Document Modesto_doc_35e2cd3217

March 2007 Wastewater Treatment Master Plan Update FINAL mo307mpCov1-6887.psd ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 i H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS Page No. GLOSSARY OF TERMS CHAPTER 1 – INTRODUCTION 1.1 PURPOSE AND SCOPE OF 1.2 WASTEWATER TREATMENT 1.2.1 Service Area and Treatment 1-1 1.2.2 Population Growth and Flow 1-4 1.2.3 Reliability of Existing Treatment Facilities 1-4 1.2.4 Treatment Capacity 1-4 1.2.5 Effluent Disposal 1-4 1.2.6 Future Discharge 1-5 1.3 GOALS AND OBJECTIVES CHAPTER 2 – WASTEWATER FLOW AND LOADS 2.1 2.2 SERVICE AREA DESCRIPTION 2.3 CURRENT SERVICE AREA AND 2.4 WASTEWATER TREATMENT PLANT FLOW 2.4.1 Cannery 2.4.2 Domestic Influent Flow 2.5 HISTORIC DOMESTIC WASTEWATER FLOW 2.5.1 Average Dry Weather 2.5.2 Average and Maximum Month Flows 2.5.3 Peak Dry Weather 2.5.4 Peak Wet Weather 2.6 HISTORIC WASTEWATER 2.6.1 BOD, TSS, and 2.6.2 Salinity 2.7 PROJECTED DOMESTIC WASTEWATER FLOWS AND LOADS 2.7.1 Projected 2.7.2 Projected Constituent CHAPTER 3 – EVALUATION OF EXISTING FACILITIES 3.1 3.2 EXISTING FACILITIES 3.2.1 Present 3-1 3.2.2 Sutter Avenue Primary Treatment 3-1 3.2.3 Cannery Process Water 3-8 3.2.4 Jennings Road Secondary Treatment 3-10 ---PAGE BREAK--- FINAL - March 2007 ii H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. 3.3 TREATMENT 3.3.1 Sutter Avenue Primary Treatment 3-17 3.3.2 Jennings Road Secondary Treatment 3-17 3.3.3 Effluent 3-19 3.4 UNIT PROCESS ASSESSMENT AND RATED CAPACITY 3.4.1 Sutter Avenue 3-21 3.4.2 Jennings Road Secondary Treatment 3-25 3.5 EFFLUENT DISPOSAL 3.6 SAN JOAQUIN RIVER FLOW 3.7 CONDITION ASSESSMENT SUMMARY CHAPTER 4 – REGULATORY REQUIREMENTS 4.1 4.2 WATER QUALITY REQUIREMENTS 4.2.1 Existing NPDES Permit 4-2 4.2.2 Waste Discharge Requirements for Land 4-11 4.2.3 Projected Regulatory 4-12 4.2.4 Compliance Strategy 4-15 4.3 LAND APPLICATION OF 4.3.1 Alternative Daily Cover 4-19 4.3.2 Landfill 4-20 4.4 AIR QUALITY REQUIREMENTS CHAPTER 5 – EVALUATION OF PRIMARY TREATMENT ALTERNATIVES 5.1 5.2 IDENTIFICATION OF PRIMARY TREATMENT IMPROVEMENTS 5.3 DEVELOPMENT OF REQUIRED COMMON IMPROVEMENTS 5.3.1 5-3 5.3.2 Primary Effluent 5-3 5.3.3 Primary Effluent Pump 5-5 5.3.4 Design 5-6 5.3.5 Conceptual Cost Estimate 5-6 5.4 DEVELOPMENT OF PRIMARY TREATMENT UPGRADE ALTERNATIVES 5.4.1 Alternative 1: Upgrade Primary Treatment Facilities at Sutter Avenue 5-8 5.4.2 Alternative 2: Relocate Primary Treatment Facilities to Jennings Road... 5-13 5.5 ALTERNATIVES SCREENING 5.5.1 Non-Economic 5-19 5.5.2 Cost 5-19 5.6 RECOMMENDED ALTERNATIVE FOR PRIMARY ---PAGE BREAK--- FINAL - March 2007 iii H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. CHAPTER 6 – EVALUATION OF DOMESTIC EFFLUENT DISPOSAL ALTERNATIVES 6.1 6.2 NEAR-TERM CAPACITY 6.3 DEVELOPMENT OF ALTERNATIVES FOR LONG-TERM CAPACITY 6.3.1 Long-Term Alternative 1: Land Disposal, Continued Seasonal Secondary Effluent Discharge, BNR/Tertiary Year-Round 6-3 6.3.2 Long-Term Alternative 2: Additional Land for Irrigation, Continued Seasonal Discharge of Secondary Effluent 6-3 6.3.3 Long-Term Alternative 3: Land Disposal, BNR/Tertiary Facilities for all River Discharges, 6-5 6.3.4 Long-Term Alternative 4: All Land Disposal (No River 6-5 6.4 ALTERNATIVES SCREENING 6.4.1 Non-Economic Factors 6-5 6.4.2 Cost 6-5 6.5 RECOMMENDED CHAPTER 7 – EVALUATION OF BNR/TERTIARY TREATMENT ALTERNATIVES 7.1 7.2 PLANNING 7.3 BNR/TERTIARY CAPACITY REQUIREMENTS 7.4 NEAR-TERM CAPACITY 7.5 IMPROVEMENTS TO THE EXISTING SECONDARY TREATMENT FACILITIES 7-5 7.5.1 Fixed Film Reactors 7-5 7.5.2 Dissolved Air Flotation (DAF) 7-5 7.5.3 Phase 1A Improvements 7-6 7.5.4 Secondary Effluent Chlorination Facilities 7-6 7.5.5 Flood Protection 7-7 7.5.6 Outfall 7-8 7.6 DEVELOPMENT OF BNR/TERTIARY 7.6.1 Alternative 1A - Conventional Activated Sludge, Media Filtration............... 7-8 7.6.2 Alternative 1B – Activated Sludge/Membrane Filtration (Membrane Bioreactor or 7-15 7.6.3 Alternative 2A - Nitrifying Trickling Filter, Media Filtration 7-20 7.6.4 Alternative 2B– Nitrifying Trickling Filters, Membrane Filtration 7-24 7.6.5 Alternative 3A – Conversion of Recirculation Channel, Media Filtration 7-24 7.6.6 Alternative 3B - Conversion of Recirculation Channel to Activated Sludge Process, Membrane 7-32 7.6.7 Tertiary Disinfection 7-32 ---PAGE BREAK--- FINAL - March 2007 iv H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. 7.7 BNR/TERTIARY ALTERNATIVES 7.7.1 Non-Economic 7-36 7.7.2 Cost 7-36 7.8 SELECTION OF APPARENT BEST CHAPTER 8 – STRATEGIC PLAN, RECOMMENDED PROJECT, AND IMPLEMENTATION PLAN 8.1 8.2 COMPLIANCE STRATEGY 8.2.1 Salinity and 8-1 8.2.2 Metals 8-5 8.3 TERTIARY TREATMENT FOR ALL RIVER DISCHARGES (FULL TERTIARY TREATMENT) 8.4 GROUNDWATER 8.5 RECOMMENDED 8.5.1 Sutter Avenue Primary Treatment Plant Improvements 8-7 8.5.2 Primary Effluent Pipeline (also referred to as 8-12 8.5.3 Jennings Road Secondary Treatment 8-13 8.5.4 Special Planning 8-15 8.5.5 Project Implementation 8-16 ---PAGE BREAK--- FINAL - March 2007 v H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) LIST OF APPENDICES A - July 27, 2006 Memorandum Prepared by the City That Describes Estimated Sewer Flow Projections B - Historical Influent Flows from January 2000 Through December 2005 at the Sutter Avenue Facility C - Technical Memorandum Summarizing the Findings from the Parshall Flume Investigation D - Water Quality Data E - Derivation of Allowable Effluent Discharge to River (without DAF) F - Pattern of the Mean Merced River Losses of Water Due to Diversions G - Pattern of Droughts H - Memo Summarizing the Condition-Assessment Site Visit I - Waste Discharge Requirements for Discharge to San Joaquin River (Order No. 5-01-120) J - Waste Discharge Requirements for Land Disposal (Order No. 99-112) K - November 2005 Study Entitled “Update of Modesto Ranch Salt Study” Prepared by EOA, Inc. L - Process Sizing Calculations for Alternative 1 M - Process Sizing Calculations for Alternative 2 N - Detailed Breakout Of The Cost Estimate For Each Alternative O - March 2006, Carollo Engineers Domestic Wastewater Near-Term Capacity Study P - Derivation of Land Cost Estimates Q - Feasibility Study for the DAF Project and Predicted DAF Effluent Quality R - Draft Alternative Disinfection Analysis, August 2005 S - City of Turlock Water Quality Control Facility UVT Test Results T - Condor Engineering Report ---PAGE BREAK--- FINAL - March 2007 vi H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. LIST OF TABLES Table 2.1 Service Area Table 2.2 Historical Cannery Segregation Flows Table 2.3 2005 Flow Table 2.4 Average Influent Flows to the Sutter Avenue Facility and Peaking Factors Table 2.5 Historical Influent Water Quality Characteristics Table 2.6 Influent Water Quality Characteristics – Salts Table 2.7 Projected Flows and Loadings Table 3.1 Design Criteria for Headworks Table 3.2 Design Criteria for Primary Treatment Table 3.3 Design Criteria for Primary Solids Handling Facilities Table 3.4 Design Criteria for Cannery Process Water Facilities Table 3.5 Design Criteria for Secondary Treatment Facilities Table 3.6 Design Criteria for Effluent Storage Table 3.7 Design Criteria for Effluent Disinfection Table 3.8 Design Criteria for River Discharge Facilities Table 3.9 Design Criteria for Ranch Irrigation Facilities Table 3.10 Effluent Limits and Historical Effluent Characteristics Table 3.11 Allowable Land Application Rates and Historical Values Table 3.12 Primary Clarifier Existing Table 3.13 Existing Secondary Treatment Facility Loadings/Criteria at 2030 Table 3.14 Current (2005) Effluent Disposal Capacity for Varying River Flow Table 4.1 Summary of Current NPDES Permit Effluent Limitations Table 4.2 Summary of NPDES Compliance Options Wastewater Facilities Strategic Master Plan Table 5.1 Preliminary Design Criteria for the Common Improvements Table 5.2 Conceptual Cost Estimate for Common Primary Treatment Table 5.3 Design Criteria for Sludge Dewatering at Sutter Avenue Primary Plant..........5-11 Table 5.4 Preliminary Unit Process Sizing for Primary Treatment Alternative 1 Table 5.5 Preliminary Unit Process Sizing for Primary Treatment Alternative 2 Table 5.6 Non-Economic Comparison of Primary Treatment Alternatives Table 5.7 Primary Treatment Alternatives Conceptual Cost Estimate Table 6.1 Alternatives to Provide Near Term Effluent Disposal Capacity Table 6.2 Non-Economic Comparison of Disposal Alternatives Table 6.3 Estimated Unit Prices Table 6.4 Required Additional Capacity at Buildout of SOI and Unincorporated Areas Currently Not Table 6.5 Annual Cost ---PAGE BREAK--- FINAL - March 2007 vii H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. LIST OF TABLES Table 7.1 BNR/Tertiary Treatment Capacity Requirements Table 7.2 BNR/Tertiary Alternatives -Required Unit Table 7.3 Design Criteria - Alternative 1A - Conventional Activated Sludge Table 7.4 Design Criteria for Alternative 1B – Conventional Activated Sludge/ Membrane Filtration (MBR) Table 7.5 Design Criteria for Alternative 2A - Nitrifying Trickling Filters/Media Table 7.6 Design Criteria for Alternative 2B - Nitrifying Trickling Filters/Membrane Table 7.7 Design Criteria for Alternative 3A – Recirculation Channel Media Table 7.8 Design Criteria for Alternative 3B – Recirculation Channel/Membrane Table 7.9 Disinfection Alternatives Conceptual Cost Table 7.10 Non-Economic Comparison of BNR/Tertiary Alternatives Table 7.11 Category of Cost Table 7.12 Cost Estimating Table 7.13 Estimated Capital Costs – Alternative 1 – Activated Sludge Table 7.14 Estimated Capital Costs – Alternative 2 – Nitrifying Trickling Table 7.15 Estimated Capital Costs – Alternative 3 – Recirculation Channel Table 7.16 Operations and Maintenance Cost Table 7.17 Cost Comparison of Alternatives for BNR/Tertiary Table 8.1 Strategic Plan Table 8.2 Wastewater Treatment Capital Table 8.3 Wastewater Treatment Capital Improvements Program ---PAGE BREAK--- FINAL - March 2007 viii H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. LIST OF FIGURES Figure 1.1 Wastewater Treatment Facilities Location Figure 1.2 Wastewater Treatment Facilities Schematic Figure 2.1 Service Figure 2.2 Projected Sewer Service Area Figure 2.3 Hourly Flow - June 8, Figure 2.4 Wastewater Flow Figure 2.5 Projected Influent Figure 3.1 Layout of Existing Facilities at the Sutter Avenue Facility Figure 3.2 Layout of Existing Facilities at the Jennings Road Facility Figure 3.3 Process Schematic for the Sutter Avenue Figure 3.4 Process Schematic for the Jennings Road Facility Figure 3.5 San Joaquin River Flows 1999 - Figure 3.6 Frequency-Distribution Plot for San Joaquin River Flows at Patterson...........3-29 Figure 3.7 Available Domestic Effluent Disposal Figure 3.8 Map of San Joaquin Valley Project Area and Figure 4.1 Dissolved Oxygen Model Figure 5.1 Capacity Life for Existing Flow-Related Treatment Processes at Sutter Avenue Primary Treatment Plant Figure 5.2 Primary Effluent Outfall Hydraulic Profile Figure 5.3 Primary Treatment Alternative 1 Conceptual Levee Construction at Sutter Avenue Figure 5.4 Conceptual Layout - Mechanical Sludge Figure 5.5 Typical Sections for Filled Areas Figure 5.6 Primary Treatment Alternative 1 Modifications to Sutter Avenue Facility........5-15 Figure 5.7 Primary Treatment Alternative 2 Proposed Modifications to Sutter Avenue Facility Figure 5.8 Primary Treatment Alternative 2 Propsed Primary Treatment and Solids Handling Facilities at Jennings Road Facility Figure 6.1 Effluent Disposal Alternative 1 - Continue Land Disposal/Seasonal Secondary Effluent Discharge, Add BNR/Tertiary for Year-Round Discharge Figure 6.2 Effluent Disposal Alternative 2 - More Land for Irrigation, Continue Seasonal Discharge of Secondary Figure 6.3 Effluent Disposal Alternative 3 - Continue Land Disposal of Secondary Effluent, BNR/Tertiary Treatment for All River Discharges Year Figure 6.4 Effluent Disposal Alternative 4 - Land Application Only (Zero Discharge) Figure 7.1 Domestic Wastewater Capacity Requirements Figure 7.2 Alternative 1A - Activated Sludge/Conventional Filtration Figure 7.3 Alternative 1A - Conventional Aeration/Media Filtration Proposed Improvements to Jennings Road Figure 7.4 Alternative 1B - Activated Sludge/Membrane Filtration ---PAGE BREAK--- FINAL - March 2007 ix H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\CovTOCFinalDraft.doc City of Modesto WASTEWATER MASTER PLAN PHASE 2 UPDATE MASTER PLAN REPORT TABLE OF CONTENTS (Continued) Page No. LIST OF FIGURES Figure 7.5 Alternative 1B - Activated Sludge/Membrane Filtration - Proposed Improvements to Jennings Road Facility Figure 7.6 Alternative 2A - Nitrifying Trickling Filters/Media Figure 7.7 Alternative 2A - Nitrifying Trickling Filter/Media Filtration Facilities Conceptual Layout Figure 7.8 Alternative 2B - Nitrifying Trickling Filters/Membrane Filtration Figure 7.9 Alternative 2B - Nitrifying Trickling Filter/Membrane Filtration Facilities Conceptual Layout Figure 7.10 Alternative 3A - Recirculation Channel/Media Figure 7.11 Conceptual Layout Alternative 3A - Recirculation Channel/Media Filtration Figure 7.12 Alternative 3B - Recirculation Channel/Membrane Filtration Figure 7.13 Conceptual Layout Alternative 3B - Recirculation Channel/Membrane Filtration Figure 8.1 Recommended Project - Recirculation Channel/Conventional Filtration Figure 8.2 Conceptual Layout - Recommended Project Sutter Avenue Facility Figure 8.3 Conceptual Layout - Recommended Project Jennings Road Facility Figure 8.4 BNR/Tertiary Treatment Phasing at Jennings Road Figure 8.5 Alternative Project Phasing at Jennings Road ---PAGE BREAK--- FINAL - March 2007 1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Glossary.doc City of Modesto GLOSSARY OF TERMS 10-Year, 24-Hour Storm Event: A 10-year, 24-hour storm event means the maximum 24-hour precipitation event with a probable recurrence interval of once in 10 years. 10TH PERCENTILE RIVER FLOWS: The lowest 10th percentile flows in the San Joaquin River based on historical records for Patterson. AAF: Annual Average Flow (average flow over 365 days). ACTIVATED SLUDGE: A secondary treatment process in which primary effluent is aerated to convert wastes to microorganisms, which are subsequently removed by secondary clarification. AMMF: Average day, maximum month (maximum average for the year). ADWF: Average Dry Weather Flow; is the average flow though the system during dry weather, which is defined as June through August. ANAEROBIC DIGESTION: Digestion of organic and inorganic matter in the absence of oxygen. By products of anaerobic digestion are methane and carbon dioxide gas. BAR SCREEN: A mechanism that removes debris and rags from raw wastewater. BNR/Tertiary Treatment: Biological Nutrient Removal and Tertiary Treatment. This is a two-phase process in which Nitrogen is removed, followed by additional filtration, and a high level of disinfection. BOD5: Five Day - Biochemical Oxygen Demand; is a widely used parameter for measuring organic pollution; BOD5 is a measurement of the oxygen demand of microorganisms used in the biochemical oxidation of organic matter. Measure by the amount of oxygen depleted in a sample after five days. Can Seg: Cannery Segregation Line, a separate line to isolate cannery process flows from domestic wastewater. CCTV: Closed Circuit Television Cameras that monitor sewer lines. CIP: Capital Improvement Program. CPD: Comprehensive Planning Districts. CTR: California Toxics Rule - limitations for metals and toxicity for discharges to inland surface waters. d/D: The maximum flow depth to pipe diameter ratio is the maximum ratio of depth of the water in the pipe to the diameter of the pipe. ---PAGE BREAK--- FINAL - March 2007 2 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Glossary.doc DAF: Dissolved Air Flotation. Used to separate particles from a liquid phase by using fine air bubbles to float the particles to the surface. Used to remove algae from treatment pond effluent. DHS: Department of Health Services. DISINFECTION: Disinfection of treated water before discharge to deactivate pathogens or organisms carried over from treatment process. ELECTIRCAL CONDUCTIVITY (EC): A measurement of concentrations of salt and other minerals. See TDS. FACULTATIVE PONDS: See oxidation ponds. FIRM CAPACITY: Maximum designed capacity of the system, with the largest unit out of service. FIXED FILM REACTOR: A biological reactor that employs a biological film or slime layer adhered to either a plastic or natural media. The purpose of the reactor is waste stabilization and the removal of organics. gpd: Gallons per day. gpm: Gallons per minute. GRIT REMOVAL: Removal of sand and similar debris before subsequent treatment. HEADWORKS: The facilities that provide influent pumping and preliminary treatment to remove large particles such as rags and grit. HYDRAULIC MODEL: Mathematical hydraulic model used to calculate flows and capacity of the collection system. PROFILE: Pressure profile in terms of feet and water. Jennings Road Secondary Treatment Facility. Also known as Secondary Plant. MEDIA FILTRATION: Use of sand or cloth to filter water. mgd: Million Gallons Per Day. MICRO FILTRATION: Use of membranes to filter water. MIXED LIQUOR: Contents of an aeration basin containing microorganisms that treat BOD. MMF: Maximum flow. NITRIFYING TRICKLING FILTER: Similar to a Fixed Film Reactor but used to remove ammonia nitrogen from secondary or tertiary effluent. ---PAGE BREAK--- FINAL - March 2007 3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Glossary.doc NPDES: National Pollutant Discharge Elimination System is a permit program enforced by the USEPA to limit pollution from point sources and non-point sources. O&M: Operations and Maintenance. OUTFALL or PARALLEL OUTFALL: The cannery process flow pipeline that conveys cannery process water to the land application site at the Secondary Plant. This outfall also conveys primary effluent to Jennings Road treatment facility, or from the Jennings Road facility to the San Joaquin River. OXIDATION PONDS: Stabilization ponds that may be aerated to supply oxygen in order to remove organic matter and settle solids. PARSHALL FLUME: An open channel flow meter. PDWF: Peak Dry Weather Flow; the maximum flow during dry weather conditions. PPP: Pollution precaution plan. PRIMARY CLARIFIER: A sedimentation process that settle out solids by gravity. PRIMARY EFFLUENT: Wastewater that has undergone primary treatment. PS: Pump station. PWWF: Peak Wet Weather Flow; the maximum flow during wet weather conditions. RECIRCULATION CHANNEL: Channel associated with the oxidation ponds, used to provide initial treatment prior to the oxidation ponds. RCP: Reinforced Concrete Pipe is concrete pipe with steel rebar added in the concrete to increase strength. RCP may be susceptible to corrosion. RO: Reverse osmosis (a membrane system to remove salinity and other minute constituents). ROWD: Report of Waste Discharge. A document submitted with NPDES to permit removal application. Regional Water Quality Control Board. SAPTF: Sutter Avenue Primary Treatment Facility. Also known as Primary Plant. SCADA: Supervisory Control and Data Acquisition; monitoring and control equipment within wastewater treatment plants and collection system (lift stations). SECONDARY CLARIFIERS: Basins that settle out secondary solids from aeration basins. SECONDARY EFFLUENT: Wastewater that has undergone secondary treatment. SECONDARY TREATMENT: A biological process to remove organic matter in wastewater. ---PAGE BREAK--- FINAL - March 2007 4 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Glossary.doc SIP: State Implementation Plan (metals and toxicity limitations in effluent discharged to inland surface waters). SOI: Sphere of Influence. SSO: Sanitary Sewer Overflows; exceedance of sewer collection system capacity. STORAGE PONDS: Ponds for storing treated wastewater. TDS: Totals dissolved solids. TMDL: Total maximum daily loads. TITLE 22: California regulations for recycled wastewater. TRUNK SEWER: Backbone sewer pipeline used for conveyance of sewer flows from smaller diameter collection mains. TSS: Total Suspended Solids - a measure of solid material contained in wastewaters. Main parameter in designing solids handling facilities. UV: Ultra violet radiation. Used for disinfection of wastewater effluent. VCP: Vitrified Clay Pipe. VSS: Volatile Suspended Solids - a measure of organic material inside an anaerobic digester. WCO: Water quality objectives. WDR: Waste Discharge Requirements - issued by the state to cover land disposal requirements. WLA: Waste load allocation. WWTP: Waste Water Treatment Plant. ---PAGE BREAK--- FINAL - March 2007 1-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\01.doc Chapter 1 INTRODUCTION 1.1 PURPOSE AND SCOPE OF PROJECT The Modesto wastewater master plan was last updated in 1995. The City commissioned the current update to address the following issues: • How much will the flows increase as the City’s sphere of influence (SOI) is fully developed by 2030, and what facilities are needed to accommodate the increased flows over the next 24 years? • What improvements to existing treatment facilities are required to improve reliability? • What is the current treatment capacity, and what facilities need to be expanded? • What are the effluent disposal constraints, and how should the City expand its effluent disposal capacity? • What will the future wastewater treatment requirements be and how should the City plan for meeting them? 1.2 WASTEWATER TREATMENT ISSUES 1.2.1 Service Area and Treatment Facilities The City of Modesto provides wastewater treatment service for residences, commercial businesses, and industry within the City boundaries, North Ceres, Empire, and isolated unincorporated county land (“islands”) dispersed within the city limits. The vast majority of wastewater generated within the service area receives primary and secondary treatment at two distinct treatment facilities. These wastewater flows are designated as “domestic” for the purpose of this report. The Sutter Avenue Primary Treatment Plant is located at south end of Sutter Avenue next to the Tuolumne River. The Jennings Road Secondary Treatment Plant is located next to the San Joaquin River (SJR), on Jennings Road near West Main Street. A 6.5-mile long outfall pipeline conveys primary-treated effluent from the Sutter Avenue plant to the Jennings Road plant. Secondary effluent from the Jennings Road Plant is either used for irrigation of 2,526 acres of City owned land, stored in reservoirs, or discharged to the SJR during the months of October through May. Seasonal cannery process water is conveyed separately to City owned land via the cannery segregation (“can seg”) pipeline where it is combined with secondary effluent and used for irrigation. A location map is provided in Figure 1.1. A schematic of the City’s wastewater treatment system is shown in Figure 1.2. ---PAGE BREAK--- mo606mpf34-6887.ai Figure 1.1 WASTEWATER TREATMENT FACILITIES LOCATION MAP WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Sutter Avenue Primary Treatment Plant “Can Seg” Pipeline Primary Effluent Outfall Jennings Road Secondary Treatment Plant 1-2 ---PAGE BREAK--- mo606mpf29-6887.ai Domestic Wastewater Primary Treatment (Sutter Ave) Secondary Treatment (Jennings Road) Beneficial Reuse at Modesto Ranch Discharge Season Oct. 1 - May 31 “Can Seg” Pipeline Primary Effluent Outfall Food Industry Process Water BNR Tertiary Storage Reservoirs San Joaquin River Figure 1.2 WASTEWATER TREATMENT FACILITIES SCHEMATIC WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 1-3 ---PAGE BREAK--- FINAL - March 2007 1-4 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\01.doc 1.2.2 Population Growth and Flow Projections Based on the City’s current growth projections, buildout of the City’s SOI is anticipated to occur by about 2030. By 2030, the sewer service area (SOI plus North Ceres) is anticipated to grow to a population of about 355,000. Average annual flows to the treatment facilities are projected to grow from a current flow of 25.8 million gallons per day (mgd) to 41.5 mgd. Segregated cannery process flows have averaged as high as 18 mgd over an approximate 90 day discharge season. Representative industrial dischargers have indicated a desire to have a future available capacity of 25 mgd. 1.2.3 Reliability of Existing Treatment Facilities The Sutter Avenue primary plant was first constructed in 1929, but some of the facilities that are now in operation were built in 1960. The facility has undergone several upgrades, the last of which occurred in 1998 to upgrade the headworks. Many of the treatment structures are over 40 years old. Some treatment structures will require rehabilitation or expansion to improve treatment reliability. The outfall pipeline is also over 35 years old, and is constructed of unlined, reinforced concrete. Its interior shows signs of severe corrosion. The pipeline also lacks sufficient capacity to convey peak flows to the Jennings Road secondary treatment facility. Rehabilitation of the pipeline will be required. The Jennings Road secondary plant was first constructed in the late 1960s and last upgraded in 1984. Some facilities will require rehabilitation to improve reliability. 1.2.4 Treatment Capacity The Sutter Avenue primary plant and the Jennings Road secondary plant have adequate treatment capacity to accommodate the projected growth until 2030. Whereas wastewater treatment capability is adequate, the Jennings Roads secondary plant is operating at its rated disposal capacity, depending on climatic conditions and flows in the San Joaquin River. 1.2.5 Effluent Disposal Limitations As previously stated, secondary-treated effluent from the Jennings Road plant is disposed of in two ways. The effluent is used for irrigation of the City’s 2,526 acres of ranch land, located next to the Jennings Road treatment facilities. The other method of disposal is to discharge secondary effluent to the San Joaquin River. Currently the City normally discharges about 60 percent of the secondary effluent to the ranch land and 40 percent to the river. The ranch land is used as pasture for dairy cows (heifers) and to grow fodder crops. The ranch is also used by the City to dispose of dried solids from the Sutter Avenue plant as well as for the application of segregated cannery process water. Land application is regulated by the Regional Water Quality Control Board (Regional Board) via Waste ---PAGE BREAK--- FINAL - March 2007 1-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\01.doc Discharge Regulations (WDRs). The WDRs limit the amount of flow that can be applied. The irrigation flow rate cannot exceed biochemical oxygen demand (BOD) loading limits and the flow cannot cause ponding of water on the ground. Weather also affects the irrigation rates, as it determines the evaporation-transpiration rate of the crops. River discharges are governed by the City’s National Pollutant Elimination System (NPDES) permit, which is also regulated by the Regional Board. Treated effluent must meet secondary treatment standards for BOD, suspended solids and pathogens. The permit allows only seasonal discharges to the river – from October through May. During the non-discharge months, the City stores excess effluent, not used for irrigation, in storage reservoirs. Additionally, the discharge flow is limited by the amount of river flow. A dilution ratio of 20:1 (river to effluent flow) must be maintained, based on daily average flow from the plant. River flows depend on rainfall and snow melt in the watershed, and how upstream dams are regulated by the state and federal agencies. River flows in four out of the last four years were at the lowest 10th percentile, which severely limited the volume of water that could be discharged to the river over the season. Adding to the complexity of issues that affect the City’s effluent discharge volume and treatment standards, there are competing uses for the water in the San Joaquin and its tributaries. The SJR water is primarily used for agriculture. Additional flow is expected to be released by upstream dams in the near future to support salmon runs. The river flow also contributes to the water supply for domestic use in the Delta. The municipal water users closely monitor water quality from treated effluent discharges because it can affect the drinking water quality. The City’s NPDES permit requirements could be influenced by municipal water agencies. The City’s current NPDES permit expires in 2006. At this time, the City has filed for a permit renewal, and the Regional Board is currently preparing the new permit. The Regional Board plans to issue a draft permit by the end of 2006. At that time, the draft permit will be circulated by the Regional Board to affected parties for comments, including water agencies. 1.2.6 Future Discharge Requirements Standards applicable for the land application of domestic and industrial wastewater are subject to increased scrutiny. In addition, it is anticipated that requirements applicable to river discharges will become more stringent in the future. The San Joaquin River has been designated an impaired water body, which triggers requirements for high levels of treatment. Water quality standards will also be established under the California State Implementation Plan and the California Toxics Rule. These regulations focus primarily on toxic constituents and metals concentrations. In addition, nitrate removal and tertiary treatment will likely be required in the future to comply with public health standards associated with drinking water supply. Disinfection byproducts from using chlorine are becoming a public health issue. ---PAGE BREAK--- FINAL - March 2007 1-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\01.doc Salt loadings to the San Joaquin are of concern. The State Water Resources Control Board and the Regional Board are preparing salt limits for dischargers to the river. The specific impacts to the City in the future are unknown at this time, but it is likely that some form of salt control (treatment or source control) will be required in the future. 1.3 GOALS AND OBJECTIVES The project goals were established as follows: • Provide a long-range plan that is flexible in meeting current treatment requirements and future regulations. • Develop a phased implementation plan. • Develop a cost-effective plan that considers total life cycle costs as well as capital costs. • Minimize ratepayer impacts and combined utility rates. ---PAGE BREAK--- FINAL - March 2007 2-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc Chapter 2 WASTEWATER FLOW AND LOADS 2.1 INTRODUCTION This chapter presents an analysis of wastewater flow and loading characteristics. Historical flow and loading data are presented, followed by a projection of the flows and loads projected at build-out. The flow and load projections will be used as the basis for the design criteria and cost analyses for wastewater improvements. The major topics discussed in this chapter are as follows: • Service Area Description. • Land Use Characteristics. • Current and Projected Population. • Wastewater Flow Components. • Historic Domestic Wastewater Flow. • Historic Domestic Wastewater Characteristics. • Projected Domestic Wastewater Flows and Loads. 2.2 SERVICE AREA DESCRIPTION The City’s wastewater service area includes wastewater flows from Modesto, Beard Industrial Area, northern Ceres, the unincorporated community of Empire and unincorporated County islands dispersed within the City limits. The service area, encompassing about 27,436 acres, is presented in Figure 2.1. Included in the total acreage are 1,066 acres for northern Ceres, 353 acres for Empire, 997 acres for unincorporated County islands, and 2,022 acres for the Beard Industrial Park. 2.3 CURRENT SERVICE AREA AND POPULATION Modesto is the largest incorporated city in Stanislaus County and accounts for approximately 42 percent of the County’s population (as of 2000). The build-out of the City’s Sphere Of Influence (SOI) is estimated to occur at about 2030 and was used as the basis of planning for this report. Appendix A includes a memorandum prepared by City staff that describes updated population projections that were used for this master plan. It should be noted the SOI study area presented herein encompasses an area somewhat less than that contained in the City’s General Plan Area. The difference in these planning areas is the result of the exclusion of the Salida and Beckwith/Dakota Comprehensive Planning Districts for the purpose of future sewer service area planning. ---PAGE BREAK--- Figure 2.1 SERVICE AREA WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO mo606mpm1-6887.ai 2-2 ---PAGE BREAK--- FINAL - March 2007 2-3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc Table 2.1 summarizes the current and projected population for the service area. Figure 2.2 is a plot of the projected population. Table 2.1 Service Area Population Wastewater Master Plan Phase 2 Update City of Modesto, California Year Estimated Sewer Service Population(1) 2000 201,100 2001 205,400 2002 211,100 2003 215,600 2004 218,500 2005 219,900 2010 236,800 2015 261,700 2020 290,800 2025 321,800 2030 355,000 Notes: From July 27, 2006 memorandum - William Wong (see Appendix A) rounded to the nearest 100. 2.4 WASTEWATER FLOW COMPONENTS The City’s system collects wastewater from residential, commercial and industrial sources. This section provides a description of these flows and also provides a summary of the flow-monitoring program that was conducted as part of the collection system master plan. 2.4.1 Cannery Segregation In 1999, the City constructed modifications to the wastewater collection system to separate cannery process flows from domestic flows. The cannery process flows are now routed through an existing outfall, now referred to as the cannery segregated, or “Can Seg” pipeline. The Can Seg line bypasses the Sutter Avenue plant and flows directly to ranch land adjacent to the Jennings Road Facility for land application. Table 2.2 summarizes cannery process flows segregated for land application. As shown, most recent equivalent annual average can seg flows have been on the order of 4 mgd. It is the premise of this master plan that the preferred long term approach is to continue segregation and direct land application of these process waters. However, detailed scientific studies are anticipated to be required to verify appropriate land application rates ---PAGE BREAK--- mo606mpf1-6887.ai Figure 2.2 PROJECTED SEWER SERVICE AREA POPULATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 2000 Includes city limits & sphere of influence & North Ceres. See Appendix 2A 150,000 200,000 250,000 300,000 350,000 400,000 2005 2010 2015 2020 2025 219,900 2030 2035 Year Population 355,000 2-4 Legend Past population Projected population ---PAGE BREAK--- FINAL - March 2007 2-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc Table 2.2 Historical Cannery Segregation Flows Wastewater Master Plan Phase 2 Update City of Modesto, California 2000 2001 2002 2003 2004 2005 Discharge Period, days 70 65 83 85 93 82 Total Annual Volume, MG 1,256 1,003 1,513 1,513 1,705 1,378 Average Day(1), mgd 17.9 15.4 18.2 17.8 18.3 16.8 Minimum Day, mgd 4.5 0.3 2.4 4.3 3.7 11.0 Maximum Day, mgd 23.5 22.2 24.8 22.6 25.1 21.1 Equivalent Annual Flow, mgd(2) 3.4 2.7 4.1 4.1 4.7 3.8 Notes: Average Day flow calculated pertains only to those days with measured flow. Total Annual Volume divided by 365 days. and methodologies. Pending the results of the evaluations, future equivalent annual average can seg flows of 4 mgd have been used for the purpose of this master plan. 2.4.2 Domestic Influent Flow All wastewater received at the treatment facilities from industrial, commercial, and residential sources exclusive of segregated cannery process flows are defined as “domestic” wastewater flows. historical domestic influent flows from January 2000 through December 2005 at the Sutter Avenue Facility were obtained from the flow records provided by the City. A summary of these data can be found in Appendix B. Flows during Modesto’s dry weather months for 2004 (June through September) are lower than the wet weather months. In part this is because the wet season typically contributes higher than normal sewer flows due to inflow and infiltration (I/I) following storm events. A hydraulic model of the existing collection system was developed as part of the collection system master plan. Two flow-monitoring programs were conducted to assist in the development of the design flow criteria, and to correlate actual collection system flows to the hydraulic model predicted flows. Flow monitoring and rain gauge data were used to calibrate the collection system hydraulic model for dry and wet weather flow. These data are included in the collection system master plan. 2.4.2.1 Parshall Flume Investigation Based on analysis of data collected during the dry weather flow-monitoring program (March 6 to June 11, 2004), the average dry weather flows (ADWF) influent to the Sutter Avenue Facility measured approximately 26.6 million gallons per day (mgd). During this period, the flows measured by the parshall flumes at the Sutter Avenue plant averaged ---PAGE BREAK--- FINAL - March 2007 2-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc approximately 21.8 mgd, which is approximately 18 percent or 4.8 mgd lower than the flows measured during the flow-monitoring program. Field calibration of the parshall flumes indicated that the flumes were underestimating the influent flow. The inaccuracies are believed to be caused by poor upstream flow conditions and deformations in the flume liner. A technical memorandum summarizing the findings from the parshall flume investigation is included in Appendix C. In late 2004 the City recalibrated the flumes to account for the metering errors. All 2005 data are corrected. influent flow data for 2005 are presented in Table 2.3. Table 2.3 2005 Flow Data(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Month Domestic Influent Flow, mgd Peaking Factor January 25.8 February 26.4 March 25.2 April 24.9 May 24.7 June 28.2 July 25.8 August 24.5 September 25.0 October 28.0 November 25.6 December 26.1 Average Annual Flow 25.8 Average Dry Weather Flow (ADWF)(2) 25.8 1.02 Average Dry Maximum Month Flow (ADMMF) 28.1 1.09 Notes: From corrected Influent meter at Sutter Avenue Primary Treatment Plant. June to August. 2.5 HISTORIC DOMESTIC WASTEWATER FLOW As explained in the previous section, the influent flow meter at the primary plant has been underestimating the actual influent flows. Therefore, the historical flow data collected prior to 2005 at the plant was not used directly for the flow and loads analysis. However, these data were used to determine peaking factors. ---PAGE BREAK--- FINAL - March 2007 2-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc 2.5.1 Average Dry Weather Flow The average dry weather flow (ADWF) is the average flow that occurs during the dry weather season (without infiltration/inflow from rainfall). For the purposes of this analysis, the dry weather season is defined as the months of June through September. 2.5.2 Average and Maximum Month Flows Using the historical data records obtained from the City, peaking factors were developed for the following flow conditions: annual average flow (AAF), average dry weather flow (ADWF) and average day maximum month flow (ADMMF). These values are presented in Table 2.4. Table 2.4 Average Influent Flows to the Sutter Avenue Facility and Peaking Factors(1) Wastewater Master Plan Phase 2 Update City of Modesto, California 2000 2001 2002 2003 2004 2005(4) Adopted Value AAF, mgd 24.8 25.5 24.3 22.9 22.8 25.8 - ADWF(2), mgd 24.1 25.0 24.2 22.1 23.0 26.2 - ADMMF(3), mgd 24.9 25.5 24.6 23.4 23.0 28.1 - ADWF Peaking Factor 0.97 0.98 1.00 0.97 1.0 10.2 1.02 ADMMF Peaking Factor 1.12 1.08 1.09 1.11 1.11 1.09 1.10 Notes: Because of the error associated with the influent flow monitoring at the Sutter Avenue Facility, values for 2000 to 2004 were only used to determine ratios. The values were not used to directly project flow. ADWF is defined as the average daily flow rate from June through August. ADMMF is defined as the highest average. Flows for 2005 have been corrected according to recalibrated flow mater. 2.5.3 Peak Dry Weather Flow Peak dry weather flow (PDWF) is the highest observed hourly flow that occurs during the dry weather season. Hourly flow records were used to estimate the peak hour flow during dry weather. Figure 2.3 is a plot of hourly flow for one day out of June 2005. The peak hour to average flow was approximately 1.4. Using the hydraulic model developed for the collection system master plan, the peaking factor was computed at 1.5. To be conservative, a peak hour to average peaking factor of 1.5 was adopted for this master plan. 2.5.4 Peak Wet Weather Flow Peak wet weather flow (PWWF) is the highest hourly flow that occurs during a rainfall event. The wet weather season typically lasts from October through May. ---PAGE BREAK--- Figure 2.3 HOURLY FLOW - JUNE 8, 2005 WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 0.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 2.00 4.00 6.00 8.00 10.00 Time Flow (mgd) 12.00 14.00 16.00 18.00 20.00 22.00 mo606mpf2-6887.ai 2-8 ---PAGE BREAK--- FINAL - March 2007 2-9 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc The City mitigates peak wet weather flows at the primary plant by pumping down the largest upstream interceptors to the treatment plant prior to a storm. This is accomplished by overriding automatic controls and pumping down levels in the wet well. This provides equalizing storage in the collection system that reduces the impact of peak flows. Therefore, peak flow rates measured at the primary plant are not necessarily representative of actual peak flow conditions. Accordingly, the hydraulic model developed for the collection system was used to estimate the PWWF. Based on these hydraulic calculations, the 2004 PWWF is estimated to be 71.7 mgd. 2.6 HISTORIC WASTEWATER CHARACTERISTICS This section presents the wastewater characteristics for the primary plant influent. 