ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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Although no significant water quality impacts were identified for the project,the project would exceed currently adopted standards for aluminum(although a water effects ratio [WER] study has been completed to identify an appropriate site-specific objective for total aluminum in the San Joaquin River that is both sufficiently protective of aquatic life and identifies available assimilative capacity for aluminum in the river under which the WQCF can discharge its effluent); however,this impact was determined to be less than significant because the current adopted standard is believed,based on available science,to be overly protective of water quality and aquatic resources. The MF/RO process would reduce the concentration and loadings of aluminum and other metals in the effluent compared to the proposed project. This treatment technology is evaluated in the analysis provided below. ENVIRONMENTAL ANALYSIS Environmental Impacts This alternative would increase WQCF treatment capacity to 27 mgd ADWF and would expand the wastewater collection system and treated effluent disposal system with the same facilities proposed as part of the project. In addition,this alternative would construct additional facilities within the developed boundaries of the WQCF. Because similar facilities would be constructed in similar areas,the Advanced Wastewater Treatment Alternative would have impacts similar to the proposed project for land use and agricultural resources,terrestrial biological resources, soils and seismicity,paleontological resources,public services and utilities, cultural resources, transportation and circulation,noise,air quality,visual.[Similar] Hazardous Materials Implementation of the Advanced Wastewater Treatment Alternative would maintain WQCF effluent pollutant loading to the San Joaquin River at the currently permitted 9.87 mgd level as WQCF discharge capacity increases to 27 mgd. However,advanced wastewater treatment employing MF/RO technology could result in"cross media impacts,"or the interrelated impacts caused by removal of a pollutant from one medium to one or more other media. In the case of MF/RO,the process removes a pollutant at a certain concentration from wastewater and partitions it at a significantly higher concentration in brine and/or residuals. Pollutants, such as metals, are not destroyed,but transferred from one medium to another. Organic pollutants can be destroyed or converted to other toxic or non-toxic forms and can also be transferred from one medium to another. It should be noted that in transferring from one medium to another,the bioavailability of the pollutant may be changed significantly. MF/RO treatment results in the transfer of pollutants from wastewater into biosolids, air, and/or concentrated waste streams. Depending on regulatory limits, additional treatment of the biosolids, air, or waste streams may be required. Therefore,this alternative could result in similar or greater hazardous material impacts.[Similar or greater] Surface Water Quality Because this alternative would maintain WQCF effluent pollutant loading in the San Joaquin River at the currently permitted 9.87 mgd ADWF level as the WQCF discharge capacity increases,treated effluent pollutant mass loading to the river would not increase above that realized once the WQCF discharges at its current permitted capacity of 9.87 mgd ADWF. Similarly,near- and far-field pollutant concentrations would not increase above those expected to occur once the WQCF discharges effluent at its current permitted capacity. Furthermore, RO would reduce effluent concentrations of TDS,metals(including aluminum), ammonia, and organic compounds, and would lower electrical conductivity. While this alternative is projected to reduce pollutant concentrations in WQCF effluent compared to post-project levels at 27 mgd,the extent of MF/RO treatment considered in this alternatives analysis would not decrease downstream constituent concentrations from pre- project(9.87 mgd)conditions; the MF/RO facilities would be designed to maintain downstream TDS and metals mass loading to the San Joaquin River at pre-project levels. Further,it is anticipated that implementation of the Advanced Wastewater Treatment Alternative would reduce aluminum levels to below the existing NPDES daily maximum effluent limit for the parameter. Although effluent pollutant concentrations would decrease with EDAW Manteca WQCF and Collection System Master Plans EIR Alternatives to the Proposed Project 7-10 City of Manteca