrooms and Lockers) Buildings at the treatment plant house four general functions: General office space and operations areas including locker space and showers, laboratory space for analytical work associated with process control and monitoring, plant and utilities maintenance, and process space for chemical storage, handling, and equipment. The Control Building houses the plant operations staff, plant process monitoring room, laboratory, lunch room/meeting room, men's and women's shower/locker rooms, blower room, maintenance shop, and miscellaneous storage rooms. There are up to 18 people on the day shift, with Thursday having the largest regularly scheduled staff size at 17. The numbers of each staff classification are as follows: • 6 Operators 2 Mechanics • 1 Maintenance Person 9/18/00 Draft 11-60 Wastewater Master Plan 2131wwmp DRAFT • 1 Electrician • 1 Assistant Superintendent • 1 Chief Operator • 1 Lab Supervisor • 2 Laboratory Technicians • 2Inspectors • 1 Administration Clerk Two staff positions will probably be added for the expansion of the secondary treatment facilities and solids treatment improvements. If tertiary treatment is constructed at the plant, another additional 3 staff positions would probably be required. The laboratory space is currently adequate, but there is no room for expansion. The maintenance shop size is just adequate. The main men's locker room could accommodate two or three extra people. Deficiencies After visiting the site and discussing space requirements with key plant staff, five deficiencies were identified: 1. Laboratory staff has indicated that a window would enhance their work space. 2. The Chief Operator has no enclosed office area for private conversation. 3. Women's Restroom and Shower—There is only one lavatory, which is enclosed in the accessible toilet compartment. Calculations of required toilets based on Appendix Chapter 29 of the California Building Code show that a minimum of two toilets are required for men and women. There is currently only one toilet for women. 4. Women's Locker Room—The women's locker space within the Control Building is inadequate and should be expanded to provide additional lockers and washrooms separate from the toilet facilities. 5. Maintenance Vehicles Parking—The maintenance shop in addition to providing space for maintenance activities is used for parking vehicles after normal work hours. A separate garage is needed to protect equipment and small utility vehicles and allow expansion of maintenance activities within the maintenance shop. Recommended Improvements • The laboratory has exterior walls on two sides, and the addition of windows would be relatively simple. Windows matching the existing could be installed, with opening vents. As an alternative, glass block could be installed in the existing concrete block walls, giving a view of the outside but not adding the problems of open windows altering the heating, cooling and fume hood air flows. 9/18/00 Draft 11-61 Wastewater Master Plan 213\wwmp • By relocating the clothes washer and dryer from the existing utility room to the room presently occupied by the Maintenance Superintendent, accessible showers can be installed in that room for the women staff. In addition, the existing shower can be converted to the required additional toilet, and one or two lavatories can be installed adjacent to the new toilet. _• The Senior Plant Mechanic's office can be relocated to the second floor adjacent to the air handling units. The space is currently unused, but is served only by a spiral staircase located inside the workshop. A new exterior stair is proposed on the west side of the building, outside the current Maintenance office. To accommodate the new office, the exterior louvers will be removed from the area directly outside the room, and a door and windows will be installed. The wall separating the office from the air handling units will be replaced with an acoustically separating wall (gypsum board on acoustical channels on studs, with sound insulation between studs). An acoustical ceiling will be installed in the office, with insulation above the ceiling to stop sound coming over the top of the wall. • The unused concrete pad north of the digesters near Sludge Lagoon No. 1 should be converted to Maintenance parking. There is no easy way to provide the Chief Operator with an enclosed office area. It might be possible to add two walls to the existing area used by the Chief Operator. Recommended improvements to the Control Building and maintenance parking are shown in Figure 11-11. Electrical Service The plant has dual 2,000 Amp, 480V, 3-phase utility power feeds and no standby power generators. The south feed is PG&E Meter No. 29159 and the north feed is SMUD Meter No. 29467. The common point of power interconnectivity is at the main switchboard and the bus tie transfer switch. This has proved reliable except during the most extreme conditions where power failures have effected the entire West Coast. The City has considered an additional power feed to the Northern California Power Agency (NCPA) electrical generating facility located behind the treatment plant. This facility uses reclaimed water from the Water Pollution Control Plant for steam generation and cooling. As a result, the NCPA facility is dependent on the treatment plant for continued operation. Given the lack of any data to suggest that the power supply is inadequate, it does not appear reasonable at this time to add standby power facilities. However, as treatment requirements become more stringent or wastewater reuse involves public contact, the regulatory requirements for standby power must be addressed. An evaluation of power supply alternatives is beyond the scope of the master plan. This evaluation should be provided as part of the predesign of the treatment plant improvements. 9/18/00 Draft 11-62 Wastewater Master Plan 2131wwmp NEW WOMEN'S LOCKER ROOM (EXISTING UTILITY ROOM) LUNCH ROOM Figure 11-11 City of Lodi Water Pollution Control Facility Recommended Control Building Improvements NOTES: LEGEND: e SC4F iu r[[r W E S Y 0 S DRAFT The addition of new influent pumps, aeration blowers, and other facilities will exceed the current capacity of the main switchgear. Preliminary calculations show that the maximum running loads could be as high as 2,200 amps on a service rated at 2,000 amps. Running loads would be greater if effluent filtration or other processes are added. In addition, distribution panels DP -B 1 and DP - B2, which are rated at 1,600 amps, will have to be replaced or supplemented with new electrical equipment. Flood Protection FEMA flood insurance rate maps show the 100 -year flood elevation for the treatment plant area at elevation 8 feet based on the 1929 National Geodetic Vertical Datum. The treatment plant site is at elevation 9 feet or above based on an unknown datum. Entrance to structures is located at elevation 10 feet or above. Storm water on the treatment plant site sheet flows across the site to surrounding ditches and sloughs. Flood protection for the plant appears adequate to maintain operations during the 100 -year storm event. The basis of treatment plant elevations and reference datum should be identified in relation to the 1929 datum in order to confirm actual elevation differences between existing treatment plant elevations and flood elevations. SUMMARY OF TREATMENT PLANT IMPROVEMENT RECOMMENDATIONS Some treatment plant deficiencies could be addressed by several alternatives. The comparison of alternative improvements discussed in this section is summarized in Table 11-11. All recommended treatment plant improvements needed over the 20 year planning period are summarized in Table 11-12. Estimated total project costs of the facilities and improvements needed by the year 2004 are shown in Table 11-13. Some of the treatment process alternatives must be compared with other alternatives not related to treatment plant improvements. These comparisons are performed later in Section 13. 9/18/00 Draft 11-64 Wastewater Master Plan 213\wwmp - AAFT Table 11-11. Treatment Plant Improvement Alternatives Alternatives shown in bold are preferred. Alternatives shown in italics should be reevaluated for treatment plant upgrades after Year 2005 because of potential improvements in technology. 