ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -15- WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -16- CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY SAN JOAQUIN COUNTY long as the receiving water does not exceed the OEHHA cancer potency factor's equivalent 39. Mercury: Based on information submitted by the Discharger,the discharge contains mercury. receiving water concentration at a reasonable distance from the outfall(e.g.,before reaching the The Delta waterways are listed in accordance with Clean Water Act Section 303(d)as impaired drinking water intakes). A review of effluent data collected from January 2002 through for mercury based on bioaccumulation of this pollutant in fish tissue. The CTR contains criteria December 2002 showed total THMs with a maximum concentration of 17 ug/1 and an average for mercury. The CTR criteria,however,do not address bioaccumulation in the river. The concentration of 10 ug/l. Chloroform data collected over the same period showed a maximum WQCF effluent contains detectable levels of mercury below CTR priority pollutant criteria. concentration of 12 ug/1 and an average concentration of 8 ug/l. Data is not available regarding Since the CTR criteria are not based on bioaccumulation,the discharge was evaluated based on the constituent concentrations in the receiving water. Considering the available dilution based the Basin Plan's narrative toxicity objective. Any loading of mercury from the discharge may on the harmonic mean flow of the San Joaquin River,the discharge does not have a reasonable have the reasonable potential to cause or contribute to an excursion above the narrative toxicity potential to cause or contribute to an in-stream excursion above the water quality objective for objective by causing bioaccumulation in fish tissue. Health advisories by the Department of MUN use by causing exceedance of the USEPA primary MCL for total THMs or the chloroform Health Services remain in effect for human consumption offish in the Delta,including the San OEHHA cancer potency factor's equivalent receiving water concentration. Therefore,effluent Joaquin River at Manteca,due to excessive concentrations of mercury in fish flesh. These limitations for total THMs and chloroform are not included in this Order. current warnings and available fish tissue data confirm that there is currently no assimilative capacity for mercury. Therefore,water quality based effluent limitations for mercury that 36. Bromodichloromethane(BDCM)and dibromochloromethane(DBCM): Based on properly address bioaccumulation are required.A TMDL for mercury is scheduled to be information included in analytical laboratory results submitted by the Discharger,the discharge completed by December 2005. For situations like this,the SIP recommends that limiting mass has a reasonable potential to cause or contribute to an in-stream excursion above the CTR loading of the bioaccumulative pollutant should be considered in the interim at representative, criteria for BDCM and DBCM. The CTR includes standards for the protection of human health current levels pending development of the TMDL. A mass load limit for mercury is included in based on a one-in-a-million cancer risk for these organic constituents. The criteria for waters this Order. If the Regional Board determines that a mercury offset program is feasible for from which both water and organisms are consumed are 0.56 ug/1 and 0.41 ug/1 for BDCM and Dischargers subject to a NPDES permit,then this Order may be reopened to reevaluate the DBCM,respectively. The maximum observed effluent concentrations for BDCM and DBCM interim mercury mass loading limitations)and the need for a mercury offset program for this are 3.5 ug/1 and 1.2 ug/l,respectively. Effluent limitations for BDCM and DBCM are included Discharger. in this Order based on the CTR criteria for the protection of human health. The Discharger is able to comply with the limitations. NONPRIORITY POLLUTANTS 37. Trichlorophenol: Based on information included in analytical laboratory results submitted by 40. Temperature: The State Board Water Quality Control Plan for Control of Temperatures in the Discharger,the discharge has a reasonable potential to cause or contribute to an in-stream Coastal and Interstate Waters and Enclosed Bays and Estuaries of California(the Thermal Plan) excursion above the CTR criteria for 2,4,6-trichlorophenol. The CTR includes standards for the is applicable to this discharge. For the purposes of compliance with the Thermal Plan,the protection of human health. The 2,4,6-trichlorophenol criteria for the protection of human health discharger is considered to be an existing discharger of elevated temperature waste. Monitoring based on a one-in-a-million cancer risk for waters from which both water and aquatic organisms by the discharger indicates that the 20°F limitation of Objective 5.A.(1)a of the Thermal Plan is are consumed is 2.1 ug/l. The maximum observed effluent 2,4,6-trichlorophenol concentration is occasionally exceeded in winter months when the receiving water is at its lowest temperatures. 11 ug/l. 2,4,6-trichlorophenol has not been detected in the upstream receiving water. Effluent Modeling conducted by Resource Management Associates(RMA),subject to the model Limitations for 2,4,6-trichlorophenol are included in this Order based on the CTR standard for limitations discussed in the information sheet,indicates that the current and the expanded flows the protection of human health. The Discharger is able to comply with the effluent limitations. with continuous discharge also exceed both the 1 degree and 4 degree requirements of Objectives 5.A.(1)b and 5 A.(1)c of the Thermal Plan. The modeling also demonstrates that a 38. Bis(2-ethylhexyl)phthalate: Based on information included in analytical laboratory results timed discharge,that is,discharging only on the outgoing tide,for the increased flow exceeds submitted by the Discharger,the discharge has a reasonable potential to cause or contribute to an only the 4 degree requirement,not the 1 degree requirement. The Discharger has requested an in-stream excursion above the CTR criteria for bis(2-ethylhexyl)phthalate. The CTR includes a exception to the 4 degree requirement of Objective 5.A.(1)c of the Thermal Plan which requires standard for the protection of human health based on a one-in-a-million cancer risk for that the discharge shall not cause a surface water temperature rise greater than 4°F above the bis(2-ethylhexyl)phthalate of 1.8 ug/l. The maximum observed effluent bis(2-ethylhexyl)- natural temperature of the receiving waters at any time or place and has also requested a one phthalate concentration is 7 ug/l. Bis(2-ethylhexyl)phthalate has not been detected in the month averaging period to meet the 20 degree limit of Objective 5 A.(1)a. The Discharger has upstream receiving water. Effluent Limitations for bis(2-ethylbexyl)phthalate are included in not yet implemented measures necessary to meet conditions for any exception,including this Order based on the CTR criteria for the protection of human health. The Discharger is able installation of an in-stream real-time flow monitor in the vicinity of the outfall or construction of to comply with the effluent limitations, storage basins to provide for effluent discharges on out-going tides. Therefore,effluent and receiving water limitations are included to achieve compliance with the Thermal Plan. This Order requires that the discharger comply with the Thermal Plan and implement the necessary