ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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5.2.3 LIST OF RELATED WATER QUALITY PROJECTS The list of past,present, and probable future water quality projects used for this cumulative analysis includes those projects that have occurred or are planned to occur in the region. For the purposes of this discussion,the projects that may have a cumulative effect on the resources in the project area will often be referred to as the "related projects."Related water quality projects are identified below. MANTECA WASTEWATER QUALITY CONTROL FACILITY CURRENT OPERATIONS The City of Manteca Wastewater Quality Control Facility(WQCF)is included as a cumulative project because it currently discharges wastewater to and affects the water quality of the San Joaquin River and the Sacramento-San Joaquin Delta. The Manteca WQCF serves commercial and residential uses within the City of Manteca and a portion of the City of Lathrop. The WQCF is a combined biofilter and activated-sludge wastewater treatment plant permitted for treatment and discharge of 9.87 mgd ADWF of wastewater. Wastewater flows to the WQCF have steadily increased as the population and commercial and industrial activity in and around the city has grown. Average flows to the plant have increased from just over 4 mgd ADWF in 1991 to approximately 6 mgd ADWF in December 2005. Flows are treated to a secondary treatment level, in compliance with federal Clean Water Act (CWA)requirements,prior to discharge. Because the existing NPDES permitted capacity of the WQCF is 9.87 mgd, even without implementation of the master plan project evaluated in this EIR(proposed expansion to 27 mgd), flows at the WQCF would be expected to increase to 9.87 mgd as growth occurs within the city. Consequently, current operation of the WQCF would continue to contribute to constituent loadings to the San Joaquin River. Section 4.9,"Hydrology and Water Quality,"describes existing constituent loading concentrations from the plant. CITY OF TRACY WASTEWATER TREATMENT PLANT EXPANSION The City of Tracy Wastewater Treatment Plant(WWTP) is located in the northern portion of the City of Tracy Urban Management Plan(UMP) area and is within City of Tracy limits. The plant provides secondary treatment and disinfection prior to discharging to Old River,which flows into the San Joaquin River prior to entering the Delta. First operated in 1930,the plant has since undergone numerous upgrades and improvements to its treatment facilities to keep pace with the City's increased wastewater loads and to comply with federal and State water quality and environmental regulations. To accommodate increased wastewater flows and loadings,the City recently proposed to expand the plant's capacity from 9 mgd to 16 mgd. The proposed expansion would increase plant capacity by installing additional secondary treatment facilities,while simultaneously upgrading the plant in anticipation of more stringent effluent discharge requirements. The project includes filtration facilities added after secondary clarification to further reduce BOD,total suspended solids(TSS), and turbidity. Ammonia removal will occur through the addition of aeration basins to provide complete nitrification-denitrification of the secondary effluent. Treatment beyond tertiary level and ammonia removal was assessed but deemed not to be required(Fulton,pers. comm.,2007). CITY OF LATHROP WASTEWATER TREATMENT/RECYCLING PLANT EXPANSION The City of Lathrop currently treats and disposes its wastewater at three facilities: a City owned treatment plant located in the Crossroads Business Park,the Water Recycling Plant(WRP-1), and the City of Manteca Wastewater Quality Control Facility(WQCF). The City of Lathrop presently generates approximately 1.08 mgd of wastewater. Approximately 95% of this wastewater is conveyed to the Manteca WQCF,which discharges to the San Joaquin River,with the remainder going to WRP 1. The City of Lathrop has a contractual relationship with the City of Manteca whereby 14.7%of the Manteca WQCF's existing and future expanded capacity is allocated for Lathrop flows. The permitted capacity of the existing Manteca WQCF is 9.87 mgd,thus providing Lathrop with a capacity of 1.45 mgd(14.7% of 9.87 mgd). Flows from Lathrop to Manteca currently average approximately 0.76 mgd. Approximately 0.15 mgd of wastewater generated within the City of Lathrop is treated Manteca WQCF and Collection System Master Plans EIR EDAW City of Manteca 5-5 Cumulative Impacts