2.6.1 BOD, TSS, and Ammonia Using the historical water quality data provided by the City, annual average concentrations, average dry weather concentrations and average day maximum month concentrations were derived for each year for BOD, TSS, and ammonia. These values are presented in Table 2.5. Table 2.5 Historical Influent Water Quality Characteristics Wastewater Master Plan Phase 2 Update City of Modesto, California Concentration, mg/L Condition/Statistic 2000 2001 2002 2003 2004 Average BOD Average Annual 352 429 456 427 409 415 Maximum Month(1) 377 526 564 468 489 485 Peaking Factor 1.07 1.22 1.34 1.10 1.20 1.15 TSS Average Annual 354 393 323 286 290 329 Maximum Month 469 464 358 288 345 385 Peaking Factor(2) 1.32 1.18 1.11 1.00 1.19 1.19 Ammonia Average Annual 19 23 25 27 30 25 Maximum Month 33 26 29 37 36 32 Peaking Factor 1.74 1.13 1.16 1.37 1.20 1.28 Notes: Defined as the maximum average concentration in a given year. Ratio of Maximum Month to Average Annual. ---PAGE BREAK--- FINAL - March 2007 2-10 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc 2.6.2 Salinity Using the historical water quality data provided by the City, annual average, average dry weather and average day maximum month electrical conductivities were derived for each year. These values are presented in Table 2.6. Table 2.6 Influent Water Quality Characteristics – Salts Wastewater Master Plan Phase 2 Update City of Modesto, California Electrical Conductivity, µmhos/cm Condition/Statistic 2002 2003 2004 ADWF(1) 1,097 1,264 1,276 AAF 1,064 1,230 1,230 ADMMF(2) 1,209 1,534 1,369 Notes: Defined as the average conductivity from June through September. Defined as the maximum average conductivity in a given year. 2.7 PROJECTED DOMESTIC WASTEWATER FLOWS AND LOADS This section presents an estimate of the projected influent flows and loadings. 2.7.1 Projected Flow Flows were projected using a per capita flow of 117 gallons per capita per day (gpcd) as determined by City staff. Figure 2.4 is a plot of projected flows. 2.7.2 Projected Constituent Loadings The projected BOD, TSS, and ammonia loadings will determine the sizing of some of the treatment facilities such as the secondary processes and solids handling facilities. It is assumed that the water quality will not change significantly in the future and that future constituent concentrations will remain the same. Wastewater characteristics may be different if the current blend of residential, commercial, and industrial development changes in the future. The current and projected flows and loads are summarized in Table 2.7. Projected loadings are plotted in Figure 2.5. ---PAGE BREAK--- mo606mpf3-6887.ai - Peak wet weather flow (peak dry weather flow & infiltration/inflow) PWWF - Peak hourly flow in dry season PDWF - Maximum flow MMF - Average annual flow AAF Legend 2005 0 25 50 75 100 2010 2015 2020 2025 AAF 2030 Year Wastewater Flow, mgd Figure 2.4 WASTEWATER FLOW PROJECTION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO MMF PDWF PWWF 2-11 ---PAGE BREAK--- FINAL - March 2007 2-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\02.doc Table 2.7 Projected Flows and Loadings Wastewater Master Plan Phase 2 Update City of Modesto, California Year 2005 2010 2015 2020 2025 2030 Flows, mgd Annual Average Flow (AAF) 25.8 27.7 30.6 34.0 37.7 41.5 Average Dry Weather Flow (ADWF) Peaking Factor 1.02 1.02 1.02 1.02 1.02 1.02 ADWF 26.3 28.3 31.2 34.7 38.5 42.3 Maximum Month Flow (MMF) Peaking Factor 1.09 1.09 1.09 1.09 1.09 1.09 MMF 28.1 30.2 33.4 37.1 41.1 45.2 Peak Dry Weather Flow (PDWF) Peaking Factor 1.5 1.5 1.5 1.5 1.5 1.5 PDWF 38.7 41.6 45.9 51.0 56.6 62.3 Peak Wet Weather Flow (PWWF) Peaking Factor 2.77 2.7 2.6 2.5 2.4 2.30 PWWF 71.7 74.8 79.6 85.0 90.5 95.5 BOD Concentration, mg/L 415 415 415 415 415 415 Average Annual Loading, lbs/day 89,300 95,900 105,900 117,700 130,500 143,600 Peaking Factor 1.15 1.15 1.15 1.15 1.15 1.15 Maximum Month Loading, lbs/day 102,700 110,300 121,800 135,400 150,100 165,100 TSS Concentration, mg/L 329 329 329 329 329 329 Average Annual Loading, lbs/day 70,800 76,000 84,000 93,300 103,400 113,900 Peaking Factor 1.19 1.19 1.19 1.19 1.19 1.19 Maximum Month Loading, lbs/day 84,300 90,400 100,000 111,000 123,000 135,500 Ammonia Concentration, mg/L 25 25 25 25 25 25 Average Annual Loading, lbs/day 5,400 5,800 6,400 7,100 7,900 8,600 Peaking Factor 1.28 1.28 1.28 1.28 1.28 1.28 Maximum Month Loading, lbs/day 6,900 7,400 8,200 9,100 10,100 11,000 Electrical Conductivity, umhos/cm AAF 1,230 1,230 1,230 1,230 1,230 1,230 Peaking Factor 1.11 1.11 1.11 1.11 1.11 1.11 MMF 1,370 1,370 1,370 1,370 1,370 1,370 ---PAGE BREAK--- mo606mpf4-6887.ai Figure 2.5 PROJECTED INFLUENT LOADINGS WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 2005 0 25,000 50,000 100,000 75,000 125,000 150,000 2010 2015 2020 2025 2030 Year Loadings, lb/day TSS BOD Ammonia 2-13 ---PAGE BREAK--- FINAL - March 2007 3-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Chapter 3 EVALUATION OF EXISTING FACILITIES 3.1 INTRODUCTION The City operates two wastewater treatment facilities: the Sutter Avenue Primary Treatment Plant and the Jennings Road Secondary Treatment Plant Facility. The primary plant consists of preliminary screening, grit removal, primary clarifiers, anaerobic digesters, sludge drying beds, and other support facilities. Two 60-inch, gravity outfalls transport flow from the primary plant to the secondary plant. One pipeline is utilized for primary effluent and the second is used to convey segregated cannery process water as well as domestic flow during peak wet weather flow conditions. The secondary plant facility consists of fixed film reactors (FFRs), a recirculation channel, and facultative ponds for secondary treatment. Secondary effluent is either disinfected and discharged to the San Joaquin River or used beneficially to irrigate the City’s 2,526 acres of ranch land. Overviews of the Sutter Avenue and Jennings Road facilities are shown in Figures 3.1 and 3.2, respectively. This chapter provides an evaluation of the existing treatment facilities, including the following: • A description of the existing treatment units. • A summary of the existing treatment performance. • An assessment of the hydraulic and treatment capacities for each unit process. • An assessment of the existing effluent disposal capacity. 3.2 EXISTING FACILITIES 3.2.1 Present Operation Figures 3.3 and 3.4 show the process schematics for the existing Sutter Avenue and Jennings Road facilities, including the cannery segregation system. 3.2.2 Sutter Avenue Primary Treatment Plant 3.2.2.1 Headworks Facilities The headworks was constructed in 1998. The facilities include: • Four enclosed screw influent pumps. • Four climber-type mechanical bar screens. • Three vortex grit chambers. • Three Parshall flumes for influent flow metering. ---PAGE BREAK--- mo606mpm2-6887.cdr Anaerobic Digesters Primary Clarifier No. 2 Primary Clarifier No. 1 Primary Effluent Pump Station Sludge Thickening Facilities (Currently Not Used) Ferric Chloride Facility Figure 3.1 LAYOUT OF EXISTING FACILITIES SUTTER AVENUE FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Sludge Drying Beds Sludge Handling Building Pumping Plant No. 3 Approximate Scale 0’ 100’ Biofilters Headworks Control Building LEGEND Existing Facilities 3-2 ---PAGE BREAK--- Figure 3.2 LAYOUT OF EXISTING FACILITIES JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Fixed Film Reactor Feed Pump Station Fixed Film Reactors Irrigation Reservoir Mixing Box Irrigation Pump Station Approximate Scale 0’ 500’ mo606mpm3-6887.cdr Storage Pump Station Storage Pond No. 1 Storage Pond No. 2 Facultative Pond No. 3 Facultative Pond No. 2 Facultative Pond No. 1 Recirculation Channel Storage Forebay Chlorination Control Building Effluent Pump Station Chlorine Contact Tank Chlorine Contact Tank Forebay Storage Afterbay Irrigation Forebay LEGEND Existing Facilities 3-3 ---PAGE BREAK--- mo606mpf5-6887.cdr Figure 3.3 PROCESS SCHEMATIC SUTTER AVENUE FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Primary Effluent Pump Station Influent Pumps Bar Screens Grit Chambers Flow Metering Influent Wet Well From Collection System Domestic Wastewater Cannery Process Water Valve Gate Primary Clarifier No. 1 Primary Clarifier No. 2 To Jennings Road Facility From Collection System Pumping Plant No. 3 LEGEND 3-4 ---PAGE BREAK--- B B A mo606mpf6-6887.cdr Figure 3.4 PROCESS SCHEMATIC JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO FFR #1 FFR #2 FFR #3 ~ ~ ~ ~ FFR Pump Station Recirculation Channel Facultative Pond #1 Outfall Flowmeter Pit Primary Effluent From Sutter Avenue Facility FFR Mixing Box Oxidation Pond Inlet Box From FFR FFR Effluent Box Storage Pond #1 Storage Pond #2 Storage Forebay To Recirculation Channel Effluent Collector Effluent Pump Station Chlorine Contact Basin River Discharge Cannery Waste Pump Station Overflow Cannery Waste from Sutter Avenue Facility To Recirculation Channel Mixing Box Irrigation Reservoir Irrigation Forebay Irrigation Pump Station Storage Afterbay ~ ~ Chlorine Contact Basin Forebay From Irrigation Reservoir Facultative Pond #2 Facultative Pond #3 A To Land Application Domestic Wastewater Cannery Process Water Valve Pump Gate LEGEND Sludge Digestion Pits 3-5 ---PAGE BREAK--- FINAL - March 2007 3-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Wastewater flow enters the headworks and is pumped by three (plus one standby) enclosed screw pumps to the mechanically-cleaned bar screens. The bar screens remove rags, plastics, and other debris from the influent flow. Solids removed by the bar screens are conveyed to a screenings washer/compactor that removes some of the organic waste and reduces the moisture content. Washed and dewatered screenings are periodically taken to a nearby landfill for disposal. Screened wastewater flows through one of three vortex grit chambers, which provide grit separation to protect equipment from abrasion and to preserve digester capacity. A motor-driven impeller in each grit chamber causes organic matter to remain in suspension while grit accumulates in the bottom hopper of each chamber. The grit slurry is then pumped by recessed impeller type grit pumps and piped to four cyclone separators, which discharge the concentrated slurry into two grit classifiers for dewatering. The dewatered grit is deposited into a dumpster for landfill disposal. Design criteria for the existing headworks facilities are provided in Table 3.1. Table 3.1 Design Criteria for Headworks Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Influent Pump Station Number duty + standby 3 + 1 Type – Enclosed screw Flow capacity, each mgd 27 Horsepower, each hp 200 Year constructed 1998 Mechanical Bar Screens Number duty + standby 3 + 1 Type – Inclined climber Channel width, each ft 7 Year constructed 1998 Grit Chambers Number – 3 Type – Mechanical vortex Diameter, each ft 18 Parshall Flumes Year constructed 1998 Number – 3 Throat width, each Flume No. 1 ft 5 Flume No. 2 ft 5 Flume No. 3 ft 4 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.2.2 Primary Treatment Facilities The primary treatment facilities consist of two primary clarifiers and the effluent pump station. Effluent from the headworks enteres a distribution box where it may be split between two primary clarifiers. Flow is typically routed through a single clarifier because the hydraulic residence time in two clarifiers is excessive and can lead to odors from anaerobic conditions. The suspended solids that collect in the clarifiers are scraped into a sludge hopper and pumped to the primary solids handling facilities. Rotating skimming blades remove oil, grease and other floatables from the top of the clarifiers and deposit these into scum troughs. Scum is combined with primary sludge and pumped to the solids handling facilities. The primary effluent pump station pumps primary effluent from the primary clarifiers through the primary effluent outfall to the Jennings Road Facility for secondary treatment and disposal. Design criteria for the existing primary treatment facilities are provided in Table 3.2. Table 3.2 Design Criteria for Primary Treatment Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Primary Clarifiers Year constructed No. 1 1950’s No. 2 1960’s Number of basins – 2 Type – Circular Diameter, each ft 200 Depth, each ft 10 Primary Effluent Pump Station Year constructed 1960’s, modified in 1968 Number duty + standby 3 + 1 Type – Mixed flow propeller Capacity, each mgd 17.3 Horsepower, each hp 200 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-8 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.2.3 Primary Solids Handling Facilities The solids handling facilities at the Sutter Avenue Facility consist of the following: • Two primary anaerobic digesters (Digesters 1 and • A secondary anaerobic digester (Digester • Two uncovered digesters (Digesters 4 and 5) that serve to concentrate the digested sludge. • Sludge drying beds. The anaerobic digesters were designed to stabilize a large fraction of the volatile solids in the primary sludge. Sludge and scum from the primary clarifiers is pumped to either Digester 1 or 2. The primary digesters are equipped with three axial-flow mixing pumps, one of which is normally on standby. The primary digesters are also heated to maintain a temperature favorable for the growth of anaerobic microorganisms. Gas produced from the covered digesters is either used to fuel the boilers that heat the digester sludge, or diverted and flared in the waste gas burners. Sludge from the primary digesters is transferred to the secondary digester (Digester The overflow from Digester 3 is piped to uncovered Digesters 4 and 5 where the liquid is separated into digested sludge and liquid supernatant. Digested sludge is periodically pumped to the sludge drying beds for dewatering and the supernatant is returned to the headworks. There are 24 sludge drying beds at the Sutter Avenue Facility that are normally operated in the following manner: • Drying Bed No. 1 is for parking lot stormwater collection. • Drying Bed No. 2 is normally dedicated to the collection systems for vactor truck debris. • Drying Bed Nos. 3 through 10 are used for digester cleaning. • Drying Bed Nos. 11 through 24 are used for dewatering of primary digested sludge. Design criteria for the existing solids handling facilities at Sutter Avenue are provided in Table 3.3. 3.2.3 Cannery Process Water Facilities Cannery process water is diverted during the peak canning season into the wet well of Pumping Plant No. 3 at the Sutter Avenue Facility. Mechanically-cleaned bar screens remove large debris from the cannery flow before it is pumped into a 42-inch force main that runs along the east and south sides of the Sutter Avenue Facility before discharging into the cannery segregation outfall. ---PAGE BREAK--- FINAL - March 2007 3-9 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.3 Design Criteria for Primary Solids Handling Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Anaerobic Digesters Year constructed 1960’s Number – 5 Type Digesters 1, 2, and 3 – Fixed cover Digesters 4 and 5 – Uncovered Diameter Digesters 1 and 2 ft 104 Digester 3 ft 90 Digesters 4 and 5 ft 60 Depth Digesters 1 and 2 ft 32 Digester 3 ft 30 Digester 4 ft 22 Digester 5 ft 19.5 Sludge Drying Beds Year constructed 1960’s Number – 24 Surface area, total acres 21.2 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. Cannery process water flows to the Jennings Road Facility through a 60-inch outfall that parallels the primary effluent outfall. The two outfalls are connected upstream of the Jennings Road Facility with crossover valves, so a mixture of primary effluent and cannery process water can flow through either or both pipelines. Normally, the valves are closed and the two flow streams are not mixed. Cannery flows enter the cannery segregation pump station at the Jennings Road Facility, where it is normally pumped up to an irrigation mixing box. At the mixing box, it is blended with secondary effluent and land applied. Design criteria for the cannery waste facilities are provided in Table 3.4. ---PAGE BREAK--- FINAL - March 2007 3-10 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.4 Design Criteria for Cannery Process Water Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Mechanical Bar Screens Year constructed 1986 Number – 2 Type – Inclined climber Channel width ft 7 Pumping Plant No. 3 Year constructed 1986 Number duty + standby 3 + 1 Type – Vertical centrifugal Capacity, each mgd 13.4 Horsepower, each hp 125 Cannery Segregation Pump Station Year constructed 1986 Number Duty + Standby 2 + 1 Type – Vertical column Capacity, each mgd 14 Horsepower, each hp 200 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. 3.2.4 Jennings Road Secondary Treatment Plant 3.2.4.1 Secondary Treatment Facilities The secondary treatment facilities at the Jennings Road Facility consist of the following: • Three fixed film reactors (FFRs). • A closed-loop recirculation channel. • Three facultative ponds. Primary effluent from the Sutter Avenue Facility is routed through the FFR mixing box, where flow can be diverted to and from the recirculation channel. The FFR pump station pumps primary effluent to the top of the FFRs, where dissolved and colloidal organic matter ---PAGE BREAK--- FINAL - March 2007 3-11 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc is converted to settleable solids by microorganisms in the biofilm growing on the media surface. FFR effluent is conveyed to the FFR effluent box, where it is fed into the recirculation channel through a sluice gate. The recirculation channel is divided into four sections that surround the facultative ponds. The recirculation channel provides additional treatment through aeration and balances distribution of organic matter and ammonia loading into the facultative ponds. The recirculation channel was originally equipped with 100 floating aerators. Most of the aerators were removed after the cannery segregation and land application program was initiated, because the BOD loadings and air demands were reduced significantly. Flow from the recirculation channel is conveyed to the facultative pond inlet box and it is then pumped into the facultative ponds. The discharge line from each pump branches out over a digestion pit, where solids settle and are digested. Pond effluent flows over a weir and into an effluent collector channel and is then conveyed to either the storage forebay or the irrigation forebay. Design criteria for the secondary treatment facilities are provided in Table 3.5. Table 3.5 Design Criteria for Secondary Treatment Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Fixed Film Reactors Year constructed 1986-1987 Number – 3 Distributor type – Circular rotary Diameter, each ft 140 Volume, each cf 338,492 Recirculation Channel Year constructed 1986 Number – 1 Average depth ft 5 Surface area acres 162 Volume MG 209 Aeration capacity hp 4,160 Facultative Ponds Year constructed 1960’s Number – 3 Average depth, each ft 5 - 6 Surface area, total acres 334 Volume, total MG 618 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.4.2 Effluent Storage Facilities Effluent from the facultative ponds is piped to the storage forebay. The storage pump station transfers pond effluent from the storage forebay to the storage ponds. The storage pond effluent is either utilized to irrigate City-owned land, disinfected and discharged to the river, or split and sent both places. Secondary effluent can be discharged to the river when the following criteria are met: • It is the allowable discharge period (October through May). • The dilution factor of 20:1 is satisfied in the river. • The effluent quality meets discharge standards. Secondary effluent is used for irrigation based on agronomic requirements. During the cannery season of July through September, the land application site is irrigated with a blend of secondary effluent and cannery process water. Given the variability of irrigation water needs as well as allowable river discharge conditions, effluent storage is critical to the City’s wastewater operations. Design criteria for the effluent storage facilities are presented in Table 3.6. Table 3.6 Design Criteria for Effluent Storage Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Storage Ponds Year constructed 1986 Number – 2 Surface Area, total acre 596 Storage Capacity, total ac-ft 7,830 Storage Pump Station Year constructed 1986 Number – 4 Type – 1 vertical axial flow, 3 submersible axial flow Capacity, each mgd 19.5 Horsepower, each Vertical axial pump hp 100 Submersible axial pumps hp 134 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.4.3 Effluent Disinfection Storage pond effluent is disinfected prior to discharge to the San Joaquin River. The Jennings Road Facility currently uses gaseous chlorine for disinfection and sulfur dioxide for dechlorination. Liquid chlorine is delivered in one-ton cylinders and 20 cylinders are stored on-site in the chlorine storage building. Under normal operating conditions, one bank of 10 cylinders is on-line and one bank of 10 cylinders is on standby. Each bank of chlorine cylinders connects to a vacuum regulator. Chlorine gas is drawn from the cylinders through one of four chlorinators. The chlorinators control the chlorine feed rate to the induction unit at the inlet of the chlorine contact basin. Chlorine residual analyzers and a final effluent flow meter provide the signals used to control the chlorine feed rate and the chlorinated effluent then flows through 3 passes in the chlorine contact basin. Chlorinated effluent from the contact basin passes over an outlet weir, where sulfur dioxide is added for dechlorination. Sulfur dioxide is delivered in bulk to the Jennings Road Facility and is stored in a large pressure vessel in a separate building adjacent to the chlorine storage building. Similar to the chlorine gas, sulfur dioxide gas first passes through two vacuum regulators. The feed rate is controlled using sulfonators and the gas is delivered to the effluent through an induction unit. With signals from chlorine residual analyzers and the final effluent flow meter, enough sulfur dioxide is added to neutralize any residual chlorine. Typically, a sulfur dioxide residual is maintained in the final effluent to ensure that no chlorine is discharged to the river. The chlorine contact tank has a shallow water depth of 5 feet and wide channels (35.3 feet wide pass and 45.8 feet outside passes). The outside passes have a trapezoidal cross section and the depth to width ratio is 0.14. In 2005, there were coliform violations during the months of February and March. This may be an indication that there may be inefficiencies in the performance of the contact tank. In general, the tank is shallow with very wide channels. From experience with similar tank configurations, this can lead to flow back-mixing and short-circuiting, which reduce the actual contact time. Wind can also affect contact tanks that are shallow and wide. Flow- straightening baffles - vertical walls with regularly spaced holes - may be required to improve the performance of the contact tank. For planning purposes, it is assumed that baffles will be installed. Dye-testing and hydraulic modeling with computational fluid dynamics software should also be conducted to determine the number and location of the baffles. Design criteria for the effluent disinfection facilities are presented in Table 3.7. ---PAGE BREAK--- FINAL - March 2007 3-14 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.7 Design Criteria for Effluent Disinfection Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Chlorine Contact Tank Year Constructed 1968±, upgraded in 1986 Theoretical Contact time at 70 mgd minutes 68 Length to width ratio – 16:1 Water Depth (nominal) ft 5.0 Width of Pass Inside Pass ft 35.3 Outside Pass ft 45.8 Length of Pass ft 632 (varies) No. of Passes – 3 Volume cf 446,200 Volume MG 3.33 Depth to width ratio – 0.14 Chlorine Cylinders Number – 20 Capacity, each ton 1 Chlorinators Number – 4 Capacity 2 large units ppd 6,000 2 small units ppd 2,000 Sulfur Dioxide Bulk Tank Number – 1 Capacity tons 20 Sulfonators Number – 4 Capacity, each lbs/day 1900 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-15 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.4.4 River Discharge Facilities Two adjacent pump stations at the Jennings Road Facility, one for disinfected secondary effluent and one for site drainage, discharge to the San Joaquin River. The effluent pump station receives dechlorinated secondary effluent from the chlorine contact basin. Three vertical propeller pumps maintain a level setpoint in the effluent pump station wet well. The two smaller pumps discharge into a single outfall line, while the third, largest pump discharges to a second outfall. Flow from either of the two outfall lines can be diverted to the irrigation forebay for land application if river discharge needs to be curtailed. Adjacent to the effluent pump station is the drainage pump station. The drainage pump station receives drainage from a peripheral drainage ditch, which collects upstream runoff and groundwater releases. The drainage discharged from the ditch passes through three manual bar screens and one mechanically-cleaned bar screen before entering the wet well of the drainage pump station. Three constant-speed, vertical-mixed flow pumps maintain a level setpoint in the wet well and pump the drainage into a 4-foot by 4-foot culvert that drains to the river. If the river water level is low enough to allow gravity drainage, the drainage pumps are bypassed and drainage water flows directly to the square culvert and into the river. Design criteria for the river discharge facilities are provided in Table 3.8. Table 3.8 Design Criteria for River Discharge Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Effluent Pump Station Year constructed 1968± Number – 3 Type – Vertical Propeller Capacity, each mgd 2 at 18, 1 at 34 Horsepower, each hp 2 at 100, 1 at 200 Drainage Pump Station Year constructed 1968± Number – 3 Type – Vertical Mixed Flow Capacity, each mgd 10 Horsepower, each hp 75 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. ---PAGE BREAK--- FINAL - March 2007 3-16 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.2.4.5 Ranch Irrigation Facilities During the irrigation season, secondary effluent flows through the irrigation forebay to the irrigation pump station. Three submersible irrigation pumps supply the irrigation reservoir, where secondary effluent is stored prior to distribution to the irrigation area. Design criteria for the ranch irrigation facilities are provided in Table 3.9. Table 3.9 Design Criteria for Ranch Irrigation Facilities Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Irrigation Reservoir Year Constructed 1998 Surface Area acres 2.4 Depth ft 12.9 Volume ac-ft 31 Irrigation Pump Station Year Constructed 1998 Number – 3 Type – Submersible Propeller Capacity, each mgd 13.5 Horsepower, each hp 167 Irrigation Land Area acres 2,526 Notes: From Water Quality Control Plant Operation and Maintenance Manual, revised February 2005. 3.3 TREATMENT PERFORMANCE This section summarizes the current unit process performance at the Sutter Avenue and Jennings Road facilities. The majority of the existing treatment units at both facilities were originally sized for domestic wastewater as well as major seasonal contributions of cannery process flows. Since 1999, seasonal cannery process water has been segregated from domestic flows and used directly for irrigation. As a result, treatment processes at both Sutter Avenue and Jennings Road receive hydraulic and organic loadings significantly less than their original design capacity and resultant performance is generally well within acceptable standards. Conversely, the effluent disposal system’s performance and related capacity is limited due to the capability to achieve the required 20:1 dilution during periods of low river flow. NPDES monitoring reports and unit process data collected from ---PAGE BREAK--- FINAL - March 2007 3-17 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc January 2000 to September 2005 serve as the basis for the individual treatment process performance evaluation. Data collected between unit processes is not required for the NPDES permit, but is collected on an intermittent basis for special operational studies and benchmarking. The performance shown by these limited data sets may not be as representative of actual performance as would be accomplished with more rigorous monitoring. A summary of the influent water quality data and unit process performance is provided in Appendix D. The average influent BOD and total suspended solids (TSS) concentrations to the Sutter Avenue Plant, exclusive of segregated cannery flows, for the sample period described above are 419 and 327 milligrams per liter (mg/L), respectively. 3.3.1 Sutter Avenue Primary Treatment Facility 3.3.1.1 Primary Treatment Plant staff regularly monitor BOD and TSS reduction across the primary clarifiers by taking primary influent and effluent samples. Based on data collected between January 2000 and September 2005, the primary clarifiers remove on average over 60 percent BOD and over 70 percent TSS. Although these removal rates are somewhat higher than typical, they are likely the result of long detention times and relatively low hydraulic loading rates of the primary clarifiers, as well as the unique local wastewater characteristics. The average primary effluent BOD and TSS concentrations for the sample period described above are 168 and 94 mg/L, respectively. 3.3.1.2 Primary Solids Handling According to limited solids data from November 2001 to September 2005, the primary digesters (Digesters 1 and 2) reduced volatile solids by an average of 68 percent. Digester 1 had an average alkalinity of 2,700 mg/L and Digester 2 had an average alkalinity of 2,400 mg/L. The values for alkalinity and volatile solids reduction suggest that the anaerobic digesters are performing within industry standards. Little information is available to determine the performance of the sludge drying beds. However, the operations staff has indicated that the beds provide adequate sludge drying for land application purposes. 3.3.2 Jennings Road Secondary Treatment Facility 3.3.2.1 Secondary Treatment The performance of each secondary unit process, summarized below, is dependent on the sampling location, weather conditions, and the health of the natural process. Because of the many variables affecting performance, the removal rates presented provide an approximate indication of process performance. ---PAGE BREAK--- FINAL - March 2007 3-18 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Unless otherwise indicated, the process performance for the secondary treatment facilities was analyzed using data collected between January 2000 and September 2005. 3.3.2.1.1 Fixed Film Reactors Current average loadings to the FFRs are approximately 56 lb BOD/1,000 cubic feet (cf)/day with two units in service. On rare occasions, peak month loadings can reach 96 lbs BOD/1,000 cf/day. The average BOD reduction across the fixed film reactors (FFRs) is 47 percent, with a corresponding effluent BOD concentration of 88 mg/L. The original design intent of the FFRs, as shown in the 1984 design drawings, was to remove 40 percent of the influent BOD, albeit at a much higher loading. The FFRs are performing as expected based on current loadings. 3.3.2.1.2 Recirculation Channel Because the aerators are not typically operated at this time, performance should be expected to be comparable to a facultative pond with similar 7-day detention time. The average BOD reduction across the recirculation channel was approximately 32 percent, with an average effluent BOD concentration of 56 mg/L. A limited data set for the year 2000 was used to calculate an average TSS reduction of 29 percent. The average effluent TSS concentration during this period was 76 mg/L. 3.3.2.1.3 Facultative Ponds The average BOD reduction across the facultative ponds and the storage ponds was calculated to be 58 percent, with an average effluent concentration of 20 mg/L coming out of the storage ponds. Average effluent BOD concentration is typically lower than the permitted requirement of 30 mg/L for river discharge. The average TSS reduction across the facultative ponds and the storage ponds was calculated to be approximately 16 percent. The average effluent TSS concentration for this sample period was calculated to be 49 mg/L, which is greater than the permitted average of 45 mg/L when discharging to the river. This is consistent with information provided by the City that indicates river discharge has historically been limited due to high TSS concentrations. 3.3.2.2 Effluent Disinfection The existing effluent disinfection system provides adequate disinfection to reduce total coliform levels to below the existing permit limit of 23 MPN/100 mL. With the exception of a few violations in the past five years, the effluent coliform level has remained below the detection level of the coliform testing method. In addition, chlorine residual levels are consistently below the existing permit limit of 0.02 mg/L. ---PAGE BREAK--- FINAL - March 2007 3-19 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.3.2.3 Effluent Disposal The City disposes of secondary treated effluent in two ways: by irrigating 2,526 acres City-owned land, and by discharging flow to the San Joaquin River. The amount of water which can be applied to the irrigation area is dictated by agronomic conditions and required farming operations. There are several constraints in disposing of the treated effluent to the river. Per the City’s current National Pollution Discharge Elimination System (NPDES) permit, discharges to the river are only allowed from October through May. The permit also requires that a minimum dilution of 20:1 (river flow to average daily effluent flow) be maintained during the river discharge period. The volume of effluent that can be discharged is also affected by effluent quality. Algae blooms occur in the effluent storage reservoirs in October, November, and May. The algae generates high suspended solids concentrations that typically exceed discharge limits. As a consequence, discharges to the river in these months are normally not possible. Excess flows that cannot be discharged to the river or used for irrigation must be stored. The NPDES permit and the State Division of Dam Safety permit contain maximum operating levels for the storage reservoirs. There have been occasions in the past where river flows have been such that the City’s overall disposal capacity has been extremely limited. City-owned irrigation areas also serve the purpose of providing treatment and disposal of segregated cannery process water during the period of July through September. Current waste discharge requirements limit the application of segregated cannery flow combined with secondary effluent to 100 lb BOD/acre/day for the season, 150 lbs BOD/acre/day for a 30-day average, and 400 lbs/BOD/acre/day for a 7-day average. Allowable application rates are based on the entire ranch area of 2,526 acres. Previous peak loadings have exceeded allowable standards. 3.3.3 Effluent Characteristics 3.3.3.1 River Discharge Table 3.10 compares existing regulatory requirements from the NPDES permit for river discharge with historical effluent characteristics. The average and maximum river discharge concentrations listed in the table were obtained from the City’s application for renewal of their waste discharge permit that was recently submitted to the Regional Board. In general, the City is able to meet current NPDES permit requirements. BOD and TSS concentrations are typically below the regulatory requirements, however NPDES limits are occasionally exceeded. The effluent BOD concentration exceeded the existing effluent limit of 30 mg/L on 9 days during the last 5 years and the effluent TSS concentration exceeded the existing effluent limit of 45 mg/L on 5 days during the same time period. ---PAGE BREAK--- FINAL - March 2007 3-20 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.10 Effluent Limits and Historical Effluent Characteristics Wastewater Master Plan Phase 2 Update City of Modesto, California Constituent Units Current Permitted Effluent Limits Average Daily Discharge(4) Maximum Daily Discharge(4) BOD, 5-day mg/L 30(1) 9.55 48 TSS mg/L 45(1) 16.71 170 Ammonia (as N) mg/L pH-dependent 5.52 27.2 Chlorine Residual mg/L 0.02(2) 0.0 3.3 Coliform MPN/100 mL 23(3) < 2 1,600 Selenium µg/L 4.1(1) 0.73 6 Copper µg/L 4.5(1) 2.7 11 Molybdenum µg/L 10(1) 16.74 29.00 TDS mg/L 924(2) 502 912 Electrical Conductivity µmhos/cm 1,689(2) 1,069 1,715 pH – 6.5 < pH < 8.5 – 8.6 Bromodichloro-methane µg/L 137.5(2) 4.0 27.0 Dibromochloro-methane µg/L 70(2) 2.0 16.0 Notes: average. Daily maximum. median. Reported values are from effluent samples taken from December 19, 2001 to April 10, 2005. As mentioned earlier, the City consistently meets the existing chlorine residual daily maximum effluent limit of 0.02 mg/L, as well as the coliform limits. Bioassay survival rates have also consistently met NPDES requirements. 3.3.3.2 Irrigation The key discharge specification associated with irrigation of City-owned land is the allowable BOD loading for the period of time when the combined secondary effluent and segregated industrial process water are being used for irrigation. Table 3.11 presents current limits established by the Waste Discharge Requirements and data for the period 2000 through 2005. 3.4 UNIT PROCESS ASSESSMENT AND RATED CAPACITY This section examines unit process reliability and summarizes the capacity of the existing facilities. ---PAGE BREAK--- FINAL - March 2007 3-21 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.11 Allowable Land Application Rates and Historical Values Wastewater Master Plan Phase 2 Update City of Modesto, California Loading Rates (lbs BOD/acre/day) 7-day Average 30-day Average Season Average Waste Discharge Requirements 400 [PHONE REDACTED] 146 116 83 2001 175 136 98 2002 179 [PHONE REDACTED] 141 120 88 2004 147 113 95 2005 148 121 75 3.4.1 Sutter Avenue Facility 3.4.1.1 Headworks Facilities Overall, the existing headworks was designed for a nominal peak capacity of 81 million gallons per day (mgd). Current capacity is limited by influent pumping. The design includes the provision to add additional units to increase overall capacity to 108 mgd. 3.4.1.1.1 Influent Pump Station There are four screw pumps at the influent pump station with a space to add a fifth pump in the future. Each existing pump has a flow capacity of 27 mgd. Allowing for one pump as a standby, the influent pumping capacity at the Sutter Avenue Facility is 81 mgd, which is sufficient to accommodate the current peak wet weather flow (PWWF) of 71.7 mgd. To accommodate the build-out PWWF of 95.5 mgd, an additional pump will be required to be added in the space provided. 3.4.1.1.2 Bar Screens The headworks facility at Sutter Avenue has 3 duty mechanical bar screens and 1 standby mechanical bar screen. Additionally, space is provided to add a fifth screen in the future. The original design criteria in the 1996 drawings indicate that each bar screen has a rated capacity of 27 mgd, for a total capacity of 81 mgd with three screens in service. The bar screen facility can adequately handle the current range of flow rates while remaining within the recommended velocity criteria. The addition of a fifth screen will be required to accommodate the projected build-out PWWF of 95.5 mgd. 3.4.1.1.3 Grit Removal There are three vortex grit chambers at the headworks facility. The design provides for the addition of a forth unit in the future. Each grit chamber has a manufacturer’s rated capacity ---PAGE BREAK--- FINAL - March 2007 3-22 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc of 30 mgd, for a total existing capacity of 90 mgd. This is sufficient capacity to handle the current PWWF of 71.7 mgd, but is less than the 2030 PWWF of 95.5 mgd. The fourth unit should be added in the future to handle expected peak wet weather flows. 3.4.1.1.4 Influent Flow Metering Influent flow is currently measured at the headworks using two Parshall flumes, each with a throat width of 5 feet. The original design criteria indicate that each flume can handle up to 40 mgd, for a total capacity of 80 mgd. This is sufficient to handle the current PWWF. The headworks facility was constructed with an additional Parshall flume (with a 4-foot throat width) capable of measuring up to 28 mgd. Therefore, the combined rated capacity of the three Parshall flumes is 108 mgd, which is sufficient to accommodate the build-out PWWF of 95.5 mgd. 3.4.1.2 Primary Clarifiers Several parameters are used to determine the reliability and the maximum capacity of the primary clarifiers: detention time, overflow rate (OFR), and weir loading rate. Table 3.12 compares a range of standard design criteria with the existing clarifier loading in relation to the current influent flows. Table 3.12 Primary Clarifier Existing Performance Wastewater Master Plan Phase 2 Update City of Modesto, California Units Standard Design Criteria Existing Loading Detention Time ADWF hours 1.5 - 2.5 5 PWWF hours 1.5 - 2.5 4 Overflow Rate ADWF gpd/sf 800 - 1,200 847 PWWF gpd/sf 2,000 - 3,000 1,142 Weir Loading(2) ADWF gpd/ft 10,000 42,357 PWWF gpd/ft 40,000 57,086 Notes: Existing performance was calculated assuming one clarifier in service for ADWF and 2 clarifiers in service for PWWF. Due to limited weir length, the weir loading rate for circular clarifiers is typically high. ---PAGE BREAK--- FINAL - March 2007 3-23 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc To maintain reliable primary clarifier capacity with the largest unit out of service, the remaining units must be capable of handling 50 to 100 percent of the design flow. The primary clarifiers at the Sutter Avenue Facility operate within this criteria and one tank could be taken out of service during average day weather flow (ADWF) with little to no process impact. Utilizing an OFR of 1,000 gallons per day (gpd)/ square foot (sf) for ADWF and an OFR of 2,000 gpd/sf for PWWF results in an ADWF rated capacity of 31 mgd per basin and a total capacity of 63 mgd at ADWF. The estimated PWWF capacity is 126 mgd with both basins in service. By this measure, the existing clarifiers provide adequate capacity for the 2030 build-out flows. Primary Clarifier No. 2 was originally constructed as a secondary clarifier. As a result, the elevation of the effluent v-notch weir is approximately 3 feet lower than the elevation of the v-notch weir in Primary Clarifier No. 1. This means that the water surface elevation in the primary effluent pump station must be maintained at a level that does not submerge the effluent weir in Primary Clarifier No. 2. This can be accomplished by maintaining appropriate level set points in the plant control system. Primary Clarifier No. 1 was constructed with a “control” weir of the v-notch effluent weir. It is assumed that the “control” weir was originally constructed to limit the amount of free fall into the effluent drop box of Primary Clarifier No. 1. However, the weir limits the hydraulic capacity of the clarifier and should either be lowered or removed entirely. This should be evaluated further during preliminary design. The primary effluent pump station wet well is structurally and hydraulically connected to Primary Clarifier No. 2. This arrangement does not allow for the effluent launder in Primary Clarifier No. 2 to be isolated from the pump station and therefore cannot be drained. 