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REVISED WASTE DISCHARGE REQUIREMENTS ORDER NO. 97-115 5 <br /> CITY OF MANTECA AND CITY OF LATHROP <br /> WASTEWATER QUALITY CONTROL FACILITY <br /> SAN JOAQUIN COUNTY <br /> 26. The City's treatment process consists of raw influent bar screening, flow metering, and grit <br /> removal, followed by primary sedimentation, biofiltration, conventional activated sludge and <br /> secondary sedimentation. Secondary effluent is spread over agricultural fields and the excess <br /> flows are chlorinated, dechlorinated and discharged to the San Joaquin River. The Discharger is <br /> in the process of completing design work for the expansion of the treatment plant to <br /> accommodate increasing flows. At the completion of the proposed expansion the design flow <br /> will be 8.11 mgd. <br /> 27. The December 1995 Report of Waste Discharge describes the existing discharge as follows: <br /> Average Flow 5.3 mgd <br /> Design Flow 6.95 mgd <br /> B.O.D: 13 mg/1 <br /> Suspended Matter: 11 mg/1 <br /> 28. The U.S. Environmental Protection Agency(EPA) and the Board have classified this discharge <br /> as a major discharge. <br /> 29. The Board adopted a Water Quality Control Plan, Third Edition, for the Sacramento River Basin <br /> and the San Joaquin River Basin (hereafter Basin Plan), which contains water quality objectives <br /> for waters of the Basin. These requirements implement the Basin Plan. <br /> 30. Federal regulations require effluent limitations for all pollutants that are or may be discharged at <br /> a level that will cause or have the reasonable potential to cause, or contribute to an in-stream <br /> excursion above a narrative or numerical water quality standard. Based on information <br /> submitted as part of the application, in studies, and as directed by monitoring and reporting <br /> programs the Board finds that the discharge does have a reasonable potential to cause or <br /> contribute to an in-stream excursion above a water quality objective for BOD, total suspended <br /> matter, settleable matter, temperature, dissolved oxygen, chlorine residual, total coliform, <br /> ammonia and oil and grease. <br /> 31. The beneficial uses of the San Joaquin River downstream of the discharge are municipal and <br /> domestic, industrial, and agricultural supply; water contact and noncontact recreation; esthetic <br /> enjoyment; navigation; groundwater recharge, fresh water replenishment; hydropower <br /> generation; and preservation and enhancement of fish, wildlife and other aquatic resources. <br /> 32. The beneficial uses of the underlying groundwater are municipal and domestic, industrial and <br /> domestic supply. <br /> 33. The State Water Resources Control Board (SWRCB) Water Quality Control Plan for Control of <br /> Temperatures in Coastal and Interstate Waters and Enclosed Bays and Estuaries of California <br /> (the Thermal Plan dated 18 September 1975) is applicable to this discharge. Effluent Limitation <br /> C.6 and Receiving Water Limitations E.9 and E.10 are included to achieve compliance with the <br /> Thermal Plan. <br />