Document Modesto_doc_f9233cbe9e

June 2008 Draft Wastewater Treatment Master Plan Supplement ---PAGE BREAK--- 2 7 0 0 Y G N A C I O V A L L E Y R O A D , S U I T E 3 0 0 • W A L N U T C R E E K , C A L I F O R N I A 9 4 5 9 8 • ( 9 2 5 ) 9 3 2 - 1 7 1 0 • F A X ( 9 2 5 ) 9 3 0 - 0 2 0 8 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\Cover_TOC.doc City of Modesto Wastewater Treatment Master Plan Jennings Road Secondary Treatment Facility WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT DRAFT June 2008 ---PAGE BREAK--- DRAFT - June 26, 2008 i H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\Cover_TOC.doc City of Modesto, California WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT TABLE OF CONTENTS Page CHAPTER 1 - PURPOSE AND 1-1 CHAPTER 2 - OBJECTIVES 2-1 CHAPTER 3 - FLOW AND LOADINGS PROJECTIONS 3-1 3.1 Historic Wastewater 3-1 3.2 Projected 3-6 3.2.1 Flow 3.2.2 Projected Constituent CHAPTER 4 - EFFLUENT LIMITATIONS AND DISCHARGE SPECIFICATIONS............ 4-1 4.1 Seasonal Discharge of Secondary Effluent to the San Joaquin River (October 1 - May 31) 4-1 4.2 Effluent Limitations - Year-Round Tertiary-Level Treated Discharge 4-3 4.3 Impacts to the Wastewater Master 4-4 4.3.1 Ammonia Limits 4.3.2 Nitrates/Nitrites 4.3.3 Trihalomethanes (Chlorodibromomethane, Dichlorobromomethane)............4-8 4.3.4 Metals 4.3.5 Carbon 4.3.6 Salinity (as Electrical CHAPTER 5 - TREATMENT ALTERNATIVES FOR EFFLUENT DISPOSAL CAPACITY 5-1 5.1 Project History and 5-1 5.1.1 Recommended Project in 2007 Master Plan 5.1.2 Preliminary Design of Phases 1A and 1B BNR/Tertiary Facilities 5.1.3 Design of Phase 1A BNR/Tertiary Facilities 5.2 LIQUID Treatment Alternatives to Meet New Waste Discharge Requirements........ 5-3 5.2.1 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge ..5-6 5.2.2 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment 5.3 Solids 5-19 5.3.1 Treatment Via Existing Recirculation Channel and Facultative Ponds........5-20 5.3.2 Anaerobic 5.3.3 Aerobic 5.3.4 Cost 5.4 Salinity 5-28 CHAPTER 6 - EVALUATION OF BNR/TERTIARY TREATMENT ALTERNATIVES......... 6-1 6.1 Non-Economic 6-1 6.2 Cost 6-1 6.2.1 Use of Master Planning Level Cost ---PAGE BREAK--- DRAFT - June 26, 2008 ii H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\Cover_TOC.doc 6.2.2 Scope and Level of Accuracy 6.2.3 Basis of Cost Evaluations 6.2.4 Cost CHAPTER 7 - DEVELOPMENT OF RECOMMENDED 7-1 7.1 7-1 7.2 Recommended 7-1 7.2.1 Sutter Avenue Primary Treatment Plant Improvements 7.2.2 Primary Effluent Pipeline (also referred to as 7.2.3 Jennings Road Secondary Treatment Plant 7.2.4 Special Planning 7.2.5 Capital Improvement Program (CIP) 7.3 Renewable Energy 7-8 7.3.1 Solar Power 7.3.2 Wind Power CHAPTER 8 - REVISIONS TO WASTE DISCHARGE COMPLIANCE STRATEGY AND IMPLEMENTATION 8-1 8.1 8-1 8.2 Waste Discharge Requirement Compliance Strategy 8-1 8.3 Project Implementation 8-1 LIST OF APPENDICES A - City of Modesto NPDES Permit B - Larry Walker and Associates Metals Analysis C - MBR Pilot Test Metals Results ---PAGE BREAK--- DRAFT - June 26, 2008 iii H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\Cover_TOC.doc LIST OF TABLES Table 3.1 Raw Wastewater Quality Characteristics (Influent to Sutter Avenue Primary Treatment Facility) 3-4 Table 3.2 Primary Effluent Water Quality Characteristics (Influent to Jennings Road Secondary Treatment 3-5 Table 3.3 Storage Pond No. 2 Effluent Water Quality 3-5 Table 3.4 Derivation of Projected Flows (Scenario A) 3-6 Table 3.5 Projected Flows and 3-9 Table 4.1 New Effluent Limitations - Seasonal Discharge 4-2 Table 4.2 Effluent Limitations - Year-Round 4-3 Table 4.3 Comparison of New (2008) and 2007 Master Plan NPDES Permit Effluent Limitations 4-5 Table 5.1 Alternative 1 (Expand BNR/Tertiary Capacity and Year-Round Discharge) Requirements 5-8 Table 5.2 Design Criteria for Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round 5-10 Table 5.3 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Capacity 5-14 Table 5.4 Design Criteria for Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment 5-18 Table 5.5 Projected WAS Production for BNR/Tertiary Phases 5-20 Table 5.6 Facultative Pond BOD Loadings if Used for Sludge 5-21 Table 5.7 Estimated Sludge Accumulation on Pond Bottom 5-21 Table 5.8 Estimated Pond Cleaning Cycle 5-22 Table 5.9 Design Criteria for Anaerobic 5-23 Table 5.10 Design Criteria for Aerobic 5-25 Table 5.11 Estimated Capital Costs for Solids Handling Alternatives 5-26 Table 5.12 Operations and Maintenance Cost Estimate 5-26 Table 5.13 Cost Comparison of Alternatives for Solids Handling 5-27 Table 5.14 Comparison of WAS Processing 5-27 Table 5.15 Design Criteria for Reverse Osmosis System 5-29 Table 5.16 Estimated Capital Costs for Reverse Osmosis Systems 5-29 Table 6.1 Non-Economic Comparison of Alternatives to Achieve New Waste Discharge 6-2 Table 6.2 Category of Cost Estimates 6-3 Table 6.3 Cost Estimating 6-4 Table 6.4 Estimated Capital Costs 6-5 Table 6.5 Operations and Maintenance Cost Estimate 6-6 Table 6.6 Estimated Replacement Parts/Periodic 6-7 Table 6.7 Cost Comparison of Alternatives for BNR/Tertiary 6-8 Table 7.1 Total Revised Wastewater Treatment Capital Costs 7-2 Table 7.2 Wastewater Treatment Capital Improvements 7-9 ---PAGE BREAK--- DRAFT - June 26, 2008 iv H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\Cover_TOC.doc Table 7.3 Estimated Incremental Power Demand for Recommended 7-10 Table 8.1 Changes to Waste Discharge Requirements 8-2 Table 8.2 Strategic Plan 8-3 LIST OF FIGURES Figure 3.1 Modesto WWTP Average Influent Flow 2005 - 3-2 Figure 3.2 Projected Population Scenarios at Buildout of SOI - Mid 3-3 Figure 3.3 Master Plan and Scenario A 3-7 Figure 5.1 2007 Master Plan BNR/Tertiary Treatment Phasing at Jennings Road 5-2 Figure 5.2 Phase 1A Activated Sludge/Membrane Bio-Reactor (MBR) Schematic....... 5-4 Figure 5.3 Site Layout - BNR/Tertiary Project Phase 1A 5-5 Figure 5.4 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge . 5-7 Figure 5.5 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge 5-9 Figure 5.6 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge Phases 1A, 2 and 3 5-11 Figure 5.7 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Capacity 5-13 Figure 5.8 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Capacity Schematic 5-15 Figure 5.9 Alternative 2 Site Layout - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Capacity Phase 5-16 Figure 5.10 Alternative 2 Site Layout and Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Capacity Phases 1A, 2, and 3 5-17 Figure 5.11 Solids Handling Alternatives 5-24 Figure 7.1 Recommended Project Schematic 7-3 Figure 7.2 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge Phases 1A, 2 and 3 7-4 Figure 8.1 Required Tertiary Treatment Capacity Needs and Phasing Plan 8-6 Figure 8.2 Near-Term Project Schedule 8-7 Figure 8.3 Long-Term Project 8-8 ---PAGE BREAK--- DRAFT - June 26, 2008 1-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\01.doc Chapter 1 PURPOSE AND BACKGROUND The City of Modesto’s (City) Wastewater Treatment Master Plan (Master Plan) was developed during the 2005 to 2006 timeframe and was formally adopted in March 2007. The plan was prepared using city-furnished population growth rates available at the time. In addition, the plan relied upon anticipated wastewater discharge permit conditions for the Jennings Road Secondary Treatment Facility based on several meetings and discussions with staff of the Regional Water Quality Control Board Housing and resultant near-term population growth has slowed considerably in the last 12 months. In addition, the adopted a new waste discharge order on May 2, 2008. This order contains discharge limits for seasonal secondary effluent discharges to the San Joaquin River which are considerably more restrictive than those currently in effect and as indicated from previous communications with the Consequently, a master plan supplement is required to address changes in population trends as well as the more restrictive waste discharge requirements. Consistent with the premise of the original Master Plan, it is the City’s desire to continue the practice of land application of segregated cannery process water. Detailed specific studies are anticipated to be required to verify appropriate land application rates and methodologies. Accordingly, the analysis presented herein focuses on the treatment and disposal of domestic wastewater flows. ---PAGE BREAK--- DRAFT - June 26, 2008 2-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\02.doc Chapter 2 OBJECTIVES The objectives of this Wastewater Treatment Master Plan Supplement (Supplement) are as follows: 1. Revise the projected flow and loadings according to most recent housing growth projections. 2. Develop and evaluate alternatives to meet the new waste discharge order for seasonal secondary effluent river discharges. 3. Update the recommended Master Plan Capital Improvement Program (CIP) based on the findings of items 1 and 2 above. 4. Revise the strategic plan for wastewater improvements, including the recommended timeline for capital improvements. 5. Revise the capital improvements program. 6. Revise the projected cash flow to be used by others to update future wastewater rate increases. ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc 3-1 Chapter 3 FLOW AND LOADINGS PROJECTIONS During the last 12 months, the City has experienced a time where essentially no new residential units were added within the City’s sphere of influence. Influent flows to the Modesto wastewater treatment facilities exhibited a pattern consistent with the reduction in housing growth. Figure 3.1 is a plot of flow records since 2005. Average flows for each month increased steadily until the fall of 2006. At that point, the flows began to decline, eventually returning to 2005 levels by the end of 2007. In the 2007 Master Plan, an annual population growth rate of 1.6 percent to 2011 and 1.75 percent thereafter, was used to project future flows. For this Supplement, a range of growth scenarios were considered to test the effect on future treatment capacity requirements, as well as the timing of the capacity needs. In all cases, it was assumed that the growth rate for the next two years (2008 and 2009) would be a minimal 0.7 percent. This rate was selected based on growth rates that occurred in the past economic decline during the mid-1990s. The basis for each population growth scenario is as follows: • Scenario A - 0.7 percent growth from 2008 to 2009, 1.6 percent from 2010 to 2011, 1.75 percent thereafter. • Scenario B - 0.7 percent growth from 2008 to 2010, 1.6 percent thereafter. • Scenario C - 0.7 percent growth from 2008 to 2010, 1.3 percent thereafter. Figure 3.2 is a plot of the population projections for each of the scenarios. Although a reduced growth rate is currently being experienced, the City expects the growth rate will return to the 1.75 percent per year used in the 2007 Master Plan subsequent to housing market recovery. As indicated in Figure 3.2, the population growth rate slowed to near zero growth during the economic downturn in the early 1990’s. However, after economic recovery, the growth rate increased to about 2 percent over the next 10 years. Therefore, it appears reasonable that a similar pattern would occur when the housing market returns to more typical conditions. Accordingly, projected flows for this master plan supplement are based on Scenario A above. 3.1 HISTORIC WASTEWATER CHARACTERISTICS Wastewater biochemical oxygen demand (BOD), total suspended solids (TSS), and ammonia concentrations were updated based on the most recent data provided by the City. Values for annual average, average day maximum month, and resultant peaking factor are presented for the raw wastewater, primary effluent, and storage pond effluent in Tables 3.1, 3.2 and 3.3, respectively. ---PAGE BREAK--- mo508mpf11-6887.ai 3-2 Figure 3.1 MODESTO WWTP AVERAGE INFLUENT FLOW 2005-2007 WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO 10 15 20 25 30 35 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05 Sep-05 Oct-05 Nov-05 Dec-05 Jan-06 Feb-06 Mar-06 Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07 Nov-07 Dec-07 Month -Year Flow (mgd) ---PAGE BREAK--- mo608mpf5-6887.ai Figure 3.2 PROJECTED POPULATION SCENARIOS AT BUILDOUT OF SOI – MID-DENSITY WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO 100,000 150,000 200,000 250,000 300,000 350,000 400,000 1986 1996 2006 2016 2026 2036 2046 Year Population Historical Population Data Scenario B - 0.7% (2008-2010), 1.6% thereafter Mid-Density: SOI Build-Out Scenario A - 0.7% (2008-2009), 1.6% (2010-2011), 1.75% thereafter Scenario C - 0.7% (2008-2010), 1.3% thereafter 3-3 ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc 3-4 Table 3.1 Raw Wastewater Quality Characteristics (Influent to Sutter Avenue Primary Treatment Facility) Wastewater Treatment Master Plan Supplement City of Modesto, California Concentration 2005 2006 2007 2005 - 2007 Average Flow (mgd) Average Annual 25.8 27.2 25.5 26.2 Maximum Month(1) 28.1 30.5 28.9 29.1 Peaking Factor(2) 1.09 1.12 1.13 1.11 BOD (mg/L) Average Annual 443 469 444 452 Maximum Month 535 594 538 556 Peaking Factor 1.21 1.27 1.26 1.23 TSS (mg/L) Average Annual 325 391 381 366 Maximum Month 384 612 605 534 Peaking Factor 1.18 1.57 1.59 1.46 Ammonia (mg/L) Average Annual 32 27 26 28 Maximum Month 40 47 36 41 Peaking Factor 1.26 1.72 1.38 1.46 Electrical Conductivity (µmhos/cm) Average Annual 1300 1153 1296 1250 Maximum Month 1770 1316 1404 1496 Peaking Factor 1.36 1.14 1.08 1.19 Notes: Defined as the maximum average concentration in a given year. Ratio of Maximum Month to Average Annual. ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc 3-5 Table 3.2 Primary Effluent Water Quality Characteristics (Influent to Jennings Road Secondary Treatment Facility) Wastewater Treatment Master Plan Supplement City of Modesto, California Concentration, mg/L 2005 2006 2007 Average BOD Average Annual 274 280 262 272 Maximum Month(1) 329 399 328 352 Peaking Factor(2) 1.2 1.42 1.25 1.29 TSS Average Annual 110 106 119 112 Maximum Month 185 208 179 191 Peaking Factor 1.69 1.96 1.49 1.71 Ammonia Average Annual 27 N/A N/A 27 Maximum Month 34 N/A N/A 34 Peaking Factor 1.26 N/A N/A 1.26 Notes: Defined as the maximum average concentration in a given year. Ratio of Maximum Month to Average Annual. Table 3.3 Storage Pond No. 2 Effluent Water Quality Characteristics (Secondary Effluent before Chlorination) Wastewater Treatment Master Plan Supplement City of Modesto, California Concentration, mg/L 2005 2006 2007 Average BOD Average Annual 23 26 28 26 Maximum Month(1) 37 61 50 49 Discharge Season 26 30 21 26 Non-discharge Season 18 19 40 26 Peaking Factor(2) 1.57 2.34 1.83 1.91 TSS Average Annual 41 43 51 45 Maximum Month 77 77 102 85 Discharge Season 36 37 37 37 Non-discharge Season 51 63 77 64 Peaking Factor 1.87 1.67 2.03 1.71 Ammonia Average Annual 2.4 3.5 2.6 3 Maximum Month 8.2 13.9 7.0 10 Discharge Season 3.0 4.8 2.8 3.5 Non-discharge Season 1.2 0.6 1.3 1.1 Peaking Factor 3.33 3.98 2.66 3.32 Notes: Defined as the maximum average concentration in a given year. Ratio of Maximum Month to Average Annual. ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc 3-6 3.2 PROJECTED LOADINGS 3.2.1 Flow Flows for the Master Plan were projected using a unit flow of 117 gallons per capita per day (gpcd) as determined by City staff. Table 3.4 summarizes the derivation of projected flows based on the updated population projections previously described . Figure 3.3 is a plot of this same information. As indicated, the assumed growth Scenario A results in a year 2030 flow of 40.7 million gallons per day (mgd) compared to the flow of 41.5 mgd used for the 2007 Master Plan. Table 3.4 Derivation of Projected Flows (Scenario A) Wastewater Treatment Master Plan Supplement City of Modesto, California Year Anticipated City Growth Rate WWMP Study Area (SOI + N. Ceres) Population Expected Wastewater Flow (based on 117gpd/cap) 2005 219,908 25.8 2006 222,388 26.1 2007 0.70% 224,007 26.3 2008 0.70% 225,638 26.5 2009 0.70% 227,279 26.7 2010 1.60% 230,862 27.1 2011 1.60% 234,500 27.6 2012 1.75% 239,069 28.1 2013 1.75% 244,405 28.7 2014 1.75% 249,809 29.4 2015 1.75% 255,283 30.0 2016 1.75% 260,829 30.6 2017 1.75% 266,448 31.3 2018 1.75% 272,141 32.0 2019 1.75% 277,909 32.6 2020 1.75% 283,753 33.3 2021 1.75% 289,676 34.0 2022 1.75% 295,677 34.7 2023 1.75% 301,760 35.4 2024 1.75% 307,924 36.2 2025 1.75% 314,172 36.9 2026 1.75% 320,505 37.6 2027 1.75% 326,925 38.4 2028 1.75% 333,432 39.2 2029 1.75% 340,029 39.9 2030 1.75% 346,717 40.7 WWMP = Wastewater Master Plan SOI = Sphere of influence ---PAGE BREAK--- mo508mpf13-6887.ai Figure 3.3 MASTER PLAN AND SCENARIO A FLOWS WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO 0 5 10 15 20 25 30 35 40 45 1995 2000 2005 2010 2015 2020 2025 2030 2035 Month-Year Flow (MGD) Actual Average Day Master Plan Projection Supplement Projection 3-7 ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc 3-8 3.2.2 Projected Constituent Loadings The projected BOD, TSS, and ammonia loadings will determine the sizing of the major 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 constituent concentrations will remain the same during the planning period. The current and projected flows and loads are summarized in Table 3.5. The average primary effluent BOD concentration over the period 2005 to 2007, is 272 milligrams per liter (mg/L). However, at times during the canning season when segregated industrial process water is not diverted for direct land application, BOD values can be greater than 600 mg/L. These extremely high BOD values are not typically sustained for more than 2 to 3 weeks. Excessive loadings will be bypassed directly to the existing ponds to maintain appropriate design conditions for the bionutrient removal (BNR)/tertiary treatment facilities. Conceptual design of treatment systems at the Jennings Road facility as described in Chapter 5 herein, is based on a primary effluent BOD of 300 mg/L. ---PAGE BREAK--- DRAFT - June 26, 2008 3-9 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc Table 3.5 Projected Flows and Loadings Wastewater Master Plan Supplement City of Modesto, California Year 2005-2007 Average 2010 2015 2020 2025 2030 Influent to Sutter Ave. (Primary Plant) Flows, mgd Annual Average Flow (AAF) 26.2 27.1 30 33.3 36.9 40.7 Average Dry Weather Flow (ADWF) Peaking Factor 1.00 1.00 1.00 1.00 1.00 1.00 ADWF 26.2 27.1 30.0 33.3 36.9 40.7 Maximum Month Flow (MMF) Peaking Factor 1.11 1.11 1.11 1.11 1.11 1.11 MMF 29.1 30.1 33.3 37.0 41.0 45.2 Peak Dry Weather Flow (PDWF) Peaking Factor 1.42 1.42 1.42 1.42 1.42 1.42 PDWF 37.2 38.5 42.6 47.3 52.4 57.8 Peak Wet Weather Flow (PWWF) Peaking Factor 2.77 2.70 2.60 2.50 2.40 2.30 PWWF 71.7 73.2 78.0 83.3 88.6 93.6 BOD Concentration, mg/L 452 452 452 452 452 452 Average Annual Loading, lbs/day 98,800 102,200 113,100 125,500 139,100 153,400 Peaking Factor 1.23 1.23 1.23 1.23 1.23 1.23 Maximum Month Loading, lbs/day 121,500 125,700 139,100 154,400 171,100 188,700 TSS Concentration, mg/L 366 366 366 366 366 366 Average Annual Loading, lbs/day 80,000 82,700 91,600 101,600 112,600 124,200 Peaking Factor 1.46 1.46 1.46 1.46 1.46 1.46 Maximum Month Loading, lbs/day 116,800 120,700 133,700 148,300 164,400 181,300 Ammonia Concentration, mg/L 28 28 28 28 28 28 Average Annual Loading, lbs/day 6,100 6,300 7,000 7,800 8,600 9,500 Peaking Factor 1.46 1.46 1.46 1.46 1.46 1.46 Maximum Month Loading, lbs/day 8,900 9,200 10,200 11.400 12,600 13,900 ---PAGE BREAK--- DRAFT - June 26, 2008 3-10 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\03.doc Table 3.5 Projected Flows and Loadings Wastewater Master Plan Supplement City of Modesto, California Year 2005-2007 Average 2010 2015 2020 2025 2030 Electrical Conductivity, µmhos/cm Average Annual 1,250 1,250 1,250 1,250 1,250 1,250 Peaking Factor 1.19 1.19 1.19 1.19 1.19 1.19 Maximum Month 1,500 1,500 1,500 1,500 1,500 1,500 Primary Effluent (Influent to Jennings Road Facility - Secondary Plant) BOD Concentration, mg/L 272 272 272 272 272 272 Average Annual Loading, lbs/day 59,900 61,500 68,100 75,500 83,700 92,300 Peaking Factor 1.29 1.29 1.29 1.29 1.29 1.29 Maximum Month Loading, lbs/day 77,300 79,300 87,800 97,400 108,000 119,100 TSS Concentration, mg/L 112 112 112 112 112 112 Average Annual Loading, lbs/day 24,500 25,300 28,000 31,100 34,500 38,000 Peaking Factor 1.71 1.71 1.71 1.71 1.71 1.71 Maximum Month Loading, lbs/day 41,900 43,300 47,900 53,200 59,000 65,000 Ammonia Concentration, mg/L 27 27 27 27 27 27 Average Annual Loading, lbs/day 5,900 6,100 6,800 7,500 8,300 9,200 Peaking Factor 1.26 1.26 1.26 1.26 1.26 1.26 Maximum Month Loading, lbs/day 7,400 7,700 8,600 9,500 10,50 11,600 ---PAGE BREAK--- DRAFT - June 26, 2008 4-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc Chapter 4 EFFLUENT LIMITATIONS AND DISCHARGE SPECIFICATIONS The issued final Waste Discharge Requirements (WDRs) on May 2, 2008. The key discharge limits are as follows. The adopted WDRs are included in Appendix A. 4.1 SEASONAL DISCHARGE OF SECONDARY EFFLUENT TO THE SAN JOAQUIN RIVER (OCTOBER 1 - MAY 31) The WDR allows blending of secondary and tertiary effluent (from the Phases 1A and subsequent tertiary projects) to achieve discharge requirements. The discharge limits are summarized in Table 4.1. In addition, effluent discharges to the river must meet the following requirements: • Percent Removal: The average percent removal of biochemical oxygen demand (BOD) 5-day 20 degrees C and total suspended solids (TSS) shall not be less than 85 percent. • Acute Whole Effluent Toxicity. Survival of aquatic organisms in 96-hour bioassays of undiluted waste shall not be less than: – 70 percent, minimum for any one bioassay. – 90 percent, median for any three consecutive bioassays. • Total Residual Chlorine. Effluent total residual chlorine shall not exceed: – 0.01 milligrams per liter (mg/L), as a 4-day average. – 0.02 mg/L, as a 1-hour average. • Total Coliform Organisms. Effluent total coliform organisms shall not exceed: – 23 most probable number (MPN) per 100 milliliters (mL), as a 7-day median. – 240 MPN/100 mL, more than once in any 30-day period. • Average Daily Discharge Flow. The Average Daily Discharge Flow shall not exceed 70 mgd. • Manganese. The discharge of total recoverable manganese shall not exceed a concentration of 50 micrograms per liter (µg/L) as an annual average. • Iron.The discharge of total recoverable iron shall not exceed a concentration of 300 µg/L as an annual average. • Electrical Conductivity (Interim Limits). The average discharge of salinity, measured as electrical conductivity, shall not exceed 1,341 micromhos per centimeter (µmhos/cm). This interim performance-based limitation shall be in effect until the waste load allocations established in the total maximum daily load (TMDL) for salt and boron in the lower San Joaquin River (SJR) are in effect. ---PAGE BREAK--- DRAFT - June 26, 2008 4-2 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc Table 4.1 New Effluent Limitations - Seasonal Discharge (2008) Wastewater Treatment Master Plan Supplement City of Modesto, California Effluent Limitations Parameter Units Average Average Weekly Maximum Daily Instantaneous Minimum Instantaneous Maximum mg/L 30 45 90 – – 5-Day BOD at 20 degrees C lbs/day 17,514(1) 26,271(1) 52,542(1) – – mg/L 45 60 105 – – Total Suspended Solids lbs/day 26,271(1) 35,028(1) 61,299(1) – – Aluminum (Total) µg/L 373 – 750 – – mg/L 0.9 – 2.1 – – Ammonia lbs/day 525(1) – 1226(1) – – Carbon Tetrachloride µg/L 4.5(2) – 8.9 – – Chloride mg/L 216 – 282 Chlorodibromomethane µg/L 5.0 – 14.5 – – Dichlorobromomethane µg/L 9.6 – 25.7 – – Molybdenum (Total) µg/L – – 23 – – mg/L 42 – – – – Nitrate + Nitrite (as N) lbs/day(1) 24,520 – – – – µg/L 4.1 – 8.2 – – Selenium (Total) lbs/day 2.4(1) – 4.8(1) – – PH Std. Units – – – 6.5 8.5 Notes: Based on a design flow of 70 mgd. Assuming a minimum of 20:1 dilution (river flow to effluent discharge) during seasonal discharges. ---PAGE BREAK--- DRAFT - June 26, 2008 4-3 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc The final limits are not required until July 2022, or July 2026, depending on whether it is a non-critically dry year or critically dry year. The final limits are as follows: – From October 1 - March 31, the effluent electrical conductivity at 25 degrees C shall not exceed 1,000 µmhos/cm as a average. – From April 1 - May 31, the effluent electrical conductivity at 25 degrees C shall not exceed 700 µmhos/cm as a average. • Aluminum.The discharge of total recoverable aluminum shall not exceed a concentration of 200 µg/L as an annual average. 4.2 EFFLUENT LIMITATIONS - YEAR-ROUND TERTIARY-LEVEL TREATED DISCHARGE Effluent limitations for tertiary, year round discharge are summarized in Table 4.2. Table 4.2 Effluent Limitations - Year-Round Discharge Wastewater Treatment Master Plan Supplement City of Modesto, California Effluent Limitations Parameter Units Average Average Weekly Maximum Daily Instantaneous Minimum Instantaneous Maximum mg/L 10 15 20 – – 5-Day BOD @ 20 degrees C(2) lbs/day 400(1) 600(1) 800(1) – – mg/L 10 15 20 – – Total Suspended Solids(2) lbs/day 400(1) 600(1) 800(1) – – mg/L 0.9 – 2.1 – – Ammonia lbs/day 36(1) – 84(1) – – Aluminum (Total) µg/L 373 – 750 – – Chloride mg/L 216 – 282 – – Molybdenum (Total) µg/L – – 23 – µg/L 4.1 – 8.2 – – Selenium (Total) lbs/day 0.16(1) – 0.33(1) – – mg/L 10 – – – – Nitrate (as N) lbs/day(1) 400 – – – – mg/L 1 – – – – Nitrite (as N) lbs/day(1) 40 – – – – PH Std. Units – – – 6.5 8.5 Note: Based on a design flow of 4.8 mgd. These are lower than seasonal discharge limits. ---PAGE BREAK--- DRAFT - June 26, 2008 4-4 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc The additional requirements are as follows: • Percent Removal: The average percent removal of BOD 5-day. • 20 degrees C and total suspended solids shall not be less than 85 percent. • Acute Whole Effluent Toxicity. Survival of aquatic organisms in 96-hour bioassays of undiluted waste shall not be less than: – 70 percent, minimum for any one bioassay. – 90 percent, median for any three consecutive bioassays. • Total Coliform Organisms. Effluent total coliform organisms shall not exceed: – 2.2 most probable number (MPN) per 100 mL, as a 7-day median. – 23 MPN/100 mL, more than once in any 30-day period. – 240 MPN/100 mL, at any time. • Turbidity. Effluent turbidity shall not exceed: – 2 nephelometric turbidity unit (NTU), as a daily average. – 5 NTU, more than 5 percent of the time within a 24-hour period. – 10 NTU at any time. • Average Daily Discharge Flow. The average daily discharge flow of tertiary treated water shall not exceed 4.8 mgd. • Manganese. The discharge of total recoverable manganese shall not exceed a concentration of 50 µg/L as an annual average. • Iron.The discharge of total recoverable iron shall not exceed a concentration of 300 µg/L as an annual average. • Electrical Conductivity. Final discharge limits are not required until July 2022 or July 2026, depending on whether it is a non-critically dry year. The electrical conductivity shall not exceed the following: – From September 1 to March 31, the effluent electrical conductivity at 25 degrees C shall not exceed 1,000 µmhos/cm as a average. – From April 1 to August 31, the effluent electrical conductivity at 25 degrees C shall not exceed 700 µmhos/cm as a average. • Aluminum. The discharge of total recoverable aluminum shall not exceed a concentration of 200 µg/L as an annual average. 4.3 IMPACTS TO THE WASTEWATER MASTER PLAN The new WDR has a potential impact on the Master Plan relative to both seasonal and year round river discharge. Specific limits of concern include ammonia, nitrates/nitrites, trihalomethanes, metals, and carbon tetrachloride, and electrical conductivity. Table 4.3 ---PAGE BREAK--- DRAFT - June 26, 2008 4-5 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc Table 4.3 Comparison of New (2008) and 2007 Master Plan NPDES Permit Effluent Limitations Wastewater Treatment Master Plan Supplement City of Modesto, California 2007 Master Plan New 2008 Limits Constituent Averaging Period Units Seasonal Discharge Limits Year Round Discharge Limits Seasonal Discharge Limits Year Round Discharge Limits BOD5 Average mg/L 30 10 30 10 Weekly Average mg/L 45 15 45 15 Daily Maximum mg/L 90 20 90 20 TSS Average mg/L 45 10 45 10 Weekly Average mg/L 60 15 60 15 Daily Maximum mg/L 105 20 105 20 Settleable Solids Average mL/L 0.1 Daily Maximum mL/L 0.2 Ammonia Average mg/L 2.6 to 32.6(1) 0.9 0.9 Daily Maximum mg/L 8.0 2.1 2.1 Chlorine Residual Daily Maximum mg/L 0.02 0 4-Day Average mg/L 0.01 0.01 1-Hour Average mg/L 0.02 0.02 Total Coliform 7-Day Median MPN/100 mL 23 2.2 23 2.2 Daily Maximum MPN/100 mL 500 23 240 23 Selenium (Total) Average µg/L 4.1 4.1 4.1 Daily Maximum µg/L 8.2 8.2 8.2 Copper (Total) Average µg/L 4.5 4.5 Daily Maximum µg/L 8.3 8.3 Molybdenum Average µg/L 10 10 Daily Maximum µg/L 15 15 23 TDS Daily Maximum µg/L 924 924 ---PAGE BREAK--- DRAFT - June 26, 2008 4-6 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc Table 4.3 Comparison of New (2008) and 2007 Master Plan NPDES Permit Effluent Limitations Wastewater Treatment Master Plan Supplement City of Modesto, California 2007 Master Plan New 2008 Limits Constituent Averaging Period Units Seasonal Discharge Limits Year Round Discharge Limits Seasonal Discharge Limits Year Round Discharge Limits EC Daily Maximum µmhos/cm 1,689 1,689 Average µmhos/cm - 1,341(2) 1,341(2) Chlorodibromomethane Daily Maximum µg/L 137.5 14.5 Average µg/L 5.0 Dichlorobromomethane Daily Maximum µg/L 70 70 25.7 Average µg/L 9.6 Carbon Tetrachloride Annual Average µg/L 4.5(4) 4.5(4) Daily Maximum µg/L 8.9 Manganese Annual Average µg/L 50 50 Iron Annual Average µg/L 300 300 Nitrate Average mg/L 10 42 10 Nitrite Average mg/L 1 1 pH Instantaneous Std. Units 6.5 - 8.5 6.5 - 8.5 6.5 - 8.5 6.5 - 8.5 Turbidity Instantaneous NTU 2 2 Flow Average Daily MGD 70 4.8 70 4.8 Aluminum Annual Average µg/L 200 200 200 200 Daily Maximum µg/L 750 Average µg/L 373 Notes: Calculated based on pH and temperature. Range is from 32.6 at pH 6.5 to 2.6 at pH 8.5. Interim limits. UV disinfection (which does not produce triholomethanes) will be used for year-round discharge. Calculated value based on 20:1 dilution. ---PAGE BREAK--- DRAFT - June 26, 2008 4-7 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc presents a comparison of waste discharge requirements anticipated from previous communication with staff and outlined in the 2007 Master Plan to the new requirements. 4.3.1 Ammonia Limits Existing discharge requirements that were in effect during development of the Master Plan allowed for a “floating” ammonia limit. The limit depended on the temperature and pH of the effluent. The ammonia limit ranged from 32.6 mg/L at a pH of 6.5, to 2.6 mg/L at a pH of 8.5. In contrast, the new discharge order has a fixed average limit of 0.9 mg/L, regardless of pH or temperature. In order to achieve this limit the treatment process must be robust and controllable, especially in the winter months when temperatures are low and it is more difficult to nitrify. 