ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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mass loading in the San Joaquin River from the time the WQCF reaches its current permitted August 2005 conditions due to the blending of surface water from the South County capacity of 9.87 MGD(AWDF)through the proposed build-out capacity of 27 MGD(ADWF),it Water Supply Program with the City's groundwater. The blending of surface water with is estimated that a maximum effluent-to-land disposal capacity of 18 MGD or a maximum groundwater for the potable water supply has significantly decreased the electrical MF/RO capacity of 21 MGD would be required. The implementation of either alternative would conductivity(EC)measured in WQCF effluent when comparing pre-and post-August maintain WQCF effluent mass loading to the San Joaquin River at the currently permitted 9.87 2005 plant effluent measurements(LWA,2006b). MGD(ADWF)level as WQCF discharge capacity increases to 27 MGD(ADWF). The costs of implementing an alternative control measure would be above and beyond the proposed project CONSISTENCY WITH ANTIDEGRADATION POLICIES costs associated with increasing WQCF discharge capacity to 27 MGD(ADWF). The proposed project,a 17.13'MGD(ADWF)increase in WQCF discharge capacity with Land application of undisinfected,denitrified,secondary effluent would offset projected accompanying nitrification-denitrification,tertiary filtration,and UV disinfection treatment reductions in San Joaquin River water quality as a result of the proposed project,and would also upgrades to treat the increased flow,is determined to comprise best practicable treatment or provide an additional water supply source to the region. An 18 MGD effluent-to-land disposal control and is consistent with Federal and State antidegradation policies for the following operation would cost an estimated$79.2 million to construct and an additional$0.9 million per reasons: year to operate. An economic impacts model estimates that these costs would have adverse • The increase in permitted discharge capacity is necessary to accommodate important socio-economic effects,including a loss of 55 jobs per year to the local economy for the 20-year economic and social development in the City and surrounding communities,and is life-cycle of the alternative control measure. Additionally,land application of secondary treated consistent with the City's General Plan. Failure to approve the increase,or alternatively effluent would add salts(as measured by total dissolved solids(TDS))to the groundwater basin requiring the City to implement control measures that would maintain existing water underlying the application site(s). Addition of salts to groundwater at a concentration greater quality and mass emissions in the San Joaquin River,would have significant adverse than the Title 22 Secondary MCL recommended level of 500 mg/L,or greater than ambient economic and social impacts on the City and surrounding communities and their citizens background quality,would produce an unfavorable environmental impact,especially in light of and businesses. the existing,elevated salinity and boron levels found in Central Valley surface waters and groundwater. Effluent-to-land disposal also carries the risk of causing groundwater mounding in • The increase will not adversely affect existing or probable beneficial uses of the San the area(s)of land application. A final unfavorable environmental impact of the effluent-to-land Joaquin River,nor will it cause water quality to fall below applicable water quality disposal alternative is an increase in energy consumption and air emissions due to the substantial objectives. power requirements of pumping effluent to storage ponds and then to land application sites. . The increase,while causing slight increases in downstream water quality concentrations Similar to the effluent-to-land disposal alternative,the implementation of MF/RO would offset for some constituents(ammonia(October through May),dissolved arsenic,dissolved estimated reductions in San Joaquin River water quality due to an increase in WQCF effluent copper,total cyanide,methylene blue active substances(MBAS),nitrate,nitrite,total discharged above the current permitted 9.87 MGD(ADWF)capacity. A 21 MGD MF/RO mercury,and EC(September through March)),will produce slight decreases in treatment facility would cost an estimated$134.7 million to construct and an additional$13.1 downstream concentrations for others(total suspended solids,total aluminum,dissolved million per year to operate. An economic impacts model estimates that these costs would have iron,and dissolved manganese). The proposed increase in discharge capacity is also adverse socio-economic effects,including a loss of 177 jobs per year to the local economy for projected to cause minor increases in downstream water quality concentrations for the 20-year life-cycle of the alternative control measure. Moreover,MF/RO treatment would biochemical oxygen demand(BOD)and EC(April through August),as well as a produce adverse environmental impacts resulting from the concentration of toxic compounds, moderate increase for ammonia(June through September). Total aluminum currently removal and transference of these toxic substances to various other media,brine and crystallized exceeds its water quality objective in the San Joaquin River upstream of the WQCF residuals disposal,and the substantial energy requirements of the process with their associated outfall. natural resource and air quality impacts. • The benefits of maintaining existing water quality and mass emissions for the PROPOSED PROJECT AND ADDITIONAL MEASURES constituents analyzed are not commensurate with the costs of additional treatment. The small decrease in quality with respect to the constituents considered in the analysis is The proposed project is designed to minimize impacts on water quality while allowing for unlikely to affect beneficial uses of the San Joaquin River. measured growth in the City and providing overall wastewater treatment system stability. In . Based on the above,the requested increase in permitted capacity is consistent with addition to the proposed project,the City continues to pursue other significant system improvements and source control efforts to ensure the highest discharge water quality and Federal and State antidegradation policies in that the lowering of water quality for several improve receiving water quality. The following project will improve the WQCF's overall pollutants is necessary to accommodate important economic or social development,will discharge water quality: • Increased use of high quality surface water within the service area. The City's potable WQCF requested maximum discharge capacity of 27 MGD(ADWF)less existing NPDES-permitted discharge of water supply is expected to improve in quality,with respect to EC,as compared to pre- 9.87 MGD(ADWF)results in a net requested increase in discharge capacity of 17.13 MGD(ADWF). City of Manteca Antidegradation Analysis ES-111 June 2007 City of Manteca Antidegradation Analysis ES-IV June 2007