9/18/00 Draft 11-65 Wastewater Master Plan 213\wwmp Major Subjective Major Subjective Capital Cost, Life Cycle Process Alternative Improvements Advantages Disadvantages dollars Cost Influent Mechanically cleaned bar screens Only one submerged moving part Large openings 510,000 n/a Screening High clearance requirement Continuous self-cleaning screenPl Finer screen Need separate washing and compacting 650,000 n/a High loading capacity Proven Spiral basket screens Combined screening, washing, and Limited capacity 690,000 n/a compacting Grit Removal Aerated grit tanks Preaeration Larger facility 1,900,000 2,000,000 Vortex grit removal system Lower energy use Grit hopper plugs more often 1,200,000 1,300,000 Compact Disinfection Gas system containment, scrubbing Fewer truck deliveries Safety 1,400,000 2,800,000 Chlorination byproducts Liquid hypochlorite and bisulfite (outside Simple and safe More truck deliveries 260,000 3,400,000 suppliers) Chlorination byproducts On-site liquid hypochlorite generation Fewer truck deliveries Complexity 1,100,000 3,900,000 Increased maintenance Chlorination byproducts Ultraviolet disinfection No chlorination byproducts Less reliable disinfection w/o filtration 4,800,000 7,700,000 No chemical deliveries or handling High maintenance Better virus kill Sludge Line Sludge Lagoon #1 Easier to implement 430,000 n/a Lagoons One new lagoon, abandon existing Leaves room for plant expansion Requires more land 1,200,000 n/a Lagoon #I Moves potential odor sources west Convert aerated pond Most capacity Requires digested sludge pumping 930,000 n/a Closest to Irrigation Boxes Sludge Drying lagoons Simple Requires more land 4,300,000 4,500,000 Dewatering Paved drying beds Moderate labor 5,000,000 6,500,000 Mechanical dewatering Low land requirements High labor 2,800,000 5,300,000 High chemical usage Effluent Granular media filtration Proven 8,000,000 9,800,000 Filtration Membrane filtration Fewer particle breakthroughs 17,000,000 27,800,000 Fuzzy filters Compact 6,500,000 8,300,000 Alternatives shown in bold are preferred. Alternatives shown in italics should be reevaluated for treatment plant upgrades after Year 2005 because of potential improvements in technology. 9/18/00 Draft 11-65 Wastewater Master Plan 213\wwmp tAFT Table 11-12. Summary of All Treatment Plant Improvement Recommendations Process Deficiencies Recommended Improvements Flow at Upgrade Year Headworks Capacity Modify existing headworks Construct new headworks 7 8.5 2004 2020 Screening No screening - only comminuting Continuous self-cleaning screens 7 2004 Grit Removal Marginal performance, no room for expansion Aerated grit tanks Or Vortex grit removal system 8.5 2020 Cross Channel Gates Capacity Repair gates 6.5 Immediate Septage Receiving Station Capacity, plugging Upgrade existing for less plugging, easier maintenance Construct new station 7 8 2004 2015 Domestic Influent Pumps Capacity Install larger pumps or impellers, or increase speed 7 2004 Industrial Influent Pumps Capacity, redundancy Upgrade one pump, install a small third pump Immediate Primary Clarifiers Capacity Two new clarifiers 9.5 >2020 Aeration Basins Capacity Treatment level Upgrade diffusers (completed 12/99) Two new aeration basins Three more aeration basins (to 12 Mgd capacity) 6.5 7 8.5 Immediate 2004 2020 Aeration Basins Process stability Replace diffusers with mixers 7 2004 Secondary Clarifiers Capacity, redundancy Flocculent injection system Construct a third clarifier 6.5 7 Immediate 2004 Blowers Capacity Two new blowers 7 2004 Blower Control Efficiency - not demand -matching Automate, including air manifold valves 7 2004 RAS Pumps Excessive capacity Trim impellers 6.5 Immediate WAS Pumps Excessive capacity Downsize or trim impellers for 2 pumps 6.5 Immediate Disinfection Safety Improved reliability Liquid hypochlorite and bisulfite (outside suppliers) Enhanced CCT flushing 7 7 2004 2004 WAS Thickening Capacity Redundancy Continuous operation, restore polymer system Construct second DAFT 6.5 7 Immediate 2004 DAFT Subnatant No disinfection Return subnatant to headworks ' 7 2004 Anaerobic Digestion Capacity, redundancy Construct fourth digester Construct fifth digester 7 8.5 2004 2020 9/18/00 Draft 11-66 Wastewater Master Plan 213\wwmp ZAFT (a) Improvements shown in italics are alternatives which should be reevaluated for treatment plant upgrades after Year 2005 because of potential improvements in technology. 9/18/00 Draft 11-67 Wastewater Master Plan 213\wwmp Flow at Process Deficiencies Recommended Improvements Upgrade Year Sludge Grinder Low effectiveness Move to sludge recirculation line 7 2004 Sludge Lagoons Storage capacity, redundancy Convert aerated pond to sludge lagoon, abandon unlined Sludge Lagoon No. l 7 2004 Sludge Dewatering Compliance with possible future discharge Drying lagoons NIA If & when requirements required Nitrogen Removal Compliance with possible future discharge Two additional basins, denitrification compartments, N/A See Sec. 13 requirements mixed liquor recycle Advanced Heavy Metals Compliance with possible future discharge Chemical precipitation N/A See Sec. 13 Removal requirements Tertiary Filtration Compliance with possible future discharge Granular media filtration NIA See Sec. 13 requirements Or Fuzzyfilters Maintenance Shop Parking Construct parking garage 7 2004 Maintenance Supervisor's Space Move upstairs 7 2004 Office Women's Locker Room Space, lockers Expand 6.5 Immediate Control System Manual control adjustment, no SCADA Install centralized automated control system with 7 2004 manual override features (a) Improvements shown in italics are alternatives which should be reevaluated for treatment plant upgrades after Year 2005 because of potential improvements in technology. 9/18/00 Draft 11-67 Wastewater Master Plan 213\wwmp Table 11-13. Estimated Costs of Treatment Plant Improvements Common to All Process Alternatives (a) Item Estimated Capital Cost, dollars (b) Provide Additional Capacity Modify Domestic Pumps 210,000(`) Replace Industrial Pump, add 3rd 360,000(`) AS Thickening Improvements 1,540,000(`) New Anaerobic Digester 1,710,000 (`) Sludge Lagoon Capacity 930,000 Subtotal 4,750,000 Comply with Regulatory Requirements 2 New Aeration Basins 4,440,000 (d) New Secondary Clarifier 2,700,000 (d) RAS/WAS Improvements 1,360,000 (d) Liquid Hypochlorite, Bisulfite 260,000 (d) Storage Pond Aeration 250,000 (d) Operations Building Improvements 150,000 (d) Odor Control Facilities 890,000 (d) Subtotal 10,050,000 Rehabilitation & Operations Improvements Headworks Improvements 260,000 Influent Screening 650,000 Septage Receiving Station 60,000 Clarifier Polymer Feed System 290,000 Control System Upgrades 319,700 Miscellaneous Operational Upgrades 140,300 Subtotal 1,720,000 Common Improvements Total 16,520,000 Value of Previously Deferred Components 4,390,000 (a) Treatment plant costs associated with individual alternatives not included in this table. rol All Costs shown include escalation to an ENR index of 7000, plus allowances for engineering, administration and contingencies. Component deleted from last plant expansion project. (d) Facilities required, in part, to restore capacity lost when operations were adjusted to nitrify ammonia in response to changes in discharge requirements. 9/18/00 Draft 11-68 Wastewater Master Plan 213\wwmp REFERENCES ' W.W. Eckenfelder, Jr. Industrial Water Pollution Control. Third Edition, McGraw-Hill, 2000. z Whitley Burchett and Associates. Granular -Media Filtration, Synthetic -Medium Filtration, and Microfiltration for Wastewater Reclamation: A Case Study. CWEA Annual Conference, April 2000. 