4.3.1.1 Seasonal Discharge Currently the City does not consistently remove ammonia from storage pond effluent during the discharge season. Ammonia levels typically rise in the winter months when biological activity slows due to low temperatures. The ponds are massive, and the pond water reaches the average ambient air temperature. Concentrations are also likely increasing in these months because the algae die off and release ammonia. The current pond system can adequately meet the previous pH and temperature-based floating limits for ammonia. However, additional treatment (nitrification) will be required to consistently remove ammonia in the winter. The treatment for storage pond effluent would likely consist of nitrifying trickling filters or other fixed film type reactors. 4.3.1.2 Year Round Discharge The Master Plan adopted the concept of utilizing the activated sludge process to provide nitrification and denitrification for year round discharge. The most cost-effective approach was to use the existing recirculation channel as a nitrification and denitrification reactor. However, due to its large volume with limited hydraulic and aeration control, it is unlikely that the recirculation channel will be a reliable process to meet the new, lower fixed ammonia limit, especially during the winter. Accordingly, the aeration basin configuration required to meet the new permit requirements for nitrification is a plug-flow type reactor with fine bubble aeration. The reactor would consist of a new concrete tank with dividing walls. Year round discharge would be required to accommodate growth, even if seasonal discharge continues beyond 2018. ---PAGE BREAK--- DRAFT - June 26, 2008 4-8 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc 4.3.2 Nitrates/Nitrites 4.3.2.1 Seasonal Discharge The new discharge requirements have a nitrates/nitrites limit of 42 mg/L for seasonal, secondary effluent discharges. According to historical data, this limit can be achieved without additional treatment (denitrification). 4.3.2.2 Year Round Discharge The nitrate level of 10 mg/L is the same as the basis for the Master Plan, so no changes are required for the Supplement. 4.3.3 Trihalomethanes (Chlorodibromomethane, Dichlorobromomethane) Trihalomethanes (THMs) are produced when chlorine reacts with organic carbon in the effluent. THMs at high enough levels are considered a human health hazard. 4.3.3.1 Seasonal Discharge The WDR will allow dilution from river water to achieve trihalomethane (THM) limits as long as the 20:1 river flow to effluent flow ratio is maintained. Therefore, during seasonal discharge it is likely that THM limits can be achieved. This means that chlorination could continue to be used as the disinfection process for seasonal discharges. 4.3.3.2 Year Round Discharge For year-round discharge, river flows can be low and do not normally provide the required 20:1 dilution ratio. Therefore, a non-chlorine type of disinfection process would be required. The process adopted for the Master Plan was ultra violet (UV) light radiation. Therefore, no changes are required by this Supplement. 4.3.4 Metals Limits 4.3.4.1 Seasonal Discharge According to an analysis by Larry Walker and Associates (Appendix the metals limits for seasonal discharges can be achieved with the current treatment facilities. The facultative ponds have historically been effective in removing metals. 4.3.4.2 Year Round Tertiary Discharge The BNR/tertiary treatment required for year round discharge will not incorporate the facultative ponds which are effective in removing metals. Therefore, the BNR/tertiary process must be capable of removing metals without using the facultative ponds. Pilot testing of a membrane bioreactor (MBR) in 2007 indicated that metals limits can be achieved with the MBR process (Appendix Other tertiary processes, such as media filtration, may not be adequate to reduce metals levels to within standards. Therefore, it is assumed that the MBR process will be used for metals removal. ---PAGE BREAK--- DRAFT - June 26, 2008 4-9 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc 4.3.5 Carbon Tetrachloride 4.3.5.1 Seasonal Discharge The WDRs have a carbon tetrachloride average limit of 4.5 µg/L and a maximum daily limit of 8.9 µg/L. According to the historical data this limit can be achieved. It should be noted that the limit takes into account dilution credit. 4.3.5.2 Year Round Discharge There is no carbon tetrachloride limit in the WDR requirements for year round discharge. 4.3.6 Salinity (as Electrical Conductivity) 4.3.6.1 Seasonal and Year-Round Discharge The interim limits for EC can currently be met without additional treatment. These interim limits are expected to be in effect until 2022 or 2026, depending on whether the year is a critically dry year or a normal year. For critically dry years, compliance is not required until 2026. The City will need to plan for further treatment or develop new waste management practices to reduce EC in river discharges. The future limits will require a 25 percent reduction in EC from current levels, for September 1 through March 31, and a 48 percent reduction for April 1 through August 31. The new WDRs require that the City submit a workplan and schedule for complying with the new EC limits by June 1, 2009. Options to reduce EC include: • Source Control. Reduce salinity by changing the potable water source from groundwater to surface water. The City has already converted 40 percent of its supply to surface water and is expected to convert 80 percent by 2010. In addition, the City will need to mandate salt reduction measures by industries and the public (such as banning the use of water softeners). The combined effect of these measures should be evaluated to estimate future effluent EC levels in the effluent. • Water Reuse. The total salinity mass load to the river can be reduced by diverting some of the effluent to water reuse. However, the salinity concentration would not be reduced by this approach. The current WDR requires a concentration-based limit, so using the mass-based emission approach would be a change in policy that would need to be approved by the regulatory agencies. • Additional Treatment. Additional treatment to reduce EC may be required. The most accepted salinity reduction process is reverse osmosis (RO). If the MBR process is utilized for BNR/tertiary treatment, it would be sufficient for pretreatment of the flow before reverse osmosis. Therefore, additional ultra filtration would not be required in subsequent phases if the MBR process is selected. Approximately 50 percent of the river discharge flow would require RO to meet future EC limits. For example, at 2030, ---PAGE BREAK--- DRAFT - June 26, 2008 4-10 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\04.doc the required RO capacity would be approximately 13 mgd, assuming the non- desalinated effluent would be blended with the RO effluent. The reverse osmosis alternative is developed further in Chapter 5. ---PAGE BREAK--- DRAFT - June 26, 2008 5-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Chapter 5 TREATMENT ALTERNATIVES FOR EFFLUENT DISPOSAL CAPACITY EXPANSION 5.1 PROJECT HISTORY AND DEVELOPMENT The recommended project described in the Master Plan, as modified by the preliminary design of the initial project phases, is summarized in the following paragraphs. 5.1.1 Recommended Project in 2007 Master Plan The Master Plan covered the planning period of 2007 to 2030. The year 2030 was selected as the projected buildout date. The recommended project, as described in the Master Plan, was to expand the effluent disposal capacity at the Jennings Road Treatment Plant by adding biological-nutrient removal (BNR) and tertiary treatment. BNR/tertiary treatment would be provided for a portion of the flow, which would be discharged year round to the river. The recommended project was predicated on two assumptions: that land application of secondary effluent would continue through the planning period, and that seasonal secondary discharges to the river within limits of existing discharge requirements would be allowed through 2016. After 2016, all river discharges would be upgraded to year round tertiary treatment. As a result, the upgrade to tertiary treatment would be implemented in 4 phases (1A, 1B, 2, and Figure 5.1 is an illustration of the effluent disposal expansion needs and the above assumptions during the planning period based on the previous projected Master Plan flow of 41.5 million gallons per day (mgd) at year 2030. The recommended treatment system to expand the effluent disposal capacity consisted of the following components: • Utilize the recirculation channel for a nitrification/denitrification reactor (add aerators and divider walls for anoxic zone). • Secondary clarification. • High rate flocculation/sedimentation. • Media filtration. • UV Disinfection. 5.1.2 Preliminary Design of Phases 1A and 1B BNR/Tertiary Facilities The preliminary design of Phases 1A and 1B was completed in 2007. During the preliminary design phase, the recommended tertiary process was modified from activated sludge/media filtration to MBR. The MBR process was chosen because it was the most effective treatment process with respect to metals removal, and it is perceived by the regulatory community as the best available treatment process for tertiary treatment. ---PAGE BREAK--- mo508mpf14-6887.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 5.1 2007 MASTER PLAN BNR/TERTIARY TREATMENT PHASING AT JENNINGS ROAD FACILITY WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO 5-2 ---PAGE BREAK--- DRAFT - June 26, 2008 5-3 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc 5.1.3 Design of Phase 1A BNR/Tertiary Facilities The design of Phase 1A was completed in June 2008. The design closely follows the preliminary design recommendations. Construction is scheduled be complete in the winter of 2010. The design includes a primary effluent pump station, fine screen, an oxidation ditch for the nitrification/denitrification reactor, a packaged membrane tank, and in-vessel UV disinfection. The capacity of the system will be 2.3 mgd, designed for a constant flow rate. Figure 5.2 shows the process flow diagram and relative total design flow capacity. To provide a sufficient source of carbon for the denitrification process, the feed for the MBR plant will be primary effluent (flow upstream of the fixed film reactors). The Phase 1A facilities will be located near the fixed film reactors (see layout, Figure 5.3). The area is master planned for future expansions of the MBR process. Tertiary effluent from the Phase 1A site will be conveyed to the river via a new 18-inch pipeline. A second pipeline is planned for future expansions. 5.2 LIQUID TREATMENT ALTERNATIVES TO MEET NEW WASTE DISCHARGE REQUIREMENTS Alternatives were developed for the Supplement to comply with the new waste discharge requirements issued in 2008. There are two important changes from the basis of the Master Plan. The first, is the requirement to meet a fixed average ammonia limit of 0.9 milligrams per liter (mg/L). Secondly, pilot studies completed as part of the Phase 1A design, have determined that membranes are required to achieve metals limits. There are two basic options available to comply with the ammonia limit. The first is to eliminate seasonal river discharges and replace the equivalent flow with a year-round discharge of BNR/tertiary effluent. This would essentially advance the anticipated date to achieve full tertiary treatment year round river discharge by three years (from 2016 to 2013). The second option is to provide nitrification of the storage pond effluent and continue to discharge nitrified, secondary effluent during the current seasonal discharge period. A summary of each alternative is described below: Alternative 1: • Current land disposal practices. • Add BNR/tertiary facilities to provide for year-round river discharge of all remaining flows. • Discontinue seasonal river discharges. Alternative 2: • Current land disposal practices. • Add nitrifying trickling filters for seasonal secondary river discharges. ---PAGE BREAK--- Recirculation Channel San Joaquin River FFRs Facultative Ponds Storage Reservoirs Irrigation BNR Oxidation Ditch Membrane Tanks DAF UV Disinfection (In-Vessel) 2.3 mgd Seasonal Discharge 13.2 mgd 2.3 mgd 27.2 14.0 mgd 3 mgd Figure 5.2 PHASE 1A - ACTIVATED SLUDGE/ MEMBRANE BIO-REACTOR (MBR) SCHEMATIC WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO LEGEND 29.5 - Denotes design flow in mgd 29.5 mgd mo608mpf6-6887.ai Return Activated Sludge Waste Activated Sludge Chlorine Contact Tank 5-4 ---PAGE BREAK--- mo508mpf9-6887.ai LEGEND Phase 1A Figure 5.3 SITE LAYOUT BNR/TERTIARY PROJECT PHASE 1A WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO CHEMICAL SKIDS IN VESSEL UV UV ELECTRICAL OPERATIONS CENTER TANKS STAND BY GENERATOR DIVERSION AND VALVES MEMBRANE SKIDS SKID MOUNTED MEMBRANE TANKS OPERATIONS CENTER UV ELECTRICAL DIVERSION VALVES IN VESSEL UV MEMBRANE SKIDS CHEMICAL SKIDS ELECTRICAL BUILDINGS STAND BY GENERATOR FINE SCREENS OXIDATION DITCH PHASE 1A PRIMARY EFFLUENT PUMP STATION 5-5 ---PAGE BREAK--- DRAFT - June 26, 2008 5-6 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc • Add BNR/tertiary facilities for year-round river discharge to accommodate incremental growth. 5.2.1 Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge Alternative 1 consists of expanding the BNR/tertiary facilities at the current site for Phase 1A to increase the capacity to discharge tertiary effluent year round. Based on the compliance schedule contained on the tentative discharge requirements, the first expansion beyond that provided by Phase 1A would need to be on line by the year 2013. At this time, secondary effluent discharges from the storage ponds to the river would end. However, use of secondary treated effluent for irrigation of the Modesto ranch land would continue. Figure 5.4 is a plot of required staging of the capacity expansions over the planning period. Table 5.1 presents the capacity requirement calculations. The staging was developed based on a 10th percentile river flow, as per the Master Plan. As indicated, the next two phases would be Phase 2 and 3. Phase 1B would be eliminated because the new discharge requirements essentially require BNR/tertiary treatment three years earlier. Seasonal discharge and use of the dissolved air flotation (DAF) unit would be eliminated. As a result, Phase 2 would have a capacity of 18.4 mgd. The treatment process would be similar to the Phase 1A process train. However, a plug flow type aeration basin would be used instead of the oxidation ditch reactor used for Phase 1A. The aeration basin would be aerated with fine bubble diffusers to provide increased efficiency. A blower building would also be required. Waste solids from the activated sludge process would initially be discharged to the recirculation channel and facultative ponds (see Section 5.3 herein for solids handling discussion). In 2008, the City constructed a DAF system to remove algae from the storage pond effluent and reduce TSS levels to within discharge limits. Per the 2007 Master Plan, it is estimated that the DAF system will extend the seasonal discharge season by about three months, which is equivalent to an increase of effluent flow by 3.0 mgd on an annual average flow basis. Under Alternative 1, the DAF system would not be needed after 2013, because seasonal discharges of secondary effluent would end at this time. The DAF system could be reassigned to treat cannery wastes, or to thicken waste activated sludge. In addition, open-channel, low pressure UV would be used for disinfection. See Figure 5.5 for a process flow diagram for all phases. Design criteria are presented in Table 5.2. Figure 5.6 shows a conceptual facility layout for Phases 2 and 3. A new 42-inch tertiary effluent pipeline would be constructed for Phase 2 and would be sufficient for Phase 3 as well. ---PAGE BREAK--- mo608mpf7-6887.ai 27.2 29.5 34.7 40.7 24.2 14.0 5.9 Year 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 2013 2008 2015 2016 2020 2025 2022 2030 Figure 5.4 ALTERNATIVE 1 EXPAND BNR/TERTIARY CAPACITY AND YEAR-ROUND DISCHARGE WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO Projected Domestic Wastewater Flow(1) (annual average flow) Domestic secondary effluent to land (8.1 mgd) (2,526 acres) BNR/tertiary river discharge Phase 1A 2.3 mgd Phase 2 18.4 mgd(2) Phase 3 6.0 mgd Seasonal river discharge of secondary effluent (10.2 mgd(3)) DAF (3.0 mgd) Net evaporation loss (5.9 mgd) Notes: 1. Based on 0.7% growth to 2009, 1.6% growth to 2011 and then 1.75% growth to 2030. 