SITE INFORMATION AND CORRESPONDENCE 1980-1999

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FACT SHEET, ATTACHME* -7- WASTE DISCHARGE REQUIREMENTS ORDER NO. 2000-**** CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY 2 Criteria Continuous Concentration,an estimate of the highest concentration of a material in surface water to which an aquatic community can be exposed indefinitely without resulting in an unacceptable effect. 3 Criteria Maximum Concentration,an estimate of the highest concentration of material in surface water to which an aquatic community can be exposed briefly without resulting in an unacceptable effect. 4 Assuming hardness of 110 mgA. 5 Expressed as dissolved metal. 6 Expressed as total recoverable metal. Cyanide: Cyanide is found in industrial effluents associated with steel, petroleum, plastics, synthetic fibers, metal plating, mining and chemical industries. The Basin Plan water quality objective for cyanide is a maximum concentration of 10 µg/1. EPA's ambient water quality criteria for protection of aquatic life are a continuous concentration of 5.2 µg/1 (30-day average, chronic criteria), and a maximum concentration of 22 µg/1 (expressed as a 1-hour average, acute criteria). Effluent sampling results show cyanide concentrations have exceeded the EPA acute and chronic criteria, as well as the Basin Plan objective. The detection level for the analyses exceeded the criteria during 1997. Effluent limitations for cyanide have been included in this Order based on the Basin Plan objective and the chronic criteria, with no mixing zone designated. The Discharger is not currently capable of meeting this limit. Lead: EPA's ambient water quality criteria for protection of aquatic life are a continuous concentration of 2.8 µg/1 (30-day average, chronic criteria), and a maximum concentration of 72 µg/1 (expressed as a 1-hour average, acute criteria),based on a water hardness of 110 mg/1. These criteria were originally developed using metals concentrations expressed as total recoverable metals. Whereas the dissolved fraction of metals more closely approximates the biologically available fraction, conversion factors were used to predict how different the criteria would be if they had been based on measurement of the dissolved concentrations in all of the toxicity tests. These Conversion Factors (CF) from total recoverable to dissolved, have the effect of reducing the water quality criteria concentrations. For lead, the conversion factor for both the acute and chronic criteria is hardness dependent, and is expressed as: CF=1.46203-[ln(hardness)(0.145712)]. For a hardness of 110 mg/l, the CF=0.777. 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 which established the criteria. Therefore, the water quality criteria, expressed as dissolved metal, has been divided by the conversion factor for purposes of comparing with analytical results (for total recoverable metals) and for establishing an effluent limitation. Effluent monitoring for lead has shown the median concentration to be 1.5 µg/1, and the highest measured to be 10 µg/1. Sampling results have shown that the total recoverable concentration of lead in the effluent has exceeded the converted chronic criteria for protection of aquatic life in 3 of 18 samples. Effluent limitations for lead have been included in this Order based on the converted chronic criteria. Mercury: Effluent monitoring for mercury has shown the median concentration to be non-detectable at <0.2 µ.g11, and the highest measured to be 0.63 µg/1. The accuracy of the analyses is questionable without implementing"clean technique" (EPA Method 163 1) for sample collection, handling, and analyses. The current EPA Ambient Water Quality Criteria for continuous concentration of mercury