9/18/00 Draft 11-69 Wastewater Master Plan 213\wwmp SECTION 12. ODOR CONTROL INTRODUCTION The current odor situation at the Lodi Plant was evaluated through site visits, assessment of existing data, and discussion with City staff. The plant receives relatively few formal odor complaints; however, many people are aware of the facility because of its visible location along the I-5 freeway. With increased development in the vicinity of the plant in the future, improved odor control will become necessary. OVERVIEW OF ODOR SOURCES Strong odors are emitted from the plant at times. Based on existing information, the factors listed below are the primary odor sources at the plant (in approximate order of importance/priority). Influent Sewers/Headworks Historical information indicates that both the domestic and industrial sewers contain high- strength odor at times which is released at the entrance to the plant and at the headworks facility. The industrial sewer has peak emissions during the canning season period, however, the domestic sewer has more consistently strong odor through most months of the year. Ventilation from the headworks emits influent odors directly to the atmosphere. Grit Washing and Storage In summer especially, the grit washing and loadout area is very odorous due to high sulfide and other reduced sulfur and nitrogen compounds. Primary Sedimentation Basins The primary sedimentation basins (PSBs) are odorous at areas where there is turbulence, i.e. inlet channels, outlet channels, and particularly at the drop weirs, but also at the scum drawoff points. The quiescent portion of the PSBs does not appear to have major odor emissions. The weir area has by far the greatest turbulence, and, therefore, the greatest odor emissions from the PSBs. Septage Discharge Significant peak odor events occur at the headworks and to some extent at the primary PSBs whenever a load of septage is discharged to the influent sewer. Grease Truck Unloading and Scum Sump Trucked grease is unloaded directly to this sump beside the PSBs and fed directly to the digesters. This unloading and sump operation creates a very strong localized odor, especially in the warmer months. 9/18/00 Draft 12-1 Wastewater Master Plan 213% wvmp Digesters There are, some odor emissions from the annular spaces on the two floating cover digesters and exposed sludge at overflow points. There can also be digester gas leaks at gas release valves or other gas leakage at times. Digester Gas Combustion Digester gas contains high-strength odorants, particularly hydrogen sulfide and other reduced sulfur compounds. Current hydrogen sulfide concentrations in the raw digester gas at Lodi are between 1,000 and 2,000 ppm. Therefore, any leakage of raw gas presents a serious odor emission. The sulfur compounds are largely oxidized to sulfur dioxide during combustion and sulfur dioxide also has a distinctive odor. Therefore, it is desirable to keep the hydrogen sulfide content in digester gas to a minimum. There are also corrosion and related problems when burning digester gas with high hydrogen sulfide content. New air emission rules require Lodi to burn only gas which has less than 200 ppm hydrogen sulfide. An iron sponge system was installed 10 years ago to extend the life of the boilers. However, if this unit is fed the current high concentrations, the media life in the iron sponge system is greatly shortened. Sludge Lagoon No. 2 Under most conditions, the lagoon is probably not a significant odor source at the plant. However, when it is being cleaned or sludge is being removed, it may present more of a problem. Dissolved Air Flotation Thickener (DAFT) The DAFT can be odorous at times, especially if fed waste activated sludge (WAS) that has gone septic due to short-term storage. DAFTs are best fed fresh WAS on a continuous basis to minimize odor emissions. Land Application Sites At certain times of the year and under certain conditions there can be significant odor from the wastewater application fields near the plant. Also, stabilized biosolids, when applied to the nearby agricultural fields, can be odorous if not applied and managed properly. Odors from land application of wastewater and biosolids are minimized through proper loading rates and operational practices as discussed previously in Sections 8, 9 and 10. Other sources at the plant are not considered major odor sources. However, under unusual conditions, the effluent ponds or other sources may be noticeable downwind. Once the primary odor sources at the plant are controlled, the remaining sources can be better evaluated to determine the extent of their impact and define further odor controls that could be required. The emphasis in this section is on controlling odor at the major sources—the influent sewers, headworks, trucked waste discharges, PSBs, and solids processing odors. The land application facilities and associated odor control needs were discussed in Sections 8 and 9. 9/18/00 Draft 12-2 Wastewater Master Plan 213\wwmp DRAFT WASTEWATER ODORANTS Most odorous wastewater substances can be categorized as reduced or partially -reduced compounds. Hydrogen sulfide (H2S), which is a common sewer and wastewater gas, is an inorganic reduced sulfur compound. Odorous organic reduced compounds include mercaptans and organic sulfides such as dimethyl sulfide. Other compounds, such as aldehydes, ketones, and carboxylic acids (all non -hazardous), usually come from industrial discharge or from the organics in domestic wastewater. In general, odorous compounds are the result of biological activity, such as anaerobic decomposition of organic matter containing sulfur and nitrogen. Aerobic decomposition or solids -processing which involves heating the sludge can contribute to the production of odorous compounds as well. Table 12-1 presents characteristics of common odorants at wastewater treatment plants. Table 12-1. Common Odorous Compounds in Wastewater Compound Name Formula Molecular Weight Volatility at 25°C, ppm (v/v) Detection Threshold, ppm (v/v) Recognition Threshold, ppm (v/v) Odor Description Acetaldehyde CH3CHO 44 Gas 0.067 0.21 Pungent, fruity Allyl mercaptan CH2:CHC H2SH 74 0.0001 0.00015 Disagreeable, garlic Ammonia NH3 17 Gas 17 37 Pungent, irritating Amyl mercaptan CH3(CHZ)4SH 104 0.0003 — Unpleasant, putrid Benzyl mercaptan C6HSCHZSH 124 0.0002 0.00026 Unpleasant, strong n -Butyl amine CH3(CH2)NH2 73 93,000 0.080 1.8 Sour, ammonia Chlorine C12 71 Gas 0.080 0.31 Pungent, suffociating Dibutyl amine (C4H9)2NH 129 8,000 0.016 — Fishy Diisopropyl amine (C3H7)2NH 101 0.13 0.38 Fishy Dimethyl amine (CH3)2NH 45 Gas 0.34 — Putrid, fishy Dimethyl sulfide (CH3)2S 62 830,000 0.001 0.001 1 Decayed cabbage Dyphenyl sulfide (C6H5)2S 186 100 0.0001 0.0021 Unpleasant Ethyl amine C2HSNH2 45 Gas 0.27 1.7 Ammonialike Ethyl mercaptan CZHSSH 62 710,000 0.0003 0.0001 Decayed cabbage Hydrogen sulfide 142S 34 Gas 0.0005 0.0047 Rotten eggs Indole C6H4(CH)2NH 117 360 0.0001 — Fecal, nauseating Methyl amine CH3NH2 31 Gas 4.7 — Putrid, fishy Methyl mercaptan CH3SH 48 Gas 0.0005 0.0010 Rotten cabbage Ozone 03 48 Gas 0.5 — Pungent irritating Phenyl mercaptan C6HSSH 110 2,000 0.0003 0.0015 Putrid, garlic Propyl mercaptan C3H7SH 76 220,000 0.0005 0.020 Unpleasant Pyridine C5HSN 79 27,000 0.66 0.74 Pungent, irritating Skatole C9H9N 131 200 0.001 0.050 Fecal, nauseating 9/18/00 Draft 12-3 Wastewater Master Plan 2131wwmp ' � 1 Compound Name Formula Volatility Molecular at 25°C, Weight ppm (v/v) Detection Threshold, ppm (v/v) Recognition Threshold, ppm (v/v) Odor Description Sulfur dioxide SO2 64 Gas 2.7 4.4 Pungent, irritating Thiocresol CH,C6H,SH 124 0.0001 — Skunky, irritating Trimethyl amine (CH3)3N 59 Gas 0.0004 — Pungent, fishy Source: Water Environment Federation, 1995 In general, the lower the molecular weight of the odorous compound, the higher its vapor pressure and its potential to transfer from the wastewater to the atmosphere. In theory, Henry's Law governs the mass transfer of odorous gases from the liquid phase to the gaseous phase. Henry's Law states that the partial pressure of the gas above liquid surface is directly proportional to the molecular concentration of the gas dissolved in liquid. In practice, wastewater pH and temperature, the rate of each odorant generation within a system, the turbulence of the wastewater stream, and air ventilation rate determine the odor concentration in the atmosphere. PLANT INFLUENT CHARACTERISTICS AND HEADWORKS SITUATION Considerable historical data are available on the plant influent characteristics. On the domestic sewer, BOD and SS are medium strength, but total sulfide concentration varies widely – from zero up to about 8 mg/L, with an average of about 4 mg/L (CDM, 1999). The plant influent pH can often be depressed below 7.0 (down to about 6.5 at times), particularly in long dry weather periods, indicating substantial anaerobic activity is occurring upstream in the interceptor system. Wastewater temperature is relatively warm in the spring through fall months (about 23 to 300C). These wastewater characteristics are conducive to high-strength odors, particularly reduced sulfur compounds. Gas phase hydrogen sulfide measurements from the influent domestic sewer are often between 2 and 20 ppm. Occasionally, hydrogen sulfide concentrations are probably well above this range. Corrosion of influent concrete pipe has