3.4.1.3 Anaerobic Digesters The capacity of the anaerobic digesters was estimated based on appropriate values for hydraulic detention time and volatile solids loading. Digesters 1 and 2 serve as the primary digesters. Therefore, the total available digester volume excludes the volume of Digesters 3, 4, and 5. Consideration should also be given to the impact of taking one of the primary digesters out of service. Based on a design loading of 0.10 lbs/VSS/CF/day and a 20-day detention, an additional primary digester will be required at an annual average influent flow of 35 mgd. 3.4.1.4 Sludge Drying Beds Sludge Drying Bed Nos. 11 through 24 are normally used to store digested primary sludge. The operations staff typically fills one drying bed at a time, initially to a depth of 18 inches. ---PAGE BREAK--- FINAL - March 2007 3-24 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Each bed takes between two to four weeks to fill. The beds are then left to dry until the annual bed cleaning, so the actual sludge drying time varies with each bed. Based on projected flows through 2030, it appears that the existing sludge drying area will be adequate for the foreseeable future. Of primary concern, however, is the recent data which indicates the sludge drying area is within the flood plain of the Tuolumne River. Additionally, future regulations may significantly limit the viability of solar sludge drying at the Sutter Avenue site. Consequently, mechanical sludge dewatering and/or lining of the sludge beds is considered likely in the future. 3.4.1.5 Outfall Facilities The outfall facilities consist of: the primary effluent pump station and primary effluent outfall to the Jennings Road Facility. 3.4.1.5.1 Primary Effluent Pump Station The primary effluent pump station has four pumps, each with a rated flow capacity of 17.3 mgd. Typical reliability criteria for a major pump station would be to pump the PWWF with the largest pump out of service. Analysis of the primary effluent pumps shows that the rated capacity of the pumps cannot be achieved due to system hydraulics. The pumps will run off of their operating curves if operated above approximately 80 percent speed. As such, the capacity of the primary effluent pump station was calculated assuming three pumps (one remaining as standby) operating at 80 percent speed. As a result, the capacity is estimated to be 50 mgd, which is sufficient for the current ADWF of 26.6 mgd, but not the PWWF of 71.7 mgd. The City has reported that they can pump down the collection system when wet weather events are anticipated to store the excess flow in the collection system trunk lines. This mode of operation provides the City with an alternate method for handling peak flow events. 3.4.1.5.2 Primary Effluent Outfall The capacity of the primary effluent outfall was determined by simulating the hydraulics in the 6.5-mile long pipeline. It was found that the outfall has adequate capacity to convey the current ADWF of 26.6 mgd, but cannot convey the current PWWF of 71.7 mgd without overflowing. Hydraulic modeling indicates that flows in excess of 45 mgd may cause water to rise up in some of the manholes, but would not overflow the manholes. As a result, the capacity of the outfall is rated at 45 mgd. This correlates well with the City’s experience in observing water levels in the outfall. 3.4.1.6 Cannery Process Water Facilities The cannery waste facilities consist of: Pumping Plant No. 3 (cannery waste influent pump station), the cannery waste bar screens, the cannery waste outfall between the Sutter ---PAGE BREAK--- FINAL - March 2007 3-25 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Avenue Facility and the Jennings Road Facility, and the ranch cannery waste pump station at the Jennings Road Facility. 3.4.1.6.1 Bar Screens The bar screen facility for the cannery process water consists of two screens, each having a rated capacity of 27 mgd, for a total capacity of 54 mgd with both screens on-line. The screening facility has adequate capacity for projected peak process wastewater flows with both units in service. 3.4.1.6.2 Pumping Plant No. 3 The hydraulic capacity of Pumping Plant No. 3 is 40 mgd, assuming that one pump is out of service. This is adequate to handle projected peak cannery process water flow. 3.4.1.6.3 Outfall The capacity of the cannery process water outfall was assumed to be equivalent to that of the primary effluent outfall, because the two pipelines have the same diameter and alignment. Consequently, the pipeline has an estimated capacity of 45 mgd, which is sufficient to handle peak cannery flows through the build-out period. 3.4.1.6.4 Pump Station The total capacity of the ranch pumps is 42 mgd. This is sufficient to handle the projected peak flows. 3.4.2 Jennings Road Secondary Treatment Facility The treatment units at Jennings Road were originally designed for a combination of domestic wastewater and cannery process water. Currently, canning process flows are segregated for direct land application. Consequently, secondary treatment units have adequate capacity for domestic wastewater flows throughout the planning period. However, the capacity of the effluent disposal system at Jennings Road is limited. 3.4.2.1 Fixed Film Reactors Projected 2030 average annual and peak month loadings to the FFRs are 61 and 96 lbs BOD/1,000 cf/day, respectively, with all three units in service. These unit loadings are consistent with current loadings with two units in service. Consequently, the FFRs are adequate for loadings projected throughout the planning period. The FFR pump station supplies the fixed film reactors at a constant rate. Assuming 1 standby pump, the total reliable capacity of the pump station is 115 mgd, which is sufficient for the projected buildout PWWF of 95.5 mgd. ---PAGE BREAK--- FINAL - March 2007 3-26 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.4.2.2 Recirculation Channel and Facultative Ponds As was the case with the FFRs, the recirculation channel and facultative ponds were originally designed to treat the high BOD loading that occurred during the cannery season. Since the segregation of cannery process flows, most of the aerators in the recirculation channel have not been operated and most have been removed, including the electrical facilities. Based on projected 2030 wastewater contributions, a portion of the existing aerators would need to be operated to provide adequate treatment. With additional aerators, the recirculation channel and facultative ponds have adequate capacity for buildout conditions. Table 3.13 summarizes the loading and design criteria for existing secondary treatment facilities at 2030 loadings. Table 3.13 Existing Secondary Treatment Facility Loadings/Criteria at 2030 Loadings Wastewater Master Plan Phase 2 Update City of Modesto, California 2030 Loading/Criteria Units @ AAF @ ADMMF Fixed Film Reactors Organic loading lbs BOD 1,000/cf/day 61 105 Recirculation Channel and Facultative Ponds Detention time days 4.8 4.4 Aeration Requirements horsepower 1,900 1,900 Facultative Ponds Detention time days 14 13 BOD loading rate ppd/ac 33 36 3.4.2.3 Pond Inlet Pump Station The pond inlet pump station supplies the facultative ponds. Each pump has a flow capacity of 9.2 mgd. Assuming one pump is standby, the total reliable capacity of this pump station is 74 mgd, which is sufficient for the projected ADMMF of 47.7 mgd. 3.4.2.4 Storage Pump Station The storage pump station pumps water from the storage forebay to the storage ponds. The flow capacity of each pump is 19.5 mgd, which equates to a total reliable capacity of 58 mgd. This is sufficient for the build-out ADMMF of 47.7 mgd. ---PAGE BREAK--- FINAL - March 2007 3-27 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 3.4.2.5 Effluent Disinfection The chlorine contact basin, with a volume of 2.8 million gallons (MG), provides a theoretical contact time of 56 minutes at 71.7 mgd. However, the sloped walls and wide passes may contribute to short-circuiting in the basin. Although this unit may theoretically have capacity for ultimate flows, modification or replacement should be considered due to short-circuiting concerns. The average chlorine dose applied for secondary effluent disinfection is 5 mg/L. At this dosage rate, one of the large chlorinators could treat twice the current PWWF of 71.7 mgd, and one bank of 10 chlorine cylinders would last almost one week, assuming constant peak hour wet weather flow for that entire week. 3.4.2.6 Effluent Pump Station Disinfected effluent from the chlorine contact basin flows to the wet well of the effluent pump station and is discharged to the San Joaquin River. The combined capacity of the three effluent pumps is 70 mgd, which is equivalent to the current permitted discharge capacity of the plant. 3.5 EFFLUENT DISPOSAL CAPACITY The City disposes of secondary treated effluent in two ways: by irrigating City-owned land, and by discharging flow to the San Joaquin River. The amount of water which can be applied to the irrigation area is dictated by the weather, agronomic conditions and required farming operations. The estimate of current effluent disposal capacity is based on the following assumptions: • River flows are at the lowest 10th percentile, based on river flow data from 1996 to the present. Previous studies (the Ranch Utilization Study and the March 2005 Wastewater Treatment CIP Study) used flow data from 1985 to 1994 to establish a frequency distribution of flows. However, the flow management practices of the San Joaquin River and the Merced River (which is a major tributary to the San Joaquin) have changed since 1996. As a result, the previous river flow data are not an accurate predictor for future flow conditions. Recently, additional river flow data (from Patterson at the Main Street Bridge) from 1996 to 2005 were obtained. Although the data are limited, they provide a rough basis for predicting future flows. River flows from 1999 to 2005 are shown in Figure 3.5. Figure 3.6 is a frequency distribution curve of river flows from 1996 to 2005. • The City will continue operation without the 20 percent contingency in discharging to the river to achieve the 20:1 dilution permit requirement. This procedure had been followed in previous years but has been discontinued since the fall of 2005. The ---PAGE BREAK--- mo606mpf7-6887.cdr Figure 3.5 SAN JOAQUIN RIVER FLOWS 1999-2005 WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 300,000 San Joaquin River Streamflows at Patterson October - May 250,000 200,000 150,000 100,000 50,000 0 1999 2000 2001 2002 2003 2004 2005 *San Joaquin River at Newman High Flow (90th Historical Median Flow* (50th Low Flow (10th 3-28 ---PAGE BREAK--- mo606mpf9-6887.cdr Figure 3.6 FREQUENCY-DISTRIBUTION PLOT FOR SAN JOAQUIN RIVER FLOWS AT PATTERSON WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 2,500 2,000 1,500 1,000 500 0 0 20 40 60 80 100 River Flow Percentile River Flow (Seasonal Average) (mgd) Notes: 1) Represents river flows since flow management practices changed (years 1996-2005) 3-29 ---PAGE BREAK--- FINAL - March 2007 3-30 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc 20 percent contingency was removed based on a new interpretation of the NPDES permit. Previously, operators maintained a 20 percent contingency maintained flows at 80 percent of actual allowable) flow. The system could not respond fast enough to exactly follow a 20:1 ratio. The procedure now is to maintain the 20:1 dilution according to average daily river flow. The system can reliably maintain the 20:1 ratio without the need for the contingency. • The total land application rate, including industrial flows and rainfall, is 5.4 feet/year (ft/yr). The City was able to safely irrigate in 2005 (a dry year) at the rate of 6 ft/year. A more typical irrigation rate is 5 ft/yr without causing water to pond or damaging crops. However, it is assumed that the higher irrigation rate can be used in dry years. • All of the City’s 2,526 acres will be used for irrigation. • Segregated cannery wastewater will have an average annual capacity requirement of 4 mgd (1,460 million gallons [MG] discharged over the period of July through September). Average annual segregated cannery wastewater flow in 2005 was 3.6 mgd. The current total domestic wastewater discharge capacity, is estimated to be 24.2 mgd at the 10th percentile river flow. Effluent disposal capacity consists of the following parts (see Figure 3.6): • Secondary effluent (not including cannery waste flow) to land (for irrigation) = 8.1 mgd. • Net losses from evaporation and rainfall = 5.9 mgd. • Discharge to river with 20:1 dilution = 10.2 mgd. The City has recently completed the design of a project to add dissolved air flotation (DAF) to remove algae in October and November. This will add an additional 3.0 mgd of disposal capacity during a 10th percentile year. With DAFs, the total domestic wastewater disposal capacity would be 27.2 mgd. As stated previously, the effluent disposal system at Jennings Road is dependent upon river flow conditions and resultant ability to maintain a 20:1 dilution during the allowable discharge period. Consequently, effluent disposal requirements are highly dependent upon river flow assumptions. As noted herein, the capacity deficit assumes the 10th percentile river flow condition. Table 3.14 summarizes the current effluent disposal capacity under varying river flow assumptions. Figure 3.7 illustrates the estimated effluent disposal capacity. 3.6 SAN JOAQUIN RIVER FLOW CONTROLS Various upstream flow controls and system operating methodologies based on hydrologic conditions impact the flow in the San Joaquin River. Friant Dam in Fresno County controls the San Joaquin River and most of the water from the resulting Millerton Lake is diverted southward to the Fresno area. The Merced River joins the San Joaquin River upstream of ---PAGE BREAK--- FINAL - March 2007 3-31 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Table 3.14 Current (2005) Effluent Disposal Capacity for Varying River Flow Assumptions Wastewater Master Plan Phase 2 Update City of Modesto 1 2 3 4 5 6 7 8 9 5=2+3+4 7=5+6 9=7-8 River Flow Percentile Allowable Effluent Discharge to River (without DAFs)(1) mgd Secondary Effluent to Land mgd Net Losses from Evaporation/ Rainfall mgd Current Total Effluent Disposal Capacity Without DAFs Additional Effluent Discharge Capacity from DAFs(2) mgd Total Effluent Disposal Capacity with DAFs mgd Current Influent Flow to Jennings Road mgd Available Additional Capacity with DAF mgd 10 10.2 8.1 5.9 24.2 3.0 27.2 25.8 1.4 25 12.6 8.1 5.9 26.6 3.4 30.0 25.8 4.2 50 21.2 8.1 5.9 35.2 4.5 39.7 25.8 13.9 60 23.3 8.1 5.9 37.3 4.8 42.1 25.8 16.3 75 26.8 8.1 5.9 40.8 5.1 45.9 25.8 20.1 90 62.2 8.1 5.9 76.2 5.7 81.9 25.8 56.5 Notes: Refer to Appendix E for derivation of allowable effluent discharges to river. Dissolved air flotation for algae removal. ---PAGE BREAK--- mo606mpf8-6887.cdr Figure 3.7 CURRENT DOMESTIC EFFLUENT DISPOSAL CAPACITY (WITH DAF) WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO – – – – Proposed Dissolved Air Flotation (DAF) to Remove Algae (3.0 mgd) Current Flow 25.8 mgd Effluent Disposal Capacity (Exluding segregated industrial flow) 27.2 mgd 24.2 mgd 14.0 mgd 5.9 mgd *Based on 10th percentile river flow conditions. River Discharge (10.2 mgd)* Irrigation (8.1 mgd) Net Evaporation (5.9 mgd) – 3-32 ---PAGE BREAK--- FINAL - March 2007 3-33 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc Patterson. Other tributaries that contribute to the flows at Patterson include the Mud and Salt Sloughs and minor agricultural drains. The San Joaquin Valley Project Area and Vicinity is shown in Figure 3.8. Based on recent data and operating conditions, the Merced River contributes from 45 to 52 percent of the water that flows in the San Joaquin River at Patterson. The San Joaquin River, as measured by Friant Dam releases, contributes only 5 to 23 percent of the flow that reaches Patterson. The remaining contributions come from the sloughs and agricultural drains, as previously described. The New Exchequer Dam in Merced County controls the Merced River. Most of the water from the Merced that would normally flow to the San Joaquin is diverted for agricultural and other uses. The pattern of the mean Merced River losses of water due to diversions is illustrated in Appendix F. As shown in Appendix F, in the drier year of 2003, there was less flow in the Merced River, however the diversions remained relatively the same as 2000. Therefore, it is evident that in dry years the remaining flow from Merced River that reaches the San Joaquin River at Patterson will be lower. Furthermore, in 2003, the drier year, diversions over shadow the gains in flow from tributaries during the months of February, March, and December, as opposed to the opposite pattern seen in the year 2000. This translates to reduced stream flows reaching Patterson in those months. Recently, river management practices changed as a result of environmental concerns. In the 1998, an agreement was reached with major stakeholders to provide a level of protection to the San Joaquin River to satisfy flow objectives contained in the State Water Resources Control Board 1995 Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta. The stakeholders in the plan included California State agencies (CDWR, CDFG), Federal agencies (USBR, USFWS), San Joaquin River Group parties (SJRGA and other member agencies), Central Valley Project/State Water Project export interests, and environmental community groups. This agreement, called the San Joaquin River Agreement (SJRA), has had and will continue to have a significant impact on the flow of San Joaquin River and its tributaries. A key part of this agreement is the Vernalis Adaptive Management Plan (VAMP), which is designed to protect juvenile Chinook salmon migrating from the San Joaquin River through the Sacramento-San Joaquin Delta. As a part of the VAMP, “pulse flows” to protect salmon runs are released in October and May. Although the magnitudes of the pulses change annually in response to hydrologic and biologic conditions, pulse flows have been observed at the lower San Joaquin River, including near Patterson, since 2000. The SJRA expires in year 2010, and it is unknown if the agreement will be renewed. In conclusion, river flows are expected to be higher than in the past due to the San Joaquin River Agreement, which includes a requirement for releasing pulse-flows during fall ---PAGE BREAK--- mo606mpf10-6887.cdr Figure 3.8 MAP OF SAN JOAQUIN VALLEY PROJECT AREA AND VICINITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Jennings Road WWTF Point of Discharge 3-34 ---PAGE BREAK--- FINAL - March 2007 3-35 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\03.doc and spring for salmon spawning and smolt return. Most of the flow that reaches the San Joaquin at Patterson will continue to come from the Merced River. Flow releases to the Merced will likely continue to be operated with the priority to supply agricultural uses. In dry years, the City can expect less flow at Patterson as agricultural diversions receive higher priority. Even if a certain year has average or above average rainfall, and the preceding year or years had below average rainfall, the flow releases could be controlled to retain storage in upstream reservoirs. Under these conditions, a year with average rainfall could yield low river flows consistent with a dry year. A similar pattern occurred in the years 2000 to 2004 (see Appendix F) in which river flows were near the lowest 10th percentile although rainfall was not abnormally low. In addition, droughts have occurred in roughly every 10 to 15 years since 1913 (See Appendix Accordingly, it would be prudent to be conservative in predicting river flows, and the corresponding allowable effluent discharges to the river. In the spring of 2006 the San Joaquin River levels reached flood stage for several weeks. During this time, water migrated through the flood control levees along the west border of the Modesto ranch and saturated the soil a significant distance eastward. According to City estimates, as much as one-third of the total ranch acreage of 2,526 acres was not available for irrigation, and all irrigation was delayed. Normally the late spring is when the City irrigates the most because the cannery process flows have not yet begun and the river flows (and dilution factor) are high. Instead, because of the saturated soil, all incoming flows were stored in the storage ponds for several months. Flooding of the San Joaquin River is normally a rare occasion. If the City continues to depend on seasonal discharges of effluent to the river, the impacts of this unusual event should be studied further. 3.7 CONDITION ASSESSMENT SUMMARY On January 18, 2006, Carollo Engineers visited the Sutter Avenue and Jennings Road facilities to determine the condition of some of the existing facilities. The purpose of this visit was to assess the structural condition of the following facilities: • The anaerobic digester facilities at Sutter Avenue. • The primary clarifiers and primary effluent pump station at Sutter Avenue. • The fixed film reactors at Jennings Road. All of the structures inspected were in generally good condition and should continue to remain serviceable with preventive maintenance. However, this assessment is based on the assumption that the interior and submerged surfaces are in a condition similar to the exposed surfaces. There were areas of steel corrosion and concrete damage related to corrosion. A seismic vulnerability analysis was beyond the scope of this report. A memo summarizing the site visit is included in Appendix H. ---PAGE BREAK--- FINAL - March 2007 4-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc Chapter 4 REGULATORY REQUIREMENTS 4.1 INTRODUCTION Regulatory requirements for the City of Modesto’s (City) Water Quality Control Facility (WQCF) are based on federal, state and local standards. Regulations apply to water discharged to “waters of the State”, application of water to land, biosolids reuse or disposal, and air quality. This chapter provides a review of the regulatory and permitting requirements for the WQCF. 4.2 WATER QUALITY REQUIREMENTS Water quality requirements are set nationally by the Clean Water Act (CWA). The Environmental Protection Agency (EPA) has the authority to regulate discharges to the waters of the United States under the CWA. EPA also grants authority to state agencies for regulation and enforcement of water quality standards. In California, the authority to regulate discharges falls with the State Water Resources Control Board, which authorizes Regional Water Quality Control Boards to issue National Pollutant Discharge Elimination System (NPDES) permits. The CWA was last reauthorized and substantively amended in 1987. The 1987 amendments placed renewed emphasis and focus on toxic pollutant controls. This emphasis on toxics control has the potential to seriously impact the WQCF as well as other municipal waste dischargers. If specific constituent or capacity based regulatory issues cannot be resolved through source control, user pretreatment or development of more appropriate site-specific water quality objectives (WQO), Modesto will be faced with either having to construct costly end-of-pipe treatment processes to comply with future effluent limitations on toxic pollutants and salinity, and/or purchase additional land to apply treated wastewater. The City’s current NPDES Permit was issued on May 11, 2001, as Waste Discharge Requirements (WDR) No. 5-01-120, NPDES No. CA0079103, by the (see Appendix The Permit applies to the Sutter Avenue (primary) and Jennings Road (secondary) facilities jointly in the permit. The City was issued a Cease and Desist order (Order No. 5-01-121) concurrently with the 2001 NPDES Permit because the final molybdenum effluent limitations were not immediately achievable. Interim effluent limitations, calculated based on WQCF performance, are only allowed by the State Implementation Plan(SIP) for the 2000 California Toxics Rule (CTR) WQOs. The WQCF is permitted to discharge up to 70 mgd, however, the actual river discharge capacity is limited to flows that meet the minimum 20:1 (river:effluent) dilution requirement between October 1 and May 31 of any year. The 20:1 dilution requirement for secondary treatment facilities is ---PAGE BREAK--- FINAL - March 2007 4-2 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc based on guidance by the California Department of Health Services (DHS) for protection of river beneficial uses including drinking water, agricultural, and recreational contact uses. A separate WDR was issued in 1999 (Order No. 99-112, see Appendix J) for all wastewater applied to the City’s 2,526-acre ranch, adjacent to the Jennings Road facility. The land disposal WDR was separated from the previous NPDES permit in 1999 because of the significant changes to the land disposal practices; primarily the segregation of cannery process water during the summer and application of this untreated waste stream directly to the ranch. The existing NPDES permit includes a description of the treatment operations, discharge prohibitions, background information and study requirements on specific constituent (pollutant) issues, and effluent limitations. Effluent limitations for toxic pollutants are developed according to the State Implementation Plan (SIP)1. 4.2.1 Existing NPDES Permit As required to extend the current NPDES permitted discharge, the City of Modesto submitted a Report of Waste Discharge (ROWD) for the WQCF 180 days in advance of the current permit expiring on May 11, 2006. The City delivered the ROWD to the Regional Board on May 10, 2006. Water quality based effluent limitations (WQBELs) are concentration limits placed on discharged effluent that are calculated to ensure that the receiving water will not exceed the WQO more than once in three years. When the upstream receiving water concentration already exceeds the WQO, the effluent limitation is set at the WQO. The current NPDES permit includes effluent limitations for chlorine residual, settleable solids, total suspended solids (TSS), selenium, biochemical oxygen demand (BOD5), total coliform, copper, and molybdenum. Interim effluent limitations are allowed when the receiving water WQO is based on the 2000 California Toxics Rule (CTR) and the discharger can demonstrate that it is infeasible to meet an effluent limitation for the toxic constituent. Interim limits for other types of WQOs can be included as part of a Cease and Desist Order that includes a compliance time schedule. Interim effluent limitations are developed based on actual treatment performance, and are only allowed for up to five years during which time the dischargers must come into compliance with the final effluent limitation. Effluent limitations in the current NPDES Permit are summarized in Table 4.1. The current NPDES Permit is included in Appendix I. Minimum mandatory penalties (MMP) are now required based on Senate Bill 709 (Migden Bill) for any numeric non-narrative) violation of NPDES permit provisions. Discretionary fines are also possible above the MMP. Each numeric violation results in a $3,000 fine. 1 2000. State Water Resources Control Board, Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays, and Estuaries of California. ---PAGE BREAK--- FINAL - March 2007 4-3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc Table 4.1 Summary of Current NPDES Permit Effluent Limitations (2001) Wastewater Master Plan Phase 2 Update City of Modesto, California Constituent Averaging Period Final Effluent Limitation Interim Effluent Limitation BOD5 Average 30 mg/L 17,514 lbs/day Weekly Average 45 mg/L 26,271 lbs/day Daily Maximum 90 mg/L 52,542 lbs/day TSS Average 45 mg/L 26,271 lbs/day Weekly Average 60 mg/L 35,028 lbs/day Daily Maximum 105 mg/L 61,299 lbs/day Settleable Solids Average 0.1 mL/L Daily Maximum 0.2 mL/L Ammonia Daily Maximum 30 day average Chlorine Residual Daily Maximum 0.02 mg/L 11.7 lbs/day Total Coliform Median 23 MPN/100 mL Daily Maximum 500 MPN/100 mL Selenium (Total) Average 4.1 µg/L 2.4 lbs/day Daily Maximum 8.2 µg/L 4.8 lbs/day Copper (Total) Average 4.5 µg/L 2.6 lbs/day 9.8 µg/L 5.7 lbs/day Daily Maximum 8.3 µg/L 4.8 lbs/day 14.7 µg/L 8.6 lbs/day Molybdenum Average 10 µg/L 5.8 lbs/day Daily Maximum 15 µg/L 8.8 lbs/day 81.6 µg/L 47.6 lbs/day TDS Daily Maximum 924 mg/L 539,431 lbs/day EC Daily Maximum 1,689 µmhos/cm Bromodichloromethane Daily Maximum 137.5 µg/L 65 lbs/day Dibromochloromethane Daily Maximum 70 µg/L 33 lbs/day Notes: No NPDES permit effluent limitation. Calculated based on pH and temperature. ---PAGE BREAK--- FINAL - March 2007 4-4 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.1.1 Molybdenum The molybdenum Cease and Desist (C&D) order initially expired in May 2005, however, an extension to the C&D order for the full five years to May 2006 was requested in October 20052 so that source control efforts could be fully implemented. The basis for the molybdenum effluent limitation is Table III-1 of the Basin Plan, which is intended to protect grazing animals (especially cattle) which can develop molybdenosis if forage is substantially contaminated by irrigation water with concentrations of molybdenum above 25 µg/L. There is no specific treatment process at the WQCF to remove molybdenum from wastewater, and source control was identified as the primary means to meet the final effluent limitation. Molybdenum is used as an anti-fouling agent for cooling towers, cannery processes, and is also found in some inks. The City began the cannery segregation project in 2000 to re-route cannery process flows during the summer directly to land application without treatment other than screening performed by the individual food processors. This removed a significant fraction of the molybdenum load to the WQCF headworks and effluent concentrations were proportionately lowered after a period of stabilization in the large WQCF storage facilities. However, effluent concentrations were still frequently above the effluent limitation. The City developed a pollution prevention plan (PPP) for molybdenum as required by the NPDES Permit (see “Additional Studies” section). The City has been working with industry to establish a source control program for all industries, and has begun to implement an across-the-board concentration limit. Although this “local” limit and others have not been formally adopted by City Council, industry has voluntarily begun to reduce molybdenum concentrations. The City is currently evaluating these voluntary reductions, and it is unclear whether the City will be able to fully comply without additional measures. 4.2.1.2 Copper Copper effluent limitations are based on the CTR aquatic life WQOs that increase with increasing receiving water hardness. Like molybdenum, copper influent reductions due to the cannery segregation project have resulted in lower effluent concentrations. The City developed a pollution prevention plan (PPP) for copper as required by the NPDES Permit (see “Additional Studies” section). Additionally, the SIP allows for the consideration of a metals translator study and “dynamic modeling” of compliance conditions to determine if reasonable potential exists. These studies were completed according to the required NPDES Permit schedule and conclude that there is no reasonable potential to exceed the WQO. A complete summary of the study is included below in the “Additional Studies” section. 2 October 5, 2005 letter from John Rivera, City of Modesto to Jon Ericson. Central Valley Regional Water Quality Control Board. City of Modesto Water Quality Control Facility Molybdenum Reduction Analysis ---PAGE BREAK--- FINAL - March 2007 4-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.1.3 Trihalomethanes Trihalomethanes (THMs) effluent limitations are based on CTR human health criteria. Dilution is generally acceptable in calculating THM limits, using the harmonic mean river flow and the average discharge flow. The human health WQO based on fish/organism and water consumption is significantly lower than the WQO for organism consumption alone. By comparison, the drinking water standards developed by DHS under Title 22 for regulation of drinking water standards for total THMs are generally two orders of magnitude greater than the lowest CTR human health WQO for specific THM constituents. However, drinking water standards are not used in development of NPDES permit effluent limitations when lower CTR objectives are promulgated. The WQCF cannot consistently meet effluent limitations based on the CTR even when “regulatory” dilution is considered. Regulatory dilution refers to the dilution used when calculating a WQBEL based on discharge plume models that is generally lower than the 20:1 hydraulic loading. The City prepared a PPP for THMs (see “Additional Studies” section below), but concluded that THMs were predominantly generated during the WQCF chlorination process. THMs are created when organic matter is chlorinated. To ensure complete disinfection, the WQCF currently must apply higher chlorine doses during periods of high algae and solids concentrations. This in turn increases THM production. Besides any permitted regulatory dilution, additional regulatory relief may be possible if site-specific conditions can be shown to demonstrate “exceptions” from the assumptions used to develop the CTR human health objectives. The City has begun researching these possibilities for the upcoming NPDES permit renewal. Compliance with these objectives may be possible if organic matter and algae can be removed from the chlorinated stream (through filtration, dissolved air flotation [DAF] units, or other means) or an alternate disinfection process such as ultraviolet (UV) or ozone treatment is used. 4.2.1.4 Ammonia The ammonia WQO is based on the USEPA national guidance published in 1999. The NPDES permit now incorporates these objectives for acute toxicity into a daily maximum effluent limitation. The current NPDES permit assumed that the acute toxicity WQO would govern over the chronic toxicity WQO, however, this assumption will be revisited pending the results of the dilution and mixing zone additional study (see “Additional Studies” section). The WQCF has modified discharge practices to consider both chlorination and ammonia concentrations. Ammonia concentrations tend to be higher in the spring and fall seasons, possibly related to nitrogen contributions from decaying algae in the WQCF ponds. Compliance with the ammonia effluent limitation is possible, although reasonable potential to exceed still exists because the WQCF is operated near the limitation. In this way, ammonia concentrations in the effluent limit discharge periods discharge is not possible because of elevated ammonia concentrations). ---PAGE BREAK--- FINAL - March 2007 4-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.1.5 Selenium The selenium effluent limitation is calculated based on a National Toxics Rule (NTR) objective and according to Section 1.4 of the SIP. This effluent limitation is required because the San Joaquin River is listed as impaired due to selenium concentrations and upstream river selenium concentrations can sometimes exceed the NTR objective. The WQCF has been able to meet this effluent limitation requirement during the last NPDES permit term. 4.2.1.6 Mercury No WQCF effluent limitation is currently in place for mercury, although it is specifically referenced in the current NPDES permit. As required by the NPDES permit, a mercury mass limitation study was submitted to the during the last permit term. A draft total maximum daily load (TMDL) for mercury and methyl mercury in the Sacramento-San Joaquin Delta Estuary was circulated in August 2005. Although the City’s discharge is outside of the legal definition of this TMDL area, the City’s discharge is included in the list of facilities in the Delta or waterways immediately upstream required to perform additional methyl mercury monitoring. The draft TMDL specifically states that “…discharge to the waterways near the Delta also could be assigned load reductions as part of future Basin Plan Amendments.” It is anticipated that a specific allocation will not be included in the final TMDL. However, the could introduce a mass limit for total or methyl mercury because each are considered bioaccumulative and are included in the 303(d) impairment list in the Delta. In the Draft TMDL the has proposed waste load allocations for total mercury based on the current (2005) loadings. A load allocation could also be calculated based on the NPDES permitted flow capacity. The waste load allocation development process during NPDES permitting should be carefully considered by the City as it could potentially limit disposal capacity at the WQCF. 4.2.1.7 Dissolved Oxygen Demand The has developed a TMDL for dissolved oxygen (DO) in the Stockton Deep Ship Channel (SDSC). The TMDL does not specifically evaluate the contribution of DO demand from the WQCF effluent, but does attribute critical DO depression events in the SDSC to algae in the watershed. The WQCF impact on DO in the SDSC was evaluated by the City in a study required by the NPDES permit (see “Additional Study Requirements” section). The study concluded that the City contribution is small enough to not be measurable. DO demand, is likely most dependent on the nature (species) and condition of the algae discharge in the WQCF effluent. 4.2.1.8 Salinity The has adopted a TMDL for salinity (and boron) that will require NPDES permit writers to incorporate the most applicable concentration-based WQO as an effluent limitation. The current NPDES permit was previously written based on the WQO at Vernalis. ---PAGE BREAK--- FINAL - March 2007 4-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc However, because it was not feasible to meet this objective, an interim (performance- based) effluent limit was adopted (1,689 µmhos/cm). In lieu of a final effluent limitation, the current NPDES permit refers specifically to the (at the time, not yet adopted) TMDL. The TMDL considers the Modesto discharge a lower priority because it is a nearly negligible fraction of the total watershed load. The NPDES permit writers have discretion in application of the TMDL and the associated time schedule for compliance. The Vernalis WQO for EC is 700 µmhos/cm between April 1 and August 31 and 1,000 µmhos/cm between September 1 and March 31. An effluent limitation for salinity will generally be required for the following reasons: • The upstream San Joaquin River (SJR) EC measurements can exceed this WQO, • The WQCF effluent EC measurements can exceed this WQO, and • The San Joaquin River is 303(d) listed for impairment due to salinity and boron. The NPDES permit renewal will address this issue. Because there is no existing treatment process specific to salinity reduction, salt reduction can only be accomplished with source control, modification of source (drinking) water, or construction of new facilities. Despite the potential for severe salinity restrictions in the future, current monitoring data indicate minimal impacts of salinity from domestic and industrial wastewater effluent disposal. In November 2005, a study entitled “Update of Modesto Ranch Salt Study” was prepared by EOA, Inc. (see study in Appendix The study concluded: • Segregated cannery flows represent approximately 1/3 of the total salt load to Ranch irrigation, with the remaining 2/3 contributed by domestic effluent. • Total salt loads to the Ranch are remaining essentially constant. • Discharges of secondary effluent during the allowable discharge period (October through May) do not measurably impact salinity concentrations. • Ranch irrigation does not appear to be increasing the salinity of shallow groundwater on an overall basis. • Although soil salinity levels at the Ranch are highly variable and seasonally cyclic due to the cannery season, no consistent increase in soil salinity was observed. 4.2.1.9 Additional NPDES Study Requirements The current NPDES Permit also includes provisions specifying a number of required time schedules and studies. These studies investigated issues identified by the Regional Board and included impact study on dissolved oxygen in the lower San Joaquin River and Stockton Deep Ship Channel, copper translator and dynamic modeling, and a mixing zone and dilution study. ---PAGE BREAK--- FINAL - March 2007 4-8 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.1.9.1 Dissolved Oxygen Model The City was required to assess the impact of the effluent discharge on dissolved oxygen (DO) concentrations on the San Joaquin River and the Delta. In May 2004, the City submitted a San Joaquin River Dissolved Oxygen Study to the which evaluated the potential impact of WQCF effluent discharges on DO concentrations in the lower SJR. The evaluation was based on modeling results using QUAL2E, a steady-state one- dimensional water quality model developed by USEPA. Figure 4.1 is a map of the QUAL2E “reach” structure that was used for modeling. Results of the modeling analysis showed that discharge of WQCF effluent at typical concentrations of oxygen-associated compounds - even with highly conservative assumptions of receiving water oxidation rates and dilution from tributaries - has very little effect on DO concentrations in lower SJR. These effects include: • DO concentrations were at most reduced by 0.1 percent to 1.2 percent at SJR at Vernalis; and • Percent DO saturation was reduced by 1 percent or less along all reaches of the SJR between the WQCF outfall and SJR at Vernalis. • Such small differences are within the error of the QUAL2E model and would not be easily measured in the field. Overall, the SJR DO Study demonstrated that WQCF inputs have a very small effect on DO concentrations in the SJR and SDWC. Moreover, the predicted effects were nominal even though a series of highly conservative assumptions were used during model application. Therefore, it should be concluded from the study that WQCF effluent does not significantly affect DO concentrations of SJR at Vernalis. 