2. Assumes discontinuation of secondary effluent discharge to river in 2013 and phase out of DAF. 3. Based on 10th percentile river flow conditions. 5-7 ---PAGE BREAK--- DRAFT - June 26, 2008 5-8 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.1 Alternative 1 (Expand BNR/Tertiary Capacity and Year-Round Discharge) Requirements Wastewater Treatment Master Plan Supplement City of Modesto, California 1 2 3 4 5=2+4 6=1-5 7 8 9 10=7+8+9 11=4+6+10 12=11-1 BNR/Tertiary Capacity Additions (mgd) Year Population Average Annual Flow (mgd) Secondary Effluent to Land (mgd)(3) Secondary Effluent to River, without DAF mgd(2) Secondary Effluent to River with DAF, mgd(1) Total Disposal Capacity Existing Facilities (mgd) Additional Disposal Capacity Required (mgd) Phase 1A Phase 2 Phase 3 Total BNR/Tertiary Capacity (mgd) Total Disposal Capacity (mgd) Excess Disposal Capacity Available (mgd) 2006 219,900 26.1 14.0 10.2 10.2 24.2 1.9 – – – 0.0 24.2 -1.9 2008 229,500 26.5 14.0 10.2 13.2 27.2 -0.7 – – – 0.0 27.2 0.7 2009 233,200 26.7 14.0 10.2 13.2 27.2 -0.5 2.3 – – 2.3 29.5 2.8 2011 240,500 27.5 14.0 10.2 13.2 27.2 0.3 2.3 – – 2.3 29.5 2.0 2013 267,400 28.7 14.0 10.2 13.2 27.2 1.5 2.3 18.4 – 20.7 34.7 19.2 2013 267,400 28.7 14.0 0 14.0 14.7 2.3 18.4 – 20.7 34.7 6.0 2022 309,100 34.7 14.0 0 14.0 20.7 2.3 18.4 6.0 26.7 40.7 6.0 2026 328,300 37.6 14.0 0 14.0 23.6 2.3 18.4 6.0 26.7 40.7 3.1 2030 355,000 40.7 14.0 0 14.0 26.7 2.3 18.4 6.0 26.7 40.7 0.0 Notes: DAF project adds the annual average equivalent of approximately 3.0 mgd. Assumes secondary effluent discharges to river and discontinued in 2013. DAF would no longer be used for effluent treatment and its use would be reassigned to waste-activated sludge thickening. Based on lowest 10th percentile river flow assumption. Includes evaporation/percolation loss of 5.9 mgd. Net effluent to land = 8.1 mgd. ---PAGE BREAK--- Recirculation Channel FFRs Facultative Ponds Storage Reservoirs Irrigation 14.0 14.0 mgd Figure 5.5 ALTERNATIVE 1 - EXPAND BNR/TERTIARY CAPACITY AND YEAR-ROUND DISCHARGE SCHEMATIC WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO LEGEND 40.7 - Denotes flow in mgd at 2030 40.7 mgd mo608mpf1-6887.ai UV Disinfection (Open Channel) 24.4 mgd 26.7 mgd Return Activated Sludge Waste Activated Sludge BNR Aeration Basins 2.3 mgd 24.4 mgd Phase 2 - 18.4 mgd Phase 3 - 6.0 mgd BNR Oxidation Ditch Membrane Tanks Membrane Tanks UV Disinfection (In-Vessel) 2.3 mgd Return Activated Sludge Waste Activated Sludge S a n J o a q ui n Ri v e r 5-9 ---PAGE BREAK--- DRAFT - June 26, 2008 5-10 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.2 Design Criteria for Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round Discharge Wastewater Treatment Master Plan Supplement City of Modesto, California Units Phase 1A Value Phase 2 Value Phase 3 Value Design Flow mgd 2.3 18.4 6.0 Primary Effluent BOD Concentration mg/L 300(3) 300 300 Loadings lb/day 5,800 46,000 15,000 Aeration Basins Number – 1 8 2 Volume, total MG 0.74 7.44 1.86 Blower capacity scfm 38,200 13,400 Membranes(2) Membrane design flux gfd 12 12 12 Number of trains – 4 6 2 Number of cassettes per train – 3 16 16 Number of modules per cassette – 12 47 47 RAS/WAS Pump Station RAS pumping capacity mgd 10 74 24 WAS pumping capacity mgd 0.06 0.33 0.11 Notes: Preliminary criteria based on 2030 flow of 26.7 mgd for year-round river discharge. Includes 2.3 mgd BNR/Tertiary for Phase 1A. Total 2030 design flow including land application capacity is 40.7 mgd. Unit process design criteria to be verified in preliminary design. Based on information by membrane manufacturer. Design BOD concentration of 300 mg/L was selected to account for variations of concentrations above the annual average concentration of 272 mg/L. This represents a peaking factor of 1.10. If BOD concentrations exceed 300 mg/L, the flow output through the BNR/tertiary facilities will need to be reduced proportionally, and more flow bypassed in the existing pond system. ---PAGE BREAK--- LEGEND Phase 1A Phase 2 and 3 SPLITTER BOX FINE SCREENS AERATION BASINS (PHASES 2 & 3) MEMBRANE PHASE 2 MEMBRANE PHASE 3 MEMBRANE SUPPORT FACILITIES (PHASES 2 & 3) UV ELECTRICAL SCALE: 1” = 60’ OPERATIONS CENTER mo508mpf7-6887.ai Figure 5.6 ALTERNATIVE 1 - EXPAND BNR/TERTIARY CAPACITY AND YEAR-ROUND DISCHARGE PHASE 1A, 2, AND 3 WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO OPERATIONS CENTER PHASE 2 MAIN ELEC BUILDING PHASE 2 PRIMARY EFFLUENT PUMP STATION BIO FILTERS PHASE 2 (for FFR odor control) BIO FILTERS PHASE 2 (for FFR odor control) PHASE 1A OPERATION CENTER SKID MOUNTED MEMBRANE ELECTRICAL BUILDINGS UV ELECTRICAL DIVERSION VALVES IN VESSEL UV PRIMARY EFFLUENT PUMP STATION FINE SCREENS OXIDATION DITCH PHASE 1A PRIMARY EFFLUENT PUMP STATION BLOWER BUILDING PHASE 2 UV 5-11 ---PAGE BREAK--- DRAFT - June 26, 2008 5-12 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc 5.2.2 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Capacity Under this approach, the secondary effluent discharged to the river would receive additional treatment to satisfy the new ammonia limit of 0.9 mg/L. Figure 5.7 is a plot of the required effluent disposal capacities and project phasing. Table 5.3 presents the capacity requirement calculations. For this alternative, the current equivalent annual seasonal discharge flow of 13.2 mgd would be maintained for the entire planning period. The existing dissolved air flotation units currently under construction would be used to remove algae from the pond effluent during the “shoulder” months (October, November and May) when algae concentrations are high. The seasonal discharge facilities and the chlorine contact tank currently have a capacity of 70 mgd. In some years the operations staff have had to discharge at near capacity when river flows are high in order to maintain the overall annual water balance. To retain this flexibility, it was assumed that the nitrification facilities would have the same capacity of 70 mgd. The pond effluent nitrification treatment system would consist of nitrifying trickling filters (NTFs). Another option for nitrification is the moving bed bioreactor (MBBR) process. The MBBR process was evaluated but was determined to be uneconomical. The feed flow for the nitrification system would normally be directly from the storage ponds. However, in the shoulder months when algae concentrations cause excessive total suspended solids violations, a portion of the pond effluent would be treated with the DAF system prior to the NTFs. Based on the water balance prepared for the Master Plan, it appears that the DAF would have adequate capacity (10 mgd) for the shoulder months. The NTFs would be installed with 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. The effluent disposal capacity expansion required to accommodate growth would be provided by expanding the BNR/Tertiary treatment process, with the same process train as described for Alternative 1. A process flow diagram for Alternative 2 is shown in Figure 5.8. Design criteria are listed in Table 5.4. Figures 5.9 and 5.10 shows a conceptual facility layout for the nitrification of storage pond effluent in Phase 2 and BNR/Tertiary Expansion for Phases 2 and 3, respectively. ---PAGE BREAK--- mo608mpf2-6887.ai 27.2 29.5 34.7 40.7 24.2 14.0 5.9 Year 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 2013 2008 2015 2016 2020 2025 2022 2030 Figure 5.7 ALTERNATIVE 2 ADD NITRIFICATION TO CURRENT SEASONAL DISCHARGES, EXPAND BNR/TERTIARY CAPACITY WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO Projected Domestic Wastewater Flow(1) (annual average flow) Domestic secondary effluent to land (8.1 mgd) (2,526 acres) BNR/tertiary river discharge Phase 1A 2.3 mgd Phase 2 5.2 mgd Phase 3 6.0 mgd Seasonal river discharge of nitrified secondary effluent (10.2 mgd(2)) DAF (3.0 mgd) Net evaporation loss (5.9 mgd) Notes: 1. Based on 0.7% growth to 2009, 1.6% growth to 2011 and then 1.75% growth to 2030. 2. Based on 10th percentile river flow conditions. 5-13 ---PAGE BREAK--- DRAFT - June 26, 2008 5-14 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.3 Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Capacity Wastewater Treatment Master Plan Supplement City of Modesto, California 1 2 3 4 5=2+4 6=1-5 7 8 9 10=7+8+9 11=4+6+10 12=11-1 BNR/Tertiary Capacity Additions (mgd) Year Population Average Annual Flow (mgd) Secondary Effluent to Land (mgd) Secondary Effluent to River, without DAF, mgd(1) Secondary Effluent to River with DAF, mgd(1) Total Disposal Capacity Existing Facilities (mgd) Additional Disposal Capacity Required (mgd) Phase 1A Phase 2 Phase 3 Total BNR/Tertiary Capacity (mgd) Total Disposal Capacity (mgd) Excess Disposal Capacity Available (mgd) 2006 219,900 26.1 14.0 10.2 10.2 24.2 1.9 – – – 0.0 24.2 -1.9 2008 229,500 26.5 14.0 10.2 13.2 27.2 2.3 – – – 0.0 27.2 0.7 2009 233,200 26.7 14.0 10.2 13.2 27.2 2.5 2.3 – – 2.3 29.5 2.8 2011 240,500 27.5 14.0 10.2 13.2 27.2 3.3 2.3 – – 2.3 29.5 2.0 2013 267,400 28.7 14.0 10.2 13.2 27.2 4.5 2.3 – – 7.5 34.7 19.2 2022 309,100 34.7 14.0 10.2 13.2 27.2 10.5 2.3 5.2 6.0 13.5 40.7 6.0 2026 328,300 37.6 14.0 10.2 13.2 27.2 13.4 2.3 5.2 6.0 13.5 40.7 3.1 2030 355,000 40.7 14.0 10.2 13.2 27.2 16.5 2.3 5.2 6.0 13.5 40.7 0.0 Note: DAF project adds the annual average equivalent of approximately 3.0 mgd. Nitrification added in Phases 2 and 3. Based on lowest 10th percentile river flow assumption. Includes evaporation/percolation loss of 5.9 mgd. Net effluent to land = 8.1 mgd. ---PAGE BREAK--- Recirculation Channel FFRs Facultative Ponds Storage Reservoirs BNR Aeration Basins DAF DAF UV Disinfection (Open Channel) 13.2 mgd 3 mgd 11.2 mgd 13.5 mgd 13.2 mgd 27.2 14.0 mgd Figure 5.8 ALTERNATIVE 2 ADD NITRIFICATION TO CURRENT SEASONAL DISCHARGES, EXPAND BNR/TERTIARY CAPACITY SCHEMATIC WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO LEGEND 40.7 - Denotes flow in mgd at 2030 40.7 mgd mo608mpf3-6887.ai Return Activated Sludge Waste Activated Sludge Nitrifying Trickling Filters Chlorine Disinfection 2.3 mgd 11.2 mgd BNR Oxidation Ditch Membrane Tanks Membrane Tanks 2.3 mgd Return Activated Sludge Waste Activated Sludge Irrigation UV Disinfection (In-Vessel) S a n J o a q ui n Ri v e r Phase 2 - 5.2 mgd Phase 3 - 6.0 mgd 5-15 ---PAGE BREAK--- Approximate Scale Nitrifying Trickling Filters 0’ 100’ mo508mpf10-6887.ai Figure 5.9 ALTERNATIVE 2 SITE LAYOUT ADD NITRIFICATION TO CURRENT SEASONAL DISCHARGES, EXPAND BNR/TERTIARY CAPACITY PHASE 2 WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO Nitrifying Filter Recirculation Pump Station 5-16 ---PAGE BREAK--- LEGEND Phase 1A Phase 2 and 3 SPLITTER BOX FINE SCREENS BLOWER BUILDING PHASE 2 MEMBRANE PHASE 2 MEMBRANE PHASE 3 MEMBRANE SUPPORT FACILITIES (PHASES 2 & 3) UV ELECTRICAL SCALE: 1” = 60’ OPERATIONS CENTER OPERATIONS CENTER PHASE 2 MAIN ELEC BUILDING PHASE 2 PRIMARY EFFLUENT PUMP STATION PHASE 1A OPERATION CENTER SKID MOUNTED MEMBRANE ELECTRICAL BUILDINGS UV ELECTRICAL DIVERSION VALVES IN VESSEL UV PRIMARY EFFLUENT PUMP STATION FINE SCREENS OXIDATION DITCH PHASE 1A PRIMARY EFFLUENT PUMP STATION Figure 5.10 ALTERNATIVE 2 SITE LAYOUT ADD NITRIFICATION TO CURRENT SEASONAL DISCHARGES, EXPAND BNR/TERTIARY CAPACITY FOR PHASE 1A, 2, AND 3 WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO mo508mpf8-6887.ai BIO FILTERS PHASE 2 (for FFR odor control) BIO FILTERS PHASE 2 (for FFR odor control) AERATION BASINS (PHASES 2 & 3) UV 5-17 ---PAGE BREAK--- DRAFT - June 26, 2008 5-18 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.4 Design Criteria for Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Option Wastewater Treatment Master Plan Supplement City of Modesto, California Value Units Phase 1A Phase 2 Phase 3 Design Flow mgd 70(1) Storage Pond Effluent Loadings BOD Concentration mg/L 26 Loadings lb/day 15,200 Ammonia Concentration mg/L 10 Loadings lb/day 9,400 Nitrifying Trickling Filters (NTF) Number of Units 4 Media Loading Rate lb NH3/day/ksf 0.23 Media Type plastic Specific Volume sf/cf 42 Media Volume cf 1,031,000 Media Diameter ft 92 Media Height ft 20 Media Surface Area sf 43,277,000 BNR/Tertiary Design Flow mgd 2.3 5.2 6.0 Primary Effluent BOD Concentration mg/L 300(4) 300 300 Loadings lb/day 5,800 13,000 15,000 Aeration Basins Number – 1 3 2 Volume, total MG 0.74 2.55 1.70 Blower capacity scfm 12,400 12,200 Membranes(3) Membrane design flux gfd 12 12 12 ---PAGE BREAK--- DRAFT - June 26, 2008 5-19 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.4 Design Criteria for Alternative 2 - Add Nitrification to Current Seasonal Discharges, Expand BNR/Tertiary Treatment Option Wastewater Treatment Master Plan Supplement City of Modesto, California Value Units Phase 1A Phase 2 Phase 3 Number of trains – 4 4 4 Number of cassettes per train – 3 7 8 Number of modules per cassette – 12 46 46 RAS/WAS Pump Station RAS pumping capacity mgd 10 21 24 WAS pumping capacity mgd 0.06 0.1 0.11 Notes: Preliminary criteria based on 70 mgd for seasonal river discharge to match the chlorine contact basin maximum design flow of 70 mgd. Preliminary criteria based on 2030 buildout flow of 13.5 mgd for year-round river discharge. Includes 2.3 mgd BNR/Tertiary for Phase 1A. Total 2030 design flow including land application capacity is 40.7 mgd. Unit process design criteria to be verified in preliminary design. Pro-rated based on information by membrane manufacturer. Design BOD concentration of 300 mg/L was selected to account for variations of concentrations above the annual average concentration of 272 mg/L. This represents a peaking factor of 1.10. If BOD concentrations exceed 300 mg/L, the flow output through the BNR/tertiary facilities will need to be reduced proportionally, and more flow diverted to the existing pond system. 