been verified on the domestic sewer, and there is also evidence of concrete and metal corrosion within the headworks, particularly in or adjacent to the domestic influent channels. This corrosion is caused by sulfuric acid which forms when hydrogen sulfide is absorbed onto moist surfaces where microorganisms convert hydrogen sulfide to sulfuric acid. The industrial sewer has its peak flows during the canning and food processing seasons (late summer and early fall). The industrial flow at these times contains high BOD, causing anaerobic conditions in the industrial wastewater and production of large quantities of reduced sulfur compounds. At times, this sewer can create very strong odor emissions at and prior to the headworks. There are also critical worker safety considerations when dealing with influent flows having the above characteristics. Toxic gases can accumulate in these interceptor sewers because of inadvertent discharge of chemicals upstream in the collection system, hydrogen sulfide off - gassing from the wastewater (especially at low pH), or other cause. For this reason, ventilation of 9/18/00 Draft 12-4 Wastewater Master Plan 213\wwmp influent sewers and occupied headworks rooms (particularly below -grade rooms) becomes an important issue. The plant recently modified the ventilation in this area to prevent or greatly minimize toxic gas alarms in the headworks room. Ventilation of the inlet sewers just upstream of the headworks is now provided so that this sewer foul air is prevented from entering the headworks room (reported to be 2,000 cfm of ventilation). Headworks room ventilation was increased to 7,000 cfin, with an air supply fan providing this amount of fresh supply air, and two exhaust fans at 3,500 cfm each removing foul air from the room. The exhaust fans discharge the foul air directly to atmosphere above the headworks room. This modification has improved the atmosphere in the headworks room. CHEMICAL ADDITION The plant currently utilizes no chemical addition to the influent trunk sewer to help control odor or corrosion. Using chemicals for this purpose is now a common practice at California wastewater treatment plants, and is normally cost-effective for plants with relatively high influent sulfide levels. The three most commonly used chemicals are hydrogen peroxide, sodium hypochlorite, and iron chloride. Masking agents are sometimes considered for odor control, but are generally not as effective as oxidants or sulfide binding chemicals. The plant also does not utilize iron addition to digesters for control of hydrogen sulfide in the digester gas. Iron chloride addition is regarded as the most cost-effective method to control this problem. Alternatives Hydrogen Peroxide. Hydrogen peroxide is a very effective and powerful oxidant. An advantage of hydrogen peroxide is that it decomposes into oxygen and water, thus providing dissolved oxygen to help with further prevention of septic conditions. About 15 minutes of contact time is required to achieve the full oxidizing effect of hydrogen peroxide. Since hydrogen peroxide will react with various organic material, the dosage required is greater than the dosage indicated by stoichiometric oxidation of sulfide. In general, hydrogen peroxide to sulfide weight ratios of 2:1 to 6:1 are often required. Hydrogen peroxide typically comes in 50 percent solutions, however, it can produce a highly exothermic reaction at that concentration if accidentally catalyzed. Thirty-five percent solutions are also available, which may be helpful in meeting fire prevention requirements. Sodium Hypochlorite. Sodium hypochlorite (NaOCI) is also a very powerful oxidant. It acts essentially the same as adding chlorine to wastewater, except that it is considerably safer to deal with than chlorine gas. Sodium hypochlorite is typically delivered in about 13 percent liquid solutions and is relatively easy to handle compared with most chemicals. The chemical reacts almost instantaneously with dissolved sulfide, oxidizing it to sulfate and to elemental sulfur. Sodium hypochlorite also has good performance in oxidizing organic sulfur compounds. NaOCI often requires larger on-site storage tanks than other chemical options because of its relatively low chemical content (i.e., 13 percent). Good mixing of the chemical and the wastewater at the point of injection is important. Dosage ratios by weight (NaOCI to sulfide) are usually between 4:1 and 8:1 for situations similar to the one at Lodi. 9/18/00 Draft 12-5 Wastewater Master Plan 2I3\wwmp Iron Chloride. Iron addition (either ferrous chloride or ferric chloride) at or upstream from the plant headworks could help solve multiple problems at the Lodi plant. The practice of adding iron chloride to upstream sewers to help control both influent plant sulfide as well as digester gas hydrogen sulfide is well proven. This is the basic method practiced by the Los Angeles County Sanitation Districts, as well as plants in Omaha, Nebraska, Wichita, Kansas, Phoenix, Arizona and many others. The precipitation reaction of iron (Fe) with sulfide (S) takes about 15 to 20 minutes for full effect, and, therefore, maximum effectiveness is achieved at the plant headworks by adding the chemical at least this far (about %2 mile) upstream. There are three major possibilities for the location of iron chloride feed to the system. These are described briefly as follows: 1. Direct addition to digesters. If the only problem to be solved is digester gas hydrogen sulfide control, iron can be added direct to each digester, or possibly to the sludge feed lines. This will require the least dosage rate, and would typically control digester gas hydrogen sulfide down to less than 500 ppm, and probably in the 200 to 300 ppm range, cost-effectively. 2. Iron addition at headworks. Often a more convenient location for iron feed is the headworks rather than into the digesters or sludge piping. The dosage rate may increase slightly because some sulfide in the liquid wastewater will be treated in addition to the primary goal of treating the sulfide in the thickened sludge in the digesters. The iron becomes part of the primary sludge and proceeds to the digester to control sulfide. The chloride becomes part of the effluent to the plant (adds about 20 mg/L of chloride to plant effluent). 3. Iron addition upstream (minimum 20 minutes upstream). This approach treats sulfide in influent wastewater, and, assuming the dosage is sufficient, provides iron in the primary sludge which controls sulfide in the digesters. This approach provides reduction of hydrogen sulfide and odor levels at the plant headworks and PSBs as well as digester sulfide control. Dosage rate is higher because the entire domestic flow stream is treated by the iron in this case. This approach also adds more chloride to the plant effluent. A typical dose for digester gas hydrogen sulfide control would be about 8 mg/L as FeC13. Additional dosage to control plant influent dissolved sulfide on an annual average basis is probably about 8 to 12 mg/L as FeC13. Assuming an influent average combined dose of 18 mg/L at 8.5 mgd flow rate, and a cost of 15 cents per pound of FeC13 (dry weight), the cost of the chemical is estimated to be $65,000 per year. This cost is associated with adding iron per location No. 3 identified above. Evaluation of Chemical Addition Alternatives The advantages, disadvantages, and costs of the chemical addition alternatives are summarized in Table 12-2. Hydrogen peroxide performs well and has been gaining popularity for preventing sulfide and odor generation in sewer trunk lines. Hydrogen peroxide is less costly than sodium 9/18/00 Draft 12-6 Wastewater Master Plan 213\wwmp II ' hypochlorite. Iron chloride is the lowest cost alternative and has the added benefit of reducing hydrogen sulfide in digester gas. Table 12-2. Odor Control Alternatives Summary A disadvantage of adding iron chloride is that it destroys alkalinity. Both FeC12 and FeC13 solutions typically have pH of 1 to 1.5 due to strong hydrochloric acid content. Since the Lodi plant already has problems at times with low alkalinity and low effluent pH, adding iron chloride could make this problem somewhat worse. Overall, Iron Chloride is the recommended chemical addition alternative. Pilot testing should be performed to insure that alkalinity is not decreased below an acceptable level. SEPTAGE HANDLING Current direct discharge of septage