4.2.1.9.2 Copper Translator and Dynamic Modeling Study The City’s NPDES permit (May 2001) required development of a copper compliance schedule to meet the final effluent limitations for copper. The accepted this schedule in February 2002 and the interim copper effluent limitations were extended until April 2006. In May 2003, the City submitted the Mixing Zone - Dilution & Copper Translator Study that included results of the copper translator study and a dynamic (compliance) model as allowed by the SIP, Section 1.4.1. A site-specific translator value converts the CTR) water quality objective from the dissolved concentration from which the aquatic toxicity was developed to a total recoverable concentration from which effluent limitations can be developed, if necessary. Currently the SIP defaults to a conservative more protective) value of 0.96 (dissolved to total recoverable concentration fraction). The City submitted a sampling and analysis work plan (SAP) to the in November 2001 that included a minimum of ten sampling events covering the entire seasonal discharge period. The SAP was distributed by the to several agencies and interest groups. The City did not receive any comments, and the SAP was implemented as proposed. ---PAGE BREAK--- Figure 4.1 DISSOLVED OXYGEN MODEL REACHES WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO mo606mpm17-6887.ai 4-9 ---PAGE BREAK--- FINAL - March 2007 4-10 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc Ten events were successfully sampled during 2002 and 2003 while the plant was discharging to the San Joaquin River. The results were reported in a May 2003 report submitted to the The May 2003 report also considered a near field dilution model of effluent discharge to the San Joaquin River and a dynamic model which considers the statistical occurrence of effluent and river conditions pertinent to complying with CTR copper water quality objectives (WQOs). The study demonstrated that the fraction of dissolved copper to total recoverable copper is consistently between 0.4 and 0.6 (dissolved to total recoverable fraction), and that the City discharge would equilibrate to this range. The dynamic model allows for the appropriate consideration of multiple factors that may not have concurrent critical conditions ambient hardness tends to increase with decreased river flows). The study determined that there was not a reasonable potential for exceedance of an in-stream WQO and a copper effluent limitation was not necessary. 4.2.1.9.3 Near Field Mixing Zone and Dilution Study at Effluent Discharge The City’s NPDES permit required the development of a dilution model to characterize the available dilution at the City’s effluent discharge point. Results from this model were submitted to the in May 2003 as the Mixing Zone - Dilution & Copper Translator Study. This “near-field” model can be used to incorporate dilution into calculations of in- stream water quality objectives and effluent limitations. Dilution is permitted in these calculations when the upstream ambient river concentration is already less than the water quality objective. The near-field dilution is applicable to aquatic life acute objectives and is of particular interest to the City in the cases of chlorine residual and ammonia. This study first performed a comprehensive field monitoring effort and used the data to validate a USEPA-approved numerical model. The Cornell Mixing Zone Expert System (CORMIX), a software system for the analysis, prediction, and design of aqueous pollutant discharges into water bodies, was chosen for this project. CORMIX was selected because it has been successfully applied by other point source dischargers, the level of detail matched the desired model accuracy, and the model inputs could be easily collected. The model can also be easily modified to assess the benefit of installing an effluent diffuser at the outfall. The geometry, flow, and constituent concentrations are used by the expert system section of CORMIX to evaluate the most appropriate subprogram for a particular point within a system. The major computational effort and development emphasis is on the initial, near-field mixing zone. CORMIX is approved by the EPA for use in mixing zone determinations, and has been used in many mixing zone applications. Based on the findings of this study, a minimum 2:1 dilution for acute WQOs and a minimum 4:1 dilution for chronic WQOs is protective of beneficial uses under the most critical conditions. If a diffuser is feasible at the outfall, a minimum 15:1 chronic and acute dilution is available for constituents with assimilative capacity the upstream concentration is less than the WQO and provides dilution of the effluent). Finally, it was determined that ---PAGE BREAK--- FINAL - March 2007 4-11 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc WQOs based on the protection of human health should use the harmonic mean river flow and the long-term arithmetic mean of effluent discharge flow during periods of discharge. This dilution is appropriate for long-term exposure modeling and has previously been applied by the 4.2.1.9.4 Pollution Prevention Plans Pollution Prevention Plans (PPPs) were required by the current NPDES permit to quantify the sources of certain constituents, and whether or not compliance with the effluent limitation would be possible through source control measures. PPPs were prepared in compliance with California Water Code (CWC) 13263.3(d) for molybdenum, salinity, selenium, copper, mercury, and THMS. The molybdenum C&D order required that a PPP be submitted separately by May 2002, two years before the other constituent PPPs. The PPPs determined that source reductions for molybdenum could feasibly result in effluent limitation compliance since product substitution is available. Copper and selenium source reduction is also important, however, it was also demonstrated that copper and selenium effluent limitations might not be necessary. Additionally, mercury reductions will be important because of anticipated waste load allocations, but would not impact effluent limitation compliance. Salinity source control could provide some reductions, but would not be enough to meet the anticipated TMDL-imposed effluent limitations. THMs are generated during the chlorination process and the influent load is not considered significant enough to require source controls. 4.2.2 Waste Discharge Requirements for Land Disposal A separate WDR was issued in 1999 (Order No. 99-112) for all wastewater applied to the City’s 2,530-acre ranch, adjacent to the Jennings Road facility. Previously, land disposal on the Ranch was permitted through the NPDES permit. The land disposal WDR was separated from the previous NPDES permit in 1999 because of the significant changes to the land disposal practices; primarily the segregation of cannery process flows. The WDR specifies the allowable loading rates of both the cannery process water and secondary effluent. The WDR for land disposal does not have an expiration date, but could be modified or restricted by the at any time. Violations of the WDR are not subject to MMPs, but could be subject to discretionary fines, cease and desist orders, or more serious legal prosecution. The WDR also does not provide NPDES “shielding” from third-party lawsuits. The land disposal WDR requires specific application practices and limitations. Year-round application of secondary treated effluent and July through September application of segregated cannery flows to the 2,530-acre ranch are permitted. The cannery segregated process water cannot be applied at loading rates exceeding the 400 lbs BOD5/acre/day averaged over 7 days, 100 lbs BOD5/acre/day averaged over a season, or 150 lbs BOD5/acre/day averaged over 30 days. Secondary effluent loading cannot exceed 50 lbs. BOD5/acre/day averaged over 30 days or a BOD5 concentration of 300 mg/L. The WDR ---PAGE BREAK--- FINAL - March 2007 4-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc requires that odors be mitigated, the irrigation facilities be appropriately operated (tailwater collection, no standing water, flood protection, weed minimization, etc.), and includes an extensive monitoring program. Protection of groundwater is also addressed in the WDR and a monitoring work plan and salt management study were required. Although the State has been encouraging land disposal for years, the has recently established more restrictive permitting of such operations. Application of waste by food manufacturers was specifically addressed in recent policy documents. The WDRs issued to these facilities are generally more extensive in their loading specifications and monitoring requirements. Recent informal discussion between City staff and the have indicated that it may not be feasible to expand the cannery segregation project without upgrading treatment of the cannery waste. Increasing the available land for disposal beyond the permitted 2,530 acres would require reopening of the WDR. Although not likely, the NPDES permit writers could initiate land disposal WDR modifications during the NPDES permit renewal to ensure that land disposal practices are consistent with current State policy. 4.2.3 Projected Regulatory Issues A ROWD was submitted to the on November 10, 2005. The ROWD did not request any significant changes to the WQCF discharge or operation, but deferred to the forthcoming outcome of this master planning process. It was noted in the ROWD that this master planning process would provide for disposal capacity increases to meet current and future demand. Subsequently, the City submitted a letter to the indicating the City’s intent to pursue a long term phased plan of increasing the level of treatment of domestic wastewater and the pursuit of a NPDES permit that would allow year round river discharge. The did not indicate that the application for permit renewal was insufficient, and the terms of the current NPDES permit will remain in place until superseded by the new permit. Based on the experience of other regional NPDES permit- holders, and the large workload, a new permit is not expected to be in place before the end of the 2006 calendar year. Several specific issues have been identified by the City based on the experiences of other discharges and by applying current regulatory practices to the most recently available water quality and WQCF performance data. These issues include constituent specific issues and more general policy issues. 4.2.3.1 Constituent Specific Issues A preliminary analysis of WQCF historical data indicate that under current regulatory practices several “new” constituents may require effluent limitations and additional study following the NPDES permit renewal. These constituents include aluminum, iron, manganese, and carbon tetrachloride. There will also likely be additional studies regarding previously identified constituents, including ammonia, boron, and salinity. ---PAGE BREAK--- FINAL - March 2007 4-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.3.2 Future Impacts Other potential future impacts are possible under several state and federal rules and policies. The most likely impacts would occur under the following statutes, regulations, and policies: 4.2.3.2.1 Total Mass Daily Loads There are a number of that have recently been completed. are intended to bring impaired waters of the state into compliance with water quality objectives. The TMDL process assesses all watershed sources and develops waste load allocations (WLA) for individual dischargers and load contributors. are adopted as Basin Plan amendments that must also be approved by the State Water Resources Control Board, the Office of Administrative Law (OAL), and the Federal EPA. As previously discussed, the total mercury and methyl mercury TMDL for the Sacramento – San Joaquin River Delta was adopted by the in August 2005. The WQCF discharge is not included in this phase of the TMDL, but will likely be incorporated in later Basin Plan amendments. The general policy for NPDES point discharges in the current phase of the TMDL is to “cap” total mercury at current levels no increase in the load of total mercury discharged). Similar caps were proposed for NPDES discharges of methyl mercury outside of the Sacramento River sub-region. Additional phases of this TMDL would not likely be in place before 2010. The DO TMDL study for the lower San Joaquin River and the Stockton Deep Water Ship Channel (DWSC) were adopted by the in February 2005. The TMDL study did not develop a specific WLA for the WQCF; however, an allocation was reserved for “unknown” point sources that NPDES permit writers can incorporated into permits. Moreover, the TMDL study cites algal loads to the DWSC as a significant DO demand. Because of the large storage ponds at the WQCF algal “blooms” are not atypical during certain periods. The has indicated to the City that the DO demand will likely be an issue in the NPDES permit renewal. The Salt and Boron TMDL was adopted by the in September 2004. The TMDL acknowledges that the WQCF is small relative contributor of salts and boron to the San Joaquin River. However, the TMDL specifically includes a concentration-based “WLA” for the WQCF that matches the WQO. This WQO at Vernalis on the San Joaquin River (700 µmhos/cm between April 1 and August 31 and 1,000 µmhos/cm between September 1 and March 31) is currently being reviewed. The TMDL requests that NPDES permit writers incorporate this WQO into the WQCF NPDES permit renewal. The WQCF would not be able to immediately comply with this WQO, and a time schedule may be put in place for compliance. ---PAGE BREAK--- FINAL - March 2007 4-14 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.3.3 Emerging Contaminants “Emerging contaminants” include endocrine disrupting compounds (EDCs), pharmaceuticals and personal care products and other xenobiotics. The trend of increasingly stringent requirements for wastewater treatment may ultimately require additional treatment and removal of emerging contaminants known to be present in municipal wastewater. 4.2.3.4 Basin Plan Updates The are required to do triennial reviews of the Basin Plans. These reviews can be used to modify beneficial use designations or other specific policies. These review processes should be carefully monitored since changes in polices could significantly impact WQCF operation. During the course of NPDES permit renewals, the permit writers may defer to this process as the means modify policy rather than use their more narrowly defined discretion. 4.2.3.5 CALFED Bay-Delta Program The City may be challenged by CALFED actions that may alter the Delta flows, and increase regulatory requirements for improving water quality. CALFED may also bring opportunities for wastewater recycling, watershed ecosystem, and watershed water quality partnerships that would benefit the City. 4.2.3.6 Selenium Fish Tissue Criteria The EPA has proposed draft revised WQO for selenium. This revised fish-tissue based WQO is proposed as a better indicator of the presence of selenium in a particular water body. The draft criteria have not yet been finalized and the impact on the WQCF’s ability to comply with selenium objectives is unknown at this time. Each of these potential impacts should be carefully tracked through the NPDES permitting process. 4.2.3.7 Collection System Currently the City’s collection system is not permitted through the NPDES permit. However, there have been significant regulatory efforts in recent years to eliminate sanitary sewer overflows (SSOs) from collection systems. A statewide general WDR for collection system agencies is currently in draft form and is scheduled for adoption sometime in 2006. The City would be required to apply for coverage under this general WDR. The proposed WDR requires the development of a sanitary sewer management plan (SSMP), and reporting of all SSOs. It is possible that the NPDES permit renewal could require specific collection system studies and reporting requirements. Because the collection system is not covered by an NPDES permit, any SSOs may be subject to third-party lawsuits as is allowed by the CWA. ---PAGE BREAK--- FINAL - March 2007 4-15 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.3.8 Groundwater Monitoring Groundwater monitoring is currently required at the Jennings Road and Ranch facilities as part of the land application WDR This monitoring measures the potential groundwater impact of the ponds at the Jennings Road facility and land application of treated effluent and cannery segregation flows. If the ponds are shown to impact the groundwater beneficial uses, the may require the application of “best available control technologies” (BACT). Such technologies might include underground recovery drains or pond lining. The Sutter Avenue facility also has a small unlined pond used for storage of peak wet weather flows. However, no monitoring wells are currently active at that facility. It is possible that the NPDES permit renewal will address groundwater monitoring at this location as well. 4.2.4 Compliance Strategy Options Non-compliance with the NPDES permit may result in fines, cease and desist orders, or potentially more serious legal action. It is illegal to plan for non-compliance with permit provisions. This master plan will consider existing NPDES permit requirements, impending changes to the permits, and the City’s needs to accommodate changes in the volume and nature of influent wastewater. Moreover, the could place building moratoriums on the City if the WQCF is not able to comply with the permit and building growth exacerbates any compliance problems. Compliance options should consider both regulatory options and facility improvements. Regulatory options include site-specific studies to address the applicability of WQOs to the WQCF discharge and other regional policy changes. Facility planning should also carefully consider the regulatory environment and WQCF specific and regional issues. Two other policies are important to consider, especially as the City considers WQCF expansions. The “antidegradation” policy constrains the from adopting NPDES permits that “degrade” waters of the state. Simply put, actions cannot cause receiving waters to exceed WQOs or impair known beneficial uses of those waters. In addition, the “anti-backsliding” policy does not allow NPDES permit amendments or renewals to “relax” numeric effluent limitations or discharge prohibitions of existing permits. The current WQCF has sufficient treatment capacity and with some constituent-specific exceptions, produces effluent of high enough quality to discharge to the San Joaquin River at the required 20:1 dilution. However, the WQCF does not have sufficient disposal capacity during critically dry periods when river disposal is limited by upstream flows. Although regulatory relief and source control measures may be enough for compliance for specific constituent issues, the disposal capacity issue and several specific constituent issues will likely require facility improvements. Of particular concern in the short term are ammonia, THM and DO demand issues. Salinity and mercury issue are longer-term issues that should be considered during this master planning cycle, as significant facility improvements could be necessary. ---PAGE BREAK--- FINAL - March 2007 4-16 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc The City has maintained a balance of facilities and modes of disposal that provide operational flexibility in the evolving regulatory climate. This flexibility has been decreased in recent years by local growth and tightening regulatory restrictions. The overall regulatory strategy should value operational flexibility so that any drastic changes to regulatory requirements in the future can be more easily addressed without a major facility renovation. It is speculative to make any assessments on the regulatory environment more than five years in the future. Table 4.2 summarizes the known and projected regulatory issues. In general, the regulatory options are sufficient to comply with water quality regulations, however, facility improvements are necessary to increase disposal capacity, and to potentially comply with salinity and THM effluent limitations. Facility improvements are included for issues in several cases where they might not be necessary, but directly address the issue and would be implemented based on other needs. 4.2.4.1 Facility Improvement Options Several facility improvements evaluated in this report may be required to comply with the current and future NPDES permits, and future WDRs for land disposal to the Ranch. Disposal capacity could be increased by fully utilizing the allowable discharge period (October through May), expanding the allowable NPDES permit discharge period, or upgrading facilities so that the 20:1 river dilution is not required. These options are not necessarily mutually exclusive, and could be implemented sequentially. Additional facility upgrade evaluations should consider nitrification/denitrification to address the ammonia compliance and DO demand issues and UV disinfection to address THM compliance issues. 4.2.4.1.1 Discharge Period Utilization Discharge typically only occurs between December 1 and April 15 of any year because of solids and ammonia effluent limitations that would be exceeded because of algal concentration increases in the ponds. The allowable discharge period could be increased with the additional of algae removal facilities. Flocculation/sedimentation or DAF are potential facility improvements that should be considered to better utilize the permitted discharge period. 4.2.4.1.2 Discharge Period Extension The discharge period is currently limited to the eight months between October and the end of May. Previous policy encouraged winter discharge and summer land disposal/reuse. Because land disposal in the Central Valley is now more difficult to permit, additional summer discharge of secondary effluent is a potentially feasible regulatory option. The 20:1 river dilution would be necessary for secondary effluent discharge, which would limit the allowable discharge. As mentioned previously, the basis for this dilution requirement are historical DHS guidelines and the more recent policy in the case ---PAGE BREAK--- FINAL - March 2007 4-17 H:\FINAL\MODESTO_WCO\6887E00\RPT\MASTERPLANRPT\FINAL\04.DOC Table 4.2 Summary of NPDES Compliance Options Wastewater Facilities Strategic Master Plan Wastewater Master Plan Phase 2 Update City of Modesto, California Known Issue Regulatory Options Facility Improvement Options Ammonia Effluent Limitation Perform ammonia water effects ratio study. Construct discharge diffuser to provide additional regulatory dilution. Construct algae removal facilities to reduce potential nitrogen sources for bacterial decomposition of organic matter. Construct nitrification-denitrification facilities to remove available nitrogen. Copper Effluent Limitation Dynamic compliance model updates. Translator study updates and follow-up. Copper water effects ratio, if necessary (Biotic Ligand Model). Dissolved Oxygen Demand Effluent Limitations Lower San Joaquin River modeling follow-up and updates. Algae speciation study. Construct algae removal facilities. Nutrient (nitrogen and phosphorus) removal facilities may provide some benefit, however, the SJR is considered “light-limited”. Trihalomethanes Review of WQO development, and work with regional/statewide groups to update WQO, as necessary. Construct algae removal facilities. Construct filtration as necessary to remove organic material. Construct ultraviolet disinfection facilities. Molybdenum Continued source control and pretreatment efforts with industry. Upstream receiving water monitoring to determine if assimilative capacity is available for dilution. Investigate alternate water supply during critical periods. Salinity Continue source control and pretreatment with industries. Investigate alternate water supply during critical periods. Evaluate the feasibility of reverse osmosis treatment of source water, industrial pretreatment, and treatment of partial stream at WQCF. Develop long-term strategy for compliance and contribute to regional efforts to develop salt removal “policies” including offset programs. Construct, as determined in feasibility study, reverse osmosis facilities to treat source water, industrial pretreatment, or effluent. Mercury Continue source control and pretreatment with industries and other targeted outreach. Perform in-plant methyl mercury production study and continue methyl mercury monitoring in receiving water and effluent. Participate in regional TMDL and offset efforts. Construct, as determined in feasibility study, reverse osmosis facilities to treat source water, industrial pretreatment, or effluent. Selenium Develop a site-specific objective based on fish tissue concentrations. Investigate alternate water supply during critical periods. Construct, as determined in feasibility study, reverse osmosis facilities to treat source water, industrial pretreatment, or effluent. Aluminum Use acid-soluble aluminum to comply with USEPA WQO. Perform water effects ratio study to develop site specific objective. Iron and Manganese Perform translator studies to develop site specific objectives. Construct filtration facilities to upgrade system to tertiary discharge. Emerging Constituents Participate and contribute to regional and statewide investigative efforts into the impact of emerging constituents. Construct, as determined in feasibility study, reverse osmosis facilities to treat effluent or as industrial pretreatment. ---PAGE BREAK--- FINAL - March 2007 4-18 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc of the Vacaville NPDES permit. The Vacaville permit included incorporation of agricultural beneficial uses as protected by 20:1 dilution. Additional algae removal would also be necessary and the NPDES permit would need to be revised to permit discharge during this period. 4.2.4.1.3 Tertiary Discharge Disinfected tertiary/filtered effluent meeting Title 22 §60301.230 requirements can be used for nonrestricted recreational impoundments, unrestricted irrigation of crops, various industrial processes, and other uses. Discharge of the tertiary effluent would not be subject to the 20:1 river dilution requirement, effectively increasing discharge capacity. It would also be possible within the NPDES permit to have a discharge of both tertiary and secondary effluent such that only part of the WQCF flow was filtered to meet tertiary requirements. In this way, if adequate disposal capacity could be achieved, tertiary treatment facilities could be incrementally phased to expend disposal capacity as required. A number of municipalities (Tracy, Manteca and Turlock) and a large development (Community of Mountain House) discharging to the lower San Joaquin River and Delta areas are currently constructing tertiary facilities. The general and simplified basis for installing these treatment processes was to meet water quality regulations and to ensure adequate disposal capacity to the receiving water for future expansions. 4.2.4.1.4 Additional Land Disposal The current land disposal WDR limits the hydraulic and organic loading rates to the Ranch and limits the available acreage to the current 2,530 acres. Additional disposal to the Ranch would require acquisition and permitting of additional land. 4.2.4.1.5 Nitrification/Denitrification The nitrification-denitrification process removes both mineralized and organic nitrogen. Upgrading WQCF facilities to include this process would address ammonia compliance issues and any nitrogen related effluent limitation requirements. Nitrogen is a nutrient that contributes to algal growth and potentially dissolved oxygen demand. 4.2.4.1.6 Discharge Diffuser A diffuser installed at the effluent outfall to the river (if feasible) would ensure that the WQCF effluent discharge is well mixed quickly in the river. Currently the WQCF discharge enters the river as a side-stream that, after initial partial mixing, is slowly fully mixed. A diffuser would allow for additional “dilution credit” when assessing compliance with “acute” and “chronic” WQOs and would provide significant benefit for specific constituent issues such as chlorine residual and ammonia. A diffuser would only be necessary for secondary effluent flows. ---PAGE BREAK--- FINAL - March 2007 4-19 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.2.4.1.7 UV Disinfection Ultraviolet disinfection can be used in place of chlorination-dechlorination facilities. Use of chlorine in any form has significant occupation and public health risks associated with the handling of chlorine or dechlorination compounds. Chlorination of organic compounds creates THMs. When deployed appropriately, UV disinfection does not have any regulatory drawbacks, but is more energy intensive. 4.3 LAND APPLICATION OF BIOSOLIDS Biosolids land application is regulated at the federal level by the EPA through the 40 CFR Part 503 regulations. These regulations establish standards for pollutant limits, operational standards, management practices, monitoring, record keeping, and reporting requirements. The regulation is self-implementing and imposes requirements on persons who prepare sewage biosolids or material derived from sewage biosolids and land appliers of sewage biosolids. The 40 CFR Part 503 standards became effective February 19, 1994. To land apply biosolids, the biosolids must satisfy the requirements for pollutant limitations, pathogen reduction, and vector attraction reduction as described in the following sections. The 40 CFR Part 503 identifies two levels of pathogen reduction requirements, Class A and Class B, which may be satisfied by certain treatment methods and/or by meeting pathogen limitation standards. The goal of Class A requirements is to reduce pathogens to below detectable limits. The goal of Class B biosolids is to meet adequate pathogen reduction requirements and to rely upon environmental factors at the beneficial site to further reduce pathogens. Therefore, sites that use Class B biosolids must follow additional site restrictions concerning public access, animal grazing, and crop harvesting. 4.3.1 Alternative Daily Cover Sanitary landfill operations require the application of a daily cover to the working face of the active waste cell at the end of each day. The daily cover minimizes odor generation and reduces vector attraction. Daily cover has traditionally been earth material that is either excavated from the landfill or imported. Recently, landfills have been experimenting with alternative materials for use as daily cover. Some materials that have been tested include geotextile fabrics, yard waste, and auto shredder fluff. Municipal sewage biosolids, which have been dried to greater than 50 percent solids, have also been successfully used as alternative daily cover (ADC). The City would not be required to report to any regulatory agency on a regular basis regarding the use of biosolids as landfill cover. The landfill operator, however, would be required to report to the California Integrated Waste Management Board (CIWMB) and regarding the demonstration project and final permitted operation of the landfill using biosolids as cover material. The reporting requirements for the landfill operator would be covered in their site specific Waste Discharge Permit. ---PAGE BREAK--- FINAL - March 2007 4-20 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc 4.3.2 Landfill Disposal Landfill codisposal of waste is currently regulated on the federal level by Subtitle D of the Resource Conservation and Recovery Act (RCRA). Regulatory criteria for solid waste disposal facilities, including codisposal of sewage biosolids in municipal solid waste landfills, are established under 40 CFR Part 258. However, landfill disposal in California is regulated by CCR Title 23, Chapter 15 requirements which are generally more stringent than 40 CFR Part 258. The and the Regional Boards administer biosolids disposal requirements from Chapter 15 under a Waste Discharge Requirements Order. Depending on the classification of the waste, the biosolids may be discharged to a certain “class” of landfill. Class III landfills have the least stringent requirements. Class I landfills are for hazardous waste disposal. 4.4 AIR QUALITY REQUIREMENTS Several agencies at the federal, state, and local level have jurisdiction pertaining to air pollution and odor control at wastewater treatment plants. At the federal level, the major agencies are the U.S. EPA and the Occupational Safety and Health Administration (OSHA). At the state level, the applicable agencies are the California Air Resources Board (CARB) and Cal-OSHA. At the local level, it is the San Joaquin Air Pollution Control District (SJAPCD). These agencies establish ambient air quality criteria and levels of treatment necessary to protect the public health and environment both off-site and on-site of a potential source. The also includes general nuisance (odor) provisions in NPDES permits and WDRs. These agencies also have the responsibility to permit new facilities for construction and operation and to establish new source pollutant levels and treatment requirements. The EPA issues requirements for limiting hazardous air pollutants, and sets emissions standards (NESHAPs) for major point sources. Existing facilities are subject to the federal Clean Air Act (CAA) requirements to implement maximum achievable control technology (MACT) only if a process is modified to emit toxic air contaminants above the “major” threshold (10 tons/year of a single HAP or 25 tons/year of a combination of HAPs). CARB is the lead agency for air pollution control in California, identifying and developing air quality standards. SJAPCD administers rules and regulations, and issues permits to point sources including the WQCF. The WQCF complies with existing SJAPCD requirements. Operation of the back-up emergency diesel generators, gasoline storage tanks, and digester waste gas flare require SJAPCD permits. Expansion and upgrade of these facilities would require continued compliance with SJAPCD standards through a permit revision process. ---PAGE BREAK--- FINAL - March 2007 4-21 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\04.doc Improvements and changes to wastewater process and discharge location may require revised air quality permits. However, requirements of the air quality permitting process should not have as great an impact on strategic master planning decisions as other regulatory requirements such as water quality and recycled water regulations. ---PAGE BREAK--- FINAL - March 2007 5-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Chapter 5 EVALUATION OF PRIMARY TREATMENT ALTERNATIVES 5.1 INTRODUCTION This chapter provides a description of the required primary treatment facility improvements; along with process sizing, conceptual layouts, and preliminary cost estimates. Project costs are presented for each primary treatment alternative. In addition, a non-economic analysis compares the advantages and disadvantages of each alternative. Based on this analysis, recommendations are developed and presented. 5.2 IDENTIFICATION OF PRIMARY TREATMENT IMPROVEMENTS Findings from the capacity analysis presented in Chapter 3 indicate that some of the unit processes at the Sutter Avenue primary plant have insufficient capacity to treat and convey projected flows. The influent pumping, screening and grit removal facilities, along with the primary effluent pump station, outfall pipeline, and anaerobic digestion, will require capacity and reliability upgrades. In addition to the upgrades described above, improvements associated with current and future NPDES permit provisions will be required. It is a provision of the current NPDES permit that “treatment facilities shall be designed, constructed, operated, and maintained to prevent inundation or washout due to floods with a 100-year return frequency”. Using Federal Emergency Management Agency (FEMA) floodplain maps provided by City staff, it was determined that the Sutter Avenue Facility lies within the 100-year floodplain of the Tuolumne River. As a consequence, some form of flood protection will be required. The City should also anticipate that the current practice of solar drying of digested sludge in unlined beds adjacent to the Tuolumne River will not be viable in the long term. Future digested sludge handling processes at Sutter Avenue will likely include mechanical dewatering and/or lining of the sludge drying area. 5.3 DEVELOPMENT OF REQUIRED COMMON IMPROVEMENTS This section identifies the required improvements at the Sutter Avenue Facility that are common to both of the primary treatment alternatives described in Section 5.4. Figure 5.1 presents the “capacity life” for each unit prices at Sutter Avenue. Capacity life is defined as the approximate date at which the capacity will be exceeded. ---PAGE BREAK--- mo606mpf11-6887.ai Influent pumping, barscreens, and flumes Grit Removal Primary Effluent Outfall Primary Clarifier (With one on standby) Primary effluent pump station (with current outfall) Peak wet weather flow (peak dry weather flow & infiltration/inflow) PWWF Peak hourly flow in dry season PDWF Maximum flow MMF Average annual flow AAF LEGEND 2005 0 25 50 75 100 2010 2015 2020 2025 AAF 2030 Year Wastewater Flow, mgd Figure 5.1 CAPACITY LIFE FOR FLOW-RELATED TREATMENT PROCESSES AT SUTTER AVENUE PRIMARY TREATMENT PLANT WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO MMF PDWF PWWF 5-2 ---PAGE BREAK--- FINAL - March 2007 5-3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc 5.3.1 Headworks The headworks facility was brought on-line in the fall of 1997; consequently the equipment is relatively new and should not require replacement during the planning period. The facility was designed with provisions that would allow for an easy expansion of the influent pumping, screening, and grit removal processes. 5.3.1.1 Influent Pumps and Bar Screens As described in Chapter 3, the influent screw pumps and mechanical bar screens currently have a rated capacity of 81 million gallons per day (mgd). The facilities will need to provide for a capacity of 95.5 mgd at build-out. Capacity can be added by installing a new influent screw pump and bar screen. For cost estimating purposes, it was assumed that the new equipment would be selected to match the existing equipment and structural modifications to the headworks facility would not be required. Based on the projected influent flow increases outlined in Chapter 2, the proposed improvements to the influent pumping and screening facilities should be completed by approximately 2016. 5.3.1.2 Grit Removal The current rated capacity of the grit removal facilities is 90 mgd. Motor-driven propellers have been installed in three of the four vortex grit chambers; the fourth grit chamber was constructed for future expansion. In order to increase the capacity of the grit removal facilities, a new motor-driven propeller and new grit pump should be installed. It was assumed that the new equipment would be selected to match the existing. Based on projected influent flow increases outlined in Chapter 2, expansion of the grit removal facility should be completed by 2025. 5.3.1.3 Influent Flow Meters There are two parshall flumes with 5-foot throat widths, and on flumes with a 4-foot throat width. Currently the City uses the two 5-foot flumes for flow metering, with a combined capacity of 80 mgd. The additional flume will be required to be placed into service by approximately year 2015. The additional meter would increase the rated capacity of the preliminary treatment facilities to 108 mgd, which is sufficient for the projected build-out PWWF of 95.5 mgd. 5.3.2 Primary Effluent Outfall Domestic wastewater is lifted by the primary effluent pumps and conveyed from the Sutter Avenue plant to the Jennings Road plant via the 6.5-mile primary effluent outfall. The outfall was designed to flow as a pressure pipe for approximately 1.5 miles and to flow by gravity the remaining five miles to Jennings Road. The hydraulic capacity of the gravity portion of the primary effluent outfall is estimated to be 45 mgd. A hydraulic analysis of the pipeline predicts that at 45 mgd, the pipeline would surcharge. Refer to the hydraulic profile shown on Figure 5.2. ---PAGE BREAK--- mo606mpf11a-6887.ai 340 320 300 280 240 220 200 180 160 140 120 100 80 60 40 20 0 260 Figure 5.2 PRIMARY EFFLUENT PIPELINE (OUTFALL) HYDRAULIC PROFILE WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 110 100 90 80 70 60 50 40 30 Station(+00) Station(+00) Appr oxi mat e Grad e Approx im at e Grade Access Box LEGEND Hydraulic profile at 66 mgd Hydraulic profile at 55 mgd Hydraulic profile at 44 mgd Section of outfall already lined with plastic liner Sutter Avenue Plant 56.09 Primary Effluent Pump Station (Water surface level in pump station) 55 mgd 44 mgd Access Box MH MH MH MH MH 66 mgd (peak dry weather flow at build-out) 43.6 Jennings Road Plant 5-4 ---PAGE BREAK--- FINAL - March 2007 5-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc The outfall has adequate capacity to convey the current peak dry weather flow (PDWF) of 38.7 mgd, but does not have adequate capacity for the existing PWWF of 71.7 mgd. The City currently accommodates peak wet weather flow events by using the collection system for storage and pumping primary effluent at full pump station capacity. PWWF can also be conveyed to Jennings Road by using both the primary effluent outfall and the cannery segregation outfall (a parallel 60-inch outfall that is otherwise not in service during the wet season) in conjunction. Because the cannery segregation outfall cannot be used to convey domestic primary effluent during the canning season (July through September), the primary effluent outfall needs to have adequate capacity to convey the 2030 (build-out) PDWF of 62.3 mgd. City operations staff has reported that the crown of the pipe has corroded and, in some reaches, the pipe may leak when surcharged. In an attempt to address this problem, the City has already slip-lined 4,400 feet of the gravity line with 54-inch Vylon pipe, in two separate sections. Since the outfall pipeline is in need of rehabilitation, it is recommended that it be slip-lined for the entire length of the pipeline, or an additional 32,500 feet. Slip-lining the entire outfall and converting the gravity portion to a forcemain would also increase the capacity of the outfall from 45 mgd to 64 mgd. The benefits of slip-lining are two-fold: it would address the decaying condition of the pipeline and increase the pipeline’s hydraulic capacity. Vylon pipe, the product that has been used to slip-line two segments of the gravity portion of the primary effluent outfall, is a profile-wall, flush-joint, PVC pipe. It is used primarily for gravity service, but is capable of withstanding pressures of up to 56 feet. If the entire outfall is pressurized to increase its hydraulic capacity, the pressure in the upstream portion of the pipe could potentially exceed 56 feet, but the majority of the pipeline would experience pressures below this level. For this reason, it is recommended that Vylon or a similar product be used to slip-line the remaining length of the primary effluent outfall. However, the upstream portion of the outfall, which will experience the highest pressures, should be slip-lined with a pipe rated for higher pressures. High density polyethylene pipe (HDPE) may be appropriate material for this use. The cost of these improvements is significantly less than the cost of a new parallel pipeline. Based on the projected influent flow increases outlined in Chapter 2, improvements to the primary effluent outfall should be completed by approximately 2013. However, it is recommended that the outfall be slip-lined as soon as possible to prevent failure of the outfall. 