SITE INFORMATION AND CORRESPONDENCE_1993-2003

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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0213 14 U.S.DEPARTMENT OF DEFENSE DEFENSE LOGISTICS AGENCY DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN SHARPE GROUNDWATER REMEDIATION SYSTEM SAN JOAQUIN COUNTY appropriate criteria. This Order retains the weekly average effluent limitation for total lead of 3.2 µg/L (ppb) from the previous Order as an interim limitation pending collection of new data. 24. Previous Order No. 95-258 included a monthly median effluent concentration limitation for mercury of 0.012 gg/L (ppb). The Basin Plan does not provide a numeric water quality objective for mercury. The current USEPA water quality criteria for mercury, for protection of human health for consumption of both water and organisms, is 0.050 µg/1. The USEPA is currently reviewing the ambient water quality criteria for mercury and may recommend more stringent criteria,based in part on organism uptake and bioaccumulation. The Delta has been listed as an impaired water body pursuant to Section 303(d) of the Clean Water Act for mercury, based on fish tissue concentration and not water column toxicity. The California DHS has issued health warnings regarding the consumption of fish from Delta waterways. While the SSJID Canal and French Camp Slough are not identified as impaired for mercury on the California 303(d) list, additional loading resulting from the discharge from the DDJC-Sharpe facility has the potential to cause or contribute to the impairment resulting from mercury bioaccumulation in the Delta. A TMDL for mercury is currently scheduled to be completed by December 2005. At Section 2.1.1 the SIP states: "For bioaccumulative priority pollutants for which the receiving water has been included on the CWA Section 303(d) list, the RWQCB should consider whether the mass loading of the bioaccumulative pollutant(s) should be limited to representative, current levels pending TMDL development in order to implement the applicable water quality standard'. Since mercury is known to bioaccumulate in fish and is a pollutant that is causing impairment of the Sacramento-San Joaquin Delta, the discharge must not cause or contribute to increased mercury levels in fish tissue to meet the requirements of the anti-degradation policy described in SWRCB Resolution No. 68-16 and the anti-degradation provision in 40 CFR 131.12 a 1 . The intent of this Order is to include an interim performance based effluent mass limitation for mercury. Results of limited `ultra-clean' sampling and analysis conducted by the Discharger using EPA Method SW 1631 indicate GWTP effluent mercury concentrations ranged from < 0.0005 µg/L (ppb)to 0.011 µg/L(ppb). These concentrations do not exceed the CTR human health criteria. Current mercury data is not sufficient for establishment of an interim performance based limitation. This Order requires the Discharger to collect data necessary to establish an interim performance based effluent mass limitation. Performance-based effluent limits for mercury are typically established as follows: 1) The average monthly effluent mercury concentration is calculated by adding all detected . concentrations and one-half of the reported detection levels of all non-detectable mercury concentration results; 2) From the average monthly mercury concentration and average monthly flow, a monthly mercury mass discharge is calculated; and 3) A total mass for all months is then totaled, and an average annual mass discharge is calculated.