from trucks to the influent flow makes successful odor control difficult at the plant's front-end processes (headworks and PSBs). As was previously discussed in Section 11, a better arrangement would be to store the septage in tank(s) and discharge the flow to the plant influent over the course of each day, or at least several hours of the day. Septage storage tanks can be designed in a variety of ways to limit odor production and odor emissions. The tanks would be contained and foul air withdrawn from them for treatment. HEADWORKS AREA FOUL AIR CONTAINMENT The above-described chemical addition system using iron chloride (at location No. 3) will reduce hydrogen sulfide concentrations in the headworks area, but will not eliminate the need for foul air collection and treatment. Several specific sources need to be contained in the headworks area as described below. Influent Sewers The existing arrangement of ventilation at the influent box/channels is the correct approach. At this time, we believe about 2,000 cfm should be adequate to remove the foul air from the influent 9/18/00 Draft 12-7 Wastewater Master Plan 2131wwmp Capital Annual Process Alternatives �a� Advantages _ Disadvantages Cost(,), dollars O&M Cost, dollars Chemical Sodium High performance High dose needed, high 210,000 125,000 Addition hypochlorite cost for Odor Hydrogen High performance if High dose needed, high 180,000 115,000 Control peroxide added 30 minutes cost upstream Iron chloride Treats inlet sulfide Hazardous material 160,000 65,000 and digester gas HzS (pH<2), reduces wastewater alkalinity A disadvantage of adding iron chloride is that it destroys alkalinity. Both FeC12 and FeC13 solutions typically have pH of 1 to 1.5 due to strong hydrochloric acid content. Since the Lodi plant already has problems at times with low alkalinity and low effluent pH, adding iron chloride could make this problem somewhat worse. Overall, Iron Chloride is the recommended chemical addition alternative. Pilot testing should be performed to insure that alkalinity is not decreased below an acceptable level. SEPTAGE HANDLING Current direct discharge of septage from trucks to the influent flow makes successful odor control difficult at the plant's front-end processes (headworks and PSBs). As was previously discussed in Section 11, a better arrangement would be to store the septage in tank(s) and discharge the flow to the plant influent over the course of each day, or at least several hours of the day. Septage storage tanks can be designed in a variety of ways to limit odor production and odor emissions. The tanks would be contained and foul air withdrawn from them for treatment. HEADWORKS AREA FOUL AIR CONTAINMENT The above-described chemical addition system using iron chloride (at location No. 3) will reduce hydrogen sulfide concentrations in the headworks area, but will not eliminate the need for foul air collection and treatment. Several specific sources need to be contained in the headworks area as described below. Influent Sewers The existing arrangement of ventilation at the influent box/channels is the correct approach. At this time, we believe about 2,000 cfm should be adequate to remove the foul air from the influent 9/18/00 Draft 12-7 Wastewater Master Plan 2131wwmp sewers and prevent the escape of this foul air. This foul air withdrawal rate should keep influent sewers under slight negative pressure. Septage Receiving As discussed previously in Section 11, an improved septage receiving (and possible storage) structure with bar screen and washdown pad is envisioned for the future. Foul air should be withdrawn from this receiving structure (and storage tanks, if provided) to insure that most odorants are trapped and not released directly to the atmosphere. The foul air flow rate is estimated to be 500 cfm for the structure itself, and perhaps 1,500 cfm if storage tanks are included. Headworks Room This room has, and will continue to have, substantial odor sources, especially with a new screening facility located here. Such a below -grade room should be ventilated with at least 20 air changes per hour and the newly revised ventilation system in this room may meet this criterion. A more detailed evaluation of the ventilation in this room should be undertaken to determine if fresh air supply is reaching all primary work areas. Foul air withdrawal may be improved with new intakes located low, near the floor level. The room should be kept under slightly negative pressure to prevent out -leakage of foul air. The current foul air flow rate of 7,000 cfm is assumed to be adequate at the present time. The detritus/grit tank system is also located in this room, as well as the wet wells for influent pumping of both the industrial and domestic influent streams. Grit Washing and Grit Storage/Loadout These sources are sufficiently odorous, especially in summer months, that foul air containment and treatment is necessary. The grit washing equipment can be mostly contained so that foul air is captured for treatment. Likewise, grit storage bins can be covered and flexible duct connections made to such covers for foul air withdrawal. A foul air flow rate of 2,000 cfin is estimated at this time to be required from these sources. In the future, the grit storage/loadout could include dewatered screenings as well, which would bring additional odorous material to this system. Scum/Grease Sump This sump can be covered rather easily, although corrosion protection for the walls may also be necessary. Foul air withdrawal is estimated to be 500 cfm. A connection port is needed to allow grease discharge from trucks to this sump. The above foul air sources should be combined with ductwork and fan(s) for one foul air treatment system. The combined system is desirable so that peak emissions from each source will be diluted by other sources, thus minimizing the peak impact of any given source. The elements of the foul airstreams are listed in Table 12-2 along with estimated hydrogen sulfide concentrations. Two scenarios are provided: the first set of columns shows expected concentrations if no iron is fed at upstream locations; and the second set of columns showing expected concentrations if iron is fed at least 20 minutes upstream of the headworks. The differences show that there is some advantage from upstream chemical feed as far as headworks 9/18/00 Draft 12-8 Wastewater Master Plan 2131wwmp odor is concerned—this difference could be important concerning the degree of foul air treatment required on this combined airstream. Another primary benefit of upstream iron addition is reduced PSB weir emissions. Prior to actual implementation of this system, a more detailed examination of required airflow rates and characteristics of the foul air should be confirmed through on-site tests. FOUL AIR TREATMENT FOR HEADWORKS AREA SOURCES The combined foul air from the sources (Table 12-3) is a relatively typical foul airstream from headworks-type sources at wastewater plants. There could be significant hydrogen sulfide peaks (as indicated in the table), but also peaks that would contain significant odor strength from organic compounds associated with raw wastewater, septage, grease/scum, and septic food processing wastes. The three most common methods of foul air treatment for this type of foul air are packed bed wet scrubbers, activated carbon adsorption, and bulk media biofiltration. Table 12-3. Estimated Foul Air Characteristics (Headworks and Related Sources) Foul Air Source Estimated Foul Air Flow Rate, cfm No Iron Addition UPS am With Iron Addition . Upstream Ave H2S, ppm peak H2S, ppm Ave H2S, eak H2S, ppm ppm 1. Influent Sewer Box and Channels 2,000 4 40 2 25 2. Septage Discharge (and possible storage tanks) 500 to 1,500 0.1 10 0.1 10 3. - Headworks Room 7,000 0.5 5 0.3 2 4. Grit Washing and Loadout 2,000 0.2 5 0.1 2 5. Scum/Grease Sump 500 1 50 1 50 Total and Composites 2,000 to 13,0001 1 1 10(a) 0.6 6(a) (a) Composites for peak H2S not strictly mathematical. EVALUATION OF FOUL AIR TREATMENT ALTERNATIVES The costs and subjective considerations for the foul air treatment alternatives are summarized in Table 12-4. We believe packed bed wet scrubbers should be eliminated at the outset as they are the highest cost method and have questionable performance on foul air with the characteristics identified. The other two options – activated carbon adsorption and bulk media biofiltration – can both provide