5.3.3 Primary Effluent Pump Station The existing primary effluent pump station has four vertical turbine pumps, each with a design capacity of 17.3 mgd. As discussed in Chapter 3, the primary effluent pumps cannot pump at their full capacity because of system hydraulics. By slip-lining the primary effluent outfall with a 54-inch diameter pipe, however, hydraulics are improved so that the pumps can operate at full speeds and thus reach their full flow capacities. A preliminary analysis ---PAGE BREAK--- FINAL - March 2007 5-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc shows that the existing pumps could convey approximately 64 mgd of primary effluent through a 54-inch outfall. The increased capacity would satisfy the projected peak dry weather flows until approximately 2030. The primary effluent pump station, however, needs to be able to pump the current and projected PWWF, not just dry weather flows. The current PWWF is 71.7 mgd and the build- out PWWF is 95.5 mgd. These flows are greater than the current capacity of the pump station, regardless of outfall modifications. Therefore, while slip-lining the outfall can increase the capacity of the pump station and pipeline, ultimately the pump station will need to be replaced or expanded to accommodate the projected build-out flows. As an alternative to demolishing the existing pump station, it could be kept in service and supplemented with a new pump station with a flow capacity of approximately 32 mgd. However, for cost estimating purposes, it was assumed that the existing pump station will be demolished and replaced with a new 95.5 mgd pump station. The preliminary hydraulic analysis of the new pump station was computed under the assumption that the primary effluent outfall and the cannery outfall would be used in conjunction to convey peak flows during the non-canning season (wet season). The outfall system hydraulics should be analyzed further during preliminary design of these facilities. 5.3.4 Design Criteria A summary of the design criteria for the new improvements that are common to both of the primary treatment alternatives is provided in Table 5.1. The criteria are preliminary and were used to develop cost estimates for the facilities. 5.3.5 Conceptual Cost Estimate A conceptual cost estimate for the improvements that are common to primary treatment alternatives is presented in Table 5.2. The project costs are presented in today’s dollars (June 2006). 5.4 DEVELOPMENT OF PRIMARY TREATMENT UPGRADE ALTERNATIVES As a result of the floodplain issues described in Section 5.2, an alternative to relocate the primary treatment facilities to the Jennings Road Secondary Treatment (Jennings Road) Facility was considered. Two primary treatment upgrade alternatives were evaluated: • Upgrading the primary treatment facilities at Sutter Avenue. • Abandoning the primary treatment facilities at Sutter Avenue (except the headworks) and moving the treatment facilities to Jennings Road. ---PAGE BREAK--- FINAL - March 2007 5-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Table 5.1 Preliminary Design Criteria for the Common Improvements Wastewater Master Plan Phase 2 Update City of Modesto, California Units Design Criteria(1) Influent Pump Station Number – 1 Type – Enclosed screw Flow capacity mgd 27 Horsepower hp 200 Mechanical Bar Screens Number – 1 Type – Inclined climber Channel width ft 7 Grit Chamber Number – 1 Chamber Diameter ft 18 Grit Pump Number – 1 Type – Recessed impeller Flow capacity gpm 250 Total Dynamic Head ft 41 Horsepower hp 15 Primary Effluent Pump Station Number – 4 + 1 standby Type – Mixed Flow Propeller Capacity, each mgd 23.9 Total Dynamic Head ft 46 Horsepower, each hp 200 Primary Effluent Outfall (slip-line existing) Diameter inches 54 Capacity mgd 95.5 Notes: Criteria for additional or modified facilities only. Design criteria are preliminary and should be re-evaluated during preliminary design. ---PAGE BREAK--- FINAL - March 2007 5-8 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Table 5.2 Conceptual Cost Estimate for Common Primary Treatment Improvements Wastewater Master Plan Phase 2 Update City of Modesto, California Cost in $M(1) Influent Flume Hydraulic Improvements $1.5 Bar Screen $0.6 Influent Pump $1.1 Grit Removal Unit $0.3 Primary Effluent Pump Station $9.3 Primary Effluent Outfall Lining $12.4 Total Project Cost, $M $25.2 Notes: Conceptual level costs. Based on June 2006 dollars (ENRCC1 = 8441). Include allowances for contingencies, engineering, legal, and administrative expenses. Based on flows and loads from Chapter 2, unit processes were sized and conceptual layouts were developed for facility improvements for each alternative. Cost estimates were also completed based on the conceptual level sizing and layout information in order to economically compare the two alternatives. 5.4.1 Alternative 1: Upgrade Primary Treatment Facilities at Sutter Avenue In this alternative, the existing primary clarifiers and solids handling facilities would be upgraded and remain common to both alternatives at the Sutter Avenue Facility. In addition to the improvements to the primary facilities previously described, the following will also be required as part of this alternative: • Flood control improvements required by the current NPDES discharge permit. • Expansion of the existing anaerobic digesters. • Implementation of mechanical sludge dewatering and/or lining of sludge drying beds. 5.4.1.1 Flood Control Improvements Wastewater treatment facilities should be protected against flooding that could lead to violations in discharge permit requirements and localized environmental degradation as a result of sewage spills. Upon review of FEMA floodplain maps provided by the City, it was determined that the Sutter Avenue Facility lies within the 100-year floodplain. The current NPDES permit indicates that all facilities within the 100-year floodplain shall be protected against flooding and it is likely that the future NPDES permit would continue to require floodplain protection. Alternatives available include the raising of critical facilities above the ---PAGE BREAK--- FINAL - March 2007 5-9 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc elevation of the 100 year flood or the construction of a flood control level. For planning purposes, it was assumed that a flood protection would be provided by constructing a levee system around the Sutter Avenue Facility, including the sludge drying beds. Figure 5.3 shows the floodplain and a conceptual layout of flood protection improvements. It was assumed that flood protection levee would be constructed as a berm, with the exception of the portion near the Tuolumne River. Due to space limitations, this portion of the levee would be concrete-wall construction. The top of the levee would be built to an elevation of 70 feet providing approximately two feet of freeboard above the existing 100-year floodplain elevation. For cost estimating purposes, it was assumed that the portion of the levee constructed as a berm would have a top width of 20 feet and the berm would slope at a ratio of 3:1 (horizontal: vertical). The width at the toe of the slope is dependant upon the existing grade elevation. If a levee were constructed around the perimeter of the Sutter Avenue Facility, a storm water pump station would be required for site drainage. The implementation of a flood control project at Sutter Avenue must be based on detailed hydraulic and flood studies to determine possible upstream and related impacts of the levee. These studies may be substantial, and may indicate the need for additional improvements. The studies may also show that the restriction in the flood plain from the levee system would impact upstream conditions and created more flooding. See discussion in 5.4.1.3. 5.4.1.2 Anaerobic Digester Improvements Based on the analysis presented in Chapter 3, an additional 104-foot diameter primary digester is required for reliability and to accommodate future loadings. The preliminary sizing of the new digester was completed assuming a volatile solids loading rate of 0.10 ppd/cf with three digesters on-line (includes 2 existing primary digesters and 1 new digester). 5.4.1.3 Alternative Flood Protection System - Modifications to the Existing Sludge Drying Beds/Sludge Dewatering, Adding Fill An alternative to a perimeter flood control system would be to: • Reduce the size required for sludge drying beds by adding mechanical sludge dewatering. • Adding fill to approximately two feet above flood stage around the primary treatment facilities to provide full access during a 100-year storm. The required elevation for the fill would be approximately 70 feet. • Reduce the size of the sludge drying beds so that they occupy the northern portion of the existing bed area and line the beds with cement or concrete to prevent wastewater in the biosolids from seeping into the underlying soil. ---PAGE BREAK--- mo606mpm4-6887.cdr Figure 5.3 PRIMARY TREATMENT ALTERNATIVE 1 CONCEPTUAL LEVEE CONSTRUCTION SUTTER AVENUE FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Approximate Scale 0’ 200’ LEGEND 100-Year Flood Plain Berm Construction Concrete Wall (Construction) 5-10 ---PAGE BREAK--- FINAL - March 2007 5-11 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Under this approach, the reduction of cross-sectional area for the flood plain would be significantly reduced. This may improve hydraulic conditions and potentially mitigate upstream restrictions created by adding fill. The treatment capacity of the existing sludge drying beds appears to be adequate for the projected build-out flows. However they are currently unlined and it is likely that future regulations will severely impact the viability of existing operations. For cost estimating purposes, it was assumed that the sludge drying beds would be lined to prevent migration of subnatant to the groundwater. An alterative to continuing with the use of sludge drying beds is to add mechanical sludge dewatering. Mechanical sludge dewatering would consist of belt filter presses or centrifuges. For discussion purposes, belt filter presses were assumed. Table 5.3 summarizes the design criteria for mechanical sludge dewatering at the Sutter Avenue facility. Table 5.3 Design Criteria for Sludge Dewatering at Sutter Avenue Primary Plant Wastewater Master Plan Phase 2 Update City of Modesto, California Items Units 2030 Loading/Criteria (At 41.5 mgd) Digested Sludge Characteristics Solid Feed (primary sludge only) lb/day 58,500 % Solids % 3% Hydraulic feed rate gpm 550 Belt Filter Press No. of Units 4 Belt Width Meters 2 Hydraulic Capacity, ea. gpm 160 Solids Loading Rate lb/hr/m 1,025 Operating Time 5 days/week, 10 hours/day Sludge Cake % Solids % 18% Sludge Cake Loadings Wet tons/day 155 Sludge Cake Volume Cubic ft/day 5,000 Sludge Drying Beds Area Acres 5.8 Figure 5.4 is a conceptual layout of a sludge dewatering facility and sludge cake drying beds. It is assumed that sludge cake would be trucked to the drying beds. Daily trucking of dewatered sludge to the Jennings Road site and eliminating the need for drying beds at the Sutter plant was also considered. However, this approach was eliminated at this time because of concerns that the trucking operation would impact city streets and residents. This approach should be evaluated further during preliminary design. ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 5-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Flood protection would be provided by constructing a concrete retaining wall around the existing primary clarifiers and the south side of the anaerobic digesters. Fill would also be added around the sludge cake drying beds. Flood stage for a 100-year storm, according to the FEMA flood zone map, would range from elevations 67 and 68. Figure 5.5 presents cross-sectional views of the filled areas. Approximately 199,000 cubic yards of fill would be required. Conceptual cost estimates indicate that costs for mechanical sludge dewatering and adding fill to the site would be similar to the costs estimated for retaining and lining the existing sludge drying beds,, and adding a perimeter flood protection wall The cost-effectiveness of both alternatives should be evaluated in preliminary design. 5.4.1.4 Preliminary Unit Process Sizing Design criteria for the new digester included in Primary Treatment Alternative 1 is presented in Table 5.4. The sizing is preliminary and was used to develop a conceptual cost estimate for this alternative. If this alternative is selected a more comprehensive analysis should be completed during preliminary design of these facilities. Table 5.4 Preliminary Unit Process Sizing for Primary Treatment Alternative 1 Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Anaerobic Digester Number – 1 Diameter ft 104 Volume MG 2.0 Notes: Preliminary sizing assumes projected build-out flow conditions. The process sizing calculations for this alternative are provided in Appendix L. Figure 5.6 shows the layout of the new facilities. 5.4.2 Alternative 2: Relocate Primary Treatment Facilities to Jennings Road In addition to the common improvements required for both alternatives, the following additional improvements would be required for this alternative: • Demolition of the existing primary treatment facilities at Sutter Avenue. • New primary treatment facilities at Jennings Road. • New anaerobic digesters at Jennings Road. • New sludge dewatering facilities at Jennings Road. ---PAGE BREAK--- mo606mpf36-6887.cdr (Sludge Bed Section. jpg) Figure 5.5 TYPICAL SECTIONS FOR FILLED AREAS PROJECT SUTTER AVENUE FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 5-14 ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 5-16 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Figure 5.7 shows the facilities at Sutter Avenue that would be either demolished or modified as part of this alternative. Figure 5.8 shows a conceptual layout of the new primary treatment and solids handling facilities at Jennings Road (Alternative 5.4.2.1 Demolition of Existing Primary Treatment Facilities at Sutter Avenue The cost analysis for this alternative assumes that the following existing primary treatment facilities and associated solids handling facilities would be demolished: • Primary Clarifier Nos. 1 and 2. • Primary sludge and scum pumping. • Primary flotators. • Abandoned spiro-vortex chamber. • Anaerobic Digester Nos. 1 through 5. • Sludge Drying Bed Nos. 11 through 24. 5.4.2.2 Primary Treatment Facilities at Jennings Road This alternative assumes that the headworks facility would be maintained at Sutter Avenue. Screened and de-gritted domestic wastewater would flow by gravity to the new primary effluent pump station and would then be piped to Jennings Road via the upgraded primary effluent outfall during the dry season, and via both outfalls during the wet season. The new primary treatment facilities at Jennings Road would consist of three new 165-foot diameter primary clarifiers (build-out), primary sludge and scum pumping, and associated flow splitting yard structures. By constructing a greater number of primary clarifiers, the primary treatment facilities would have increased redundancy and improved operation during low flows. The new clarifiers would have the same surface area as those at Sutter Avenue and be located near the existing fixed film reactors at Jennings Road. 5.4.2.3 Solids Handling Facilities at Jennings Road Primary sludge would be pumped to new anaerobic digesters and the digested sludge would be conveyed to new sludge drying beds. The solids handling facilities would be designed to have the same capacity as with the Sutter Avenue alternative. The required surface area of the sludge drying beds would be approximately 35 acres. The drying beds would be lined with either soil cement or concrete. A decant structure would be installed in each drying bed to allow for drainage of the leachate. The flow collected in each decant structure would be piped to a common decant pump station and returned to the primary clarifier influent flow split structure. The cost estimate also assumes that groundwater-monitoring wells would be installed upgradient and downgradient of the drying beds. ---PAGE BREAK--- Figure 5.7 PRIMARY TREATMENT ALTERNATIVE 2 PROPOSED MODIFICATIONS TO SUTTER AVENUE FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Biofilters Headworks Ferric Chloride Facility Pumping Plant No. 3 Approximate Scale 0’ 100’ LEGEND Existing Facilities Abandoned Facilities Modified Facilities mo606mpm6-6887.cdr New Primary Effluent Pump Station Approximately 21.2 Acres of Sludge Drying Beds to be Abandoned New Facilities Control Building New Influent Screw Pump New Barscreen New Grit Removal Facilities 5-17 ---PAGE BREAK--- Approximately 35 Acres Sludge Drying Beds Figure 5.8 PRIMARY TREATMENT ALTERNATIVE 2 PROPOSED PRIMARY TREATMENT AND SOLIDS HANDLING FACILITIES AT JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 5-18 Primary Clarifiers Anaerobic Digesters Approximate Scale 0’ 100’ LEGEND New Facilities at Buildout mo606mpm17-6887.cdr ---PAGE BREAK--- FINAL - March 2007 5-19 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc 5.4.2.4 Preliminary Unit Process Sizing A summary of the unit process sizing for Primary Treatment Alternative 2 is presented in Table 5.5. The sizing is preliminary and was used to develop a conceptual cost estimate for this alternative. If this alternative is selected, a more comprehensive analysis should be completed during preliminary design of these facilities. The process sizing calculations for this alternative are provided in Appendix M. Table 5.5 Preliminary Unit Process Sizing for Primary Treatment Alternative 2 Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Primary Clarifiers Number of basins – 3 Type – Circular Diameter, each ft 165 Anaerobic Digesters Number – 3 Diameter ft 104 Depth ft 32 Sludge Drying Beds Total surface area acres 35 Side water depth ft 2 Storage capacity days 110 Notes: Preliminary sizing assumes projected build-out flow conditions. 5.5 ALTERNATIVES SCREENING This section presents a comparison of the primary treatment alternatives on both an economic and non-economic basis. 5.5.1 Non-Economic Comparison The advantages and disadvantages associated with each alternative are presented in Table 5.6. 5.5.2 Cost Comparison The costs for adopting the two alternatives are compared in Table 5.7. A more detailed breakout of the cost estimate for each alternative is presented in Appendix N. ---PAGE BREAK--- FINAL - March 2007 5-20 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc Table 5.6 Non-Economic Comparison of Primary Treatment Alternatives Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Advantages Disadvantages 1 - Maintain Primary Treatment at Sutter Avenue • Fewer capital improvements required. • The Sutter Avenue facilities lie within the 100-year flood plain. • Remaining life for existing primary clarifiers and anaerobic digesters is unknown. • It may be difficult to permit the construction of the floodplain levee (Corps of Engineers). 2 - Move Primary Treatment to Jennings Road • Primary and secondary treatment facilities would be located on a common site. • New primary treatment facilities would have increased reliability and redundancy. • New primary treatment facilities would have a much longer useful life compared to the existing primary clarifiers at Sutter Avenue. • More capital improvements required. Table 5.7 Primary Treatment Alternatives Conceptual Cost Estimate Wastewater Master Plan Phase 2 Update City of Modesto, California Costs in Alternative 1 Primary at Sutter Alternative 2 Move Primary to Jennings Road Common Improvements $25.2 $25.2 Flood Protection/Stormwater PS $16.0 - Primary Treatment Improvements - $49.4 Sludge Dewatering Improvements $12.4 $38.7 Project Cost $53.6 $113.3 Notes: Conceptual costs assume build-out flow conditions. Costs are presented in today’s dollars (June 2006), San Francisco Engineering News Record Construction Cost Index (ENRCCI) = 8441. Include allowance for contingencies, engineering, legal, and administrative expenses. ---PAGE BREAK--- FINAL - March 2007 5-21 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\05.doc 5.6 RECOMMENDED ALTERNATIVE FOR PRIMARY TREATMENT Based on the results of the non-economic and cost analyses, it is recommended that the primary treatment facilities at Sutter Avenue be upgraded and remain at their current site (Alternative ---PAGE BREAK--- FINAL - March 2007 6-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Chapter 6 EVALUATION OF DOMESTIC EFFLUENT DISPOSAL ALTERNATIVES 6.1 INTRODUCTION This chapter describes alternatives for increasing the City’s current domestic effluent disposal capacity. Decisions made regarding effluent disposal will ultimately affect the alternatives evaluated for secondary and tertiary treatment. Therefore, the evaluation of disposal alternatives is presented first, and alternatives for BNR/Tertiary treatment facilities will be presented in Chapter 7. This chapter includes an evaluation of near term and long- term alternatives to expand effluent disposal capacity. It should be noted that it is the preferred approach to continue the current practice of land application of segregated cannery process water. Detailed scientific studies are anticipated to be required to verify appropriate land application rates and methodologies. The analysis presented herein will focus on the disposal of domestic wastewater flows. 6.2 NEAR-TERM CAPACITY IMPROVEMENTS In March 2006, Carollo Engineers completed the Domestic Wastewater Near-Term Capacity Study. The study evaluated alternatives to obtain effluent disposal capacity for anticipated development that is expected to occur between 2006 and 2011. The required increase in capacity for this period is estimated to be 2.3 million gallons per day (mgd). The study report is included in Appendix O. Six alternatives to meet near term capacity needs were considered. Table 6.1 summarizes the alternatives. The findings and recommendations were: • Establish 10th percentile San Joaquin River (SJR) flow as the baseline condition for design of facilities and to minimize risks of exceeding WDR/NPDES permit requirements. • Construct the dissolved air flotation (DAF) project for algae removal as soon as practicable. Review design concepts to verify consistency with long-term treatment options. • Review all aspects of the operation of the existing disposal facilities to identify and correct any inefficiencies. • Proceed with the implementation of Title 22 (tertiary) treatment for year round discharge to meet near term capacity needs. • Proceed with Alternative 2 - Tertiary treatment for 2.3 mgd capacity as soon as practicable. ---PAGE BREAK--- FINAL - March 2007 6-2 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Table 6.1 Alternatives to Provide Near Term Effluent Disposal Capacity Wastewater Master Plan Phase 2 Update City of Modesto Alternative Description Requirements Pros Cons 1 Additional land for disposal of secondary effluent • 477 acres of additional land. • DAFs for algae removal. • Land may be acquired in a relatively short time if there are willing sellers. • Consistent with current NPDES permit. • City has already completed CEQA for land acquisition. • Provides additional land for cannery process flows. • Will re-open the provisions of the existing WDRs. • May require land acquisition process if land owners are not willing to sell. 2 Tertiary treatment - discharge to river year round • 2.3 mgd tertiary facility at Jennings Road. • DAFs for algae removal. • Additional Disinfection. • Eliminates land acquisition issues. • Eliminates need to re-open WDRs. • Will require modifications to NPDES permit • Does not provide additional land for cannery process flows. • Integration into future facilities will be more costly. 3 Increased river flow • Purchase of water rights, DAFs for algae removal. • No permit revisions required. • Requires complex agreements. • Will not produce land or treatment facility that could be used in future (other than DAFs). 4 Revise NPDES permit • No structural. • No construction cost. • Anti backsliding requires legal, consulting. • Regional Board indicated this approach would not be acceptable without additional treatment. 5 DAF only • DAF for algae removal. • Low cost. • No permit revisions required. • Increased exposure to risk of exceeding capacity. 6 No Project • No Cost. • Highest exposure to risk of exceeding capacity. ---PAGE BREAK--- FINAL - March 2007 6-3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Many of the findings of the near term capacity study are applicable for long-term wastewater disposal 6.3 DEVELOPMENT OF ALTERNATIVES FOR LONG-TERM CAPACITY Four long-term disposal capacity expansion alternatives were identified to meet future disposal requirements. Alternatives 1 and 2 were developed to evaluate the assumption that the City’s NPDES permit would continue to allow secondary effluent discharges to the SJR seasonally. Alternative 1 consists of adding BNR/tertiary treatment and year-round discharge of tertiary effluent incrementally to expand the domestic effluent disposal capacity. Land disposal and secondary treatment would remain the same. Under Alternative 2, land would be added to expand domestic effluent disposal capacity. Alternatives 3 and 4 address the scenario that secondary effluent discharges to the river will not be allowed in the future. Alternative 3 evaluates the concept of adding BNR/tertiary treatment, year-round discharge to increase disposal capacity for incremental flows. Alternative 4 evaluates the zero discharge concept (all domestic effluent applied to land). The alternatives are described in the subsequent sections of this chapter. 6.3.1 Long-Term Alternative 1: Current Land Disposal, Continued Seasonal Secondary Effluent Discharge, BNR/Tertiary Year-Round Discharge In this alternative, the current methods of maximizing secondary effluent disposal to land and storing excess secondary effluent for river discharge during the allowable months would be continued. Segregated cannery process water would also continue to be disposed on land. New treatment facilities would be added to alleviate the current disposal deficiencies and to accommodate the expected increase in domestic wastewater flows over the planning period. The new facilities would treat a portion of the incoming domestic wastewater with biological nutrient removal (BNR) and tertiary treatment processes. Based on experience with other municipal discharges to the SJR, it is anticipated that the Regional Board will allow discharge of tertiary effluent to the SJR on a year-round basis and without a dilution requirement. This concept was discussed with the Regional Board staff. Figure 6.1 shows a graphical representation of this alternative. 6.3.2 Long-Term Alternative 2: Additional Land for Irrigation, Continued Seasonal Discharge of Secondary Effluent As in Alternative 1, the current methods of maximizing secondary effluent disposal to land and storing excess secondary effluent for river discharge during the allowable months would be continued in Alternative 2. Segregated cannery process water would continue to be disposed on land. Instead of moving toward tertiary treatment, however, Alternative 2 involves the purchase of more land adjacent to the Modesto Ranch to accommodate the ---PAGE BREAK--- Domestic Wastewater Primary Treatment (Sutter Ave) Secondary Treatment (Jennings Road) Beneficial Food Industry Process Water Storage Reservoirs Oct-Nov and May San Joaquin River Existing Facilities LEGEND New Facilities Additional Land Figure 6.1 EFFLUENT DISPOSAL ALTERNATIVE 1 - CONTINUE LAND DISPOSAL/SEASONAL SECONDARY EFFLUENT DISCHARGE, ADD BNR/ TERTIARY FOR YEAR-ROUND DISCHARGE WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Reuse DAF BNR Tertiary mo606mpf29a-6887.ai 6-4 ---PAGE BREAK--- FINAL - March 2007 6-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc current disposal deficiencies and the expected increase in domestic wastewater flows over the planning period. See Figure 6.2 for a graphical representation of this alternative. 6.3.3 Long-Term Alternative 3: Land Disposal, BNR/Tertiary Facilities for all River Discharges, Year-Round Alternative 3 is based on the premise that at some point in time, secondary effluent will no longer be allowed to be discharged to the SJR. Nearby communities that discharge to the San Joaquin or Delta, such as Tracy, Turlock, Manteca, Lodi, and Merced have recently been required to upgrade from secondary treatment to tertiary treatment. It is assumed that discharging tertiary effluent to the river would be performed year round and would not be subject to a dilution requirement. See Figure 6.3 for a graphical representation of this alternative. 6.3.4 Long-Term Alternative 4: All Land Disposal (No River Discharge) As with Alternative 3, this alternative assumes that in the future, permit restrictions will preclude the discharge of secondary effluent to the SJR. However, in Alternative 4, land disposal would be used instead of BNR/tertiary facilities to provide the necessary disposal capacity. Additional land would be acquired as needed to dispose of future increases in domestic wastewater flow. Alternative 4 is shown graphically in Figure 6.4. 6.4 ALTERNATIVES SCREENING The screening of treatment alternatives was done in a similar manner to that of the primary treatment alternatives by comparing the alternatives on both an economic and non- economic basis. 6.4.1 Non-Economic Factors Qualitative advantages and disadvantages of each alternative are presented in Table 6.2. 6.4.2 Cost Comparison Relative capital and annual costs were developed for each alternative. The assumed process train for BNR/tertiary would consist of aeration basins sized for nitrification/denitrification, secondary clarifiers, high-rate flocculation/sedimentation, cloth disk filters, ultraviolet (UV) radiation for disinfection, and post-aeration with mechanical aerators. Land costs, including improvements, are estimated to be $34,000/acre (June 2006 dollars). See Appendix P for the derivation of land cost estimates. Unit costs for treatment Appendix P for the derivation of land cost estimates. Unit costs for treatment processes ---PAGE BREAK--- Domestic Wastewater Primary Treatment (Sutter Ave) Secondary Treatment (Jennings Road) Beneficial Food Industry Process Water Storage Reservoirs DAF San Joaquin River Figure 6.2 EFFLUENT DISPOSAL ALTERNATIVE 2 - MORE LAND FOR IRRIGATION, CONTINUE SEASONAL DISCHARGE OF SECONDARY EFFLUENT WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Reuse 3,876 Acres Oct-Nov and May Existing Facilities LEGEND New Facilities Additional Land mo606mpf30-6887.ai 6-6 ---PAGE BREAK--- Domestic Wastewater Primary Treatment (Sutter Ave) Secondary Treatment (Jennings Road) Beneficial Food Industry Process Water BNR Tertiary Storage Reservoirs San Joaquin River Figure 6.3 EFFLUENT DISPOSAL ALTERNATIVE 3 - CONTINUE LAND DISPOSAL OF SECONDARY EFFLUENT, BNR/TERTIARY TREATMENT FOR ALL RIVER DISCHARGES YEAR ROUND WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Reuse Existing Facilities LEGEND New Facilities Additional Land mo606mpf31-6887.ai 6-7 ---PAGE BREAK--- Domestic Wastewater Primary Treatment (Sutter Ave) Secondary Treatment (Jennings Road) Beneficial Food Industry Process Water Storage Reservoirs 2,978 MG San Joaquin River Figure 6.4 EFFLUENT DISPOSAL ALTERNATIVE 4 - LAND APPLICATION ONLY (ZERO DISCHARGE) WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Reuse 6,161 Acres Existing Facilities LEGEND New Facilities Additional Land mo606mpf32-6887.ai 6-8 ---PAGE BREAK--- FINAL - March 2007 6-9 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Table 6.2 Non-Economic Comparison of Disposal Alternatives Wastewater Master Plan Phase 2 Update City of Modesto, California Disposal Alternative Description Requirements Pros Cons 1 Current Land Disposal/Seasonal Secondary Effluent Discharge, and Addition of BNR/Tertiary Facilities. • 17.3 mgd BNR/Tertiary Facility at Jennings Road. • DAFs for algae removal. • Additional Disinfection. • City is positioned to accommodate possible future permit restrictions on secondary effluent discharge to river. • Reuse water would be available. • New treatment processes for facilities staff to operate. • Long-term river discharge of secondary effluent may not be viable. 2 Current Land Disposal, Seasonal Secondary Effluent Discharge, and Addition of More Land for Land Disposal. • 3,876 acres of additional land. • DAFs for algae removal. • Disposal capacity unaffected by San Joaquin River flows. • Additional land will reopen the City’s existing WDRs. May require land acquisition process, and potentially, lining of existing ponds. • Long tern river discharge of secondary effluent may not be viable. 3 Current Land Disposal and BNR/Tertiary Facilities for All River Discharge (discontinue secondary effluent discharges to River). • 27.5 mgd BNR/Tertiary facility at Jennings Road. • DAFs for algae removal. • Additional disinfection. • City is positioned to accommodate possible future permit restrictions on secondary effluent discharge to river. • Reuse water would be available. • Disposal capacity unaffected by San Joaquin River flows. • Overall size of wastewater facilities –including land disposal site - will be the most compact. • New treatment processes for facilities staff to operate (increased operation and maintenance [O&M] costs). 4 Additional Land for Zero Discharge to River. • 6,161 acres of additional land. • DAFs for algae removal. • Disposal capacity unaffected by San Joaquin River flows. • Overall facility size will be the largest. • Additional land will reopen the City’s existing WDRs. May require land acquisition process, and potentially, lining of existing ponds. • Large amount of land difficult to acquire. ---PAGE BREAK--- FINAL - March 2007 6-10 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc were developed from similar projects recently completed by Carollo. The unit costs are summarized in Table 6.3. Table 6.4 summarizes the prorated water balance and the allocation of capacities among land disposal, secondary effluent to the river, and BNR/tertiary discharge to the river for each case. Table 6.5 presents the comparison of capital, O&M, and annualized costs for the four alternatives. 6.5 RECOMMENDED ALTERNATIVE Alternative 2 (continued seasonal secondary effluent discharge to the river and the purchase of an additional 3,876 acres of land) has a lower total cost than other alternatives. Nonetheless, it is not considered viable in the long-term due to the unlikely ability to continue the discharge of secondary effluent to the SJR. In addition, the ability to obtain and permit and additional 3,876 acres of land is also questionable. For similar reasons, Alternatives 1 and 4 are also not considered viable. It is the City’s desire to pursue the phased implementation of Alternative 3. It is believed this alternative provides the best long-term flexibility and reliability for wastewater disposal and beneficial reuse. Maximum use of existing storage and land application system is warranted while moving forward towards ultimate achievement of high quality treatment standards to achieve water quality objectives for the SJR and delta system. ---PAGE BREAK--- FINAL - March 2007 6-11 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Table 6.3 Estimated Unit Prices Wastewater Master Plan Phase 2 Update City of Modesto Unit Process Unit Costs(1) BNR/Tertiary Treatment Secondary Effluent PS $0.23/gpd BNR Aeration Basins and Blowers 0.92 Secondary Clarifiers 1.44 RAS/WAS Pump Station 0.43 High Rate Floc/Sed 0.80 Tertiary Filters 0.56 Chemical Storage 0.30 UV Disinfection 0.81 Post Aeration 0.42 Gravity Belt Thickener & Building 0.71 Sludge Drying Beds 0.52 Sludge Pump Station 0.52 Total BNR/Tertiary Treatment $7.661/gpd Land Purchase Cost $34,000/acre Storage Reservoirs $9,500/mg Note: Conceptual level costs. Based on June 2006 dollars (ENRCCI = 8441). Includes allowances for contingencies, engineering, legal, and administrative expenses. Abbreviations: gpd - gallons per day of capacity mg - million gallons ---PAGE BREAK--- FINAL - March 2007 6-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Table 6.4 Required Additional Capacity at Buildout of SOI and Unincorporated Areas Currently Not Served(1) Wastewater Master Plan Phase 2 Update City of Modesto Alternative 1 Current Disposal Practices and Add BNR/Tertiary Facilities (No additional land) Alternative 2 Current Disposal Practices and Add More Land Alternative 3 Current Land Disposal and BNR/Tertiary for All River Discharge (No secondary effluent discharge) Alternative 4 All Land Disposal (No river discharge) Domestic Flow at Buildout 41.5 41.5 41.5 41.5 Existing Capacity, mgd: Losses from Ponds (evap/perc.) 5.9 5.9 5.9 5.9 Land Application 8.1 8.1 8.1 8.1 Secondary Effluent to River 10.2 10.2 0 0 Total Existing Capacity 24.2 24.2 14.0 14.0 Additional Disposal Capacity Required 17.3 17.3 27.5 27.5 Land Requirements: Current Land Application Area, acres 2,526 2,526 2,526 2,526 Estimated Average Application Rate (Domestic and Cannery), ft/acre/year(2) 5.0 5.0 5.0 5.0 Additional Domestic Effluent Disposal Needs, ac-ft/yr 19,378 19,378 30,803 30,803 Additional Land-Required, acres 0 3,876 0 6,161 Storage Requirements: Current Storage Capacity, MG 2,553 2,553 2,553 2,553 Additional Storage Volume, MG 0 0 0 2,978 Total Storage Volume, MG 2,553 2,553 2,553 5,531 Additional Land for Storage (at 12.5 ft deep), acres 0 0 0 730 Notes: All cases assume condition of average rainfall, lowest 10th percentile river flow for secondary effluent disposal capacity requirements. Additional land application rate was assumed to be 5 ft/year. Segregated cannery flow is assumed to remain constant at 4,480 ac-ft/yr. ---PAGE BREAK--- FINAL - March 2007 6-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\06.doc Table 6.5 Annual Cost Analysis(1) Wastewater Master Plan Phase 2 Update City of Modesto Capital Costs - $ Million Operating and Maintenance Costs - $Million/Year(2) Alternative DAF(3) BNR/ Tertiary Treatment Irrigation Land Storage Pond Total Capital BNR/ Tertiary Treatment Land/ Storage Ponds Total O&M O&M Present Worth, $M(4) Total Present Worth, $M Alternative 1 - Current Disposal Practices; BNR/Tertiary Facilities $11.0(4) $132.5 $0 $143.5 $0.94 $0.04 $0.98 $12.2 $155.7 Alternative 2 - Current Disposal Practices; Addition of More Land $11.0 $131.8 $142.8 $0.20 $0.20 $2.5 $145.3 Alternative 3 - Current Land Disposal Practice; BNR/Tertiary for All River Discharge $11.0 $210.7 $0 $221.7 $1.50 $0.04 $1.54 $19.2 $240.9 Alternative 4 - Land Disposal for All Flows $209.5 $53.1 $262.6 $0.30 $0.30 $3.7 $266.3 Note: June 2006 dollars. ENRCCI = 8441. Includes allowances for contingencies, engineering, legal, and administrative costs. Incremental O&M costs only. Estimates by Brown and Caldwell. Based on P/A, and 20-year return period. ---PAGE BREAK--- FINAL - March 2007 7-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Chapter 7 EVALUATION OF BNR/TERTIARY TREATMENT ALTERNATIVES 7.1 INTRODUCTION Chapter 6 included a recommendation to add biological nutrient removal (BNR)/Tertiary treatment for year-round river discharge to incrementally increase domestic effluent disposal capacity. Based on discharge requirements for other municipal discharges to the San Joaquin River, it is assumed that year round discharges to the San Joaquin River will require removal of ammonia and, in the future, removal of nitrogen to comply with the dissolved oxygen (DO) and total maximum daily load (TMDL) requirements. In addition, it is assumed that year-round discharges will require tertiary treatment consistent with California Title 22 standards. New discharge limits will have stringent requirements for trihalomethanes (THMs). Alternative disinfection processes, such as ultra violet (UV) disinfection, may be required instead of chlorine disinfection to satisfy THM limits. Facultative pond effluent contains organic carbon, a precursor to THM formation, as well as fine particles form algae that reflect light and diminish the effectiveness of UV. 7.2 PLANNING ASSUMPTIONS In developing alternatives for BNR/Tertiary treatment, the following assumptions were made: • Domestic wastewater treatment alternatives will be evaluated independently from segregated cannery wastewater. Cannery waste treatment alternatives will be evaluated in a separate study outside this master plan. • All 2,526 acres of ranchland are available for irrigation. • Average annual segregated cannery process water flow (seasonal volume distributed over 12 months) is 4.0 million gallons per day (mgd) and will not increase over the planning period. • Land disposal application rates will remain at current rates. • Current average annual secondary effluent river disposal capacity is 10.2 mgd. This is based on the following conditions: – All storage reservoirs are in service. – River flows are at the lowest 10th percentile. – Operation without contingency safety factor. • No additional land will be purchased for irrigation. Adding land would likely “reopen” requirements for land application, according to the Regional Board. ---PAGE BREAK--- FINAL - March 2007 7-2 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc • Long-term waste discharge requirements (WDRs) and National Pollutant Discharge Elimination System (NPDES) permit conditions will be as follows: – No change to land application practices (biochemical oxygen demand [BOD] loadings and hydraulic loadings). – Current seasonal discharge of secondary effluent will be allowable until 2016. By 2016, all river discharges must meet Title 22 tertiary standards and ammonia toxicity criteria (nitrification). It is assumed that full tertiary treatment of river discharges will be included in the 2011 NPDES permit renewal, and a 5-year compliance schedule. – Year-round tertiary discharge of a portion of the flow will be allowable in year 2009. – Denitrification will be required by 2016. – THM compliance will be achieved by UV disinfection for the long-term. In the interim, it is assumed that THM limits will be met by applying dilution credits. • Treatment and storage ponds will not require lining. • Metals limitations, as contained in the California Toxics Rule, will be included in 2011 NPDES permit. • Total dissolved solids (TDS) removal is not included in this master plan. It is assumed that TDS will be controlled by source control and supplementing groundwater with surface water for the City’s drinking water supply. TDS limits and requirements are still being considered by regulators. • The dissolved air flotation (DAF) units will be online by 2008 and will add average annual river discharge capacity of 3.0 mgd. • The near-term capacity facilities (Phase 1A) will be utilized as standby contingent capacity after 2016. 