5.3 SOLIDS HANDLING The BNR/Tertiary Facilities for Alternatives 1 and 2 will produce waste activated sludge (WAS) that will need to be properly processed and disposed. The following presents an analysis of solids handling alternatives. This analysis focuses on the evaluation of options associated with Treatment Alternative 1, previously described. This provides a worst case scenario since tertiary flow for Alternative 1 is higher and a resultant greater quantity of WAS will be produced. Table 5.5 summarizes the projected WAS production for each project phase. For Phase 1A, the WAS will be sent to the existing recirculation channel and pond system. The WAS flows and loadings for Phase 1A are low compared to the current influent to the ponds of about 23 mgd, so there will be minimal impact. ---PAGE BREAK--- DRAFT - June 26, 2008 5-20 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.5 Projected WAS Production for BNR/Tertiary Phases Wastewater Treatment Master Plan Supplement City of Modesto, California Phase 1A Phase 2 Phase 3 Solids Concentration, mg/L 10,000 10,000 10,000 Flow, mgd 0.04 0.39 0.50 Mass Loading, lb/day 3,300 32,500 41,700 Volatile Solids, % 80 80 80 Volatile Solids, lb/day 2,600 26,000 33,400 The long-term WAS facilities will be sized to process WAS generated from Phases 1A, 2 and 3 combined. Three alternatives were evaluated: • Treatment via existing recirculation channel and stabilization ponds. • Anaerobic digestion. • Aerobic digestion. 5.3.1 Treatment Via Existing Recirculation Channel and Facultative Ponds Under this alternative, the WAS would be conveyed to the head of the recirculation channel. The entry point to the channel should be far enough of the intake to the existing FFR pumps to prevent recirculation of WAS over the FFRs. The WAS would be combined with FFR effluent and aerated by existing re-circulation pumping and surface aeration. Effluent from the recirculation channel would be diverted to the three facultative ponds. All three ponds would be used to treat/store WAS solids. When solids build up to a predetermined level, each pond will be sequentially taken out of service, drained and dried. Dried bottom sludge would be removed with excavating equipment, and beneficially applied to City-owned land. Under this approach, BOD loadings to the facultative ponds at Phase 3 are projected to be approximately 33 percent higher than current loadings when one pond is out of service for cleaning (see Table 5.6). Therefore, some additional BOD reduction in the aeration channel may be required when one pond is out of service. Additional treatment would be achieved by turning on more of the existing surface aerators in the recirculation channel. Currently, the City operates a minimal number of aerators (2 to 5) depending on the loadings and temperatures. The facultative ponds would digest the WAS solids on the bottom and in the sludge digestion pits. The estimated sludge accumulation on the pond bottom is shown in Table 5.7. Table 5.8 presents the estimated time when the ponds would need to be ---PAGE BREAK--- DRAFT - June 26, 2008 5-21 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.6 Facultative Pond BOD Loadings if Used for Sludge Handling Wastewater Treatment Master Plan Supplement City of Modesto, California Current (2005-2007) Phase 1A Phase 2 Phase 3 Influent Flow to Receive Channel/Ponds, mgd 26.2 24.9 14.4 14.5 Recirculation Channel Loadings lb/day 19,600 19,300 17,000 18,900 Facultative Pond BOD Loadings, lb/day 10,300 8,700 8,000 8,900 Pond Acreage(1) 334 334 216 216 BOD Loading, lb/acre/day 31 26 37 41 Note: Based on all three ponds for current conditions and Phase 1A, the two smallest ponds (1 and 2) for Phases 2 and 3, assuming the largest pond is out of service for cleaning. Table 5.7 Estimated Sludge Accumulation on Pond Bottom Wastewater Treatment Master Plan Supplement City of Modesto, California Current (2005- 2007) Phase 1A Phase 2 Phase 3 TSS Loadings to Ponds, lb/day 13,100 16,100 39,800 49,300 Assumed VSS Destruction, % 70 70 70 70 VSS Solids Reduction, lb/day 3,800 4,400 10,200 TSS in Pond Effluent, mg/L 45 45 45 45 TSS in Pond Effluent, lb/day 11,000 10,200 7,000 5,500 Net solids Accumulation in Ponds, lb/d - 2,600 24,200 31,200 Assumed Bottom Solids Concentration Solids) 3 3 3 3 Cubic yards per year 7,000 66,000 85,000 ---PAGE BREAK--- DRAFT - June 26, 2008 5-22 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.8 Estimated Pond Cleaning Cycle Wastewater Treatment Master Plan Supplement City of Modesto, California % of Facultative Ponds covered to 2 ft deep @ 3% Solids @ 4% Solids Year Year of Operation Flow to Jennings Road (mgd) Flow to BNR/Tertiary (mgd) Annual Cumulative Annual Cumulative 2013 1 28.7 14.7 5.6% 5.6% 4.2% 4.2% 2014 2 29.4 15.4 5.9% 11.5% 4.4% 8.6% 2015 3 30.0 16.0 6.1% 17.6% 4.6% 13.2% 2016 4 30.6 16.6 6.3% 23.9% 4.8% 18.0% 2017 5 31.3 17.3 6.6% 30.5% 5.0% 23.0% 2018 6 32.0 18.0 6.9% 37.4% 5.2% 28.2% 2019 7 32.6 18.6 7.1% 44.5% 5.3% 33.5% 2020 8 33.3 19.3 7.4% 51.9% 5.5% 39.0% 2021 9 34.0 20.0 7.7% 59.6% 5.7% 44.7% 2022 10 34.7 20.7 7.9% 67.5% 5.9% 50.6% 2023 11 35.4 21.4 8.2% 75.7% 6.1% 56.7% 2024 12 36.2 22.2 8.5% 84.2% 6.4% 63.1% 2025(1) 13 36.9 22.9 8.8% 93.0% 6.6% 69.7% 2026 14 37.6 23.6 9.0% 9.0% 6.8% 76.5% 2027 15 38.4 24.4 9.3% 18.3% 7.0% 83.5% 2028 16 39.2 25.2 9.7% 28.0% 7.2% 90.7% 2029(2) 17 39.9 25.9 9.9% 37.9% 7.4% 98.1% 2030 18 40.7 26.7 10.2% 48.1% 7.7% 7.7% Note: Estimated year for pond cleaning assuming 3 percent solids for bottom sludge. Estimated year for pond cleaning assuming 4 percent solids for bottom sludge. ---PAGE BREAK--- DRAFT - June 26, 2008 5-23 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc cleaned. As indicated, with an average bottom solids concentration of 3 percent, the ponds would need to be cleaned after approximately 13 years of operation of the Phase 2 facilities (Year 2025). 5.3.2 Anaerobic Digestion Traditional anaerobic digestion of thickened WAS solids would likely result in excessive foaming. To reduce foaming, the digestion process would consist of an acid phase digester followed by a methane digester. The acid phase would breakdown the cells that cause foaming. The methane phase would provide most of the volatile solids destruction and sludge stabilization. Two existing DAF units would be relocated and recommissioned as WAS thickeners. Digested sludge would be dried in solar drying beds. The dried sludge cake would be applied to the irrigation land along with the dried solids trucked from the Sutter Avenue facilities. The process flow diagram is shown in Figure 5.11. Design criteria are listed in Table 5.9. Table 5.9 Design Criteria for Anaerobic Digestion Wastewater Treatment Master Plan Supplement City of Modesto, California Value Units Phase 1A Phase 2(1) Phase 3 Acid Phase Digester Feed VSS Lb/day 35,400 VSS Loading lb/day/CF 1.0 Feed flow gpd 100,000 HRT Days 2.5 Diameter ft 25 Sidewater Depth ft 40 Volume MG 0.25 Methane Digester HRT Days 15 Diameter ft 90 Sidewater Depth ft 32 Volume MG 1.5 Notes: Based on Phase 3 loadings, but constructed under Phase 2. ---PAGE BREAK--- Figure 5.11 SOLIDS HANDLING ALTERNATIVES WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO mo608mpf8-6887.ai DAF Thickening Aerobic Digestion To Sludge Drying Beds WAS from Aeration Basin DAF Thickening To Cogeneration Ferric Chloride Addition Methane Phase Digester Acid Phase Digester To Sludge Drying Beds Excess Gas to Flare Secondary Effluent Cap Dried Sludge to Land (empty pond and solar dry) WAS from Aeration Basins WAS from Aeration Basins AEROBIC DIGESTION ANAEROBIC DIGESTION To Digester Heating RECIRCULATION CHANNEL/FACULTATIVE PONDS Recirculation Channel 5-24 ---PAGE BREAK--- DRAFT - June 26, 2008 5-25 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Assuming 50 percent volatile suspended solids (VSS) destruction, approximately 170 standard cubic feet per minute (scfm) of methane gas produced would be produced with anaerobic digestion. Heating requirements are estimated to be satisfied by 70 cubic feet per minute (cfm) of digester gas resulting in approximately 100 cfm excess gas. This gas can be used to generate electricity via a cogeneration system. The feasibility of power generation would be evaluated further during preliminary design. 5.3.3 Aerobic Digestion Under this alternative, a new concrete basin would be constructed adjacent to the aeration basins, sharing a common wall. The basin would be aerated with coarse bubble aeration. The WAS would be thickened with the DAF units. Digested WAS would be dried with solar drying beds. The process flow diagram is shown in Figure 5.11, design criteria are summarized in Table 5.10. Table 5.10 Design Criteria for Aerobic Digestion Wastewater Treatment Master Plan Supplement City of Modesto, California Value Units Phase 1A Phase 2(1) Phase 3 Hydraulic Retention Time days 30 Volume MG 3.0 Length Ft 200 Width Ft 70 Sidewater Depth ft 18 Design Mixing Energy Hp/1000cf 1.0 Required Mixing Energy Hp 200 Type of Aeration Coarse bubble Note: Based on Phase 3 loadings, but constructed under Phase 2. 5.3.4 Cost Analysis The WAS processing alternatives were evaluated on the basis of life cycle costs. Table 5.11 presents the estimated capital costs. The WAS facilities would be constructed in Phase 2, sized for projected loadings through Phase 3. Table 5.12 presents the operating and maintenance costs for each alternative. Table 5.13 summarizes the total life cycle costs. An overall comparison of alternatives, including non-economic factors, is presented in Table 5.14. ---PAGE BREAK--- DRAFT - June 26, 2008 5-26 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.11 Estimated Capital Costs for Solids Handling Alternatives Wastewater Treatment Master Plan Supplement City of Modesto, California June 2006 ENR Alternative Design Flow (mgd) Phase 2/3 Unit Process Phase 2 2013(1) $M 1 WAS to Recirculation Channel/Facultative Ponds 26.7 New WAS Inlet 0.2 Total 0.2 2 WAS to Anerobic Digestion 26.7 DAF Relocation 2.0 Acid Phase Digester 3.9 Anaerobic Digester 7.4 Flare 0.3 Gas Scrubbing System 1.5 Sludge Drying Beds 2.5 Total 17.6 3 WAS to Aerobic Digestion 26.7 DAF Relocation 2.0 Aerobic Digester 7.9 Sludge Drying Beds 2.5 Total 12.4 Notes: June 2006 dollars. ENR CCI = 8441. Estimated capital costs include the following: estimating contingency - 30%, general conditions - contractor overhead and profit - Table 5.12 Operations and Maintenance Cost Estimate(1) Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Power Cost at $0.08/kwh ($/year) Chemical Cost ($/year) Replacement Parts/ Periodic Maintenance ($/year) Labor Costs ($/year) Total Annual Cost ($/year) 1 WAS to Recirculation Channel and Facultative Ponds Phase 2 $5,000 $0 $2,000 $141,000 $148,000 2 WAS to Anaerobic Digestion Phase 2 $145,000 $14,000 $141,000 $140,000 $440,000 3 WAS to Aerobic Digester Phase 2 $152,000 $11,000 $101,000 $182,000 $446,000 Note: All O&M Costs presented in June 2006 dollars. ---PAGE BREAK--- DRAFT - June 26, 2008 5-27 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.13 Cost Comparison of Alternatives for Solids Handling Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Capital Cost Annual O&M Cost ($M/year)(2) O&M Present Worth Total Present Worth 1 WAS to Facultative Ponds Phase 2 $0.2 $0.1 $1.8(4) $2.0 2 WAS to Anaerobic Digestion Phase 2 $17.6 $0.4 $4.8 $22.4 3 WAS to Aerobic Digester Phase 2 $12.4 $0.4 $4.8 $17.2 Notes: Based on ENRCCI = 8441. Annual O&M Costs presented in June 2006 dollars. Based on P/A, 6 percent with an 18-year return period for Phase. Based on pond cleaning in 2025, $1.8 million in today’s costs. Table 5.14 Comparison of WAS Processing Alternatives Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Pros Cons WAS to Recirculation Channel Facultative Ponds • Low energy requirements • Low life cycle costs • Low capital costs • Does not require WAS thickening • Potential odors during sludge drying process • Labor intensive for periodic dredging and sludge removal • Requires operation additional existing aerators Anaerobic Digestion • Medium energy requirements • Low life cycle costs • Digester gas can be used for cogeneration in future • Odors contained in closed vessels • Stringent sulfide controls likely required for waste gas flare • Complex process • High capital cost Aerobic Digestion • Simple process • Waste gas, flare not required • Low odors • High energy requirements • Medium capital costs • Medium life cycle costs • Vulnerable to rising energy costs ---PAGE BREAK--- DRAFT - June 26, 2008 5-28 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc The alternative to process WAS in the recirculation channel and facultative ponds is clearly the most economical approach. For planning purposes, it is assumed that the recirculation channel/pond treatment system will be used. Capital costs for this alternative are minimal. The cost to drain the ponds, dry and remove the bottom sludge and apply it to land were based on discussions with dredging contractors. The cost will vary depending on the actual quantities of sludge. In addition, assumptions were made as to the bottom sludge volatile solids reduction and bottom solids concentrations. Additional analysis should be performed during preliminary design to confirm these conclusions. 5.4 SALINITY REDUCTION As described in Chapter 4, the new WDRs require compliance with new EC (salinity) levels by the year 2022 for non-critically dry years and the year 2026 for critically dry years. This section describes the likely process, should treatment be required to achieve the new salinity limits. For planning purposes, it was assumed that the salinity removal process would consist of reverse osmosis (RO). RO produces a brine concentrate that requires expensive disposal. Brine can be disposed of by using brine concentrators and evaporation ponds, or deep well injection (if permitted by regulatory agencies). To achieve the new EC limits, the design output flow for the RO system would be about 13 mgd by the year 2030 (at the end of Phase Table 5.15 lists the design criteria for the RO and brine disposal systems. Planning-level capital cost estimates were prepared for the RO system and brine disposal facilities, based on the capacity required for Phase 3. The capital costs are summarized in Table 5.16. As indicated, the cost for the RO system would be approximately $41.0 M in today’s dollars. The cost for brine disposal would be approximately $17.0 M for deep well injection or $177.5 M for the brine concentration/ evaporation pond system. These costs are very preliminary and would need to be verified in a separate study. If RO and brine disposal is required in the future, it will have a major impact on the City’s resources. It is likely that all municipal dischargers to the San Joaquin River will have similar limits, which could create a financial hardship for the entire region. Additional studies should be conducted to address the impacts and to possibly develop a regional solution to the salinity problem. Due to unknowns, it is considered too soon to include the RO/brine disposal system in the City’s capital improvements program. However, salinity will continue to be a major issue for the City and for all dischargers to the San Joaquin River. The final approach to meeting the new salinity limits will need to be refined as the overall solution evolves. ---PAGE BREAK--- DRAFT - June 26, 2008 5-29 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\05.doc Table 5.15 Design Criteria for Reverse Osmosis System Wastewater Treatment Master Plan Supplement City of Modesto, California Units Phase 1A Value Phase 2 Value Phase 3 Value WWTP Flow mgd - - 26.7 RO Feedwater flow mgd - - 13 - 15 Electrical Conductivity - - 1,250 TDS concentration mg/L - - 750 TDS loading lbs/day - - 8,100 - 9,400 Recovery Factor % - - 80 RO Permeate Flow mgd - - 11-13 Electrical Conductivity - - 33 TDS concentration mg/L - - 20 TDS loading lbs/day - - 1,800 - 2,200 Brine Flow mgd - - 2.7 - 3.0 Notes: Preliminary criteria based on 2030 flow of 26.7 mgd for year-round river discharge. Includes 2.3 mgd BNR/Tertiary for Phase 1A. Total 2030 design flow including land application capacity is 40.7 mgd. Unit process design criteria to be verified in preliminary design. Depends on brine disposal method (Zero Liquid Discharge versus Deep Well Injection). Estimated based on 0.6 empirical TDS: Conductivity factor. Table 5.16 Estimated Capital Costs for Reverse Osmosis Systems Wastewater Treatment Master Plan Supplement City of Modesto, California June 2006 ENR Alternative Design Flow (mgd) Unit Process Phase 2 2013(1) $M 1 Zero Liquid Discharge 26.7 RO System 41.0 Brine Concentrator 94.2 Brine Ponds 83.3 Total 218.5 2 Deep Well Injection 26.7 RO System 41.0 Deep Well Injection 17.0 Total 58.0 Notes: June 2006 dollars. ENR CCI = 8441. Estimated capital costs include the following: estimating contingency - 30%, general conditions - contractor overhead and profit - engineering, legal and administrative - 20%, change order contingency - ---PAGE BREAK--- DRAFT - June 26, 2008 6-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Chapter 6 EVALUATION OF BNR/TERTIARY TREATMENT ALTERNATIVES This chapter presents a comparison of the alternatives to comply with new discharge requirements based on non-economic and economic factors. 