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INFORMATION SHEET • • 17 <br /> WASTE DISCHARGE REQUIRMENTS ORDER NO.R5-2002-0213 <br /> U.S.DEPARTMENT OF DEFENSE <br /> DEFENSE LOGISTICS AGENCY <br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN <br /> SHARPE GROUNDWATER REMEDIATION SYSTEM <br /> SAN JOAQUIN COUNTY <br /> additional loading resulting from the discharge from the DDJC-Sharpe facility has the potential to <br /> cause or contribute to the impairment resulting from mercury bioaccumulation in the Delta. A <br /> TMDL for mercury is currently scheduled to be completed by December 2005. <br /> At Section 2.1.1 the SIP states: "For bioaccumulative priority pollutants for which the receiving <br /> water has been included on the CWA Section 303(d) list, the RWQCB should consider whether the <br /> mass loading of the bioaccumulative pollutant(s) should be limited to representative, current levels <br /> pending TMDL development in order to implement the applicable water quality standard'. Since <br /> mercury is a bioaccumulative pollutant included on the CWA 303(d) list for the Delta, the intent of <br /> this Order is to include an interim performance based effluent limitation for mercury. <br /> Results of limited `ultra-clean' sampling and analysis conducted by the Discharger using EPA <br /> Method SW 1631 indicate GWTP effluent mercury concentrations ranged from< 0.0005 µg/L <br /> (ppb) to 0.011 gg/L(ppb). These concentrations do not exceed the CTR human health criteria. <br /> Current mercury data are not sufficient for establishment of an interim performance based <br /> limitation. This Order requires the Discharger to collect data necessary to establish an interim <br /> performance based effluent mass limitation. <br /> Performance-based effluent limits for mercury are typically established as follows: 1) The average <br /> monthly effluent mercury concentration is calculated by adding all detected concentrations and <br /> one-half of the reported detection levels of all non-detectable mercury concentration results; 2) <br /> From the average monthly mercury concentration and average monthly flow, a monthly mercury <br /> mass discharge is calculated; and 3)A total mass for all months is then totaled, and an average <br /> annual mass discharge is calculated. <br /> Following the establishment of the interim limit,the mass of mercury discharged shall not-exceed <br /> the interim mercury mass limit twelve months on a running average. In calculating for <br /> compliance, the Discharger shall count all non-detect measures at one-half of the detection level <br /> and apply the monthly average flow from the sampled discharge. If compliance with the effluent <br /> limit is not attained due to the non-detect contribution,the Discharger will be directed to improve <br /> and implement available analytical capabilities and compliance will be evaluated with <br /> consideration of the detection limits. For each calendar month, the Discharger shall calculate <br /> twelve-month mass loadings. For monthly measures,monthly loadings shall be calculated using <br /> the average monthly flow and the average of all mercury analyses conducted that month. The <br /> Discharger shall submit a cumulative total of mass loadings for the previous twelve months with <br /> each self-monitoring report. Compliance will be determined based on the previous 12-month <br /> moving averages over the previous twelve months of monitoring. <br /> Until sufficient data are collected to establish a performance based interim effluent mass <br /> limitation, this Order shall include a preliminary mercury mass limitation(annual limitation)using <br /> the concentration and average flow limitations of the previous Order(0.000012 mg/L (ppm)x 8.34 <br />