7.3 BNR/TERTIARY CAPACITY REQUIREMENTS As described previously, the capacity needs are based on the 10th percentile river flow and projected wastewater flows. Table 7.1 lists the projected effluent disposal capacity needs for river discharge through the year 2030, the projected date of buildout of the City’s sphere of influence. The required additional capacity at 2030 is projected to be 27.5 mgd. Figure 7.1 is a graphical representation of the projected capacity needs. ---PAGE BREAK--- FINAL - March 2007 7-3 H:\FINAL\MODESTO_WCO\6887E00\RPT\MASTERPLANRPT\FINAL\07.DOC Table 7.1 BNR/Tertiary Treatment Capacity Requirements Wastewater Master Plan Phase 2 Update City of Modesto, California 1 2 3 4=2+3 5=1-4 6 7 8 9 10 11=7+8+9+10 12=4+6+11 13=12-1 Capacity Additions Year Population Average Annual Flow (mgd) Secondary Effluent to Land (mgd) Secondary Effluent to River, mgd(3) Total Disposal Capacity Existing Facilities (mgd) Additional Disposal Capacity Required (mgd) DAF Addition (mgd) Phase 1A Phase 1B Phase 2 Phase 3 Total BNR/Tertiary Capacity (mgd) Total Disposal Capacity (mgd) Excess Disposal Capacity Available (mgd) 2005 219,900 25.8 14.0 10.2 24.2 1.6 - - - - - 0.0 24.2 -1.5 2008 229,500 26.8 14.0 10.2 24.2 2.6 3.0 - - - - 0.0 27.2 0.4 2009 233,200 27.1 14.0 10.2 24.2 2.9 3.0 2.3 - - - 2.3 29.5 2.4 2011 240,500 28.1 14.0 10.2 24.2 3.9 3.0 2.3 2.5 - - 4.8 32.0 3.9 2016 267,400 31.3 14.0 10.2 24.2 7.1 3.0 2.3 2.5 - - 4.8 32.0 0.7 2016 267,400 31.3 14.0 0 14.0 17.3 2.5 20.0 - 22.5 36.5 5.2 2023 309,100 36.2 14.0 0 14.0 22.2 - - 2.5 20.0 5.0 27.5 41.5 5.3 2026 328,300 38.4 14.0 0 14.0 24.4 - - 2.5 20.0 5.0 27.5 41.5 3.1 2030 355,000 41.5 14.0 0 14.0 27.5 - - 2.5 20.0 5.0 27.5 41.5 0.0 Notes: Assumes secondary effluent discharges to river and discontinued in 2016. DAF would no longer be used for effluent treatment and its use would be reassigned. Assumes Phase 1A (near-term improvements) will be discontinued after Phase 2 is initiated. Based on lowest 10th percentile river flow assumtion. ---PAGE BREAK--- 27.2 29.5 32.0 36.5 41.5 24.2 14.0 5.9 Year * Based on 10th percentile river flow conditions. Assumes discontinuation of secondary effluent discharge to river in 2016 and phase out of DAF and Phase 1A Capacity for Land Discharge Capacity for River Discharge Capacity for Tertiary-Treated Effluent Discharge Capacity Deficiencies Domestic Wastewater Flow, mgd 2005 50 40 30 20 10 0 2010 2011 2008 2009 2015 2016 2020 2025 2023 2030 Projected Domestic Wastewater Flow (annual average flow) Domestic secondary effluent to land (8.1 mgd) (2,526 acres) Net evaporation loss (5.9 mgd) DAF (3.0 mgd) Seasonal river discharge of secondary effluent (10.2 mgd*) BNR/tertiary river discharge** Figure 7.1 DOMESTIC WASTEWATER CAPACITY REQUIREMENTS WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO mo606mpf13-6887.ai 7-4 ---PAGE BREAK--- FINAL - March 2007 7-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc 7.4 NEAR-TERM CAPACITY IMPROVEMENTS Included in all alternatives are near-term improvements (see discussion in Chapter It is assumed that the near-term improvements will consist of adding DAF for algae removal from pond effluent, nitrification, and filtration. The capacity of the near-term improvements will be 5.3 mgd, and will provide sufficient capacity until year 2011. 7.5 IMPROVEMENTS TO THE EXISTING SECONDARY TREATMENT FACILITIES This section identifies the improvements that are associated with the existing secondary treatment train at the Jennings Road Facility. These improvements are common to all BNR/Tertiary alternatives described in Section 7.6. 7.5.1 Fixed Film Reactors (FFRs) There are three existing FFRs at the Jennings Road Facility. As described in Chapter 3, primary effluent from the Sutter Avenue Facility is conveyed to the FFR Influent Mixing Box and flows by gravity to the wet well of the FFR Pump Station, where flow is split between the FFRs. Plant staff currently split flow between FFR Nos. 1 and 3. FFR No. 2 is normally off-line because it is not required to treat current BOD loadings. The original influent distributor mechanisms on FFR Nos. 1 and 3 have recently been replaced with stainless steel units. The influent distributor mechanism in FFR No. 2 has not been replaced and, according to plant staff, is seriously corroded. In order to bring FFR No. 2 back on-line, the influent distributor mechanism should be replaced and upgraded to stainless steel to avoid future problems with corrosion. Plant staff has also indicated that the plastic media in FFR No. 2 should also be replaced. Therefore, the conceptual cost estimates include an allowance for media replacement for FFR No. 2. 7.5.2 Dissolved Air Flotation (DAF) The City will be constructing a new DAF facility to remove algae from the secondary effluent in order to increase the river discharge capacity of the Jennings Road Facility. Algae grows in the facultative and storage ponds during the summer months, which leads to an increase in the pond effluent total suspended solids (TSS) concentration. Assuming all effluent water quality limits are met, the City’s current NPDES permit allows discharge to the river between October 1 and May 31. However, the TSS concentration in the treatment and storage pond effluent (due to the algae) typically precludes the City from taking advantage of this effluent disposal option during the months of October and November and sometimes May. Thus, the City’s discharge period is effectively reduced to a total of 5 months. By bringing the DAF facility on-line to remove algae from the storage pond effluent, the City ---PAGE BREAK--- FINAL - March 2007 7-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc would be able to fully utilize the river disposal option for the full 8-month period allowed in the discharge permit. It was assumed for this analysis that the new DAF facility would be online by the year 2008. Appendix Q contains a feasibility study for the DAF project and predicted DAF effluent quality. 7.5.3 Phase 1A Improvements Phase 1A includes the addition of an initial 2.3 mgd of nitrification/tertiary facilities as described in Chapter 6 and Appendix O herein. Preliminary design will verify final process selection. For the purposes of this master plan, the use of nitrifying trickling filters followed by high rate flocculation/sedimentation and filtration has been assumed. 7.5.4 Secondary Effluent Chlorination Facilities The City currently operates a gaseous chlorine disinfection system at the Jennings Road Facility for disinfection of secondary effluent prior to river discharge. There are safety risks associated with the use, storage, and transportation of chlorine gas. For this reason, the City has evaluated other disinfection methods in place of chlorination. In the Draft Alternative Disinfection Analysis, August 2005, the following four disinfection alternatives were evaluated: • Bulk Sodium Hypochlorite. • On-Site Sodium Hypochlorite Generation. • Ultraviolet Radiation. • Improvements to the existing Gaseous Chlorine system. A copy of this report is included in Appendix R. The alternatives were evaluated under the following criteria: safety, feasibility, ability to meet present and future discharge requirements, capital costs, and operations and maintenance (O&M) costs. Construction of new bulk sodium hypochlorite and bulk sodium bisulfite systems is recommended to replace gaseous chlorine and sulfur dioxide as the disinfection/dechlorination method for secondary effluent discharges. On-site sodium hypochlorite generation has the lowest present worth cost, but is not recommended because few on-site generation systems with capacity large enough to serve the Jennings Road Facility are in operation. The on-site systems of a similar size that are in operation have only been in operation 4 years or less. Ultraviolet disinfection of secondary effluent was not chosen because the pond effluent has low ultra violet light transmittance (UVT) values. Coagulated and filtered pond effluent yielded a UVT of 43 percent. A value of at least 55 percent is required for UV disinfection to be feasible. In addition, for UV to be effective the TSS concentration in the effluent must be ---PAGE BREAK--- FINAL - March 2007 7-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc 5 milligrams per liter (mg/L) or less to achieve the required coliform limit of 23 most probable number (MPN)/100 milliliters (ml). Filtration would be required to meet this TSS concentration. As discussed previously in Chapter 4 - Regulatory Requirements, it is anticipated that the new NPDES permit for river discharge will include stringent requirements for triholomethanes (THMs). Further testing of pond effluent that has undergone DAF treatment to remove algae will be required to predict future THM concentration in the effluent. However, based on previous experience, DAF alone may not be adequate to remove enough organic material to lower THM concentration to within the new permit limits, even if dilution credits are obtained. The City of Turlock Water Quality Control Facility has similar treatment processes that may be applicable for Modesto. The processes include: Fixed film reactors, activated sludge, high rate flocculation/sedimentation and filtration. The Turlock effluent was sampled to check for UV transmittance to predict potential UVT for Modesto’s effluent. The sample had a UVT of about 80 percent. See Appendix S for test results. UV disinfection is cost-effective at UVT levels above 55 percent. Assuming the Modesto effluent would have similar transmittance values as measured for Turlock, UV would be the preferred disinfection process for Title 22, year-round discharges. The recommended strategy for disinfection of secondary effluent discharges to the river is to continue chlorination and add DAF units. The DAFs will remove organic material and lower the concentration of THM precursors. It is assumed for this master plan that the lower organic material levels and reduced chlorination dosages will lower THM concentrations to within permit levels, including at least a 20:1 dilution factor. Full-scale testing will need to be done to confirm the effectiveness of the DAF in reducing THMs. The DAF may need to operate during the entire river discharge period to remove organic material. The DAF is currently sized for a capacity of 10 mgd. During most of the discharge season the required discharge flow will exceed 10 mgd. Therefore flows over 10 mgd will bypass the DAF. It is unknown at this time how the blended secondary/DAF effluent will affect THM levels. 7.5.5 Flood Protection Improvements Improvements to the flood control levees are required to prevent seepage from the river to the irrigation fields during periods of high river flows. Seepage may also be threatening the foundation of the existing chlorine building. Initial investigations indicate that improvements will be required to control ground subsidence near the chlorine building, improve the stability of the levees where sand boils have occurred and install a new retaining wall at the chlorine building. Condor Engineering developed a budget cost of $400,000 for these improvements in their preliminary investigation in May 2006 (see report in Appendix Some or all of the flood control work may be funded by the Federal Emergency ---PAGE BREAK--- FINAL - March 2007 7-8 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Management Agency (FEMA). It is assumed for this master plan that 50 percent of the levee improvement costs will be funded by FEMA, with the remainder funded by the City. 7.5.6 Outfall Improvements The outfall, from the effluent pump station to the river, should be replaced. The existing outfall is corroded and leaking in some locations. In addition, a diffuser may be added in the river bed to increase the initial dilution for effluent constituent with assimilative capacity in the river. Additional evaluation of the feasibility of a diffuser should be conducted in preliminary design. 7.6 DEVELOPMENT OF BNR/TERTIARY ALTERNATIVES Figure 7.1 (see page 7-4) presents the projected domestic effluent disposal capacity requirements for the Jennings Road Facility. As discussed previously, the preferred method to increase disposal capacity is to add treatment facilities that will allow year-round river discharge for a portion of the flow, without the need to meet the 20:1 dilution requirements. In order to meet the effluent water quality requirements for year-round river discharge, a new BNR/tertiary treatment facility is proposed. As shown in the figure, the BNR/tertiary facilities will need to be sized for an ultimate capacity of 27.5 mgd at projected build-out flow conditions. The project will be constructed in phases as required to meet BNR/tertiary capacity demands. A summary of project phasing is provided in Chapter 8. Three alternatives for BNR/tertiary treatment were evaluated: activated sludge, nitrifying trickling filters, and conversion of the recirculation channel to an extended aeration reactor. Each alternative was evaluated with the option of media filtration, or membrane filtration. Table 7.2 outlines the unit processes required for each alternative. Effluent filtration (sand or cloth disk filters) has a lower operating cost then membrane filtration, and it is relatively simple to operate. Coupled with a high-rate flocculation/sedimentation process, filtration may also remove a percentage of metals concentrations by precipitation. Membranes may also remove metals. Membranes are often perceived as the “best available control technology” for meeting the stringent metals limits contained in the State Implementation Plan (SIP) and California Toxics Rule (CTR). Membranes also would provide pretreatment for reverse osmosis membranes if they are required in the future to remove salts. 7.6.1 Alternative 1A - Conventional Activated Sludge, Media Filtration The facilities associated with Alternative 1A are outlined briefly below. The process schematic and conceptual layout for this alternative are provided in Figures 7.2 and 7.3, respectively. The design criteria are shown in Table 7.3. ---PAGE BREAK--- FINAL - March 2007 7-9 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.2 BNR/Tertiary Alternatives -Required Unit Processes Wastewater Master Plan Phase 2 Update City of Modesto, California Category Unit Processes Alternative 1A - Activated Sludge/Media Filtration • Aeration basins, designed for nitrification and denitrification • Secondary Clarification • Flocculation/ sedimentation • Filtration • UV Disinfection • Solids Handling Alternative 1B – Activated Sludge/ Membrane Filtration (MBR) • Aeration basins, designed for nitrification and denitrification • Membranes, in separate basin • UV Disinfection • Solids Handling Alternative 2A - Nitrifying Trickling Filter/Media Filtration • Nitrifying tricking filters • De-nitrifying filters • Flocculation/sedimentation • Filtration • UV Disinfection Alternative 2B – Nitrifying Trickling Filter/Membrane Filtration • Nitrifying trickling filters • De-nitrifying filters • Membranes • UV Disinfection • Filtration Alternative 3A - Conversion of Recirculation Basin/Media Filtration • Aerators for recirculation channel • Secondary Clarification • Flocculation/Sedimentation • Filtration • UV Disinfection • Solids Handling Alternative 3B – Conversion of Recirculation Basin/ Membrane Filtration • Aerators for recirculation channel • Membranes in separate basin • UV Disinfection • Solids Handling ---PAGE BREAK--- FFRs Irrigation BNR Aeration Basins Return Activated Sludge Secondary Clarifiers Filtration High Rate Flocculation UV Disinfection 27.5 mgd 27.5 Waste Activated Sludge Sludge Drying Anaerobic Digestion Sludge Thickening 41.5 mgd 14.0 14.0 mgd Figure 7.2 ALTERNATIVE 1A - ACTIVATED SLUDGE/ MEDIA FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout San Joaquin River Recirculation Channel Treatment Ponds Storage Reservoirs mo606mpf15 -6887.ai 7-10 ---PAGE BREAK--- Sludge Drying Beds RAS/WAS Pump Station Aeration Basins Flow Split Structure FFR Effluent Pump Station Aeration Blower Building RAS/WAS Pump Station Secondary Clarifiers Flocculation/ Sedimentation Tanks Effluent Filters Flow Split Structure Digester Support Building Anaerobic Digester Anaerobic Digester GBT Building mo606mpm18-6887.cdr Figure 7.3 ALTERNATIVE 1A - CONVENTIONAL AERATION/MEDIA FILTRATION PROPOSED IMPROVEMENTS TO JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 7-11 Approximate Scale 0’ 100’ LEGEND New Facilities at Buildout ---PAGE BREAK--- FINAL - March 2007 7-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.3 Design Criteria - Alternative 1A - Conventional Activated Sludge Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Design Flow mgd 27.5 Fixed Film Reactor Effluent BOD Concentration mg/L 100 Loadings lb/day 22,900 Aeration Basins Number 8 Volume, total MG 8.9 MLSS Concentration mg/L 2,500 Blower capacity scfm 18,000 Secondary Clarifier Type – Circular Number – 5 Diameter, each ft 125 RAS/WAS Pump Station RAS pumping capacity mgd 27.5 WAS pumping capacity mgd 0.3 Flocculation/Sedimentation Type – High-Rate Number of units – 4 Rapid mix volume, total gal 117,000 Flocculation reactor volume, total gal 175,000 Clarifier volume, total gal 970,000 Filtration Type – Cloth Disk Number of filters – 12 Number of disks per filter – 12 Surface area per disk sf 53.8 Surface area, total sf 7,750 Sludge Thickening Type – Gravity Belt Thickener Number – 2 Belt width m 1.5 Anaerobic Digesters Number – 2 Diameter ft 55 Volume, total MG 1.1 ---PAGE BREAK--- FINAL - March 2007 7-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.3 Design Criteria - Alternative 1A - Conventional Activated Sludge Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Sludge Drying Beds Total surface area acres 6 Depth ft 2 Storage capacity days 117 Notes: Preliminary criteria based on 2030 build-out flow of 27.5 mgd for year-round river discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. 7.6.1.1 Aeration and Secondary Clarification The main components of the conventional aeration system include the following: • Aeration basins containing submerged diffusers. • Aeration air blower facility. • Secondary clarifiers. • Return activated sludge (RAS)/waste activated sludge (WAS) pumping. Aeration basins would be constructed of reinforced concrete and are open to the atmosphere. Aeration blowers supply oxygen to the wastewater. The aeration air is piped from the blower facility to the aeration basin and distributed throughout the aeration tank using submerged diffusers. In order to achieve nitrification and denitrification, the aeration basins would be staged and divided into anoxic and aerobic zones. Some form of internal solids recycle between the aerobic and anoxic zones would be required for denitrification flow. To nitrify ammonia, a solids retention time (SRT) of at least 8 to 10 days at a mixed liquor suspended solids (MLSS) concentration between 2,000 and 3,000 mg/L is typically recommended. An MLSS concentration of 2,500 mg/L and an SRT of 10 days were assumed for the purposes of this analysis. As shown in Figure 7.2, the aeration blower facility would be sited very close to the aeration basins, to minimize the length of aeration air piping. The aeration requirement was estimated using the BOD and ammonia loading values for the FFR effluent. These values were estimated based on the performance of the existing facilities. Effluent from the aeration basins would flow by gravity to the secondary clarifiers. Industry standard design criteria recommend an overflow rate in the range of 400 to 700 gallons per day per square foot (gpd/sf) for secondary clarifiers at average flow conditions. The secondary clarifiers were sized using an overflow rate of 460 gpd/sf (with all clarifiers in service). ---PAGE BREAK--- FINAL - March 2007 7-14 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Return activated sludge (RAS) would be pumped from the secondary clarifiers and returned to the aeration basins, in order to maintain the design MLSS concentration of 2,500 mg/L. A recycle rate of 100 percent of the influent flow was assumed for the preliminary sizing of the RAS pump station. WAS would be pumped from the secondary clarifiers and piped to the solids handling facilities (see Section 7.6.1.4). The WAS flow rate was estimated assuming a solids concentration of 0.7 percent (7,000 mg/L). 7.6.1.2 High-Rate Flocculation/Sedimentation High-rate flocculation sedimentation would be used as an intermediate step to remove small particles in the secondary effluent, or to serve as a buffer to remove secondary solids carry-over that could occur during process upsets. In addition, preliminary test results at other facilities indicate that the high-rate flocculation/sedimentation process could reduce metal concentrations. This would be beneficial because this alternative would require bypassing the ponds which have been very effective in removing metals. It is unlikely, however, that the flocculation/sedimentation process would be as effective as the ponds. Therefore, this alternative poses a risk that metals concentrations would not be removed to low enough levels to satisfy the CTR limits. The main features of the high-rate flocculation/sedimentation system are: • Rapid mix basin. • Two-stage flocculation/sedimentation chamber. • High-rate sedimentation basin. The rapid mix basin would serve as the chemical injection point. It was assumed that primary coagulant in the form of ferric chloride would be added to the rapid mix basin and polymer would be added to the flocculation chamber. This would promote flocculation of the influent particles, which will serve to enhance sedimentation. The rapid mix chamber was sized assuming a detention time of 6 minutes. A two-stage flocculation/sedimentation chamber (similar to the Densadeg process by Infilco Degremont) was assumed. This integrated process consists of three zones: the reactor zone (flocculation), the presettling/thickening zone, and the clarification zone (sedimentation). Preliminary sizing for the reactor and clarification zones was completed assuming a hydraulic detention times of 9 and 47 minutes, respectively. 7.6.1.3 Filtration Tertiary filtration can be achieved with a variety of technologies, such as continuous backwash (CBW) sand filters, cloth-media disk filters, or deep bed sand filters. For the purposes of this analysis, the cloth-media disk filter was assumed. To determine the preliminary sizing of the filtration system, a filter feed rate of 2.5 gallons per minute per square foot (gpm/sf) was assumed. ---PAGE BREAK--- FINAL - March 2007 7-15 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc If this alternative is selected, a further review of the various tertiary filtration technologies should be conducted during preliminary design. 7.6.1.4 Solids Handling The proposed solids handling facilities would consist of the following: • Gravity Belt Thickener (GBT). • Anaerobic Digesters. • Sludge Drying Beds. WAS from the secondary clarifiers would be pumped to a GBT for thickening of the sludge. The GBT facility was sized assuming a WAS concentration of 7,000 mg/L and a hydraulic loading rate of approximately 200 gallons per minute per meter (gpm/m). Thickened WAS would be pumped to anaerobic digesters. The anaerobic digesters were sized assuming a volatile suspended solids (VSS) loading of 0.10 pounds per day per cubic foot (ppd/cf). At this loading rate, the proposed digesters would have a hydraulic retention time (HRT) of just under 30 days. These values fall within industry standard loading rates of 0.10 to 0.15 ppd/cf and HRTs of 20 to 30 days. Digesting secondary sludge alone may cause foaming issues. As an alternative, although energy-intensive, aerobic digestion could be used. This should be evaluated further in preliminary design. Digested sludge would be piped to sludge drying beds for dewatering and further stabilization. The sludge drying beds were sized assuming a TSS loading of 12 pounds per square foot per year (lbs/sf/yr) and a sidewater depth of 2 feet. 7.6.1.5 Preliminary Unit Process Sizing A summary of the unit process sizing for the conventional aeration alternative is presented in Table 7.3. The sizing is preliminary and was used to develop a cost estimate for this alternative. If this alternative is selected, a more comprehensive analysis should be completed during preliminary design of these facilities. 7.6.2 Alternative 1B – Activated Sludge/Membrane Filtration (Membrane Bioreactor or MBR) The facilities associated with Alternative 1B are outlined below. The process schematic and conceptual layout for this alternative are shown in Figures 7.4 and 7.5 respectively. Design criteria are presented in Table 7.4. 7.6.2.1 Membrane Bioreactor An activated sludge system with membrane filtration is referred to as the membrane bioreactor process (MBR). The main components of the MBR system include the following: ---PAGE BREAK--- Recirculation Channel San Joaquin River FFRs Treatment Ponds Storage Reservoirs Irrigation BNR Aeration Basins Microfiltration UV Disinfection 27.5 mgd 27.5 14.0 14.0 mgd Figure 7.4 ALTERNATIVE 1B - ACTIVATED SLUDGE/ MEMBRANE FILTRATION (MBR) WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout 41.5 mgd mo606mpf16 -6887.ai 7-16 Return Activated Sludge Waste Activated Sludge Sludge Drying Anaerobic Digestion Sludge Thickening ---PAGE BREAK--- mo606mpm9-6887.cdr Approximate Scale 0’ 100’ Aeration Blower Building FFR Effluent Pump Station Aeration Basins Digester Support Building GBT Building Anaerobic Digesters Pump Gallery Figure 7.5 ALTERNATIVE 1B - ACTIVATED SLUDGE/ MEMBRANE FILTRATION - PROPOSED IMPROVEMENTS TO JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 7-17 Sludge Drying Beds Approximate Scale 0’ 100’ Membrane Tanks ---PAGE BREAK--- FINAL - March 2007 7-18 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.4 Design Criteria for Alternative 1B – Conventional Activated Sludge/Membrane Filtration (MBR) Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Design Flow mgd 27.5(2) Fixed Film Reactor Effluent BOD Concentration mg/L 100 Loadings lb/day 22,900 Aeration Basins Number – 6 Volume, total MG 3.0 Blower capacity scfm 30,000 Membranes(2) Membrane design flux gfd 12.5 Number of trains – 12 Number of cassettes per train – 9 Number of modules per cassette – 60 RAS/WAS Pump Station RAS pumping capacity mgd 120 WAS pumping capacity mgd 0.3 Sludge Thickening Type – Gravity belt thickener Number – 2 Belt width m 1.5 Anaerobic Digesters Number – 2 Diameter ft 55 Volume, total MG 1.1 Sludge Drying Beds Total surface area acres 6 Depth ft 2 Storage capacity days 117 Notes: Preliminary criteria based on 2030 build-out flow of 27.5 mgd for year-round river discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. Information provided by membrane manufacturer. ---PAGE BREAK--- FINAL - March 2007 7-19 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc • Preliminary fine screening. • Aeration basins containing submerged diffusers. • Aeration air blower facility. • Membrane basins. • Permeate pumping. • Membrane air scour blowers, backpulse and chemical cleaning facilities. • RAS/WAS pumping. Additional preliminary screening for the MBR process would be required to remove fibrous material not removed by the upstream mechanical bar screens at the Sutter Avenue Facility. A fine screening facility would be constructed of the fixed film reactors. Depending upon the type of membrane chosen flat sheet versus hollow fiber), the fine screen opening would range between 0.75 mm to 3.0 mm. The MBR process would be configured as a 2-step reactor, with the first basin serving as a plug flow activated sludge reactor and the second basin housing the membranes. The two basins could either be close-coupled or completely separate. A separate membrane basin permits independent optimization of the aeration equipment and activated sludge process, as well as isolated membrane cleaning. The geometry of the aeration basins would be selected to achieve nitrification and denitrification. Based on information provided by the membrane manufacturer, an SRT of 20 days and an MLSS concentration of 8,000 mg/L were used to determine the preliminary sizing of the aeration basins. As shown in Figure 7.5, the aeration blower facility would be sited close to the aeration basins to minimize the aeration air piping. The aeration requirement was estimated using the BOD and ammonia loading in the FFR effluent. The membranes used in this process are of a polymeric filtration media with pore sizes ranging between 0.04 microns to 0.4 microns to sieve and separate solids, effectively taking the place of a more traditional secondary clarifier coupled with a media filter. Preliminary sizing of the membrane facilities was completed using information provided by membrane manufacturers. RAS would be pumped from the membrane tank and returned to the aeration basins. For cost estimating purposes, an RAS recycle rate of 400 percent of the influent flow was assumed for the preliminary sizing of the RAS pump station. The recycle rate is much higher for this alternative (when compared to 100 percent for the conventional aeration alternative) because the MLSS concentration is higher. ---PAGE BREAK--- FINAL - March 2007 7-20 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc WAS will be pumped from the membrane tank and piped to the solids handling facilities. The WAS flow rate was calculated using a solids concentration of 0.8 percent, which is identical to the MLSS concentration in the aeration basins. This assumption was made because WAS is typically not concentrated between aeration basins and membrane tanks. 7.6.2.2 Solids Handling The configuration of the solids handling facilities for the MBR alternative is assumed to be identical to the conventional aeration alternative (Alternative 1A). The conceptual layout of the solids handling facilities is provided in Figure 7.5. 7.6.2.3 Preliminary Unit Process Sizing A summary of the unit process sizing for the MBR alternative is presented in Table 7.4. The sizing is preliminary and was used to develop a cost estimate for this alternative. If this alternative is selected, a more comprehensive sizing analysis should be completed during preliminary design of these facilities. 7.6.3 Alternative 2A - Nitrifying Trickling Filter, Media Filtration Under this alternative nitrifying trickling filters, denitrification fluidized beds and conventional filtration would be added of the facultative ponds. The process flow diagram layout are shown in Figures 7.6 and 7.7 respectively. Design criteria are summarized in Table 7.5. The main feature of this alternative is that the existing facultative pond system would be utilized. This would take advantage of metals removal that the ponds have demonstrated in the past. The down side to this alternative is the risk of more restrictive use requirements that could be imposed by the regional board in the future. These additional requirements could potentially include the requirement to line the existing treatment ponds with an impermeable layer. Costs to line the ponds are estimated to range from $80 million to $100 million. 7.6.3.1 Nitrifying Trickling Filters Nitrifying trickling filters (NTF) would be used for the facultative pond effluent. The DAFs would be used upstream to remove algae. The NTFs would consist of plastic media. NTFs are usually plagued with snails that can significantly reduce the effectiveness of the process. To control snail growth the NTF walls would be designed to allow periodic flooding of the media. The snails would be killed by adding ammonia or other chemicals, and submerging the media for several days. Under this alternative, the DAF system would need to be expanded to match the tertiary flow. ---PAGE BREAK--- Recirculation Channel San Joaquin River FFRs Treatment Ponds Storage Reservoirs Irrigation Nitrifying Trickling Filters Denitrifying Filters UV Disinfection 27.5 mgd 27.5 mgd Sludge Drying 14.0 mgd High Rate Floc/Sed Filtration Methanol Aeration Figure 7.6 ALTERNATIVE 2A - NITRIFYING TRICKLING FILTERS/MEDIA FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout 41.5 mgd mo606mpf17-6887.ai 7-21 ---PAGE BREAK--- Approximate Scale 0’ 100’ mo606mpm10-6887.cdr Figure 7.7 ALTERNATIVE 2A - NITRIFYING TRICKLING FILTER/MEDIA FILTRATION FACILITIES CONCEPTUAL LAYOUT WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Nitrifying Trickling Filters Fluidized Bed Reactor Flocculation/ Sedimentation UV Disinfection Filters Sludge Drying Beds 7-22 ---PAGE BREAK--- FINAL - March 2007 7-23 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.5 Design Criteria for Alternative 2A - Nitrifying Trickling Filters/Media Filtration Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Design Flow mgd 27.5 Oxidation Pond Effluent Loadings BOD Concentration mg/L 20 Loadings lb/day 4600 Ammonia Concentration mg/L 30 Loadings lb/day 6900 Nitrifying Trickling Filters (NTF) NTF Effluent Ammonic Loadings Concentration mg/L 20 Loading lb/day 4600 Number of Units 3 Media Loading Rate lb NH3/day/ksf 0.32 Media Type plastic Specific Volume sf/cf 40 Media Volume cf 127,000 Media Diameter ft 90 Media Height ft 20 Media Surface Area sf 15,200,000 Fluidized Bed Reactor (denitrification) NTF Effluent NO3 Loadings Concentration mg/L 20 Loading lb/day 4600 Number 1 Media Fluidized sand Volume cf 11,700 Depth ft 16 Area sf 800 Methanol Requirement lb/day 6 gal/day 2,100 Flocculation/Sedimentation See Design Criteria for Alternative 1A Filtration (cloth disk filters) See Design Criteria for Alternative 1A Sludge Drying Beds Total Surface Area acres 1 Depth ft 2 Note: Preliminary criteria based on 2030 build-out flow of 27.5 mgd for year-round river discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. ---PAGE BREAK--- FINAL - March 2007 7-24 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc 7.6.3.2 Denitrifying Fluidized Bed Reactors Fluidized bed reactors, operating under anaerobic conditions, would be used to remove nitrates. Methanol would be used as a carbon source to facilitate denitrification. 7.6.3.3 High-Rate Flocculation/Sedimentation This would be the same as Alternative 1. 7.6.3.4 Disinfection This would be the same as Alternative 1. 7.6.3.5 Filtration This would be the same as Alternative 1. 7.6.4 Alternative 2B– Nitrifying Trickling Filters, Membrane Filtration This alternative would be the same as Alternative 2A except the flocculation/sedimentation and effluent filters would be replaced with membrane filters (micro-filtration). The progress flow diagram and conceptual layout are shown in Figures 7.8 and 7.9 respectively. The design criteria are shown in Table 7.6. 7.6.5 Alternative 3A – Conversion of Recirculation Channel, Media Filtration This alternative would consist of adding new aeration equipment to the existing recirculation channel to convert it into an extended-aeration basin. The basin would be designed to nitrify and denitrify. The City currently has aerators, but many are not operable and are inefficient. It was assumed that all new aerators would be furnished. A portion of the channel would be partitioned and converted to an anoxic zone for denitrification. A process flow diagram is shown in Figure 7.10. The conceptual layout can be seen in Figure 7.11. Design criteria are summarized in Table 7.7. The effluent filtration/disinfection system would be the same as Alternative 1A. Due to the large volume available in the recirculation channel, the system will be able to operate with a low mixed liquor suspended solids concentration. This may result in lower sedimentation costs However, pending preliminary design, the potential cost reductions were not included in the cost estimates. Due to the long retention time in the recirculation channel, the sludge yield will be low, and WAS will be stabilized. Therefore, additional digestion would not be required. The WAS solids would be thickened and sent directly to sludge drying beds. ---PAGE BREAK--- Recirculation Channel San Joaquin River FFRs Treatment Ponds Storage Reservoirs Irrigation Nitrifying Trickling Filter De-Nitrifying Filters UV Disinfection 27.5 mgd Methanol 14.0 mgd Membranes Aeration 27.5 mgd Figure 7.8 ALTERNATIVE 2B - NITRIFYING TRICKLING FILTERS/MEMBRANE FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout 41.5 mgd mo606mpf19-6887.ai 7-25 ---PAGE BREAK--- mo606mpm11-6887.cdr Figure 7.9 ALTERNATIVE 2B - NITRIFYING TRICKLING FILTER/MEMBRANE FILTRATION FACILITIES CONCEPTUAL LAYOUT WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Membrane Tanks UV Disinfection Nitrifying Trickling Filters Fluidized Bed Reactor 7-26 Sludge Drying Beds Approximate Scale 0’ 100’ ---PAGE BREAK--- FINAL - March 2007 7-27 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.6 Design Criteria for Alternative 2B - Nitrifying Trickling Filters/Membrane Filtration Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value Design Flow mgd 27.5 Oxidation Pond Effluent Loadings BOD Concentration mg/L 20 Loadings lb/day 4600 Ammonia Concentration mg/L 30 Loadings lb/day 6900 Nitrifying Trickling Filters (NTF) NTF Effluent Ammonia Loadings Concentration mg/L 20 Loading lb/day 4600 Number of Units 3 Media Loading Rate lb NH3/day/ksf 0.32 Media Surface Area Required sf 14,300,000 Media Type plastic Specific Volume sf/cf 40 Media Volume cf 127,000 Media Diameter ft 90 Media Height ft 20 Media Surface Area sf 15,200,000 ---PAGE BREAK--- FINAL - March 2007 7-28 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.6 Design Criteria for Alternative 2B - Nitrifying Trickling Filters/Membrane Filtration Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value Fluidized Bed Reactor (denitrification) NTF Effluent NO3 Loadings Concentration mg/L 20 Loading lb/day 4600 Number 1 Media Fluidized sand Volume cf 11700 Depth ft 16 Area sf 800 Methanol Requirement lb/day 6 gal/day 2100 Membranes Membrane Design Flux gfd 12.5 Number of Trains 12 Number of cassettes per train 9 Number of modules per cassette 60 Sludge Drying Beds Total Surface Area acres 1 Sidewater Depth ft 2 Notes: Preliminary criteria based on 2040 buildout flow of 27.5 mgd for year-round river discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. ---PAGE BREAK--- Recirculation Channel San Joaquin River FFRs Treatment Ponds Storage Reservoirs Irrigation High Rate Floculation UV Disinfection 27.5 mgd Filtration 14.0 mgd Secondary Clarifiers 14.0 mgd Sludge Drying Sludge Thickening Aeration Figure 7.10 ALTERNATIVE 3A - RECIRCULATION CHANNEL/MEDIA FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout 41.5 mgd 27.5 mgd mo606mpf21-6887.ai 7-29 Return Activated Sludge Waste Activated Sludge ---PAGE BREAK--- Mo606mpm12-6887.cdr Figure 7.11 CONCEPTUAL LAYOUT ALTERNATIVE 3A - RECIRCULATION CHANNEL/MEDIA FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Approximate Scale 0’ 100’ Flocculation/ Sedimentation Tanks Effluent Filters Flow Split Structure FFR Effluent Pump Station Secondary Clarifiers Flow Split Structure RAS/WAS Pump Station RAS/WAS Pump Station GBT Building 7-30 Sludge Drying Beds Approximate Scale 0’ 100’ Conversion of Recirculation Channel to Extended Aeration Basin (add new floating aerators) ---PAGE BREAK--- FINAL - March 2007 7-31 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.7 Design Criteria for Alternative 3A – Recirculation Channel Media Filtration Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Design Flow mgd 27.5 Fixed Film Reactor Effluent BOD Concentration mg/L 100 Loadings lb/day 22,900 Aeration Basin (Converted Recirculation Channel) Number – 1 Volume, total MG 169 Mixed Liquor SS mg/L 500 Solids Retention Time days 55 Aeration Air Required lb/day O2 30,000 Secondary Clarifier Type Circular Number 5 Diameter, each ft 125 RAS/WAS Pump Station RAS pumping capacity mgd 27.5 WAS pumping capacity mgd 0.3 Flocculation/Sedimentation Type High-Rate Number of Units 4 Rapid mix volume, total gal 117,000 Flocculation reactor volume, total gal 175,000 Clarifier volume, total gal 970,000 Filtration Type Cloth Disk Number of Filters 12 Number of disks per filter 12 Surface area per disk sf 53.8 Surface area, total sf 7,750 Sludge Thickening Type – Gravity belt thickener Number – 2 Belt width m 1.5 Sludge Drying Beds Total Surface Area acres 7 Depth ft 2 Storage Capacity days 117 Notes: Preliminary design criteria based on 2030 build-out flow of 27.5 mgd for year-round discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. Information provided by membrane manufacturer. ---PAGE BREAK--- FINAL - March 2007 7-32 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc 7.6.6 Alternative 3B - Conversion of Recirculation Channel to Activated Sludge Process, Membrane Filtration This alternative would be the same as Alternative 3A except membrane filtration would be used instead of the media filtration train. The process schematic is shown in Figure 7.12 and the conceptual layout is shown in Figure 7.13. Design criteria are summarized in Table 7.8. Membrane filtration would be used to produce Title 22 water. This process would take advantage of a low mixed liquor concentration in the converted recirculation channel. At low MLSS concentrations the membranes can generally operate at higher flux rates. Clarifiers, flocculation/sedimentation and media filtration would not be required. 