6.1 NON-ECONOMIC COMPARISON The non-economic advantages and disadvantages associated with each alternative are presented in Table 6.1. 6.2 COST ANALYSIS 6.2.1 Use of Master Planning Level Cost Estimates The cost estimates prepared for this Supplement 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 the 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. 6.2.2 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 6.2 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. ---PAGE BREAK--- DRAFT - June 26, 2008 6-2 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Table 6.1 Non-Economic Comparison of Alternatives to Achieve New Waste Discharge Requirements Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Description Treatment Requirements Pros Cons 1 Current Land Disposal/Discontinuation of Seasonal Secondary Effluent Discharge, and Addition of BNR/Tertiary Facilities for Year-round Discharge. • 24.4 mgd BNR/Tertiary Capacity (in addition to Phase 1A capacity of 2.3 mgd). • Total BNR/Tertiary Treatment Capacity of 26.7 mgd for the planning period. • Process is proven for nutrient removal during cold weather. • Recycled water would be available for future use and potential recovery of some of the capital costs. • Year-round discharge is unaffected by San Joaquin River flows. • Will satisfy likely requirements in the future to provide BNR/tertiary treatment of all river discharges. • New treatment processes (increased operation and maintenance [O&M] costs) for facilities staff to operate. • BNR/tertiary would need to operate year round, compared to seasonal operation for Alternative 2. • Waste activated sludge in ponds may require periodic removal. 2 Current Land Disposal, add Nitrification to Seasonal Secondary Effluent Discharge, Continue Phase 1A BNR/Tertiary, add BNR/Tertiary treatment and year-round discharge to accommodate growth • Nitrification treatment for up to 70 mgd. • DAFs for algae removal (utilize DAFs currently under construction). • Continuation of Phase 1A BNR/Tertiary Treatment Capacity of 2.3 mgd. • Additional BNR/tertiary treatment capacity of 11.2 mgd. • Total BNR/Tertiary Treatment Capacity of 13.5 mgd for the planning period. • Nitrification Facilities need only seasonal operation. • Nitrification process is a simple operation, familiar to operators. • Reduces the capacity needs for BNR/Tertiary Treatment compared to Alternative 1. • Requires a large area • Long term river discharge of nitrified secondary effluent may not be viable. • Large treatment capacity required to maintain annual water balance. • Additional BNR/Tertiary treatment is still required to accommodate growth. • Nitrification process may need slight BOD addition to maintain growth on media. Process is also subject to loss of efficiency due to snails that reduce the biofilm. • Nitrification process requires start up and shut down each year. • Seasonal river discharges are affected by the river flows. ---PAGE BREAK--- DRAFT - June 26, 2008 6-3 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc 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. Table 6.2 Category of Cost Estimates(1) Wastewater Treatment Master Plan Supplement City of Modesto, California Primary Characteristic Secondary Characteristic Estimate Class Level of Project Definition (Expressed as Percent 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% to +100% 1 Class 4 1% to 15% Study or Feasibility Equipment Factored or parametric Models L: - 15% to - 30% H: +20% to +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% to +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: to +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: to +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 percent level of confidence) for a give scope. If the range index value of represents 0.005 percent of project costs, then an index value of 100 represents 0.5 percent. Estimate preparation effort is highly dependent upon the size of the project and the quality of estimating data and tools. ---PAGE BREAK--- DRAFT - June 26, 2008 6-4 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc 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. 6.2.3 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 manufacturer’s 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 labor needs and resource requirements. A summary of the criteria used for estimating costs is presented in Table 6.3. Table 6.3 Cost Estimating Criteria Wastewater Treatment Master Plan Supplement 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 30 percent for all processes except MBR and aeration basins @ 20% Project Cost Factor Total of 20 percent for engineering, legal, administrative, and construction support Interest Rate 6 percent for amortization purposes Amortization Period 22 years It should be noted that all costs are presented in June 2006 dollars (ENR CCI = 8441). This was done so as to provide comparable capital cost data to that shown on the Master Plan. 6.2.4 Cost Comparison A present worth analysis was performed to compare the two alternatives on the basis of capital and operating costs. Table 6.4 presents estimated capital costs for each alternative on a phased basis, excluding certain common items. Table 6.5 is a summary of O&M costs. Table 6.6 shows a breakdown of the replacement costs for phases 2 and 3 for each alternative. Total present worth costs are presented in Table 6.7. The recommended project at the Jennings Road facility is Alternative 1 - Expand BNR/Tertiary Capacity and Year-Round River Discharge. The recommended project offers the overall lowest cost and provides the greatest future flexibility with regard to new water quality standards and potential water reuse. ---PAGE BREAK--- DRAFT - June 26, 2008 6-5 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Table 6.4 Estimated Capital Costs Wastewater Treatment Master Plan Supplement City of Modesto, California Capital Cost Alternative Design Flow (mgd) Phase 2/3 Unit Process Phase 2 2013(1) $M Phase 3 2022(1) $M 1 Activated Sludge, Membrane Filtration (MBR), UV 18.4/6.0 PE Pump Station 5.2 1.7 Fine Screens 4.0 1.3 Aeration Basins 22.9 7.5 Blower Building 9.3 3.0 RAS/WAS Pump Station 5.0 1.7 Membrane Tanks 48.0 15.7 UV Disinfection 11.4 3.7 Effluent Pipeline 10.5 0.0 New WAS inlet 0.2 0.0 Standby Power 2.0 0.7 Total $118.5 $35.3 2 Nitrifying Trickling Filters (NTF) 70.0/0 NTF Pump Station 35.1 0 NTFs 141.0 0 Activated Sludge, Membrane Filtration (MBR), UV 11.2/6.0 PE Pump Station 1.5 1.7 Fine Screens 1.1 1.3 Aeration Basins 6.5 7.5 Blower Building 2.6 3.0 RAS/WAS Pump Station 1.4 1.7 Membrane Tanks 13.6 15.7 UV Disinfection 3.2 3.7 Effluent Pipeline 6.4 0.0 New WAS inlet 0.2 0.0 Standby Power 0.6 0.7 Total $213.2 $35.3 Notes: June 2006 dollars. ENR CCI = 8441. Estimated capital costs include the following: estimating contingency - 30%, general conditions - contractor overhead and profit - engineering, legal and administrative - 20% and change order contingency - ---PAGE BREAK--- DRAFT - June 26, 2008 6-6 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Table 6.5 Operations and Maintenance Cost Estimate(1) Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Power Cost at $0.08/kwh ($/year) Chemical Cost ($/year) Labor Costs ($/year) Replacement Parts/ Periodic Maintenance ($/year) Total Annual Cost ($/year) Phase 2 $1,142,000 $51,000 $1,328,000 $864,000 $3,386,000 1 Activated Sludge, Membrane Filtration (MBR), UV Phase 3 $382,000 $17,000 $387,000 $281,000 $1,067,000 Phase 2 $799,000 $15,000 $658,000 $1,681,000 $3,153,000 2 Nitrifying Trickling Filter, Activated Sludge, Membrane Filtration (MBR), UV Phase 3 $382,000 $17,000 $387,000 $281,000 $1,067,000 Note: All O&M Costs presented in June 2006 dollars. ---PAGE BREAK--- DRAFT - June 26, 2008 6-7 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Table 6.6 Estimated Replacement Parts/Periodic Maintenance Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Design Flow (mgd) Unit Process Phase 2 2013 $M Phase 3 2022 $M 1 Activated Sludge, Membrane Filtration (MBR), UV PE Pump Station $42,000 $14,000 Fine Screens $32,000 $11,000 Aeration Basins $187,000 $61,000 Blower Building $76,000 $25,000 RAS/WAS Pump Station $41,000 $13,000 Membrane Tanks $391,000 $128,000 UV Disinfection $93,000 $30,000 Effluent Pipeline 0 0 New WAS Inlet $2,000 0 Total $864,000 $281,000 2 Nitrifying Trickling Filters (NTF) 70.0 NTF Pump Station $1,436,000 0 Activated Sludge, Membrane Filtration (MBR), UV 11.2/6.0 PE Pump Station $12,000 $14,000 Fine Screens $9,000 $11,000 Aeration Basins $53,000 $61,000 Blower Building $21,000 $25,000 RAS/WAS Pump Station $12,000 $14,000 Membrane Tanks $111,000 $128,000 UV Disinfection $26,000 $30,000 Effluent Pipeline 0 0 New WAS inlet $2,000 0 Total $1,681,000 $281,000 Note: June 2006 dollars. ENR CCI = 8441. ---PAGE BREAK--- DRAFT - June 26, 2008 6-8 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\06.doc Table 6.7 Cost Comparison of Alternatives for BNR/Tertiary Treatment Wastewater Treatment Master Plan Supplement City of Modesto, California Alternative Capital Cost Annual O&M Cost ($M/year)(2) O&M Present Worth Subtotal Present Worth Phase 2 $118.5 $3.4 $36.7 $155.2 Phase 3 35.3 1.1 7.3 42.6 1 Activated Sludge, Membrane Filtration (MBR), UV Total $153.8 $4.5 $44.0 $197.8 Phase 2 $213.2 $3.2 $34.1 $247.3 Phase 3 35.3 1.1 7.3 42.6 2 Nitrifying Trickling Filter, Activated Sludge, Membrane Filtration (MBR), UV Total $248.5 $4.3 $41.4 $289.9 Notes: Based on June 2006 dollars, ENR CCI = 8441 (see Table 6.4). Annual O&M Costs presented in June 2006 dollars (see Table 6.5). Based on P/A, 6 percent with an 18-year return period for Phase 2 and a 9-year return period for Phase 3. ---PAGE BREAK--- FINAL - March 2007 7-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc Chapter 7 DEVELOPMENT OF RECOMMENDED ALTERNATIVE 7.1 INTRODUCTION This chapter presents the recommended alternative for upgrading the Jennings Road Facility. The overall recommended wastewater treatment capital improvement program (CIP) includes the upgrade of facilities at Jennings Road plus improvements to the Sutter Avenue Primary Treatment plant and Primary Effluent Outfall as described in the Master Plan. The implementation plan includes proposed staging of the project through year 2030. 7.2 RECOMMENDED PROJECT The recommended wastewater treatment CIP 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. • Specific special planning studies required throughout the planning period. These studies include engineering system analysis, periodic Master Plan updates, and detailed scientific studies to verify appropriate loadings and land application methodologies associated with segregated cannery process flows. The project components and estimated costs associated with the updated 2030 population projection are summarized in Table 7.1. All costs are based on June 2006 data to be consistent with those presented in the Master Plan and include allowances for contingencies, engineering, legal, and administrative expenses. Figure 7.1 is a schematic diagram for the recommended project. Figure 7.2 presents preliminary site plans for the Jennings Road improvements. Each major project component is described in the following paragraphs. 7.2.1 Sutter Avenue Primary Treatment Plant Improvements The improvements to the Sutter Avenue Primary Treatment Plant remain the same as the 2007 Master Plan, with most improvements being deferred to Phase 2A (2018) except for the Primary Effluent Pump Station and Anaerobic Digester improvements, which remain scheduled for Phase 2 (2013), as per the Master Plan. ---PAGE BREAK--- FINAL - March 2007 7-2 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc Table 7.1 Total Revised Wastewater Treatment Capital Costs Wastewater Treatment Master Plan Supplement 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 23.2 Jennings Road Secondary Treatment Plant Dissolved Air Flotation Project 8.0 BNR/Tertiary Improvements Phase 1A Improvements 20.6 Phase 2 and 3 Improvements PE Pump Station 6.9 Fine Screens 5.3 Aeration Basins 30.4 Blower Building 12.3 RAS/WAS pump station 6.7 Membrane Tanks 63.7 UV Disinfection 15.1 Effluent Pipeline from Tertiary Plant to Exist. Outfall 10.5 New WAS inlet 0.2 Standby power 2.7 Reverse Osmosis System (if required) 0(2) Brine Disposal (if required) 0(2) Operations Center 3.5 Subtotal BNR/Tertiary Improvements 177.9 Improvements to Existing Facilities Conversion from Chlorine Gas to Hypochlorite 1.4 Effluent Pump Station Improvements 3.0 Outfall Improvements 4.0 Flood Control Improvements 0.2 Fixed Film Reactor Improvements and Odor Control 7.5 Subtotal Improvements to Existing Facilities 16.1 Subtotal Jennings Road Secondary/Tertiary Plant 202.0 Special Planning Studies 10.6 Total Project 277.0 Note: Conceptual level costs. Based on June 2006 dollars (ENRCCI = 8441). Includes allowances for contingencies, engineering, legal and administrative expenses. These processes may be required to comply with the future salinity TMDL in either 2022 or 2026. Costs range from $58 M to $218 M depending on brine disposal system chosen (see Chapter Costs are not included at this time pending further development of a salinity reduction program. ---PAGE BREAK--- Figure 7.1 RECOMMENDED PROJECT SCHEMATIC WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO Anaerobic Digesters (add one) Existing Facilities Sutter Avenue Improvements Jennings Road Improvements Facilities to be Discontinued at Phase 2 LEGEND Sludge Drying Beds (line with concrete) Cannery Wastewater (Season: Jul-Sep) Headworks Facility (add 1 pump, bar screen, and grit removal mechanism) 40.7 mgd at Build-Out Domestic Wastewater Sutter Avenue Facility Primary Clarifiers Pumping Plant No. 3 FFRs 14 mgd 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) Primary Effluent PS Recirculation Channel 60-inch Primary Effluent Outfall (add plastic liner) 60-inch Cannery Process Water Outfall Primary Effluent PS FFR Influent PS Influent PS Storage Ponds Dissolved Air Flotation Jennings Road Facility mo608mpf9-6887.ai Aeration Basins Membrane Tanks WAS Phase 1A - 2.3 mgd Oxidation Ditch To Recirculation Channel/ Facultative Ponds Permeate RAS WAS Permeate RAS Ultraviolet Disinfection (Open Channel) UV Disinfection (In-Vessel) Rotary Fine Screens Rotary Fine Screens Phase 2 and 3 - 24.4 mgd To Recirculation Channel/ Facultative Ponds 7-3 ---PAGE BREAK--- LEGEND Phase 1A Phase 2 Phase 3 PHASE 1A OPERATION CENTER SKID MOUNTED MEMBRANE ELECTRICAL BUILDINGS UV ELECTRICAL DIVERSION VALVES IN VESSEL UV AERATION BASINS PHASE 2 MEMBRANE LAYDOWN AREA MEMBRANE TANKS PHASE 2 MEMBRANE TANKS PHASE 3 RAS PUMP STATION PHASE 2 MEMBRANE SUPPORT EQUIPMENT BUILDING PHASE 2 RAS/WAS PUMP STATION PHASE 2 UV CHANNEL PHASE 2 UV CHANNEL PHASE 3 FINE SCREENS PHASE 2 OPERATIONS CENTER PHASE 2 RAS PUMP STATION PHASE 3 MEMBRANE SUPPORT EQUIPMENT BUILDING PHASE 3 MAIN ELEC BUILDING PHASE 2 PE PUMP STATION PHASE 3 PRIMARY EFFLUENT PUMP STATION PE PUMP STATION PHASE 2 FINE SCREENS PHASE 3 FINE SCREENS BIO FILTERS PHASE 2 BIO FILTERS PHASE 2 AERATION BASINS PHASE 3 UV ELECTRICAL PHASE 2 OXIDATION DITCH PHASE 1A BLOWER BUILDING PHASE 2 BIO FILTER COVER BIO FILTER COVER BIO FILTER COVER Figure 7.2 ALTERNATIVE 1 - EXPAND BNR/TERTIARY CAPACITY AND YEAR-ROUND DISCHARGE PHASE 1A, 2, AND 3 WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO mo608mpf4-6887.ai 7-4 ---PAGE BREAK--- DRAFT - June 26, 2008 7-5 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc 7.2.2 Primary Effluent Pipeline (also referred to as Outfall) The 2007 Master Plan contained a project to rehabilitate the interior of the primary effluent pipeline. A preliminary design of the pipeline rehabilitation project was completed in March 2008. The report outlined a rehabilitation plant that is similar to the recommendations in the 2007 Master Plan. The project will generally consist of cured-in-place plastic lining. Additional project elements include new access structures installed every 2,000 feet, air and vacuum valve assemblies, new cross-connections to the cannery segregation pipeline, junction box modifications, and modifications to the primary effluent pump station piping. 