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Table 4: Potential Sources and Proposed TMDL Completion Dates of Pollutants/Stressors for Order No.R5-2005-0110. Only effluent limits at the 9.87 MGD(ADWF)design treatment <br /> Select Delta Waterways contained in 2006 Clean Water Act Section 303(d)List capacity are presented because the WQCF is currently permitted to operate up to 9.87 MGD <br /> Pollutant/Stressor Potential Sources Proposed TMDL Completion (ADWF)and this antidegradation analysis considers water quality impacts of a WQCF permitted <br /> Chlorpyrifos Agriculture,Urban Runoff/Storm Sewer 2019 wastewater discharge from 9.87 MGD(ADWF)to 27 MGD(ADWF). Effluent limitations for <br /> ammonia as nitrogen,copper,cyanide,bis(2-ethylhexyl)phthalate,bromodichloromethane, <br /> DDT Agriculture 2011 dibromochloromethane,and 2,4,6-trichlorophenol were calculated with applicable dilution <br /> Diazinon Agriculture,Urban Runoff/Storm Sewer 2019 credit. <br /> Dioxin Point Source 2019 <br /> Electrical Conductivity Agriculture 2019 <br /> Exotic Species Source Unknown 2019 <br /> Furan Compounds Contaminated Sediments 2019 <br /> Group A Pesticides Agriculture 2011 <br /> Mercury Resource Extraction(abandoned mines) 2006 <br /> Pathogens Urban Runoff/Storm Sewer,Recreational 2008 <br /> and Tourism Activities(non-boating) <br /> PCBs Point Source 2019 <br /> Unknown Toxicity Source Unknown 2019 <br /> NPDES PERMIT REQUIREMENTS <br /> The WQCF currently operates and discharges treated effluent to the San Joaquin River under the <br /> requirements of NPDES permit No.CA0081558(Order No.R5-2004-0028),issued by the <br /> Central Valley Regional Water Quality Control Board in March 2004. The permit includes three <br /> sets of effluent limitations for discharge to the San Joaquin River based on the design treatment <br /> capacity of the WQCF as it undergoes its scheduled improvements. The permit contains effluent <br /> limitations for design treatment capacities of 6.95,8.11,and 9.87 MGD(ADWF). In April 2005, <br /> the City requested that the effluent limitations for bromodichloromethane and <br /> dibromochloromethane be modified based upon current treatment plant performance. The <br /> WCQF had historically operated in a non-nitrifying or partially nitrifying mode,which typically <br /> produced an effluent with elevated levels of ammonia. In November 2003,the treatment process <br /> was converted to full nitrification mode to reduce ammonia. Without ammonia in the effluent, <br /> organochlorines are formed,which are less effective disinfectants than chloramines. <br /> Consequently,more chlorine is required for disinfection,thereby increasing concentrations of <br /> disinfection byproducts,including bromodichloromethane and dibromochloromethane. The City <br /> is in the process of adding UV disinfection in order to ultimately reduce and/or eliminate the use <br /> of chlorine,which should eliminate the presence of disinfection byproducts from the effluent. <br /> The addition of UV disinfection is part of the Schedule D WQCF improvements,and is therefore <br /> currently under construction. In the meantime,it was necessary for the City's NPDES permit to <br /> be amended by Resolution No.R5-2005-0110(amended WDR Order No.R5-2004-0028)to <br /> increase the effluent limitations for bromodichloromethane and dibromochloromethane by re- <br /> calculating dilution credits using new effluent data collected while the WQCF was operating in <br /> full nitrification mode. Resolution No.R5-2005-0110 also contains effluent limitations for <br /> design treatment capacities of 6.95,8.11,and 9.87 MGD(ADWF). Table 5 presents the effluent <br /> limits(at a 9.87 MGD(ADWF)design treatment capacity)contained in the City's NPDES <br /> permit as adopted by the Regional Water Board in Order No.R5-2004-0028 and as amended by <br /> City of Manteca Antidegradation Analysis II June 2007 City of Manteca Antidegradation Analysis 12 June 2007 <br />