SITE INFORMATION AND CORRESPONDENCE 1980-1999

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FACT SHEET, ATTACHMEP C WASTE DISCHARGE REQUIREMENTS ORDER NO. 5-00- CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY limitation, if it is determined to be necessary, and allows the Board to reopen the permit to add effluent limits for mercury. In the interim, the Discharger is required to develop a program for identification and control of mercury discharges within the collection system. Zinc: The Basin Plan's numerical water quality objective for dissolved zinc is a maximum concentration of 100 gg/1, which is equivalent to a total recoverable concentration of 101 µg/1. EPA's ambient water quality criteria for protection of freshwater aquatic life are a continuous concentration of 110 gg/l (4-day average, chronic criteria), and a maximum concentration of 120 gg/l (expressed as a 1-hour average, acute criteria), using a water hardness of 110 mg/1. These criteria were.originally developed using metals concentrations expressed as total recoverable metals, but have been converted to be expressed as dissolved metals. For zinc, the acute CF=0.978 and the chronic CF=0.986. 40CFR 122.45(c) requires that permit limits be expressed as total recoverable metal. A reasonable assumption is that the metal concentration in the receiving water is biologically available to the same extent as during the toxicity testing. Therefore, the water quality criteria, expressed as dissolved metal, has been divided by the conversion factor, and presented in the table, above, for the purpose of comparing the measured effluent concentrations with the criteria. Sampling results shown that effluent concentrations of zinc have exceeded the converted acute and chronic criteria, and also the Basin Plan water quality objective if converted to a total recoverable metal concentration. The Basin Plan objective is the most stringent. An effluent limitation for zinc has been included in this Order based on the Basin Plan objective, with no mixing zone designated. The Discharger is not currently capable of meeting this limit. Bis(2-ethylhexyl) phthalate (DEHP): DEHP has a low solubility in water. It is commonly found in plastic products and containers, hospital and laundry discharges, and can also be found in adhesives, paper, pesticides, and flexible plastic pipes. The National Toxics Rule receiving water limitation for DEHP is 1.8 gg/l (30-day average, chronic criteria) for surface waters where the designated beneficial use is drinking water, and 5.9 gg/1 (30-day average, chronic criteria) where drinking water is not a designated beneficial use. The California Department of Health Services Maximum Contaminant Level for DEHP is 4 gg/1. Effluent sampling results showed that DEHP has been detected in the effluent at significant concentrations above the limitations two times since the previous permit renewal, but not in the last four years. No effluent limitation for DEHP has been included in this Order. However, the Discharger is required to monitor for DEHP. i) Pesticides and Unknown Toxicity The Sacramento-San Joaquin Delta has been listed as an impaired water body pursuant to Section 303(d) of the Clean Water Act because of: (1) diazinon and chlorpyrifos (organophoshate pesticides), (2) aldrin, dieldrin, chlordane, endrin,heptachlor, heptachlor epoxide, hexachlorocyclohexane (including lindane), endosulfan and toxaphene (chlorinated hydrocarbon pesticides), (3) DDT, and (4) unknown toxicity. The Basin Plan requires that; no individual pesticides shall be present in concentrations that adversely affect beneficial uses; discharges shall not result in pesticide concentrations in bottom sediments or aquatic life that adversely affects beneficial uses; total chlorinated hydrocarbon pesticide concentrations shall not be present in the