7.6.7 Tertiary Disinfection Analysis Two alternatives for tertiary disinfection were evaluated as part of this Master Plan update: • Bulk Sodium Hypochlorite. • Ultraviolet Radiation (UV). On-site sodium hypochlorite generation and gaseous chlorine were ruled out for tertiary disinfection based on results presented in the Alternative Disinfection Analysis (Appendix 7.6.7.1 Disinfection Alternatives Comparison The two proposed disinfection systems, bulk sodium hypochlorite and UV, were compared on an economic and non-economic basis. The conceptual level construction, O&M and total annualized costs for a 27.5 mgd facility are summarized in Table 7.9. The cost estimates indicate that the project costs are more for UV than the bulk sodium hypochlorite facilities. However, the O&M costs associated with the bulk sodium hypochlorite facility are estimated to be 3 to 4 times more than the O&M costs for a UV facility. On-going UV disinfection research indicates that UV systems are becoming more efficient, providing more disinfection capacity with less equipment. It is reasonable to expect that the cost of UV facilities will decrease in the future and those savings could be realized for this project. Two of the main benefits of UV disinfection are related to water quality: no disinfection by- products (THMs) are generated and UV achieves superior virus inactivation. In addition, for river discharge, no de-chlorination is required for a UV system. Due to the stringent THM limits anticipated for river discharges, the UV disinfection system was selected for all four alternatives. ---PAGE BREAK--- Recirculation Channel FFRs Storage Reservoirs Irrigation UV Disinfection 27.5 27.5 41.5 Microfiltration 14.0 14.0 Sludge Drying Sludge Thickening Aeration 27.5 Figure 7.12 ALTERNATIVE 3B - RECIRCULATION CHANNEL/MEMBRANE FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND 41.5 - Denotes flow in mgd at buildout San Joaquin River Treatment Ponds mo606mpf23-6887.ai 7-33 Return Activated Sludge Waste Activated Sludge ---PAGE BREAK--- mo606mpm13-6887.cdr GBT Building Membrane Tanks Pump Gallery Figure 7.13 CONCEPTUAL LAYOUT ALTERNATIVE 3B - RECIRCULATION CHANNEL/MEMBRANE FILTRATION WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 7-34 Sludge Drying Beds Approximate Scale 0’ 100’ Conversion of Recirculation Channel to Extended Aeration Basin (add new floating aerators) ---PAGE BREAK--- FINAL - March 2007 7-35 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.8 Design Criteria for Alternative 3B – Recirculation Channel/Membrane Filtration Wastewater Master Plan Phase 2 Update City of Modesto, California Units Value(1) Design Flow mgd 27.5 Fixed Film Reactor Effluent BOD Concentration mg/L 100 Loadings lb/day 22,900 Aeration Basin (Converted Recirculation Channel) Number – 1 Volume, total MG 169 Mixed Liquor SS mg/L 500 Solids Retention Time days 55 Aeration Air Required lb/day O2 30,000 Membranes(2) Membrane design flux gfd 12.5 Number of trains – 12 Number of cassettes per train – 9 Number of modules per cassette – 60 RAS/WAS Pump Station RAS pumping capacity mgd 120 WAS pumping capacity mgd 0.3 Sludge Thickening Type – Gravity belt thickener Number – 2 Belt width m 1.5 Sludge Drying Beds Total surface area acres 7 Sidewater depth ft 2 Storage capacity days 97 Notes: Preliminary criteria based on 2030 build-out flow of 27.5 mgd for year-round discharge. Total 2030 design flow including land application capacity is 41.5 mgd. Unit process design criteria to be verified in preliminary design. Information provided by membrane manufacturer. ---PAGE BREAK--- FINAL - March 2007 7-36 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.9 Disinfection Alternatives Conceptual Cost Estimate(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Conceptual Costs Cost Category UV/Media Filtration UV/Membrane Filtration Bulk Sodium Hypochlorite Project Cost(3), $M $10.9 $7.0 $3.3 O&M Cost(4), $M/year $0.5 $0.3 $1.4 Present Worth O&M Cost(5), $M $5.7 $3.4 $16.1 Total Lifecycle Cost(6), $M $16.6 $10.4 $19.4 Notes: The conceptual costs assume the 2030 build-out flow requirement of 27.5 mgd for the BNR/tertiary facilities. Costs are presented in June 2006 dollars, San Francisco Engineering News Record Construction Cost Index (ENRCCI) = 8441. Project costs include project cost factor of 30 percent (engineering, legal, administration and construction) and 20 percent estimating contingency. O&M costs are presented in June 2006 dollars. P/A, 20 years = 11.47 7.7 BNR/TERTIARY ALTERNATIVES SCREENING This section presents a comparison of the BNR/tertiary alternatives on both an economic and non-economic basis. 7.7.1 Non-Economic Comparison The advantages and disadvantages associated with each alternative are presented in Table 7.10. 7.7.2 Cost Analysis 7.7.2.1 Use of Master Planning Level Cost Estimates The cost estimates prepared for this master plan primarily serve two purposes: 1) to compare capital costs, and 2) to develop an aggregate project cost for the overall capital improvement program. Master planning level cost estimates have wide accuracy ranges. Modifications typically occur during design phase of a project including changes that may have occurred to the project scope, existing facilities, and other assumptions on which the project is based. Consequently, the cost estimates developed during the design stage are often different than the master planning level cost estimates. ---PAGE BREAK--- FINAL - March 2007 7-37 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.10 Non-Economic Comparison of BNR/Tertiary Alternatives Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Description Advantages Disadvantages 1A Activated Sludge/Media Filtration • Less reliant on long-term use of existing pond system. • Conventional Processes - well proven. • Large number of unit processes. • Generates secondary solids. • May not remove metals without pond. • Requires pipeline from FFR to effluent PS. 1B Activated Sludge/ Membrane Filtration (MBR) • Less reliant on long-term use of existing pond system. • Fewer unit processes. • Provides pretreatment for future RO. • Membrane may remove some metals. • New technology. • Loss of pond for metals removal. • High O&M costs. • Requires pipeline from FFR to effluent PS 2A Nitrifying Trickling Filter/Media Filtration • Simple operation. • Does not generate significant solids. • Best use of existing facilities. • Good metals removal from ponds. • Snail infestations require periodic removal by flooding and chemical addition. • Requires methanol for denitrification. • Not impacted by potential pond lining requirement. • Requires periodic dredging of ponds. 2B Nitrifying Trickling Filter/ Membrane Filtration • Low solids generation • Potential better metals removal • High degree of treatment • Snail infestations require periodic removal by flooding and chemical addition. • Requires methanol for denitrification. • Not impacted by potential pond lining requirement. • Requires periodic dredging of ponds. 3A Conversion of Recirculation Channel/ Media Filtration • Uses existing facilities • No separate sludge digestion • Requires pipeline from FFRs to effluent PS • Less efficient aeration. 3B Conversion of Recirculation Channel/ Membrane Filtration • Uses existing facilities • No separate sludge digestion • Fewer unit processes • Provides pretreatment for future RO • Membranes may remove some metals • New technology • High O&M costs • Requires pipeline from FFRs to effluent PS • Less efficient aeration ---PAGE BREAK--- FINAL - March 2007 7-38 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc 7.7.2.2 Scope and Level of Accuracy The Association for the Advancement of Cost Engineering International (AACE International, formally known as the American Association of Cost Engineers) has suggested levels of accuracy for five estimate classes. Table 7.11 presents a summary of these five estimate classes and their characteristics including expected accuracy ranges. The quantity and quality of the information required to prepare an estimate depends on the end use for that estimate. Typically, as a project progresses from the conceptual phase to the study phase, preliminary design and final design, the quantity and quality of information increases, thereby providing data for development of a progressively more accurate cost estimate. A contingency is often used to compensate for lack of detailed engineering data, oversights, anticipated changes and imperfections in the estimating methods used. As the quantity and quality of data improve, smaller contingency allowances are typically utilized. For the projects developed as a part of this master plan, cost estimates are developed following the AACE International Recommended Practice No. 18R-97 estimate Class 5. Very limited information is available at the time when a Class 5 estimate is developed. Therefore, Class 5 estimates virtually always use stochastic estimating methods such as cost to capacity curves and various scaling factors resulting in a lump sum cost. Subsequently, estimated costs have wide accuracy ranges. Typical accuracy ranges for Class 5 estimates are -20 percent to -50 percent on the low side, and +30 percent to +100 percent on the high side, depending on the technological complexity of the project, availability and accuracy of appropriate reference information, and the inclusion of an appropriate contingency determination. Class 5 estimates are prepared for any number of strategic business planning purposes, including, but not limited to, project screening, evaluation of resource needs and budgeting, and long-range capital planning. 7.7.2.3 Basis of Cost Evaluations The costs presented in this master plan are based on preliminary layouts, preliminary unit process sizing and conceptual alternative configurations. Construction costs, therefore, are estimated based on unit costs developed from estimating guides, equipment manufacturers information, unit prices, and construction costs of similar facilities and configurations at other locations. O&M costs are based on historical operating costs from other facilities, as well as estimated manpower needs and resource requirements. A summary of the criteria used for estimating costs is presented in Table 7.12. 7.7.2.4 Cost Analysis A present worth analysis was performed to identify a ranking of alternatives on the basis of costs. Tables 7.13 through 7.15 present estimated capital costs for each alternative. Table 7.16 is a summary of O&M costs. ---PAGE BREAK--- FINAL - March 2007 7-39 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.12 Cost Estimating Criteria Wastewater Master Plan Phase 2 Update City of Modesto, California Item Assumption Costs in Time and Place Costs are based on June 2006 costs in Northern California Cost Index Engineering News Record Construction Cost Index (ENRCCI) of 8441. Construction Contingency 20 percent Project Cost Factor Total of 30 percent for engineering, legal, administrative, and construction support. Interest Rate 5 percent for amortization purposes. Amortization Period 20 years Table 7.11 Category of Cost Estimates(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Primary Characteristic Secondary Characteristic ESTIMATE CLASS LEVEL OF PROJECT DEFINITION Expressed as % of Complete Definition END USAGE METHODOLOGY Typical Estimating Method EXPECTED ACCURACY RANGE Typical Variation in Low and High Ranges(2) PREPARATION EFFORT Typical Degree of Effort Relative to Least Cost Index of 1(3) Class 5 0% to 2% Concept Screening Capacity Factored, Parametric Models, Judgment, or Analogy L: -20% to –50% H: +30% - +100% 1 Class 4 1% to 15% Study or Feasibility Equipment Factored or parametric Models L: - 15% to -30% H: +20% - +50% 2 to 4 Class 3 10% to 40% Budget, Authorization, or Control Semi-Detailed Unit Costs with Assembly Level Line Items L: - 10% to -20% H: +10% - +30% 3 to 10 Class 2 30% to 70% Control or Bid/ Tender Detailed Unit Cost with Forced Detailed Take-Off L: - 5% to –15% H: - +20% 4 to 20 Class 1 50% to 100% Check Estimate or Bid/Tender Detailed Unit Cost with Detailed Take-Off L: - 3% to –10% H: - +15% 5 to 100 Notes: Table 7.11 comes from the AACE International Recommended Practices and Standards, No. 18R-97 The state of process technology and availability of applicable reference cost data affect the range markedly. The value represents typical percentage variation of actual costs from the cost estimate after application of contingency (typically at a 50% level of confidence) for a give scope. If the range index value of represents 0.005% of project costs, then an index value of 100 represents 0.5%. Estimate preparation effort is highly dependent upon the size of the project and the quality of estimating data and tools. ---PAGE BREAK--- FINAL - March 2007 7-40 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.13 Estimated Capital Costs – Alternative 1 – Activated Sludge(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Design Flow (mgd) Unit Process Capital Cost(2) $M 1A Activated Sludge, Media Filtration 27.5 Dissolved Air Flotation Facility 11.0 Mixed Liquor Pump Station 3.9 Aeration Basins (nitrification/denit.) 25.3 Secondary Clarifiers 39.6 RAS/WAS Pump Station 11.9 High Rate Flocculation/Sedimentation 22.0 Media Filtration 14.1 UV Disinfection 11.0 Effluent Pump Station Improvements 3.0 Sludge PS 14.3 GBT 19.6 Anaerobic Digesters 32.4 Sludge Drying Beds 2.5 Chemical Storage/Feed Facilities 8.2 Tertiary Effluent Pipeline 7.2 Total 226.0 1B Activated Sludge, Membrane Filtration (MBR) 27.5 Dissolved Air Flotation Facility 11.0 Mixed Liquor Pump Station 3.9 Membrane Bioreactors 104.5 UV Disinfection 6.9 Effluent Pump Station Improvements 3.0 Sludge PS 14.3 GBT 19.6 Anaerobic Digesters 32.4 Sludge Drying Beds 2.5 Chemical Storage/Feed Facilities 8.2 Tertiary Effluent Pipeline 7.2 Total 213.5 Notes: Analysis excludes facilities common to all alternatives including FFR improvements, initial DAF project, Phase 1A improvements, hypochlorite conversion, as well as flood protection and outfall improvements. June 2006 dollars. ENR CCI = 8441. Includes allowances for contingencies, engineering, legal, and administrative expenses. ---PAGE BREAK--- FINAL - March 2007 7-41 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.14 Estimated Capital Costs – Alternative 2 – Nitrifying Trickling Filter Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Design Flow (mgd) Unit Process Capital Cost $M 2A Nitrifying Trickling Filters, Media Filtration 27.5 Dissolved Air Flotation Facility 30.3 Aeration for Recirculation Channel 7.3 Nitrification Filter Pump Station 6.9 Nitrifying Trickling Filters 55.4 De-Nitrification Filters 9.7 High Rate Flocculation/Sedimentation 22.0 Media Filtration 14.1 Chemical Storage/Feed Facilities 8.2 UV Disinfection 11.0 Sludge Drying Beds 0.4 Effluent Pump Station Improvements 3.0 Total 168.3 2B Nitrifying Trickling Filters, Membrane Filtration 27.5 Dissolved Air Flotation Facility 30.3 Aeration for Recirculation Channel 7.3 Nitrification Filter Pump Station 6.9 Nitrifying Trickling Filters 55.4 De-Nitrification Filters 9.7 Microfiltration membranes 90.8 Chemical Storage/Feed Facilities 8.2 UV Disinfection 6.9 Sludge Drying Beds 0.4 Effluent Pump Station Improvements 3.0 Total 218.9 Notes: Analysis excludes facilities common to all alternatives including FFR improvements, initial DAF project, Phase 1A improvements, hypochlorite conversion, as well as flood protection and outfall improvements. June 2006 dollars. ENR CCI = 8441. Includes allowances for contingencies, engineering, legal, and administrative expenses. ---PAGE BREAK--- FINAL - March 2007 7-42 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Table 7.15 Estimated Capital Costs – Alternative 3 – Recirculation Channel(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Design Flow (mgd) Unit Process Capital Cost(2) $M 3A Recirculation Channel, Media Filtration 27.5 Dissolved Air Flotation Facility 11.0 Mixed Liquor Pump Station 3.9 Aeration for Recirculation Channel 10.0 Secondary Clarifiers 39.6 RAS/WAS Pump Station 11.9 High Rate Flocculation/Sedimentation 22.0 Media Filtration 14.1 Chemical Storage/Feed Facilities 8.2 UV Disinfection 11.0 Effluent Pump Station Improvements 3.0 GBT 19.6 Sludge Drying Beds 2.5 Tertiary Effluent Pipeline 7.2 Total 164.0 3B Recirculation Channel, Membrane Filtration 27.5 Dissolved Air Flotation Facility 11.0 Mixed Liquor Pump Station 3.9 Aeration for Recirculation Channel 10.0 Microfiltration membranes 90.8 Chemical Storage/Feed Facilities 8.2 UV Disinfection 6.9 Effluent Pump Station Improvements 3.0 GBT 19.6 Sludge Drying Beds 2.5 Tertiary Effluent Pipeline 7.2 Total 163.1 Notes: Analysis excludes facilities common to all alternatives including FFR improvements, initial DAF project, Phase 1A improvements, hypochlorite conversion, as well as flood protection and outfall improvements. June 2006 dollars. ENR CCI = 8441. Includes allowances for contingencies, engineering, legal, and administrative expenses. ---PAGE BREAK--- FINAL - March 2007 7-43 H:\FINAL\MODESTO_WCO\6887E00\RPT\MASTERPLANRPT\FINAL\07.DOC Table 7.16 Operations and Maintenance Cost Estimate(1)(2) Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Power Cost $/year at $0.08/kwHr Chemical Cost $/year Replacement Parts or Periodic Maintenance Labor Costs Total Cost $/year 1A Activated Sludge, Media Filtration, UV $1,198,000 $600,000 $333,000 $1,414,000 $3,545,000 1B Membrane Bioreactor (MBR) $1,904,000 $107,000 $1,801,000 $1,399,000 $5,211,000 2A Nitrifying Trickling Filter, Media Filtration, UV $899,000 $1,357,000 $413,000 $1,414,000 $4,083,000 2B Nitrifying Trickling Filter, Microfiltration/UV $1,270,000 $864,000 $1,881,000 $1,399,000 $5,414,000 3A Conversion of Recirculation Channel, Floc/Sed, Media Filtration, UV $1,110,000 $590,000 $413,000 $1,414,000 $3,527,000 3B Conversion of Recirculation Channel, Micro Filtration, UV $2,456,000 $97,000 $1,881,000 $1,399,000 $5,833,000 Note: All O&M costs presented in June 2006 dollars. Relative O&M costs developed for secondary treatment processes only for the purpose of alternative comparison. ---PAGE BREAK--- FINAL - March 2007 7-44 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\07.doc Total present worth costs are presented in Table 7.17. As indicated, Alternative 2A (nitrifying trickling filter/media filtration), 3A (recirculation channel/media filtration), and 3B (recirculation channel/membranes) offer the apparent lowest capital and present worth costs. 7.8 SELECTION OF APPARENT BEST ALTERNATIVE In a workshop held on June 13, 2006, the three alternatives and their variations were evaluated. Alternative 3 with either media filtration or membranes was selected as the apparent best alternative. The basis for the selection was as follows: • Lowest capital cost. • Lowest present worth cost. • Utilizes much of the existing secondary treatment facilities. • Does not require the use of methanol for denitrification as required for Alternatives 2A and 2B. Methanol is difficult to store and transport due to safety restrictions and air quality permitting. • High effluent quality. The final selection of either conventional filtration or membranes will be made during preliminary design. The membrane alternative offers the advantages of lower capital costs, fewer unit processes, and a higher quality effluent. Conventional filtration has the advantage of lower operating and corresponding reduced overall present worth costs. Final process selection will be based on a more detailed analysis of capital and operating costs as determined by final design criteria. For the purpose of this master plan, Alternative 3A (recirculation channel/media filtration) is shown as the recommended alternative pending more detailed analysis. ---PAGE BREAK--- FINAL - March 2007 7-45 H:\FINAL\MODESTO_WCO\6887E00\RPT\MASTERPLANRPT\FINAL\07.DOC Table 7.17 Cost Comparison of Alternatives for BNR/Tertiary Treatment(1) Wastewater Master Plan Phase 2 Update City of Modesto, California Alternative Capital Cost $M(2) Annual O&M Cost $M/year(3) O&M Present Worth $M(4) Total Present Worth $M 1A Activated Sludge, Media Filtration, UV 226.0 3.5 40.1 266.1 1B Activated Sludge, Membrane Filtration (MBR), UV 213.5 5.2 59.6 273.1 2A Nitrifying Trickling Filter, Media Filtration, UV 168.3 4.1 47.0 215.3 2B Nitrifying Trickling Filter, Membrane Filtration, UV 218.9 5.4 61.9 280.8 3A Conversion of Recirculation Channel, Floc/Sed, Media Filtration, UV 164.0 3.5 40.1 204.1 3B Conversion of Recirculation Channel, Membrane Filtration, UV 163.1 5.8 66.5 229.6 Notes: For 27.5 mgd capacity. Based on ENRCCI = 8441 (from Table 7.15) In today’s costs. Includes labor, power, chemicals, and replacement of consumables (from Table 7.16). Based on P/A, 5% and 20-year return period. ---PAGE BREAK--- FINAL - March 2007 8-1 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Chapter 8 COMPLIANCE STRATEGY, RECOMMENDED PROJECT, AND IMPLEMENTATION PLAN 8.1 INTRODUCTION This chapter presents a compliance strategy, the recommended project, and an implementation plan. The purpose of the compliance strategy is to identify a range of options available to City to meet existing and future regulatory requirements. Regulators are developing surface water discharge limitations for constituents such as salinity, trihalomethanes (THMs), metals, and dissolved oxygen. In addition, criteria are also being considered that may have implications regarding unlined treatment ponds and land application of cannery process water. The compliance strategy will address the course of action the City may consider to respond to potential future regulatory changes beyond the next permit. The recommended project combines and summarizes the conclusions of Chapters 5 through 7.The implementation plan includes proposed staging of the project through buildout at year 2030. 8.2 COMPLIANCE STRATEGY The strategy for regulatory compliance addresses the following: • Current and future regulatory issues associated with wastewater treatment and effluent disposal. • Strategies for possible compliance with regulatory issues. • Applicable components of this master plan that address regulatory issues. • Future additions or modifications to the City’s wastewater treatment facilities to comply with future regulatory issues. Table 8.1 is a summary of the strategy to comply with potential future regulations. Details of compliance strategies for various regulatory issues were presented previously in Chapter 4. The regulatory issues that could have the highest potential future impact on the City include: limits for salinity, boron, and metals; tertiary treatment for all river discharges; groundwater limitation associated with unlined ponds and land application of segregated cannery wastewater. 8.2.1 Salinity and Boron The primary strategy for complying with potential salinity and boron limits is to continue implementing source control from industrial, commercial, and domestic users. In addition, the City is expanding its surface water supply. Surface water has lower salinity levels than the groundwater supply. The combined effect of source control and changing drinking water quality will contribute to reducing salinity in the wastewater. The Regional Water Quality Control Board is developing a total maximum daily load (TMDL) for salinity contributions from Modesto. While the TMDL does not consider the Modesto effluent to be a significant fraction of the total watershed salinity loading, the recommended project ---PAGE BREAK--- FINAL - March 2007 8-2 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.1 Strategic Plan Wastewater Master Plan Phase 2 Update City of Modesto, California Regulatory Issue Projected Compliance Date Compliance Strategy Applicable Master Plan Facility Components Potential Future Additions/Modifications Sutter Avenue Primary Treatment Plant: Protection for 100-year Flood - Sutter Avenue Plant 2011 Construct flood control levee around plant and sludge drying beds Flood control levees Containing Peak Wet Weather Flows at Sutter Ave. Plant 2011 Expand headworks hydraulic capacity Influent pumping, flow meter, screening and grit removal Conveying Peak Flows from Sutter Avenue Plant to Jennings Rd Plant 2011 Expand primary effluent pump station and primary effluent pipeline Primary Effluent Pump Station, lining of primary effluent pipeline Groundwater Impacts - Sutter Avenue Facilities 2011 Install groundwater monitoring wells Line sludge drying beds and install subnatant return lines Jennings Road Secondary Treatment Plant: Effluent Disposal Capacity Deficiencies 2008 - 2011 Add tertiary treatment at Jennings Rd for year round discharge to river DAF and Tertiary facilities Title 22 Compliance for all river discharges 2016 Add tertiary treatment at Jennings Rd for year round discharge to river Tertiary facilities Ammonia 2011 Add BNR Facilities for year round discharge to river Nitrification/denitrification in recirculation channel Copper 2011 Continue dynamic compliance model studies, translator study and copper water effects ratio studies Non-structural Dissolved Oxygen Demand (nitrate removal) 2016 Add BNR Facilities for year round discharge to river Nitrification/denitrification in recirculation channel ---PAGE BREAK--- FINAL - March 2007 8-3 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.1 Strategic Plan (Continued) Wastewater Master Plan Phase 2 Update City of Modesto, California Regulatory Issue Projected Compliance Date Compliance Strategy Applicable Master Plan Facility Components Potential Future Additions/Modifications Trihalomethanes (THMs) 2011 Add DAF for algae removal, tertiary facilities to remove organic material, UV disinfection DAF, coagulation/filtration or membrane filtration, UV disinfection Molybdenum 2011 Source control, upstream receiving water monitoring to determine if assimilative capacity is available for dilution, continue changeover to surface water for drinking water supply Outfall Diffuser Salinity and Boron Unknown Source control, convert to potassium hydroxide from sodium hydroxide at food processing industries, changeover to surface water for drinking water supply, evaluate reverse osmosis, evaluate membrane filtration for tertiary facilities to provide pretreatment for RO membranes, investigate offset programs Non-structural Reverse Osmosis and Brine disposal facilities Mercury 2011 Source control, industrial pretreatment, perform in-plant methyl mercury monitoring in receiving water and effluent, participate in regional TMDL and offset efforts Membrane filtration or high rate flocculation/sedimentation/media filtration to reduce metals Reverse Osmosis and Brine disposal facilities Selenium 2011 Develop site-specific objective based on fish tissue concentrations, change to surface water drinking water supply Membrane filtration or high rate flocculation/sedimentation/media filtration to reduce metals Reverse Osmosis and Brine disposal facilities ---PAGE BREAK--- FINAL - March 2007 8-4 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.1 Strategic Plan (Continued) Wastewater Master Plan Phase 2 Update City of Modesto, California Regulatory Issue Projected Compliance Date Compliance Strategy Applicable Master Plan Facility Components Potential Future Additions/Modifications Aluminum 2011 Use acid-soluble aluminum to comply with USEPA WQO, perform water effects ratio study to develop site specific objectives Membrane filtration or high rate flocculation/sedimentation/media filtration to reduce metals Reverse Osmosis and Brine disposal facilities Iron and Manganese 2011 Perform translator studies to develop site specific objectives Membrane filtration or high rate flocculation / sedimentation / media filtration to reduce metals Reverse Osmosis and Brine disposal facilities Emerging Constituents Unknown Monitor continuing research in this area Non-structural Reverse Osmosis and Brine disposal facilities, ozonation Groundwater Impacts - Jennings Road Facilities Unknown Continue Modesto Ranch Salt Studies to monitor salt impacts None Reverse Osmosis and Brine disposal facilities, lining of treatment ponds BOD Loading Rates for Segregated Cannery Wastewater applied to Land Unknown Conduct parallel study to evaluate allowable loadings at Modesto Ranch. Study to be done by City. Establish budget for scientific studies Pretreatment at industries or centrally at Jennings Road Protection for 100-year Flood - Jennings Rd Plant 2011 Improve levees at San Joaquin River Levee improvements ---PAGE BREAK--- FINAL - March 2007 8-5 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc includes year round discharges as opposed to the seasonal discharge (October through May) currently allowed. Biological nutrient removal (BNR)/tertiary treatment will not reduce salinity levels. Additional salt loadings to the river from the expanded discharge season (June through September) may trigger additional requirements or anti-degradation studies and, potentially, salinity reduction. If required, the most likely treatment process to remove salinity is reverse osmosis (RO). RO would be applied for a portion of the effluent and blended with the remaining effluent. The strategy for adding RO in the future is to select tertiary processes that would be compatible with future RO. Membrane filtration would provide the required pretreatment for RO membranes. A detailed evaluation of membrane filtration and conventional media filtration will be conducted during preliminary design. If membrane filtration is reasonably close to the overall present worth cost of conventional filtration, then membrane filtration should be selected. 8.2.2 Metals Limits The City’s existing treatment ponds play a significant role in reducing metals concentrations in the effluent. The strategy for the future is to maintain the use of the recirculation channel and facultative ponds as much as possible in future treatment schemes to maintain current levels of metals removal. High-rate flocculation/sedimentation or membrane filtration will also be key components of the BNR/tertiary treatment train to reduce metals. The actual metals reductions from either process will need to be evaluated in pilot studies during preliminary design to accurately predict performance. The most critical metals constituents that could impact the City’s effluent discharge to the river include mercury and molybdenum. The is developing a TMDL for total mercury. The draft TMDL contains a waste load allocation based on Modesto’s current (2005) total mercury loadings. The City is currently permitted for a maximum flow to the river of 70 million gallons per day (mgd). In comparison, projected discharges of tertiary effluent at build out are 27.5 mgd. However, in the future the discharge period would be extended from seasonal to year round. Total volume discharged to the river for year round discharge would be 10.0 billion gallons per year compared to current actual effluent discharges of 4.8 billion gallons per year, based on 13.2 mgd annual average flow (with dissolved air flotation [DAF] added). If the interpretation were to use the current permitted flow of 70 mgd for the entire discharge season, the current permitted flow would amount to 14.8 billion gallons per year. Clarification will be required for calculation of the current TMDL loadings. If actual current river discharges are used as the basis for calculating waste load allocations (WLAs) it would result in a cap on current mercury loads that could be discharged to the river. Source control or treatment by RO would be required to reduce total mercury levels. ---PAGE BREAK--- FINAL - March 2007 8-6 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Molybdenum is used as an anti-fouling agent for cooling towers and in manufacturing some types of ink. Molybdenum also occurs naturally in potatoes, the main ingredient for one major food processor in Modesto. The City has applied for an extension to the Cease and Desist Order, which had a compliance date of 2005. There are currently no molybdenum removal processes included in the BNR/tertiary expansion project. The City will need to continue to work with industries to reduce molybdenum. If feasible, an outfall diffuser may provide dilution credits for molybdenum. As described in Chapter 4, the upstream receiving water concentration should be monitored to evaluate the feasibility of acquiring dilution credits. The strategy is to continue source control and to evaluate the feasibility of constructing an outfall diffuser in the San Joaquin River to achieve dilution credits. 8.3 TERTIARY TREATMENT FOR ALL RIVER DISCHARGES (FULL TERTIARY TREATMENT) All municipal dischargers that discharge to the San Joaquin River and river delta system year round are currently being required to upgrade to tertiary treatment. In discussions with the it appears likely that full tertiary treatment all discharges to the river must meet tertiary treatment) will be required in the future. It is assumed for the purpose of this master plan that full tertiary treatment will be required in the 2011 permit, with a 5-year compliance schedule. This would result in a 2016 compliance date for full tertiary treatment. The 2006 permit is currently being prepared. The strategy is to provide for full tertiary by 2016. 8.4 GROUNDWATER LIMITATIONS The cumulative effects of applying domestic secondary effluent and segregated cannery wastewater to land are being assessed by the The Board is also considering the effects of wastewater constituents on groundwater from the unlined recirculation channel, facultative ponds, and effluent storage ponds. According to discussions with the Regional Board staff, there is a potential for the Board to require installation of an impervious liner under these facilities in the future. Lining the ponds would not be economically feasible. The costs to line the recirculation channel and oxidation ponds are estimated to range from $90 million to $100 million. If lining is required, the most practical approach would be to replace the treatment ponds (recirculation channel and facultative ponds) with new concrete aeration basins or oxidation ditches. The recommended project includes the use of the recirculation channel over the entire planning period. If lining is required in the future, new concrete aeration basins would be added and the recirculation channel and facultative ponds abandoned. This would be essentially the same as Alternative 1A or 1B as described previously in Chapter 7. However, the concrete basins would need to be sized to provide secondary treatment for land disposal as well. It is assumed for this master plan that the effluent storage ponds would continue to be used in any case since the secondary treatment process will remove nitrogen in the effluent before it is stored in the storage ponds. ---PAGE BREAK--- FINAL - March 2007 8-7 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc The direct land application of segregated cannery process water is also being scrutinized by the The strategy to address this is to perform detailed scientific studies to verify appropriate land application rates and methodologies. 8.5 RECOMMENDED PROJECT The recommended project consists of the following components: • Improvements to the Sutter Avenue Primary Treatment Plant to expand its hydraulic capacity, solids treatment capacity and to provide protection for a 100-year flood event. • Relining the primary effluent outfall (from Sutter Avenue to Jennings Road) to increase its hydraulic capacity and to improve reliability. • Expansion and upgrade of the Jennings Road Secondary Treatment Plant to increase domestic effluent disposal capacity and to comply with projected discharge requirements. • Detailed scientific studies to verify appropriate BOD loadings and land application methodologies associated with segregated cannery process flows. The project components and estimated costs associated with 2030 buildout are summarized in Table 8.2. All costs are based on June 2006 data and include allowances for contingencies, engineering, legal, and administrative expenses. Figure 8.1 is a schematic diagram for the recommended project. Figures 8.2 and 8.3 present preliminary site plans for the Sutter Avenue and Jennings Road improvements. Each major project component is described in the following paragraphs. 8.5.1 Sutter Avenue Primary Treatment Plant Improvements • Influent Flowmeter Improvements. The influent flowmeters consist of three Parshall flumes (2 are operational, one is standby). As described previously in Chapter 3, the flumes have poor entrance conditions and the flume liners are deformed. Improvements will consist of upstream flow straightening baffles to even out the flow pattern just upstream of the flumes. The standby flume will be required to accommodate projected peak wet weather flows. • Influent Pump Station Expansion. The additional pump will provide sufficient capacity for the projected design peak wet weather flow. The existing influent pump station consists of four screw type pumps. A fifth pump will be added in an expansion slot already provided in the structure. • Influent Bar Screen. A new bar screen is needed to expand the hydraulic capacity of the headworks to accommodate the projected peak wet weather flows. The additional bar screen mechanism will be installed in an expansion area already provided in the headworks structure. ---PAGE BREAK--- FINAL - March 2007 8-8 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.2 Wastewater Treatment Capital Costs Wastewater Master Plan Phase 2 Update City of Modesto, California Costs in $M(1) Sutter Avenue Primary Treatment Plant Influent Flume Hydraulic Improvements 1.5 Bar Screen 0.6 Influent Pump 1.1 Grit Removal Unit 0.3 Primary Effluent Pump Station 9.3 Anaerobic Digester 4.8 Flood Control Improvements 14.0 Stormwater Pump Station 2.0 Sludge Dewatering 7.6 Subtotal Sutter Avenue Primary Plant 41.2 Primary Effluent Pipeline Lining of Existing Pipeline 12.4 Jennings Road Secondary Treatment Plant (Based on Alternative 3A) Dissolved Air Flotation Project 11.0 BNR/Tertiary Improvements Phase 1A Improvements 8.6 Mixed Liquor Pump Station 3.9 Aeration for Recirculation Channel 10.0 Secondary Clarifiers 39.6 RAS/WAS Pump Station 11.9 High Rate Flocculation/Sedimentation 22.0 Media Filtration 14.1 Chemical Storage/Feed Facilities 8.2 UV Disinfection 11.0 Gravity Belt Thickeners 19.6 Sludge Drying Beds 2.5 Effluent Pipeline from Tertiary Plant to Exist. Outfall 7.2 Subtotal BNR/Tertiary Improvements 169.6 Improvements to Existing Facilities Conversion from Chlorine Gas to Hypochlorite 0.5 Effluent Pump Station Improvements 3.0 Outfall Improvements 4.0 Flood Control Improvements 0.2 Fixed Film Reactor Improvements 1.8 Subtotal Improvements to Existing Facilities 9.5 Subtotal Jennings Road Secondary/Tert. Plant 179.1 Land Application Studies 1.0 Total Project 233.7 Note: Conceptual level costs. Based on June 2006 dollars (ENRCCI = 8441). Includes allowances for contingencies, engineering, legal and administrative expenses. ---PAGE BREAK--- Figure 8.1 RECOMMENDED PROJECT SCHEMATIC WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO Anaerobic Digesters (add one) Existing Facilities Sutter Avenue New Facilities Jennings Road Long-Term Facilities Jennings Road Near-Term Facilities LEGEND Sludge Drying Beds (line with concrete) Cannery Wastewater (Season: Jul-Sep) Headworks Facility (add 1 pump, bar screen, and grit removal mechanism) Domestic Wastewater Sutter Avenue Facility Primary Clarifiers Pumping Plant No. 3 FFRs Facultative Ponds Chlorine Contact Tank Effluent PS S a n J o a q ui n Ri v e r Land Application Site (2,526 Acres) Recirculation Channel Effluent PS Recirculation Channel (new aerators) 60-inch Primary Effluent Outfall (add plastic liner) 60-inch Cannery Process Water Outfall Primary Effluent PS FFR Influent PS Influent PS Storage Ponds Nitrification Trickling Filters Filters Dissolved Air Flotation Jennings Road Facility Secondary Clarifiers Flocculation/ Sedimentation Filters Ultraviolet Disinfection Effluent PS WAS RAS Sludge Drying Beds Gravity Belt Thickener To Recirculation Channel Near Term Improvements mo606mpf33-6887.cdr 8-9 ---PAGE BREAK--- ---PAGE BREAK--- Mo606mpm16-6887.cdr Approximate Scale 0’ 100’ Flocculation/ Sedimentation Tanks Effluent Filters Flow Split Structure FFR Effluent Pump Station Secondary Clarifiers Flow Split Structure RAS/WAS Pump Station RAS/WAS Pump Station GBT Building Sludge Drying Beds Approximate Scale 0’ 100’ Figure 8.3 CONCEPTUAL LAYOUT - RECOMMENDED PROJECT JENNINGS ROAD FACILITY WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO 8-11 Conversion of Recirculation Channel to Extended Aeration Basin (add new floating aerators) ---PAGE BREAK--- FINAL - March 2007 8-12 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc • Grit Removal. A new grit removal mechanism will be installed in an existing vortex grit chamber structure. This project component is also required to accommodate projected peak wet weather flows • Primary Effluent Pump Station. It is assumed for the master plan that the existing primary effluent pump station will be replaced with an entirely new structure. The pump station will be designed to provide a set of dry weather pumps and wet weather pumps, each contained in separate wet wells. The pumps will be selected to pump the design peak flows through the primary effluent pipeline. The primary effluent pipeline will be lined with a plastic liner (see Primary Effluent Pipeline Lining, below), which will reduce the diameter of the pipe and therefore change the hydraulic conditions from the current unlined pipeline. An alternative to constructing an entirely new pump station would be to add a separate wet weather pump station and retain the existing pumps for dry weather pumping. The existing pumps would be compatible with the hydraulic conditions for pumping dry weather flows in the fully lined pipeline. This alternative should be evaluated during preliminary design. • Additional Anaerobic Digester. One anaerobic digester will be added to increase solids processing capacity and increase reliability of the solids processing system. The digester will be of similar design as the existing digesters, except the structure will be constructed of reinforced concrete instead of steel. • Sludge Dewatering. The existing sludge drying beds will be lined with soil-cement or fiber-reinforced concrete to prevent water in the sludge (subnatant) from seeping into the underlying soil. A drain system will also be added to collect supernatant and return it to the head of the plant for treatment. An alternative to lining the sludge drying beds would be to construct mechanical sludge dewatering facilities. This alternative will be evaluated during preliminary design. • Flood Control Improvements. A flood control levee will be constructed around the Sutter Avenue site to protect the treatment plant from a 100-year flood, as required by the City’s National Pollutant Discharge Elimination System (NPDES) permit. The levee system will consist of earth and concrete walls. Additional studies will be required to assess the impacts of the flood control levee on the river flow to prevent backing up flows and causing flooding upstream. These studies will be used to refine the shape and length of the flood control levee. • Stormwater Pump Station. A new storm water pump station will be added to remove storm water collected within the confines of the flood control levee. 