7.2.3 Jennings Road Secondary Treatment Plant The Jennings Road Treatment Facilities for Phases 2 and 3 will be based on the membrane bioreactor (MBR) process, consisting of aeration basins followed by filtration with membranes. Disinfection will be achieved with ultraviolet light to prevent the formation of trihalomethanes. For the purpose of this Supplement, the solids handling process is based on utilization of the existing recirculation channel and facultative ponds for stabilization, storage, and eventual dewatering. Dried solids will be beneficially applied to the City’s ranch land. Additional consideration of solids handling options will be performed during preliminary design. Salinity removal should also be evaluated in the future to determine if a salinity removal process is required. 7.2.3.1 DAF System The dissolved air flotation (DAF) project is complete and is designed to remove algae from storage pond effluent to extend the river discharge period and thereby increase the existing effluent disposal capacity. A capacity increase of approximately 3.0 million gallons per day (mgd) (at 10th percentile river flow) is estimated to be gained from the DAF system addition. When seasonal discharge is discontinued in 2013, the DAFs will no longer be needed to remove algae. The DAF units may be recommissioned for other uses, such as sludge thickening or cannery waste biochemical oxygen demand (BOD) reduction. 7.2.3.2 Phase 1A Improvements Phase 1A includes the addition of 2.3 mgd of biological nutrient removal (BNR)/tertiary treatment facilities. Design has been completed and the facilities are expected to be operational by the winter of 2010. The improvements include a primary effluent pump station, fine screens, an oxidation ditch, membranes, ultraviolet (UV) disinfection, and an effluent discharge pipeline. Phase 1A improvements will also include the conversion of the gaseous chlorine system at the secondary discharge facility to liquid hypochlorite. 7.2.3.3 Phases 2 and 3 Improvements Primary Effluent Pump Station. Primary effluent (PE) will be diverted just upstream of the primary effluent metering vault. The PE pump station will consist of submersible non-clog ---PAGE BREAK--- DRAFT - June 26, 2008 7-6 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc pumps in a wet well. Based on historical BOD loadings and consistent with Phase 1A design, primary effluent will be the only feed for the aeration basins. Therefore, pump redundancy will be provided for reliability. Fine Screens. The fine screens will remove debris and inert suspended materials from the PE flow. The screen opening size will be 1 mm to protect the membranes and to meet requirements from the MBR vendors. Fine screening will be achieved with internally fed, rotating drum screens. The screens will be washed with internal and external high-pressure spray nozzles. Screenings are conveyed by the rotating action of the drum to the opposite end of the screen. The solids will be washed and compacted prior to temporary storage in dumpsters. Aeration Basins and Blower Building. Concrete aeration basins will provide nitrification/denitrification. The aeration basins will have an anoxic zone at the entrance to the basin that is approximately 33 percent of the total volume with submersed mixers. Aeration and will be achieved with fine bubble diffusers in the aerobic zone. Return activated sludge (RAS) will be mixed with PE and added to the anoxic zone of the aeration basins. A separate building will be provided to house the aeration blowers. RAS/WAS Pump Station. The return activated sludge/waste activated sludge (RAS/WAS) pump station will be constructed with a common wall with the aeration basin. The RAS pumps will be sized for four times the design flow (4Q). All pumps will be submersible, with variable speed controls. Normally the RAS pumps will pump at a constant rate, but a variable speed drive will allow adjustment of the mixed liquor (ML) flow output if required to reduce the flow to the membranes. Solids will be “wasted” by sending them to the recirculation channel for treatment. Membrane Tanks. Concrete membrane tanks will be provided. To save construction costs, the membrane basins will have a common wall with the aeration basins. The manufacturer will furnish all the equipment associated with the membrane system including but not limited to membranes, permeate pumps, permeate back pulse tanks, and membrane tank blowers. The tanks and support equipment will be housed in a building adjacent to the membrane tanks. The manufacturer will also provide chemical feed facilities (citric acid and sodium hypochlorite) for membrane cleaning-in-place and instrument air facilities. Return activated sludge from the membrane tanks will be pumped back to the aeration basins. Permeate pumps will be rotary lobe pumps capable of reverse operation. Ultraviolet 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 most probable number [MPN]). UV was chosen to prevent the formation of trihalomethane (THM). ---PAGE BREAK--- DRAFT - June 26, 2008 7-7 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc UV disinfection will be performed with open channel UV systems. The UV system will utilize concrete channels that will be elevated so that the effluent can flow by gravity to the river. To save construction costs, the UV channel will utilize a common wall with the aeration basins. Membrane bio-reactor pilot testing confirmed that a design UV transmittance (UVT) of 65 percent was conservative for the design approach and that the operational UVT would be in the 72 percent to 76 percent range. Effluent Pipeline. An additional pipeline is required for Phases 2 and 3 to convey tertiary effluent from UV disinfection system to the existing river outfall. Tertiary effluent will flow by gravity. The pipeline will be approximately 12,000 feet long and 42 inches in diameter. WAS Inlet. A minor structure will be required to provide for diversion of WAS from the MBR facility to the existing recirculation channel. Standby Power. Standby power generating units will be installed to provide reliability to critical units in the event of interruption of power service from the local utility. Reverse Osmosis/Brine Disposal. Specific costs have not been included in the CIP at this time for end of pipe salinity reduction. If required, additional capital costs could exceed $200 million. Operations Center. An allowance has been provided in the overall CIP for a new operations center at the Jennings Road Facility. The new center will be required to house necessary support and control systems for the more complex BNR treatment process. This structure is an addition to what was included in the Master Plan. 7.2.3.4 Improvements to Existing Facilities Conversion From Chlorine Gas to Hypochlorite. The gaseous chlorine system used for disinfecting seasonal secondary effluent discharged to the river will be replaced with liquid sodium hypochlorite. 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 2013, 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. 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. ---PAGE BREAK--- DRAFT - June 26, 2008 7-8 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc 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. Fixed Film Reactor (FFR) Improvements and Odor Control. Improvements to the existing FFRs are recommended to increase the life of the existing structures. The improvements include a new distributor arm and replacement of the plastic media for FFR No. 2. Structural rehabilitation of the tower structural members is also included. In addition, odor control facilities for the FFRs will be added under Phase 2. The facilities will consist of an FFR odor containment and scrubbing system. Odors will be contained with accessible fiberglass or aluminum domes. Because the FFRs will be covered, entry into the top of the FFRs will be limited. The primary need to access the top of the FFR is remove debris that accumulates on the surface of the media. To reduce the need to access the domes, a primary effluent screening facility will be added for flows diverted to the FFRs. The screening facilities will be located at FFR mixing box at the Jennings Road facility. Foul air from the FFRs will be collected and passed through soil bed filters, located next to the FFRs. 7.2.4 Special Planning Studies Special planning studies outlined in the Master Plan remain the same. These special studies will be used to modify and update the Master Plan, as well as provide for scientific studies of the segregated cannery process flow land application system. 7.2.5 Capital Improvement Program (CIP) Table 7.2 summarizes the wastewater treatment CIP, including costs per each project phase. 7.3 RENEWABLE ENERGY ANALYSIS The energy use of the recommended project will increase over the current demand. Renewable energy sources were evaluated to offset future power costs. Table 7.3 summarizes the estimated demand for the BNR/Tertiary project at each phase. ---PAGE BREAK--- DRAFT - June 26, 2008 7-9 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc Table 7.2 Wastewater Treatment Capital Improvements Program Wastewater Treatment Master Plan Supplement City of Modesto, California Conceptual Level Costs - $M(1) Project Phases: DAF Phase 1A Phase 2 Phase 2A Phase 3 Total Approximate Year of Implementation: 2008 2009 2013 2018 2022 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 14.1 27.1 0.0 41.2 Primary Effluent Pipeline Lining of Existing Pipeline 23.2 23.2 Jennings Road Secondary Treatment Plant Dissolved Air Flotation Project 8.0 0.0 0.0 0.0 8.0 BNR/Tertiary Improvements Phase 1A Improvements 20.6 20.6 PE Pump Station 5.2 1.7 6.9 Fine Screens 4.0 1.3 5.3 Aeration Basins 22.9 7.5 30.4 Blower Building 9.3 3.0 12.3 ML/WAS pump station 5.0 1.7 6.7 Membrane Tanks 48.0 15.7 63.7 UV Disinfection 11.4 3.7 15.1 Effluent Pipeline from Tertiary Plant to Exist. Outfall-- 10.5 0.0 10.5 New WAS inlet 0.2 0.2 Standby power 2.0 0.7 2.7 Reverse Osmosis System 0 0 0(2) Brine Disposal 0 0 0(2) Operations Center 3.5 0.0 3.5 Subtotal BNR/Tertiary Improvements 0.0 20.6 122.0 0 35.3 177.9 Improvements to Existing Facilities Conversion from Chlorine Gas to Hypochlorite 1.4 0.0 1.4 Effluent Pump Station Improvements 3.0 0.0 3.0 ---PAGE BREAK--- DRAFT - June 26, 2008 7-10 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc Table 7.2 Wastewater Treatment Capital Improvements Program (Continued) Wastewater Treatment Master Plan Supplement City of Modesto, California Conceptual Level Costs - $M(1) DAF Phase 1A Phase 2 Phase 2A Phase 3 Total Project Phases: Approximate Year of Implementation: 2008 2009 2013 2018 2022 Costs Outfall Improvements 4.0 0.0 4.0 Flood Control Improvements 0.2 0.0 0.2 Fixed Film Reactor Improvements and Odor Control 7.5 0.0 0.0 7.5 Subtotal Improvements to Existing Facilities 0.0 1.4 11.7 3.0 0.0 16.1 Subtotal Jennings Road Secondary/Tert. Plant 8.0 22.0 133.7 3.0 35.3 202.0 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 Subtotal Special Planning Studies 0 2.6 2.8 2.1 3.1 10.6 Total Project 8.0 47.8 150.6 32.2 38.4 277.0 Note: Conceptual level costs. Based on June 2006 dollars (ENR CCI = 8441). Includes allowances for contingencies, engineering, legal and administrative expenses. See note from Table 7.1. Table 7.3 Estimated Incremental Power Demand for Recommended Project Wastewater Treatment Master Plan Supplement City of Modesto, California Estimated Incremental Usage for Phase 1A Estimated Total Usage after Phase 1A Estimated Incremental Usage for Phase 2 Estimated Total Usage after Phase 2 Estimated Incremental Usage for Phase 3 Estimated Total Usage after Phase 3 Year 2010 2010 2013 2013 2022 2022 ADWF 29.5 29.5 34.7 34.7 40.7 40.7 Daily Average, kW 500 500 1,700 2,200 600 2,800 Daily Peak, kW 500 500 1,700 2,200 600 2,800 A brief overview of the solar and wind power as alternative energy sources is given below. These will be evaluated further during the preliminary design phase to determine the feasibility for the City. ---PAGE BREAK--- DRAFT - June 26, 2008 7-11 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc 7.3.1 Solar Power Currently, the most common type of solar power is the photovoltaic (PV) cell. PV systems convert solar energy directly into electricity. Because of the climate in the Central Valley and the amount of land the City has available at their current site, solar power may be feasible. Two cost alternatives exist for procuring the PV system: Outright Purchase and Power Purchase Agreement (PPA). Outright Purchase. Under the Outright Purchase approach, the City would purchase the system and own the Renewable Energy Credits (RECs). Funding from the State Revolving Fund is not recommended, as it would eliminate the possibility of using other grants and incentives. The California Public Utilities Commission, through its California Solar Initiative (CSI), provides incentives for installation of PV systems. Payments are administered by Pacific Gas and Electric (PG&E). CSI grant funding is available up to a maximum of 1-MW system. The incentive payment levels decrease over the duration of the CSI program based on the size systems installed. The current performance based incentive for solar PV is in Tier 5, which is 32 cents per kilowatt per hour (kWh). This payment is made for the actual kWh produced during the first 5 years of operation. For a 1 megawatt (MW) facility this would result in an estimated net grant of $3.6 million. A 1-MW solar PV cell system in the Central Valley can produce from 2.2 to 2.4 million kWh per year, which is equivalent to 250 kW to 260 kW, 24 hours per day. Capital costs for a 1 MW solar PV system have ranged from $7.5 to $11.2 million at other municipal facilities in Northern and Central California. The most recent estimate of capital costs for a 1 MW PV solar system was $ 8.0 M. This would result in a net cost to the City of $4.4 million (after credit from grant). The estimated annual savings due to the 1MW PV solar system is approximately $175,000 (based on 250 kW and the current cost of power at $0.08/kWh). This would result in a simple pay back period of approximately 25 years. A 1-MW system is recommended, to maximize the use of the CSI grant funding. This would amount to approximately 8 percent of the total power usage at Phase 3. If the City chooses to purchase solar PV, the demand classification would change from Medium General Demand-Metered Time of Use Service (PG&E Rate Schedule E-19) to Small General Time of Use Schedule (A-6) with net metering. This would allow the City to sell surplus electricity back to Turlock Irrigation District (TID) during summer on-peak periods. At night, when the solar panels aren't generating power, the City would buy power at off-peak rates. This would result in savings to the City. Power Purchase Agreement. PPA involves allowing a power provider to design, build, own, and operate the PV. The City would buy power from the PPA provider at an ---PAGE BREAK--- DRAFT - June 26, 2008 7-12 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\07.doc agreed-upon rate (at a reduced price of power compared to TID rates), with an option to buy the facilities at the end of the contract term, usually five years. Ownership of Renewable Energy Credits can be negotiated, but City ownership may result in a higher rate. Power costs from a typical third PPA agreement vary between 9 and 13 cents/kWh. The City currently pays an average cost of between 8 cents / kW-hr, so the PPA may be more costly than conventional power at this time. To make investment by private power providers attractive, there is currently a 30 percent Federal Investment Tax Credit (ITC) available. This incentive is set to expire on December 31, 2008. To obtain this credit, the solar facility must be owned by a private (non-governmental) entity and must be operational by the expiration date. It is not known at this time if this ITC will be extended or not. 7.3.2 Wind Power Wind turbines convert the kinetic energy of the wind into electricity with a generator. PG&E is currently sponsoring the Self Generating Incentive Program (SGIP).The 2008 SGIP program will provide $1.50/watt for wind power up to a maximum capacity of 1 MW. The CPUC Decision 08-04-049 has raised this incentive cap to 3 MW, with the following tiered structure: • 0 - 1 MW paid at 100 percent of the current incentive rate (or $1.50/watt). • 1 - 2 MW paid at 50 percent of the current incentive rate (or $0.75/watt). • 2 - 3 MW paid at 25 percent of the current incentive rate (or $0.375/watt). Funding for projects greater than 1 MW is subject to availability of unused carryover funds from previous years, so once these unused carryover funds have been exhausted there may not be funding available for the portion above 1 MW. A 1-MW wind system is estimated to produce 200 kW, 24 hours per day. This is based on an assumed rough capacity factor of 0.2. Capital costs for a 1 MW wind system have been estimated at $3.7 million. This would result in a net cost to the City of $ 4.4 million (after credit from SGIP grant program). The estimated annual savings due to the 1 MW PV wind system is approximately $140,000 (based on 200 kW and the current cost of power at $0.08/kWh). This would result in a simple pay back period of approximately 24 years. If the City chooses to pursue wind power, an analysis needs to be performed to determine the capacity factor at the average wind speed at the Jennings Plant site as well as the impact of wind turbines on the birds in the area. ---PAGE BREAK--- DRAFT - June 26, 2008 8-1 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\08.doc Chapter 8 REVISIONS TO WASTE DISCHARGE COMPLIANCE STRATEGY AND IMPLEMENTATION PLAN 8.1 INTRODUCTION The Wastewater Treatment Master Plan presented a waste discharge requirement compliance strategy and project implementation plan. This section of the Supplement presents the revisions to the Master Plan required to address the new waste discharge requirements described in Chapter 4. This section also includes revisions to the implementation plan that are dictated by the new compliance strategies. 8.2 WASTE DISCHARGE REQUIREMENT COMPLIANCE STRATEGY The key changes to the waste discharge requirements are summarized in Table 8.1. The revised compliance strategy to accommodate the expected new waste discharge requirements (WDRs) is presented in Table 8.2. 8.3 PROJECT IMPLEMENTATION PLAN The implementation plan was revised from the Master Plan to reflect the new waste discharge requirements and their compliance schedule, and to account for updated flow and loading projections. Domestic effluent disposal capacity is still the highest priority because additional capacity will be needed to comply with the New Discharge Order. Figure 8.1 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 million gallon per day (mgd) (2010), Phase 2 - 18.4 mgd (2013), and Phase 3 - 6 mgd (2022). Phase 2A was added to spread out the costs between the Sutter Ave Facility and Jennings Road improvements. For the Supplement it was assumed that the just in time phasing plan will be adopted. Figure 8.2 is a near-term, implementation schedule for Phases 1A and 2. Figure 8.3 presents the estimated long-term schedule for all project phases. ---PAGE BREAK--- DRAFT - June 26, 2008 8-2 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\08.doc Table 8.1 Changes to Waste Discharge Requirements (WDR) Wastewater Treatment Master Plan Supplement City of Modesto, California Discharge Mode Constituent Previous WDR New WDR(1) Impacts to Compliance Strategy Seasonal Discharge Ammonia 2.6 to 32.6(2) 0.9 m/L (fixed) Eliminate seasonal discharges, replace with year round discharge of equivalent capacity Nitrate/Nitrite None 42 mg/L None Year Round Discharge Ammonia 2.6 to 32.6 0.9 mg/L (fixed) Add nitrification using activated sludge process, with plug-flow reactors Nitrate/Nitrite None 10 mg/L Add denitrification by increasing treatment volume to accommodate anoxic zones Salinity Limits EC 1,341 µmhos/cm October 1 - March 31 1,000 µmhos/cm April 1 - May 31 700 µmhos/cm Develop comprehensive salt reduction program, possible RO treatment Notes: From Final Order, May 2008 Calculated based on pH and temperature. pH typically ranges form 6.5 to 8.5. Corresponding ammonia limits are 32.6 mg/L (at pH 6.5) to 2.1 mg/L (at pH 8.5) ---PAGE BREAK--- June 26, 2008 - DRAFT 8-3 H:\FINAL\MODESTO_WCO\6887L00\RPT\MASTERPLANSUPP\FINAL DRAFT\08.DOC Table 8.2 Strategic Plan Wastewater Master Plan Supplement 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 2013 Construct flood control levee around plant and sludge drying beds Flood control levees Containing Peak Wet Weather Flows at Sutter Ave. Plant 2013 Expand headworks hydraulic capacity Influent pumping, flow meter, screening and grit removal Conveying Peak Flows from Sutter Avenue Plant to Jennings Rd Plant 2013 Expand primary effluent pump station and primary effluent pipeline Primary Effluent Pump Station, lining of primary effluent pipeline Groundwater Impacts - Sutter Avenue Facilities 2013 Install groundwater monitoring wells Line sludge drying beds and install subnatant return lines Jennings Road Secondary Treatment Plant: Effluent Disposal Capacity Deficiencies 2008 - 2013 Add BNR/tertiary treatment at Jennings Rd for year round discharge to river BNR Tertiary facilities, including nitrification and denitrification Title 22 Compliance for all river discharges 2013 Add BNR/tertiary treatment at Jennings Rd for year round discharge to river BNR Tertiary facilities Ammonia 2013 Add BNR Facilities for year round discharge to river Nitrification/denitrification facilities Copper 2013 Continue dynamic compliance model studies, translator study and copper water effects ratio studies Non-structural Dissolved Oxygen Demand (nitrate removal) 2013 Add BNR Facilities for year round discharge to river Nitrification/denitrification facilities- ---PAGE BREAK--- June 26, 2008 - DRAFT 8-4 H:\FINAL\MODESTO_WCO\6887L00\RPT\MASTERPLANSUPP\FINAL DRAFT\08.DOC Table 8.2 Strategic Plan Wastewater Master Plan Supplement City of Modesto, California Regulatory Issue Projected Compliance Date Compliance Strategy Applicable Master Plan Facility Components Potential Future Additions/Modifications Trihalomethanes (THMs) 2013 UV disinfection UV disinfection Molybdenum 2013 Source control, upstream receiving water monitoring to determine if assimilative capacity is available for dilution, continue changeover to surface water for drinking water supply Membrane Filtration 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 2013 Source control, industrial pretreatment, perform in-plant methyl mercury monitoring in receiving water and effluent, participate in regional TMDL and offset efforts Membrane 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 Carbon Tetrachloride 2013 Eliminate seasonal discharges and chlorination for disinfection BNR/tertiary facilities ---PAGE BREAK--- June 26, 2008 - DRAFT 8-5 H:\FINAL\MODESTO_WCO\6887L00\RPT\MASTERPLANSUPP\FINAL DRAFT\08.DOC Table 8.2 Strategic Plan Wastewater Master Plan Supplement City of Modesto, California Regulatory Issue Projected Compliance Date Compliance Strategy Applicable Master Plan Facility Components Potential Future Additions/Modifications Aluminum 2013 Use acid-soluble aluminum to comply with USEPA WQO, perform water effects ratio study to develop site specific objectives Membrane filtration Reverse Osmosis and Brine disposal facilities Iron and Manganese 2013 Perform translator studies to develop site specific objectives Membrane filtration Reverse Osmosis and Brine disposal facilities Emerging Constituents Unknown Monitor continuing research in this area Membrane filtration (reduces concentrations of constituents absorbed in solids). Addition of ozone or hydrogen peroxide disinfection to reduce concentrations 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 2013 Improve levees at San Joaquin River Levee improvements Salinity (Electrical Conductivity {EC}) 2022 or 2026 Continue to convert City potable water water source to surface water reuse to reduce EC loadings. Prepare salinity reduction study. Initiate discussions with the Continue source control measures and assess results in salinity reductions. Reverse Osmosis and brine disposal facilities for a portion of the effluent flow ---PAGE BREAK--- mo508mpf17-6887.ai 27.2 29.5 34.7 36.5 40.7 24.2 14.0 5.9 Year 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 2013 2008 2009 2015 2016 2020 2025 2022 2030 Figure 8.1 REQUIRED TERTIARY TREATMENT CAPACITY NEEDS AND PHASING PLAN WASTEWATER TREATMENT MASTER PLAN SUPPLEMENT CITY OF MODESTO 8-6 Projected Domestic Wastewater Flow(1) (annual average flow) Domestic secondary effluent to land (8.1 mgd) (2,526 acres) BNR/tertiary river discharge Phase 1A 2.3 mgd Phase 2 18.4 mgd(2) Phase 3 6.0 mgd Seasonal river discharge of secondary effluent (10.2 mgd(3)) DAF (3.0 mgd) Net evaporation loss (5.9 mgd) Notes: 1. Based on 0.7% growth to 2011 and then 1.75% growth to 2030. 2. Assumes discontinuation of secondary effluent discharge to river in 2013 and phase out of DAF. 3. Based on 10th percentile river flow conditions. ---PAGE BREAK--- mo508mps1-6887.ai Figure 8.2 NEAR TERM PROJECT SCHEDULE MASTER PLAN SUPPLEMENT CITY OF MODESTO 2008 2009 2010 2011 2012 2013 M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S Phase 1A - BNR/Tertiary Facilities at Jennings Rd Design Bidding and Award (3 months) Construction (18 months) Startup (6 months) Phase 2 - BNR/Tertiary Facilities at Jennings Rd, Digester and Primary Effluent Pump Station Improvments at Sutter Ave Preliminary Design (6 months) Design (12 months) Bidding and Award (3 months) Construction (30 months) Startup (6 months) Compliance Date per Tentative Order (May 2013) 8-7 ---PAGE BREAK--- mo508mps2-6887.ai Figure 8.3 LONG TERM PROJECT SCHEDULE MASTER PLAN SUPPLEMENT CITY OF MODESTO Phase 1A - BNR/Tertiary Facilities at Jennings Rd Phase 2 - BNR/Tertiary Facilities at Jennings Rd. Digester and Primary Effluent Pump Station Improvments at Sutter Ave Phase 2A - Other Sutter Ave. Improvments Phase 3 - BNR/Tertiary Facilities at Jennings Rd Compliance Date per Tentative Order (May 2013) 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Design Bidding and Award (3 months) Construction (18 months) Startup (6 months) Preliminary Design (6 months) Design (12 months) Bidding and Award (3 months) Construction (30 months) Startup (6 months) Startup Construction Design Bidding and Award Startup (6 months) Construction (24 months) Bidding and Award (3 months) Design (12 months) 8-8 ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\App_Covers.doc City of Modesto, California APPENDIX A - CITY OF MODESTO NPDES PERMIT ---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--- ---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--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\App_Covers.doc City of Modesto, California APPENDIX B - LARRY WALKER AND ASSOCIATES METALS ANALYSIS ---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--- DRAFT - June 26, 2008 H:\Final\Modesto_WCO\6887L00\Rpt\MasterPlanSupp\Final Draft\App_Covers.doc City of Modesto, California APPENDIX C - MBR PILOT TEST METALS RESULTS ---PAGE BREAK--- Appendix C Performance of MBR Pilot on Metals - Effluent Results Tertiary Wastewater Treatment Project City of Modesto, California Al Sb As Ba Be Cd Cr Co Cu Fe Pb Hg Mo Ni Se Ag Tl V Zn Result Result Result Result Result Result Result Result Result Result Result Result Result Result Result Result Result Result Result 06/14/2007 74 <5 <3 42 <0.5 0.4 <1 <10 <4 40 <1 <0.2 6 <5 <5 <0.4 <2 11 30 06/21/2007 51 <5 <3 56 <0.5 <0.3 <1 <10 <4 60 <1 <0.2 <5 <5 <5 <0.4 <2 9 <20 06/28/2007 58 0.38 2.8 74 ND ND 1.77 0.64 0.78 62 ND 0.06 4.6 0.91 5.6 ND 0.1 10 22.28 07/05/2007 30 <5 <3 53 <0.5 <0.3 <1 <10 <4 25 <1 <0.2 <5 <5 <5 <0.4 <2 10 30 07/12/2007 39 <5 <3 38 <0.5 <0.3 <1 <10 <4 68 <1 <0.2 <5 <5 <5 <0.4 <2 10 30 07/19/2007 30 0.55 3.1 17 ND ND 1.85 0.32 1.92 63 ND ND 9.63 2.06 1.52 ND ND 17 36.33 07/26/2007 55 0.5 1.33 24 ND ND 2.73 0.3 2.45 72 ND ND 7.11 5.25 0.62 ND ND 12 38.09 08/02/2007 43 0.42 2.8 25 ND 0.05 2.02 0.25 2.54 60 ND ND 8.02 5.22 1.04 ND ND 16 34.53 08/07/2007 45 0.51 1.46 26 ND ND 5.04 0.25 2.15 85 ND ND 7.72 4.86 ND ND ND 6.09 43.85 Average 47.2 0.5 2.3 39 <0.5 0.2 2.7 0.4 2.0 59 <1 < 0.2 7.2 3.7 2.2 <0.4 0.1 11 33.1 CTR Limits NA 14 150 NA NA 4.3 NA NA 4.1 NA 65 NA 10 470 5 3.4 1.7 NA 120 Notes: 1. Metal removal rates ranged from 12% to 96%. There were instances of higher levels of metals in the permeate over the influent with arsenic, molybdenum, nickel, selenium and vanadium. These results were not used in the determination of the removal rates. 2. All Results in ug/L