a high level of treatment and their overall costs are quite similar. The main difference between these two methods is space requirements. Required space for a biofilter is shown to be 4,000 to 5,000 square feet for the sources identified here. In actuality, more space than this should be set aside for long-term foul air treatment needs, since the foul air system may need to be expanded in the future with new or different headworks facilities and additional 9/18/00 Draft 12-9 Wastewater Master Plan 2131wwmp sources in this area that may, with time, need to be treated. Probably 7,000 to 10,000 square feet should be set aside for eventual biofiltration treatment facilities. When sufficient space is not available near the headworks, then implementation of activated carbon is likely to be more attractive. Both of these two methods (carbon and bulk media biofilters) would have better odor control performance and slightly reduced operating costs with the option of iron chloride fed upstream, rather than iron chloride fed at the headworks. Based on the planned facilities layout (Section 11, Figure 11-4), there is sufficient room for bulk media biofilters to the west of the digesters. Therefore biofilters are the recommended alternative for foul air treatment. A new foul air ductwork and fan system will be required to transport these foul airstreams to the treatment system. The costs for this system are not included in the costs shown in Table 12-4 because they are common to all alternatives. Total system costs are included in Section 13. Table 12-4. Advantages and Disadvantages of Foul Air Treatment Options (Lodi Headworks System) Optional System with Costs(') Advantages Disadvantages Packed Bed Wet Scrubbing • Common technology • Organic pollutant removal is (w/ NaOH and NaOCl . Small footprint poor chemicals) • Can handle particulates easily • Relatively high labor needs Capital Cost = $460,000 • Handles rapid increase in H,S • Residual bleach odor downwind O&M Cost = $50,000/yr. concentration at times • Chemicals need special handling Activated Carbon Adsorption • Common technology • Carbon regeneration or Capital Cost = $560,000 • Small footprint replacement can be complicated O&M Cost= $40,000/yr. • Organic odorants and HZS • Spent carbon disposal can be removal problem . Simple operation under normal . Higher gas pressure needed conditions • Carbon can be used rapidly at • Also helps to control VOC high pollutant concentrations emissions • Filters required to eliminate particulates in foul air Bulk Media Biofiltration . Biological technology more Large footprint (4,000 to 5,000 Capital Cost = $480,000 operator -friendly ft' minimum) 0&M Cost = $35,000/yr. • Requires no chemicals, • Little ability for process control normally Media replacement likely every . Treats wide variety of odorants 4 to 5 years • Also controls some VOCs Filters required to eliminate particulates in foul air • Relatively high gas pressure required with monitoring Capital costs shown include 20% for engineering and 40% contingency. Headworks, ductwork, and fan system costs (not shown) are estimated at $60,000. 9/18/00 Draft 12-10 Wastewater Master Plan 213\wwmp SUMMARY OF ODOR CONTROL RECOMMENDATIONS The odor control alternatives evaluated are summarized in Table 12-5. Recommended improvements are summarized in Table 12-6. Table 12-5. Odor Control Alternatives Summary Process Alternatives t'� Advantages Disadvantages Capital Cost'?, dollars Annual O&M Cost, dollars Chemical Sodium High performance High dose needed, high 210,000 125,000 Addition hypochlorite Improve foul air capture and cost sources. ventilation. Treat foul air using for Odor Hydrogen High performance if High dose needed, high 180,000 115,000 Control peroxide added 30 minutes cost upstream Iron chloride Treats inlet sulfide Hazardous material 160,000 65,000 and digester gas H2S (pH<2), reduces wastewater alkalinity Headworks Chemical Common technology, Chemical handling 460,000 50,000 Foul Air scrubbing small footprint Treatment Carbon Single operation, Carbon can be used up 560,000 40,000 adsorption small footprint rapidly with strong odor Bulk media Technology is Space requirements 480,000 35,000 biofiltration operator -friendly (') Alternatives shown in bold are recommended. (t) Includes 20% for engineering and 40% contingency. Table 12-6. Recommended Improvements Process Deficiencies Recommend Improvements Headworks and High gas -phase H2S causing odor/corrosion at Add iron chloride to upstream Digesters headworks. Digester gas H2S must meet air sewer(s). permit limits. Headworks and Strong odor impacts offsite from these odor Improve foul air capture and Related Units sources. ventilation. Treat foul air using bulk media biofiltration. 9/18/00 Draft 12-11 Wastewater Master Plan 2131wwmp DRAFT SECTION 13. EVALUATION OF COMBINED TREATMENT AND DISPOSAUR.EUSE ALTERNATIVES DESCRIPTION OF ALTERNATIVES The combined treatment and disposal/reuse alternatives were described in detail in Section 5. Summary descriptions of the alternatives and their most significant unique components are listed in Table 13-1. Table 13-1. Unique Components of Major Alternatives Alternative Description Unique Components DC -D Discharge to Dredger Cut Tertiary Treatment 500 of Additional Storage Aggressive Source Control DC -W Discharge to Dredger Cut with wetlands Tertiary Treatment for polishing treatment and storage Wetlands 250 of Additional Storage BC -D Discharge to Bishop Cut through an Outfall Pipeline outfall pipeline Tertiary Treatment Source Control BC -W Discharge to Bishop Cut through an Outfall Wetlands outfall wetlands Tertiary Treatment BC -PD Partial discharge to Bishop Cut through Outfall Pipeline an outfall pipeline, partial percolation Source Control disposal Denitrification Percolation Basins/Fields BC -PW Partial discharge to Bishop Cut through Outfall Wetlands an outfall wetlands, partial percolation Denitrification disposal Percolation Basins/Fields LD Land discharge — complete effluent Percolation Basins/Fields disposal through percolation and Denitrification agricultural irrigation reuse EVALUATION OF ALTERNATIVES FOR DENITRIFICATION Three of the seven alternatives previously listed rely on percolation disposal or land application of treated effluent. These alternatives may require some level of effluent denitrification. This can be accomplished either using wetlands as was discussed in Section 7 or using conventional anoxic denitrification in the secondary biological treatment process as was discussed in 9/18/00 Draft 13-1 Wastewater Master Plan 2l3%wwmp DRAFT Section 11. Selecting a preferred denitrification alternative first simplifies the comparison of combined treatment and disposal/reuse alternatives in this section of the Master Plan. The costs of denitrification for the full 8.5 Mgd Master Plan flow are shown in Table 13-2. As discussed in Sections 7 and 10, to remove over 40 percent of the nitrogen from a fully nitrified effluent would require approximately 60 acres of wetlands. Conventional denitrification in the secondary biological process would require two additional tanks, baffles, recycle pumps, mixers, and miscellaneous related facilities. Conventional denitrification could easily achieve 40 percent nitrogen removal without an external source of carbon. Table 13-2. Comparison of Estimated Costs for Denitrification Alternatives Denitrification Method Capital Cost O&M Life Cycle Wetlands (60 ac) 1,800,000 110,000 3,000,000 Secondary Process 5,800,000 100,000 6,900,000 Wetlands are considerably more economical than conventional denitrification in the secondary biological process. Wetlands provide some additional benefits over conventional denitrification such as TSS removal, storage, temperature adjustment, and wildlife habitat. Based on the substantial cost differential and the other benefits, wetlands are clearly the preferred method for denitrification. COSTS OF COMBINED TREATMENT AND DISPOSAL/REUSE ALTERNATIVES Costs of Alternatives Cost estimates for the unique components of the major alternatives are shown in Table 13-3. Costs for additional recommended general improvements to the treatment and disposallreuse facilities which are common to all alternatives and which will be required are not included in Table 13-3 costs. These common costs were summarized previously Table 11-13. The costs of percolation basins shown in Table 13-3 are based on assuming that the basins could be relatively simple with low containment berms and only a few widely spaced underdrains for groundwater level control. There are a couple interesting comparisons evident in Table 13-3. First, a 40 -acre outfall wetlands to Bishop Cut would cost less than an outfall pipeline. A 60 -acre outfall wetlands would cost about the same as an outfall pipeline. Second, the cost of the additional effluent storage needed for the Dredger Cut discharge alternatives make those alternatives more expensive than the Bishop Cut discharge alternatives. The only practical method for reducing effluent concentrations of heavy metals for alternatives without wetlands is source control. The capital and 0&M costs shown in Table 13-3 for source 9/18/00 Draft 13-2 Wastewater Master Plan 2131wwmp Table 13-3. Costs for Unique Components of Major Alternatives Alternative Facility Capital Costs, $ Annual O&M, $ Life Cycle Cost, $ DC -D 500 of Storage 3,800,000 108,000 4,944,000 Source Control 500,000 100,000 1,559,000 Expanded Chlorine Contact Tank 1,070,000 10,000 1,176,000 Granular Media Filtration Facilities 11,910,000 392,000 16,063,000 Alternative DC -D Totals 17,280,000 610,000 23,742,000 DC -W 130 ac Wetlands 3,900,000 182,000 5,828,000 250 of Storage 1,900,000 54,000 2,472,000 Expanded Chlorine Contact Tank 1,070,000 10,000 1,176,000 Granular Media Filtration Facilities 11,910,000 392,000 16,063,000 Alternative DC -W Totals 18,780,000 638,000 25,539,000 BC -D 7500 ft Outfall (48") 2,080,000 24,000 2,334,000 Reaeration, Diffuser 1,100,000 66,000 1,799,000 Source Control 500,000 100,000 1,559,000 Expanded Chlorine Contact Tank 1,070,000 10,000 1,176,000 Granular Media Filtration Facilities 11,910,000 392,000 16,063,000 Alternative BC -D Totals 16,660,000 592,000 22,931,000 BC -W 100 ac Wetlands 3,000,000 150,000 4,589,000 Reaeration, Diffuser 1,200,000 66,000 1,899,000 Expanded Chlorine Contact Tank 1,070,000 10,000 1,176,000 Granular Media Filtration Facilities 11,910,000 392,000 16,063,000 Alternative BC -W Totals 17,180,000 618,000 23,727,000 BC -PD 7500 ft Outfall (42") 1,850,000 24,000 2,104,000 Reaeration, Diffuser 1,100,000 66,000 1,799,000 Source Control 500,000 100,000 1,559,000 260 ac Percolation 10,140,000 100,000 11,199,000 Denitrification Wetlands 40 ac 1,200,000 80,000 2,048,000 Alternative BC -PD Totals 14,790,000 370,000 18,709,000 BC -PW Denitrification Wetlands (40 ac) 1,200,000 80,000 2,048,000 Outfall Wetlands (60 ac) 1,800,000 90,000 2,753,000 Reaeration, Diffuser 1,100,000 66,000 1,799,000 260 ac Percolation 10,140,000 100,000 11,199,000 Alternative BC -PW Totals 14,240,000 336,000 17,799,000 LD 400 ac Percolation 15,600,000 180,000 17,507,000 Denitrification Wetlands 60 ac 1,800,000 100,000 2,859,000 Alternative LD Totals 17,400,000 280,000 20,366,000 Notes: 1. All costs are based on ENR 7000. 2. Wetlands and percolation disposal costs include estimated costs for purchasing farm land at $15,000/ac. for percolation areas and $6,000 per acre for all other areas. West Yost & Associates Lodi Wastewater Master Plan overallcst.xls yr2004totals 9/18/00 control of heavy metals, and the level of success such a program could have, are no more than a rough guess. A detailed source study would be required to determine where the heavy metals are coming from and what could be done to reduce the concentrations. Then more accurate cost estimates for source control could be developed. COSTS OF ALTERNATIVES WITH SPORTS COMPLEX The Sports Complex requires a 2.5 Mgd supply of tertiary treated effluent for irrigation. If the Sports Complex is constructed, it will also reduce the amount of land available for application of industrial effluent and biosolids to 490 acres. Since 700 acres of land is recommended for biosolids and industrial effluent (see Section 10), construction of the Sports Complex would leave a deficit of 210 acres. This deficit would need to be satisfied by the purchase of additional nearby land. For the purposes of this evaluation, it was assumed that the costs of 2.5 Mgd of tertiary treatment capacity and 210 additional irrigated acres would be borne by the Sports Complex project rather than be financed through sewer rates. The allocation of 2.5 Mgd out of the 10.0 Mgd of tertiary treatment capacity (filtration facilities and chlorine contact tank capacity) to the Sports Complex project cost results in a effective capital cost reduction of $4 million for alternatives DC -D, DC -W, BC -D, and BC -W. Having 2.5 Mgd of tertiary treated water which could be discharged during the winter rather than disposed of through percolation would reduce the required percolation areas by about 110 acres for alternatives BC -PD and BC -PW. This would reduce capital costs for alternatives BC -PD and BC -PW by approximately $4.4 million. Having tertiary treatment capacity available would not affect alternative LD (land discharge) since the same amount of percolation basins and fields would be required. The total capital, O&M, and life cycle costs for all the alternatives if the Sports Complex is constructed are shown in Table 13-4. Table 13-4. Costs of Major Alternatives Assuming Sports Complex Funds 2.5 Mgd Tertiary Treatment Capacity Alternative Capital Cost, million dollars Annual 0&M, million dollars Life Cycle Cost, million dollars DC -D 13.3 0.527 18.9 DC -W 14.8 0.555 20.7 BC -D 12.7 0.509 17.9 BC -W 13.2 0.535 18.9 BC -PD 8.4 0.360 11.8 BC -PW 10.1 0.306 13.3 LD 17.8 0.280 20.8 9/18/00 Draft 13-4 Wastewater Master Plan 213\wwmp DRAFT SUBJECTIVE CRITERIA The combined treatment and disposal/reuse alternatives were compared based on the subjective criteria presented in Section 6. The results of that evaluation are summarized in Table 13-5 and discussed in the following paragraphs. Compliance with Future Discharge Requirements Alternatives DC -D was not rated highly because there are potential problems with low dissolved oxygen and low dilution in Dredger Cut which may only be partially addressed by tertiary treatment and extra storage. In addition, algae regrowth in storage reservoirs will probably significantly increase the BOD and TSS of stored effluent beyond the anticipated limit of 10 mg/L. Alternative DC -W provides improved trace metals removal and prevents algae regrowth when compared to Alternative DC -D, and was therefore given a moderate ranking. Alternative BC -D would provide substantially increased dilution, although future discharge requirements related to trace toxins and temperature could still be problematic. Alternative BC -W is rated highly because of the dilution in Bishop Cut and the polishing treatment provided by the wetlands. Alternatives BC -PD and BC -PW would reliably meet future discharge requirements provided that there continues to be adequate dilution in Bishop Cut to avoid tertiary treatment for that portion of the effluent discharged to Bishop Cut. They were only given moderate ratings because of the potential for less dilution in Bishop Cut if the proposed CalFed Delta channel modifications are constructed. Alternative LD would greatly reduce the stringency and complexity of discharge requirements by eliminating discharge to surface waters. Reliability Alternative BC -D would be straightforward and predictable, resulting in a high reliability rating. Alternative BC -W would be nearly as good as BC -D, except that the wetlands could reduce the predictability of the effluent BOD and TSS. Alternatives BC -PD, BC -PW, and LD utilize simpler processes and therefore should be relatively reliable. Flexibility Alternatives DC -D and DC -W depend entirely on discharge to Dredger Cut with the accompanying most challenging discharge requirements. This results in relatively low flexibility ratings. Alternatives BC -D and BC -W depend upon discharge to Bishop Cut with easier discharge requirements, therefore, these were given moderate flexibility ratings. The other alternatives allow more flexibility in discharge location and level of treatment. Alternatives BC - PD and BC -PW would provide facilities for both discharge to Bishop Cut and percolation disposal, resulting in a high level of flexibility. Ease of Operation and Maintenance None of the alternatives are particularly difficult to operate. Wetlands operation and maintenance were discussed in Section 7. Percolation fields or basins would need to be disked on a regular basis to maintain high infiltration rates. Tertiary treatment would add some challenges in terms of operation and maintenance. 