8.5.2 Primary Effluent Pipeline (also referred to as Outfall) • Primary Effluent Pipeline Lining. Additional hydraulic capacity in the existing 60-inch primary effluent pipeline is required to accommodate peak flows. To increase its capacity, the pipeline will be lined with a plastic liner. A portion of the pipeline has already been lined. The new liner will connect to the existing lined portion. With the ---PAGE BREAK--- FINAL - March 2007 8-13 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc liner in place, the pipeline can be pressurized to allow more flow. The existing pipeline is severely corroded on the interior. Lining the pipeline will also improve the reliability of the pipeline and reduce future maintenance costs. 8.5.3 Jennings Road Secondary Treatment Plant As stated previously herein, preliminary design of the Jennings Road treatment facilities will include a detailed evaluation of membranes versus secondary clarifiers followed by conventional filtration. Final process selection will be performed at that time. For the purposes of this discussion, secondary clarifiers and conventional filtration are presented herein. • DAF System. The DAF system will remove algae from storage pond effluent. The DAF system is expected to extend the river discharge period and thereby increase the existing effluent disposal capacity. A capacity increase of approximately 3.0 mgd (at 10th percentile river flow) is estimated to be gained from the DAF system addition. • Phase 1A Improvements. Phase 1A includes the addition of an initial 2.3 mgd of nitrification/tertiary treatment facilities as described previously herein. Preliminary design will verify final process selection. For the purposes of this Master Plan, the use of nitrifying trickling filters followed by high-rate flocculation/sedimentation and filtration has been assumed. • Fixed Film Reactor (FFR) Improvements. Improvements to the FFR are recommended to increase the life of the existing structures. The improvements include a new distributor arm for FFR No. 2 and replacement of the plastic media for FFR No. 2. Structural rehabilitation of the tower structural members is also included. • Recirculation Channel Improvements. The recirculation channel will be converted for use as an aeration basin for the activated sludge process. Improvements will include installation of new aeration, electrical and control equipment. In addition, a portion of the channel will be partitioned to provide an anoxic zone to remove nitrogen (denitrification). The anoxic zone will be equipped with mixers. The channel will also be dredged to remove solids from the channel bottom. • Mixed Liquor Pump Station. A new pump station will pump the flow from the recirculation channel to the secondary and tertiary treatment processes. The recirculation channel will contain biomass, also called mixed liquor. It is anticipated that pumps will be screw-type pumps that lift the flow with a minimum of turbulence. Turbulence shears the naturally flocculated biomass and impairs its ability to settle in the secondary clarifiers. • Secondary Clarifiers. Secondary clarifiers will settle the mixed liquor solids from the recirculation channel. • RAS/WAS Pump Station. The return activated sludge (RAS) and waste activated sludge (WAS) pump station will return the solids settled out in the secondary clarifiers ---PAGE BREAK--- FINAL - March 2007 8-14 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc to the recirculation channel. A portion of the RAS will be “wasted” by sending it to solids processing facilities. • High Rate Flocculation/Sedimentation. The high rate flocculation/sedimentation process will coagulate/flocculate the fine particles that pass through secondary clarification. The flocculated particles will be settled out and removed for disposal. Pilot testing will be required to determine the effectiveness of the flocculation/sedimentation process and to select the flocculant chemicals and dosages. From experience elsewhere, it is anticipated that ferric chloride or alum, and polymer will be used. • Media Filtration. Effluent filters will remove the remaining fine particles in order to achieve a effluent turbidity of less than 2.0 nephelometric turbidity units (NTU). Filters are also required by California Title 22 water recycling standards. There are several options for filters. These include cloth media disk filters, continuously backwashed sand filters, and deep bed sand filters. The most effective filter type will be determined during preliminary design. The filters should be operated in series with the flocculation/sedimentation pilot tests. In addition to pilot testing for media filtration, it is recommended that membrane filtration be tested in parallel. • Chemical Storage and Feed Facilities. The chemical feed system will store and feed coagulants for the tertiary facilities. The system will consist of storage tanks, feed pumps and polymer blending systems. • Ultra Violet (UV) Disinfection System. UV disinfection will be utilized for tertiary treated effluent to reduce pathogens to Title 22 standards (a coliform count of no greater than 2.2 MPN). UV was chosen to prevent the formation of THMs. Pilot testing is recommended to select design parameters for the UV system. The pilot testing should be conducted concurrently with the flocculation/sedimentation, filtration, and membrane pilot tests. Chlorine disinfection will remain for secondary effluent discharges to the river through 2016. • Conversion of Gas Chlorine to Sodium Hypochlorite Solution. It is assumed that the gaseous chlorine system will be replaced with a liquid sodium hypochlorite system for the interim period until secondary effluent discharges to the river are no longer allowed (assumed to be year 2016). Sodium hypochlorite is the preferred chlorination system because it eliminates the need for gaseous chlorine and the risks associated with storing and working with gas chlorine. After 2016, when all discharges to the river receive tertiary treatment and UV disinfection, some chlorine will still be needed for process control and maintenance. Accordingly, the sodium hypochlorite system will be retained for this purpose for the remainder of the planning period. • Effluent Pump Station Improvements. The effluent pump station will be improved by reinforcing the foundation and providing a cut-off wall to prevent seepage from the adjacent levee along the San Joaquin River. ---PAGE BREAK--- FINAL - March 2007 8-15 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc • Outfall Improvements. The outfall, from the effluent pump station to the river, will be replaced. The existing outfall is corroded and leaking in some locations. In addition, a diffuser may be added in the riverbed to increase the initial dilution for effluent constituents with assimilative capacity in the river. Additional evaluation of the feasibility of a diffuser should be conducted in preliminary design. • WAS Thickening Facility. The WAS will be thickened prior to being sent to the sludge drying beds. It is assumed that the thickening process will be a gravity belt thickener (GBT) because it is simple to operate and energy efficient. • Sludge Drying Beds. Sludge drying beds will provided to solar dry thickened biosolids. The beds will be lined with concrete and equipped with a drainage system to contain the subnatant and convey it to the recirculation channel for treatment. Dried biosolids will be trucked to the nearby Modesto Ranch for land application. • Tertiary Effluent Pipeline. A pipeline is required to convey tertiary effluent from the northeast corner of the existing site (near the FFRs) to the existing effluent pump station next to the chlorine contact tank and the river. The pipeline will flow by gravity and will be approximately 10,000 feet long and 60 inches in diameter. • Flood Protection Improvements. Improvements to the flood control levees are required to prevent seepage from the river to the irrigation fields during periods of high river flows. Seepage may also be threatening the foundation of the existing chlorine building. Initial investigations indicate that improvements will be required to control ground subsidence near the chlorine building, improve the stability of the levees where sand boils have occurred and install a new retaining wall at the chlorine building. Condor Engineering developed a budget cost of $400,000 for these improvements in their preliminary investigation in May 2006. Some or all of the flood control work may be funded by the Federal Emergency Management Agency (FEMA). It is assumed for this master plan that 50 percent of the levee improvement costs will be funded by FEMA, with the remainder funded by the City. 8.5.4 Special Planning Studies Special planning studies will be prepared to modify and update the Master Plan. 8.5.4.1 Engineering System Analysis Engineering system analysis will be performed annually to adapt to potential changes. 8.5.4.2 Master Plan Updates The master plan will undergo a major update every ten years. Minor updates will be prepared in between. ---PAGE BREAK--- FINAL - March 2007 8-16 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc 8.5.4.3 Segregated Cannery Process Water Studies It is the preferred approach to maintain the strategy of land application of segregated cannery process water. This approach has become increasingly scrutinized by regulatory agencies. The recommended project includes conducting detailed scientific studies of this practice to verify appropriate long-term land application rates and methodologies. 8.5.5 Project Implementation Plan Effluent disposal requirements and final waste discharge provisions will dictate the required phasing of the recommended project (including improvements to the Sutter Avenue plant and primary effluent pipeline). The effluent disposal capacity has the highest priority since it relates to growth and can be highly variable due to river flow conditions. In addition, it is the most costly of the project components, and it will require the most time for construction. Figure 8.4 shows the required tertiary treatment capacity needs and a phasing plan that would strictly follow the capacity needs for “just in time” phasing. Under this approach the tertiary phasing would be: 1A – 2.3 mgd (2009), Phase 1B – 2.5 mgd (2011), Phase 2 – 20 mgd (2016), and Phase 3 - 5 mgd (2023). An alternative phasing program would be to increase the capacity for Phase 1B to spread out costs more evenly for the phases and provide for a more modular sizing of project components. With the alternative phasing approach, the phasing would be: Phase 1A – 2.3 mgd, Phase 1B – 10.3 mgd, Phase 2 – 8.0 mgd, and Phase 3 – 6.9 mgd. The alternative phasing scheme is illustrated in Figure 8.5. Phasing should be re-evaluated during pre-design. For the master plan it was assumed that the just in time phasing plan will be adopted. Table 8.3 summarizes the wastewater treatment capital improvements program, including an estimate of cost per phase. ---PAGE BREAK--- mo606mpf35-6887.ai 27.2 29.5 32.0 36.5 41.5 24.2 14.0 5.9 Year * Based on 10th percentile river flow conditions. Assumes discontinuation of secondary effluent discharge to river in 2016 and phase out of DAF and Phase 1A Capacity for Land Discharge Capacity for River Discharge Capacity for Tertiary-Treated Effluent Discharge Capacity Deficiencies Domestic Wastewater Flow, mgd 2005 50 40 30 20 10 0 2010 2011 2008 2009 2015 2016 2020 2025 2023 2030 Projected Domestic Wastewater Flow (annual average flow) Domestic secondary effluent to land (8.1 mgd) (2,526 acres) Net evaporation loss (5.9 mgd) DAF (3.0 mgd) Seasonal river discharge of secondary effluent (10.2 mgd*) BNR/tertiary river discharge Phase 1A 2.3 Phase 1B 2.5 Phase 2 20.0** Phase 3 5.0 Figure 8.4 BNR/TERTIARY TREATMENT PHASING AT JENNINGS ROAD FACILITY ENGINEER’S REPORT CITY OF MODESTO 8-17 ---PAGE BREAK--- mo606mpf27-6887.ai 30 25 20 15 10 Flow (mgd) 5 0 2010 2015 2020 Year 2025 2030 2005 24.4 27.5 4.1 0.9 22.4 17.1 12.6 20.6 12.6 20.6 2.3 4.8 22.5 Figure 8.5 ALTERNATIVE PROJECT PHASING WASTEWATER MASTER PLAN PHASE 2 UPDATE CITY OF MODESTO LEGEND Projected Tertiary Capacity Needs “Just in Time” Phasing Plan Modular Phasing Plan 8-18 ---PAGE BREAK--- FINAL - March 2007 8-19 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.3 Wastewater Treatment Capital Improvements Program Wastewater Master Plan Phase 2 Update City of Modesto, California Conceptual Level Costs - $M(1) Project Phases: DAF Phase 1A Phase 1B Phase 2 Phase 3 Total Approximate Year of Implementation: 2008 2009 2011 2016 2023 Costs Sutter Avenue Primary Treatment Plant Influent Flume Hydraulic Improvements 1.5 1.5 Bar Screen 0.6 0.6 Influent Pump 1.1 1.1 Grit Removal Unit 0.3 0.3 Primary Effluent Pump Station 9.3 9.3 Anaerobic Digester 4.8 4.8 Flood Control Improvements 14.0 14.0 Stormwater Pump Station 2.0 2.0 Sludge Dewatering 7.6 7.6 Subtotal Sutter Avenue Primary Plant 0.0 41.2 0.0 0.0 41.2 Primary Effluent Pipeline Lining of Existing Pipeline 12.4 12.4 Jennings Road Secondary Treatment Plant Dissolved Air Flotation Project 11.0 0.0 0.0 0.0 0.0 11.0 BNR/Tertiary Improvements Phase 1A Improvements 8.6 8.6 Mixed Liquor Pump Station 0.0 0.4 2.8 0.7 3.9 Aeration for Recirculation Channel 10.0 10.0 Secondary Clarifiers 0.0 3.6 28.8 7.2 39.6 RAS/WAS Pump Station 0.0 6.0 4.7 1.2 11.9 High Rate Flocculation/Sedimentation 0.0 2.0 16.0 4.0 22.0 Media Filtration 0.0 1.4 9.9 2.8 14.1 Chemical Storage/Feed Facilities 0.8 6.0 1.4 8.2 UV Disinfection 0.0 1.0 8.0 2.0 11.0 Gravity Belt Thickeners 9.8 7.8 2.0 19.6 Sludge Drying Beds 0.2 1.8 0.5 2.5 Effluent Pipeline from Tertiary Plant to Exist. Outfall 7.2 0.0 0.0 7.2 Subtotal BNR/Tertiary Improvements 8.6 42.4 85.8 21.8 169.6 Improvements to Existing Facilities Conversion from Chlorine Gas to Hypochlorite 0.5 0.0 0.0 0.0 0.5 Effluent Pump Station Improvements 3.0 0.0 0.0 3.0 Outfall Improvements 4.0 0.0 0.0 4.0 Flood Control Improvements 0.2 0.2 Fixed Film Reactor Improvements 1.8 1.8 Subtotal Improvements to Existing Facilities 0.0 0.5 9.0 0.0 0.0 9.5 Subtotal Jennings Road Secondary/Tert. Plant 11.0 9.1 51.4 85.8 21.8 179.1 ---PAGE BREAK--- FINAL - March 2007 8-20 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\08.doc Table 8.3 Wastewater Treatment Capital Improvements Program Wastewater Master Plan Phase 2 Update City of Modesto, California Conceptual Level Costs - $M(1) Project Phases: DAF Phase 1A Phase 1B Phase 2 Phase 3 Total Approximate Year of Implementation: 2008 2009 2011 2016 2023 Costs Special Planning Studies Engineering System Analysis 0 0.6 0.8 1.1 1.1 3.6 Master Plan Updates 1.0 2.0 1.0 2.0 6.0 Land Application Studies 1.0 1.0 Subtotals 0 2.6 2.8 2.1 3.1 10.6 Total Project 11.0 24.1 95.4 87.9 24.9 243.3 Note: Conceptual level costs. Based on June 2006 dollars (ENRCCI = 8441). Includes allowances for contingencies, engineering, legal and administrative expenses. ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX A - JULY 27, 2006 MEMORANDUM PREPARED BY THE CITY THAT DESCRIBES ESTIMATED SEWER FLOW PROJECTIONS ---PAGE BREAK--- City of Modesto Memo To: Mike Britten, Jose Gutierrez – Carollo Engineers From: William Wong – City of Modesto CC: Rich Ulm, Jack Bond – City of Modesto Date: 7/27/06 Re: Estimated Sewer Flow Projections The City of Modesto Community and Economic Development Department (CEDD) recently prepared a memorandum regarding population projections within the City’s Sphere of Influence (SOI) at buildout (copy attached). This population projection will be used in support of a determination of the need for capacity and improvements at the City’s sanitary sewer treatment facility. This analysis focuses on comparing estimated sewer flow demands from updated residential land uses to the sewer demands from population growth. The May 4, 2006 CEDD analysis by Miguel Galvez refines and updates General Plan acreage figures and population assumptions that may affect municipal levels of service. It is expected that the assumptions of the current General Plan will be modified and incorporated into the next comprehensive update of the General Plan and accompanying MEIR. Anticipated Flow Projections – Based On Land Use Updates Using the information contained in the May 4, 2006 memorandum “Final Memo on Projected General Plan Buildout Population of the SOI” from the CEDD memorandum, the projected Village Residential densities have been increased, from 5.1 DU/ac1 to the new range of 5.75 - 7.5 dwellings units per acre. Using the Mid-density value of 6.6 dwellings per acre, the following assumptions were made: Table 1 - Assumptions 6.6 DU2/ac (Mid-density from May 4, 2006 memo) 2.9 People/DU (From May 4, 2006 memo) 100 Gpd/cap (From Current City of Modesto Standards) Anticipated per acre flow 1,914 gpd/ac The flow factor of 1,914 gpd/ac differs from the actual flow coefficient of 1,260 gpd/ac generated by the 2004 sewer flow-monitoring program for Village Residential (VR) from the Draft Wastewater Master Plan update. The generated VR wastewater flows are based on current densities, and would likely 1 From the 1995 Urban Area General Plan (amended in 2003) 2 DU = Dwelling Unit z Page 1 ---PAGE BREAK--- z Page 2 increase with the proposed density increases, as indicated in the CEDD memorandum. Therefore, it would be prudent to factor these new densities for design purposes. Table 2 – Estimated Sewer Flow based on Land Use 6.6 DU/acre) Land use Designation Developable acreage within SOI (acres) Using expected 90% build-out of developable acres3 Flow Coefficient (gpd/ac) Anticipated sewer flow (mgd) Residential and Village Residential 3 5,121 4,608.6 1,914 8.82 Residential (North Ceres) 4 – Assumes Ceres Residential Densities similar to Modesto 146 131.4 1,914 0.25 Underdeveloped Residential in SOI 3 325 292.5 1,914 0.56 Regional Commercial 3 389 350.0 1,000 0.35 Commercial (estimated vacant within the City Limits) 100 90.0 1,000 0.09 Business Park 3 2,168 1,951.3 890 1.74 Mixed Use 3 17 14.9 1,100 0.02 Industrial (vacant in SOI) 5 1,456 1,310.4 1,000 1.31 Industrial (underdeveloped in SOI) 5 1,793 1,613.7 1,000 1.61 Anticipated Buildout Flow Subtotal: 14.8 mgd 2005 Annual Flow: 25.8 mgd Total Build-out Flow (based on land use): 40.6 mgd Assuming that 90% of the developable acreage will develop at build-out, the anticipated additional generated flow, based on land use, will range from 13.5 to 16.1 MGD, with the mid-range flow at 14.8 MGD. However, based on the variable proposed densities, anticipated total flow at build-out can be reasonably expected to range between 39.3 to 41.9 MGD, with 40.6 MGD being the mid-range buildout flow. Intensification of existing industrial customers that discharge to the cannery segregation facilities was not included in this estimate, and will be analyzed at a later date. Anticipated Flow Projections – Based On Population Projections The CEDD memorandum trend analysis was used to estimate the residential growth rate for the SOI. From 2000-2005, the annual growth rate has been an approximately 1.91%, and over the last 10 years, the annual rate has been 1.55%. The CEDD memorandum forecasts a growth rate between 1.60- 1.90%. The CEDD memorandum projects the population of the SOI buildout to be between 333,640 to 356,843 people, with a mid-range population of 344,910 people. It is important to note that there are yearly fluctuations in the per capita flow rate. Historically, the per capita flow (gpd/cap) from 2000 to 2005 has fluctuated between 101.6 gpd/cap to 125.1 gpd/cap (See Table These fluctuations may be attributed to variations in flow from the industrial operations, changes in domestic indoor water consumption, or a combination of both. 3 From May 4, 2006 “Final Memo on Projected General Plan Buildout Population of the SOI” by Miguel Galvez 4 From Draft Wastewater Collection System Master Plan by Carollo Engineers. 5 From 2003 Urban Growth Policy Review Report. ---PAGE BREAK--- z Page 3 Table 3 - Per Capita Flow Estimate Year SOI Population Estimated Sewer Service Pop. Flow (MGD) Per Capita Flow (GPD/cap) 2000 188,856 201,130 24.6 122.3 2001 193,100 205,374 25.7 125.1 2002 198,800 211,074 23.9 113.2 2003 203,300 215,574 21.9 101.6 2004 206,188 218,462 22.4 102.5 2005 207,634 219,908 25.8 117.3 Using the average annual 2005 flow of 25.8 MGD, which includes all non-Cannery Segregation flows (residential, commercial, some industrial), and with an existing sewer service population of 219,9086, the gross per capita flow is calculated to be approximately 117.3 gpd/cap, and is used to estimate future sewer flows. Table 4 - Estimated Flow based on Population Growth at 117.3 gpd/cap Projected Population within SOI at buildout North Ceres Population at build-out (est.)7 Projected Additional Population served at build- out (SOI + N. Ceres) Projected Build- out Flow (MGD) Low Density 333,640 11,900 345,540 40.5 Mid-Density 344,910 11,900 356,810 41.9 High Density 356,843 11,900 368,743 43.3 From the CEDD memorandum, expected build-out population, based on low-density8 build-out of the Sewer Service Area will be 348,540 people and calculated build-out flow will be 40.5 MGD. A high- density Sewer Service Area build-out population of 368,743 and would have an expected build-out flow of 43.3 MGD. Table 5 - Population Growth within Wastewater Master Plan Study Area Year Anticipated City Growth Rate City Limits Population - New Growth Annexation into City Limits/Sewer District Estimated Population (within SOI) Projected North Ceres Population Sewer Service Area Population (SOI + N. Ceres) Expected Sewer Flow, based on 117.3 gpd/cap (MGD) 2005 207,634 210,308 9,600 219,908 25.8 2006 210,114 212,788 9,600 222,388 27.0 2007 1.60% 213,476 138 216,288 9,610 225,898 26.5 2008 1.60% 216,891 278 219,843 9,620 229,463 27.0 2009 1.60% 220,362 418 223,454 9,630 233,084 27.4 2010 1.60% 223,887 558 227,119 9,640 236,759 27.8 6 Total sewer service population in 2005 is 219,908, which includes existing service connections in Modesto Municipal Sewer District No. 1, Empire Sanitation District and North Ceres. 7 9,600 existing customers + (131.4 vacant acres x 6 units/ac x 2.9 people per unit) = 11,900 people at build-out 8 From May 4, 2006 “Final Memo on Projected General Plan Buildout Population of the SOI” by Miguel Galvez, Pg. 3. ---PAGE BREAK--- z Page 4 Table 5 - Population Growth within Wastewater Master Plan Study Area (Continued) Year Anticipated City Growth Rate City Limits Population - New Growth Annexation into City Limits/Sewer District Estimated Population (within SOI) Projected North Ceres Population Sewer Service Area Population (SOI + N. Ceres) Expected Sewer Flow, based on 117.3 gpd/cap (MGD) 2011 1.60% 227,470 698 230,841 9,650 240,491 28.3 2012 1.75% 231,450 1,273 235,397 9,768 245,166 28.8 2013 1.75% 235,501 2,546 240,721 9,887 250,608 29.4 2014 1.75% 239,622 3,820 246,115 10,005 256,121 30.1 2015 1.75% 243,815 5,093 251,582 10,124 261,706 30.7 2016 1.75% 248,082 6,366 257,122 10,242 267,364 31.4 2017 1.75% 252,424 7,639 262,736 10,361 273,097 32.1 2018 1.75% 256,841 8,912 268,427 10,479 278,906 32.8 2019 1.75% 261,336 10,185 274,195 10,597 284,792 33.5 2020 1.75% 265,909 11,459 280,041 10,716 290,757 34.2 2021 1.75% 270,563 12,732 285,968 10,834 296,802 34.9 2022 1.75% 275,297 14,005 291,976 10,953 302,929 35.6 2023 1.75% 280,115 15,278 298,067 11,071 309,138 36.3 2024 1.75% 285,017 16,551 304,242 11,189 315,432 37.1 2025 1.75% 290,005 17,824 310,503 11,308 321,811 37.8 2026 1.75% 295,080 19,098 316,851 11,426 328,278 38.6 2027 1.75% 300,244 20,371 323,288 11,545 334,833 39.3 2028 1.75% 305,498 21,644 329,816 11,663 341,479 40.1 2029 1.75% 310,844 22,917 336,435 11,782 348,217 40.9 2030 1.75% 316,284 24,190 343,148 11,900 355,048 41.7 Based on the growth rate information, a growth rate projection of 1.60% was used through 2011, followed by a growth rate of 1.75% from 2012 to the expected build-out of the SOI in approximately 2030. The expected population within the SOI at build-out will be approximately 343,000 people, which is reasonably close to the projected mid-range buildout value from the CEDD memorandum. Since the City has a sewer service agreement to take a portion of the City of Ceres wastewater, the expected Sewer Service Area (SOI + North Ceres) build-out population is estimated to be 355,000, and the corresponding sewer flows will be 41.7 MGD by 2030. Conclusions: Three different methods were used to analyze and project future flows. The first method incorporates revised land uses of the General Plan, which have been updated from GIS and General Plan Amendments. The resulting anticipated generated flow based on land use is between 39.3 to 41.9 MGD. The second method used anticipated densities from the City’s Planning Department to derive population projections to generate projected wastewater flows between 40.5 MGD to 43.3 MGD. The third method uses growth projections based on historical Annual Growth Rates, based on the Department of Finance population estimates, which generated a build-out flow of 41.7 MGD. ---PAGE BREAK--- z Page 5 Table 6 - Estimated Sewer Service Area Build-out Flow Ranges Wastewater flows based on: Low Range (MGD) Mid-Range (MGD) High Range (MGD) Land Use 39.3 40.6 41.9 CEDD Population Projections 40.5 41.9 43.3 Growth Rate 41.7 Due to the difficulty of projecting the future sewer flows into the City of Modesto’s wastewater system, and due to probable variations of population growth trends, demographics, future General Plan Amendments, etc., it can be reasonably concluded that, based the best information provided to date, the City can reasonably expect the buildout sewer flow to fall between the range of 39.3 to 43.3 MGD. Attachment: “Final Memo on Projected General Plan Buildout Population of the SOI” ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX B - HISTORICAL INFLUENT FLOWS FROM JANUARY 2000 THROUGH DECEMBER 2005 AT THE SUTTER AVENUE FACILITY ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX C - TECHNICAL MEMORANDUM SUMMARIZING THE FINDINGS FROM THE PARSHALL FLUME INVESTIGATION ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX D - WATER QUALITY DATA ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX E - DERIVATION OF ALLOWABLE EFFLUENT DISCHARGE TO RIVER (WITHOUT DAF) ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX F - PATTERN OF THE MEAN MERCED RIVER LOSSES OF WATER DUE TO DIVERSIONS ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX G - PATTERN OF DROUGHTS ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX H - MEMO SUMMARIZING THE CONDITION-ASSESSMENT SITE VISIT ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX I - WASTE DISCHARGE REQUIREMENTS FOR DISCHARGE TO SAN JOAQUIN RIVER (ORDER NO. 5-01-120) ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX J - WASTE DISCHARGE REQUIREMENTS FOR LAND DISPOSAL (ORDER NO. 99-112) ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX K - NOVEMBER 2005 STUDY ENTITLED “UPDATE OF MODESTO RANCH SALT STUDY” PREPARED BY EOA, INC. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- City of Modesto APPENDIX L - PROCESS SIZING CALCULATIONS FOR ALTERNATIVE 1 DRAFT - August 28, 2006 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\6thDraft\Appendix.doc ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX M - PROCESS SIZING CALCULATIONS FOR ALTERNATIVE 2 ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX N - DETAILED BREAKOUT OF THE COST ESTIMATE FOR EACH ALTERNATIVE ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX O - MARCH 2006, CAROLLO ENGINEERS DOMESTIC WASTEWATER NEAR-TERM CAPACITY STUDY ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX P - DERIVATION OF LAND COST ESTIMATES ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX Q - FEASIBILITY STUDY FOR THE DAF PROJECT AND PREDICTED DAF EFFLUENT QUALITY ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX R - DRAFT ALTERNATIVE DISINFECTION ANALYSIS, AUGUST 2005 ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX S - CITY OF TURLOCK WATER QUALITY CONTROL FACILITY UVT TEST RESULTS ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 1 Table 1 Full Scale and Bench Scale Results from 2-22 Experiment number Coagulant and polymer Treatment description Dose, mg/L Turbidity, NTU UV Transmittance, % Secondary effluent none 3:40 pm - 7.47 74.3 Densadeg influent 1 none 3:40 pm 6.27 74.5 Densadeg effluent 2 FeCl3 / cat. poly. 3:40 pm 35/2.2 1.34 76.7 Filtered effluent 2 FeCl3 / cat. poly 3:40 pm 35/2.2 1.18 77.3 Densadeg influent 3 none 5:30 pm - 7.02 71.9 Filtered Densadeg influent 4 none 5:30 pm - 2.27 76.1 1-A FeCl3 / cat. poly. 30/2.08 1.24 76.6 1-B FeCl3 / cat. poly. 30/1.56 1.31 75.7 1-C FeCl3 / cat. poly. 30/1.04 2.43 72.5 1-D FeCl3 / cat. poly. Bench scale simulated Densadeg effluent 30/0.52 3.24 69.6 1-AF FeCl3 / cat. poly. 30/2.08 0.98 79.3 1-BF FeCl3 / cat. poly 30/1.56 0.89 79.7 1-CF FeCl3 / cat. poly 30/1.04 76.7 76.7 1-DF FeCl3 / cat. poly Filtered bench simulated Densadeg effluent 30/0.52 79.7 79.7 Densadeg influent none 7:50 pm 6.86 73.5 Densadeg effluent 2 FeCl3 / cat. poly. 7:50 pm 35/2.2 1.30 75.9 Filtered effluent 2 FeCl3 / cat. poly 7:50 pm 35/2.2 1.17 77.7 1 Densadeg influent is the equalization basin effluent taken prior to the pumpstation that pumps the water to the Densadeg system 2 Samples were collected from the full scale system 3 10 gallons of Densadeg influent collected at 5:30 pm were used during Experiment 1. 4 Bench scale filtration without coagulant/polymer addition was performed on the Densadeg influent for comparative purposes ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 2 Figure 1-PSD, turbidity, and UVT results from water samples collected from the full scale system at 3:40 pm 2/22/06 Figure 2-PSD, turbidity, and UVT results from water samples collected from the full scale system at 7:50 pm on 2/22/06 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Secondary effluent-3:40 pm (7.47 NTU, 74.3%) Densadeg influent-3:40 pm (6.27 NTU, 74.5%) Densadeg effluent-3:40 pm (1.34 NTU, 76.7%) Filter effluent-3:40 pm (1.18 NTU, 77.3%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-7:50 pm (6.86 NTU, 73.5%) Densadeg effluent-7:50 pm (1.30 NTU, 75.9%) Filter effluent-7:50 pm (1.17 NTU, 77.7%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 3 Figure 3-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 1 Figure 4- PSD, turbidity, and UVT results from filtration simulations performed during bench scale Experiment 1 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-5:30 pm (5.63 NTU, 74.5%) BS Filter effluent no chemicals (2.27 NTU, 76.1%) BS simulated DD 35/2.08 mg/L ferric/cationic (1.24 NTU, 76.6%) BS simulated DD 35/1.55 mg/L ferric/cationic (1.31 NTU, 75.7%) BS simulated DD 35/1.04 mg/L ferric/cationic (2.43 NTU, 72.5%) BS simulated DD 35/0.52 mg/L ferric/cationic (3.24 NTU, 69.6%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-5:30 pm (5.63 NTU, 74.5%) BS Filter effluent no chemicals (2.27 NTU, 76.1%) BS simulated DD filter effluent 35/2.08 mg/L (0.98 NTU, 79.3%) BS simulated DD filter effluent 35/1.56 mg/L (0.89 NTU, 79.7%) BS simulated DD filter effluent 35/1.04 mg/L (1.13 NTU, 76.7%) BS simulated DD filter effluent 35/0.52 mg/L (0.92 NTU, 79.7%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 4 Table 2 Full Scale and Bench Scale Results from 2-23 with Ferric chloride Experiment number Coagulant and polymer Treatment description Dose, mg/L Turbidity, NTU UV Transmittance, % Densadeg influent 1, 2 none 8:00 am - 6.54 76.4 Densadeg effluent 3 FeCl3 / cat. poly. 8:00 am 30/2.2 1.18 78.3 Filtered effluent 3 FeCl3 / cat. poly 8:00 am 30/2.2 1.04 79.6 Filtered Densadeg influent 4 none 8:00 am - 1.98 78.1 2-A FeCl3 / cat. poly. 30/2.08 0.93 79.1 2-B FeCl3 / cat. poly. 30/1.56 0.97 77.8 2-C FeCl3 / cat. poly. 30/1.04 1.56 75.8 2-D FeCl3 / cat. poly. Bench scale simulated Densadeg effluent 30/0.52 1.95 73.8 2-AF FeCl3 / cat. poly. 30/2.08 0.72 81.2 2-BF FeCl3 / cat. poly 30/1.56 0.61 82.0 2-CF FeCl3 / cat. poly 30/1.04 0.57 81.6 2-DF FeCl3 / cat. poly Filtered bench simulated Densadeg effluent 30/0.52 0.88 80.9 3-A FeCl3 / anion. poly. 30/2.08 1.33 78.0 3-B FeCl3 / anion. poly. 30/1.56 1.16 77.9 3-C FeCl3 / anion. poly. 30/1.02 1.56 78.2 3-D FeCl3 / anion. poly. Bench scale simulated Densadeg effluent 30/1.06 1.95 77.7 3-AF FeCl3 / anion. poly. 30/2.08 0.82 78.2 3-BF FeCl3 / anion. poly. 30/1.56 0.80 79.7 3-CF FeCl3 / anion. poly. 30/1.04 0.71 81.4 3-DF FeCl3 / anion. poly. Filtered bench simulated densadeg effluent 30/0.52 0.71 79.8 Densadeg influent none 4:10 pm 5.38 73.2 Densadeg effluent 3 FeCl3 / cat. poly. 4:10 pm 30/2.2 1.18 78.3 Filtered effluent 3 FeCl3 / cat. poly 4:10 pm 30/2.2 1.04 79.6 Filtered densadeg influent 4 FeCl3 / cat. poly 4:10 pm 30/2.2 1.64 74.1 1 Densadeg influent is the equalization basin effluent taken prior to the pump station that pumps the water to the Densadeg system. 2 15 gallons of Densadeg influent collected at 8:00 am were used during Experiments 2, 3, 4, and 5. 3 Samples were collected from the full scale system. 4 Bench scale filtration without coagulant/polymer addition was performed on the Densadeg influent for comparative purposes. ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 5 Figure 5-PSD, turbidity, and UVT results from water samples collected from the full scale system at 8:00 am on 2/23/06 Figure 6-PSD, turbidity, and UVT results from water samples collected from the full scale system at 4:10 pm on 2/23/06 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-8:00 am (6.54 NTU, 76.4%) BS Filter effluent no chemicals (1.98 NTU, 78.1%) Densadeg effluent-8:00 am (1.18 NTU, 78.3%) Filter effluent-8:00 am (1.04 NTU, 79.6%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-4:10 pm (5.38 NTU, 74.5%) BS Filter effluent no chemicals (1.64 NTU, 74.1%) Densadeg effluent-4:10 pm (1.18 NTU, 78.3%) Filter effluent-4:10 pm (1.04 NTU, 79.6%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 6 Figure 7-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 2 Figure 8- PSD, turbidity, and UVT results from filtration simulations performed during bench scale Experiment 2 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-8:00 am (6.54 NTU, 76.4%) BS Filter effluent no chemicals (1.98 NTU, 78.1%) Densadeg effluent 30/2.2 mg/L ferric cationic (1.18 NTU, 78.3%) BS simulated DD 30/2.08 mg/L ferric/cationic (0.93 NTU, 79.1%) BS simulated DD 30/1.55 mg/L ferric/cationic (0.97 NTU, 77.8%) BS simulated DD 30/1.04 mg/L ferric/cationic (1.56 NTU, 75.8%) BS simulated DD 30/0.52 mg/L ferric/cationic (1.95 NTU, 73.8%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Full scale DD filter effluent (1.04 NTU, 79.6%) BS simulated DD filter effluent 30/2.08 mg/L (0.72 NTU, 81.2%) BS simulated DD filter effluent 30/1.56 mg/L (0.61 NTU, 82.0%) BS simulated DD filter effluent 30/1.04 mg/L (0.57 NTU, 81.6%) BS simulated DD filter effluent 30/0.52 mg/L (0.88 NTU, 80.9%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 7 Figure 9-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 3 Figure 10-PSD, turbidity, and UVT results from filtration simulations performed during bench scale Experiment 3 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-8:00 am (6.54 NTU, 76.4%) BS Filter effluent no chemicals (1.98 NTU, 78.1%) Densadeg effluent 30/2.2 mg/L ferric cationic (1.18 NTU, 78.3%) BS simulated DD 30/2.08 mg/L ferric/anionic (1.33 NTU, 78.0%) BS simulated DD 30/1.55 mg/L ferric/anionic (1.16 NTU, 77.9%) BS simulated DD 30/1.04 mg/L ferric/anionic (1.02 NTU, 78.2%) BS simulated DD 30/0.52 mg/L ferric/anionic (1.06 NTU, 77.7%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Full scale DD filter effluent (1.04 NTU, 79.6%) BS simulated DD filter effluent 30/2.08 mg/L (0.82 NTU, 78.2%) BS simulated DD filter effluent 30/1.56 mg/L (0.80 NTU, 79.7%) BS simulated DD filter effluent 30/1.04 mg/L (0.71 NTU, 81.4%) BS simulated DD filter effluent 30/0.52 mg/L (0.71 NTU, 79.8%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 8 Table 3 Full Scale and Bench Scale Results from 2-23 with Alum Experiment number Coagulant and polymer Treatment description Dose, mg/L Turbidity, NTU UV Transmittance, % Densadeg influent 1, 2 none 8:00 am - 6.54 76.4 Densadeg effluent 3 FeCl3 / cat. poly. 8:00 am 30/2.2 1.18 78.3 Filtered effluent 3 FeCl3 / cat. poly 8:00 am 35/2.2 1.04 79.6 Filtered densadeg influent 4 none Bench scale filtered 8:00 am - 1.98 78.1 4-A Alum / cat. poly. 60/2.08 1.69 80.6 4-B Alum / cat. poly. 60/1.56 2.10 79.3 4-C Alum / cat. poly. 60/1.04 1.89 79.9 4-D Alum / cat. poly. Bench scale simulated Densadeg effluent 60/0.52 1.87 80.4 4-AF Alum / cat. poly. 60/2.08 0.45 84.8 4-BF Alum / cat. poly. 60/1.56 0.45 83.8 4-CF Alum / cat. poly. 60/1.04 0.42 84.0 4-DF Alum / cat. poly. Filtered bench simulated Densadeg effluent 60/0.52 0.42 79.8 5-A Alum/ anion. poly. 60/2.08 0.81 81.9 5-B Alum/ anion. poly. 60/1.56 0.79 81.7 5-C Alum/ anion. poly. 60/1.02 0.98 81.3 5-D Alum/ anion. poly. Bench scale simulated Densadeg effluent 60/1.06 2.85 79.6 5-AF Alum/ anion. poly. 60/2.08 0.58 84.2 5-BF Alum/ anion. poly. 60/1.56 0.65 82.5 5-CF Alum/ anion. poly. 60/1.04 0.57 82.8 5-DF Alum/ anion. poly. Filtered bench simulated Densadeg effluent 60/0.52 0.48 83.1 Densadeg influent none 4:10 pm 5.38 73.2 Densadeg effluent 3 FeCl3 / cat. poly. 4:10 pm 30/2.2 1.18 78.3 Filtered effluent 3 FeCl3 / cat. poly 4:10 pm 30/2.2 1.04 79.6 Filtered Densadeg influent 4 FeCl3 / cat. poly 4:10 pm 30/2.2 1.64 74.1 1 Densadeg influent is the equalization basin effluent taken prior to the pump station that pumps the water to the Densadeg system. 2 15 gallons of Densadeg influent collected at 8:00 am were used during Experiment 2, 3,4, and 5. 3 Samples were collected from the full scale system. 4 Bench scale filtration without coagulant/polymer addition was performed on the Densadeg influent for comparative purposes. ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 9 Figure 11-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 4 Figure 12-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 4 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-8:00 am (6.54 NTU, 76.4%) BS Filter effluent no chemicals (1.98 NTU, 78.1%) Densadeg effluent 30/2.2 mg/L ferric cationic (1.18 NTU, 78.3%) BS simulated DD 60/2.08 mg/L alum/anionic (1.69 NTU, 80.6%) BS simulated DD 60/1.55 mg/L alum/anionic (2.10 NTU, 79.3%) BS simulated DD 60/1.04 mg/L alum/anionic (1.89 NTU, 79.9%) BS simulated DD 60/0.52 mg/L alum/anionic (1.87 NTU, 80.4%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Full scale DD filter effluent (1.04 NTU, 79.6%) BS simulated DD filter effluent 30/2.08 mg/L (0.45 NTU, 84.8%) BS simulated DD filter effluent 30/1.56 mg/L (0.45 NTU, 83.8%) BS simulated DD filter effluent 30/1.04 mg/L (0.42 NTU, 84%) BS simulated DD filter effluent 30/0.52 mg/L (0.42 NTU, 79.8%) ---PAGE BREAK--- C:\Documents and Settings\dltucker\Desktop\Summary table.doc 10 Figure 13-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 5 Figure 14-PSD, turbidity, and UVT results from Densadeg simulations performed during bench scale Experiment 5 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Densadeg influent-8:00 am (6.54 NTU, 76.4%) BS Filter effluent no chemicals (1.98 NTU, 78.1%) Densadeg effluent 30/2.2 mg/L ferric cationic (1.18 NTU, 78.3%) BS simulated DD 60/2.08 mg/L alum/anionic (0.86 NTU, 81.9%) BS simulated DD 60/1.55 mg/L alum/anionic (0.87 NTU, 81.7%) BS simulated DD 60/1.04 mg/L alum/anionic (1.00 NTU, 81.3%) BS simulated DD 60/0.52 mg/L alum/anionic (2.50 NTU, 79.6%) 1 10 100 1000 10000 1 10 100 Particle diameter, µm Number of particles per size channesl, counts/mL Full scale DD filter effluent (1.04 NTU, 79.6%) BS simulated DD filter effluent 30/2.08 mg/L (0.60 NTU, 84.2%) BS simulated DD filter effluent 30/1.56 mg/L (0.65 NTU, 82.5%) BS simulated DD filter effluent 30/1.04 mg/L (0.56 NTU, 82.8%) BS simulated DD filter effluent 30/0.52 mg/L (0.47 NTU, 83.1%) ---PAGE BREAK--- FINAL - March 2007 H:\Final\Modesto_WCO\6887E00\Rpt\MasterPlanRpt\Final\Appendix.doc City of Modesto APPENDIX T - CONDOR ENGINEERING REPORT ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK---