SITE INFORMATION AND CORRESPONDENCE_CASE 2

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REGIONAL WATER BOARD REQ',_ 4SE (SWRCB/OCC File A-1846(a) and A '46(b)) -2- PETITIONS FOR REVIEW OF VV, E DISCHARGE REQUIREMENTS ORDER NO. R5-2007-0036 (NPDES NO. CA0079154) AND TIME SCHEDULE ORDER NO. R5-2007-0037 CITY OF TRACY, WASTEWATER TREATMENT PLANT 1. The overall level of treatment is increased from secondary to Title 22 tertiary, or equivalent treatment, reducing oxygen demanding substances and pathogen loading, 2. New ammonia effluent limits reduce effluent aquatic toxicity, oxygen demand, and nutrients; 3. New nitrate effluent limits reduce nitrate concentrations in municipal water supplies and reduce effluent nutrients; 4. New salinity effluent limits require the City of Tracy to address salt sources and ultimately reduce effluent salinity. The development of the effluent limits included modeling of effluent impacts on the south Delta and export supplies; and 5. New effluent limits for priority toxic pollutants bring the facility into compliance with the California Toxics Rule. BACKGROUND The City of Tracy (hereafter Discharger) owns and operates the Tracy Wastewater Treatment Plant (Facility), which provides sewerage services to the City of Tracy. The Facility discharges secondary treated wastewater to Old River, located within the Sacramento-San Joaquin Delta, a water of the United States. The Discharger filed a report of waste discharge and submitted an application for renewal of its Waste Discharge Requirements (WDRs) and National Pollutant Discharge Elimination System (NPDES) permit on 1 November 2000. Subsequently, on 3 February 2003, the Discharger submitted a revised report of waste discharge, which included a request for expansion. Supplemental information was received on 25 September 2003, 30 September 2003, and 29 April 2004. A site visit was conducted on 9 November 2004, to observe Facility operations and conditions. The Facility treats primarily domestic wastewater collected via the City of Tracy's wastewater collection system. The wastewater treatment plant also accepts industrial food processing wastewater from Leprino Food Company (Leprino) through a segregated industrial wastewater pipeline. The Facility is composed of a main treatment facility and an industrial facility. The main treatment facility consists of raw influent bar screening, primary sedimentation, biofiltration, conventional activated sludge, and secondary sedimentation. Secondary effluent is disinfected by chlorination and dechlorinated prior to discharge. Biosolids are thickened by dissolved air flotation, anaerobically digested, and dewatered in unlined sand drying beds. The dried biosolids are hauled off-site for land application or disposed in a landfill. The Discharger's industrial facility consists of four unlined industrial ponds (approximately 52 acres). In addition, Leprino, a local cheese manufacturer, leases two lined aerated lagoons and one 8-acre unlined oxidation pond from the Discharger for preliminary treatment of its