9/18/00 Draft 13-5 Wastewater Master Plan 2 ] 3\wwinp Table 13-5. Subjective Comparison of Alternatives Subjective Criteria Wei htin s Alternatives DC -13 I DC -W I BC -D BC -W BC -PD I BC -PW ZD Compliance with Future Discharge Requirements 1.5 1 2 3 4 3 3_ 5 Reliability 1.5 3 2 4 3 4 4 4 Flexibility 1.5 1_ 2 3 3 4 4 3 Ease of Operation and Maintenance 1 3 3 3 3 4 4 4 Ease of Implementation 1 4 3 3 3 3 3 2 Environmental Impacts 1 3 4 3 5 3 4 4 Safety 1 4 4 4 4 4 4 5 Open Space/Recreational Benefits 0.5 1 4 1 4 2 3 2 Aesthetics 0.5 3 5 3 5 3 4 2 Secondary Economic Benefits 0.5 1 2 1 2 1 2 1 Resource Management Considerations 0.5 1 41 41 41 41 2 31 2 Totals 28 35 32 40 33 38 34 Totals (weighted) 26 30.51 32.5 37.5 34.5 37.5 36.5 6/8/00 Draft West Yost Associates Lodi Wastewater Master Plan subjectivecomparison.xls Ease of Implementation Alternative LD would be considered difficult to implement rapidly because of the large additional land requirements and institutional considerations. Alternatives BC -PD, BC -PW, BC -W, and DC -W would require some additional land and therefore were only given moderate ratings. Environmental Impacts No significant adverse environmental impacts are anticipated with any of the alternatives. The wetlands alternatives (DC -W, BC -W, BC -PW) would actually provide additional positive environmental benefits. Safety All the alternatives are relatively safe. Alternative LD would involve the lowest use of chlorine and the least potential for accidents in the discharge waters. Open Space/Recreational Benefits The wetlands alternatives would provide substantial open space and recreational benefits in terms of bird and wildlife viewing. Aesthetics The wetlands alternatives would have excellent aesthetics. The land discharge alternative was rated moderately low because there would be a large continuous area with disked, bare fields and basins. Other alternatives had moderate ratings. Secondary Economic Benefits All of the alternatives would reduce secondary economic benefits compared with the current facilities because the amount of farmland in production in the area would be reduced. Construction of the Sports Complex would substantially increase secondary economic benefits, but the Sports Complex could be an adjunct to any of these alternatives. Resource Management Considerations Alternatives with tertiary treatment (DC -D, DC -W, BC -D, and BC -W) would provide the best potential for increased wastewater reclamation because the effluent could be for unrestricted agricultural or landscape irrigation. COMPARISON OF ALTERNATIVES A graphical comparison of the major alternatives is presented in Figure 13-1. The overall lowest cost alternative is BC -PW, closely followed by BC -PD and LD. The lower relative costs of these alternatives are primarily due to the lack of expensive tertiary treatment facilities. The reason that Alternative BC -PW is less costly than Alternative BC -PD is that the cost of a small outfall 9/18/00 Draft 13-7 Wastewater Master Plan 213\wwmp wetlands is lower than the cost of an outfall pipeline. Alternative BC -PW has a relatively high subjective rating compared with the other alternatives. The weakness of Alternative BC -PW is that future changes to the Delta channels could force the City to construct tertiary treatment for about 40 percent of the effluent flow or to convert entirely to the land discharge alternative. Constructing tertiary treatment facilities for 40% of the effluent flow would cost about $6 million. The transition to LD would result in the abandonment of approximately $2 million worth of f4cilities constructed for discharge to Bishop Cut plus cost an extra $5 million for more percolation basins. Alternative LD is very intriguing because it could greatly simplify future treatment and monitoring requirements. However, Alternative LD is also the most difficult alternative for which to estimate costs and performance. For example, the costs of percolation basins shown in Table 13-2 assume relatively basic basin construction with small containment berms. The costs of farm fields converted for dead level basin winter irrigation would be significantly less than the costs shown in Table 13-2, while the costs of conventional high rate rapid infiltration facilities would be slightly higher than those shown in Table 13-2. It may also be acceptable to have ammonia in the effluent if good nitrification and denitrification can be achieved in the percolation basins soil profile. This would eliminate the need for additional aeration basins and denitrification wetlands. The significant unknowns with Alternative LD are the availability of adequate land with highly permeable soil, the response of the water table, and the nitrogen removal performance. The 400 -acre estimated land requirement was based on the soils testing data and initial groundwater mounding calculations. Pilot testing and additional discussions with landowners are needed to adequately assess the actual costs and feasibility of Alternative LD. This can also be said for the percolation components of Alternatives BC -PD and BC -PW, although the smaller scale of these alternatives would make them easier to implement with less impact on the water table. Alternative BC -W has the highest subjective rating and a moderately high overall cost. If percolation disposal became too difficult to implement because of land acquisition or groundwater level control considerations, it would be the preferred alternative. Alternative BC -D is less expensive than BC -W, but not by enough to justify the loss of benefits from wetlands. The Dredger Cut discharge alternatives are relatively expensive to implement because of the need for additional storage. They also have relatively low subjective ratings because of the greater challenges in reliably meeting Year 2004 and future discharge requirements. RECOMMENDATIONS Based on current assumptions, and considering cost, Alternatives BC -PW and LD are the preferred alternatives. Selecting between these alternatives (and possibly other alternatives) would be dependent on performance of percolation disposal facilities and requirements for discharge to Bishop Cut. A stepwise approach is needed to arrive at the optimum wastewater treatment and disposal/reuse facilities. The recommended initial actions are as follows: 9/18/00 Draft 13-8 Wastewater Master Plan 213%wwmp LL O co 0 q CD M � o d o 3 co O C6 N O co N 0 N O O O O O O N et cc c0 C N N N S uoilliw';soo el*Ao a;i-I O O O O co co O N N N M N Q G I I N N � N ` v L F. L a` <. I • a� U) d p N y J p p a a U U U U U U p p O DO CO M M N -F ♦ ■ 4 X x • i I O O O O O O N et cc c0 C N N N S uoilliw';soo el*Ao a;i-I O O O O co co O N N N M DRAFT • Perform pilot testing of winter percolation disposal at full field scale during late 2000 and early 2001. • Submit an application to the Regional Water Quality Control Board for a new discharge permit for both discharge to Bishop Cut and winter percolation. This should help confirm whether or not the Master Plan assumptions for anticipated discharge requirements are correct. • Begin discussions with nearby landowners about purchasing or otherwise obtaining operating control of sufficient area for the LD or BC -PW alternatives. If the results of the percolation disposal pilot testing and discussions with landowners are positive, the cost comparisons of the LD and BC -PW alternatives should be updated. The City should then decide which of the two alternatives to pursue based on costs and land availability. If the results of the percolation disposal pilot testing and landowner discussions are negative, the City should pursue the BC -W alternative. The conceptual layouts for the BC -PW alternative is shown in Figure 13-2. Potential winter percolation areas for the BC -PW and LD alternatives were shown previously in Figure 10-1. The BC -W alternative was shown previously in Figure 7-2. Detailed facilities to accompany each preferred alternative along with other recommended general improvements are presented in Section 14. 9/18/00 Draft 13-10 Wastewater Master Plan 2131wwmp Boundary of Citp—Owned Land 0 1000 2000 Constructed Wetlands N SCALE IN FEET Percolation Disposal Area Figure 13- 2 City of Lodi Wastewater Master Plan Alternative BC - PW Conceptual Layout r' SECTION 14. RECOMMENDED WASTEWATER PROGRAM pending 7/10/00 Draft 14-1 Wastewater Master Plan 213\wwmp