SITE INFORMATION AND CORRESPONDENCE_1993-2003

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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0213 • 16 U.S. DEPARTMENT OF DEFENSE DEFENSE LOGISTICS AGENCY DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN SHARPE GROUNDWATER REMEDIATION SYSTEM SAN JOAQUIN COUNTY 26. Specific water quality objectives which apply to surface waters in the Sacramento and San Joaquin River Basins,including the Delta, are provided in Chapter III of the Basin Plan. This Order requires the collection of additional effluent and receiving water data necessary to assess the impact of the discharge on these dissolved trace metal water quality objectives of the Delta. 27. Regarding toxicity,previous studies of chlorpyrifos conducted by Regional Board staff in French Camp Slough have found chlorpyrifos concentrations as high as 0.520 gg/L (ppb), which is nearly 10 times the 96-hour Ceriodaphnia LC50 (median lethal concentration). Additionally, results of receiving water monitoring conducted by the discharger have identified significant concentrations of aluminum in the SSJID Canal and French Camp Slough. Results of receiving water monitoring in the SSJID Canal from 7 July 1998 through 11 October 2001 indicate aluminum concentrations ranged from less than 200 gg/L (ppb) to 1.3 mg/L (ppm) (4/4/2000). Results of receiving water monitoring in French Camp Slough from 7 July 1998 through 10 July 2001 indicate aluminum concentrations ranged from 3.5 mg/L (ppm) (7/7/1998) to 6.2 mg/L (ppm) (7/13/1999). Results of monitoring conducted by the Discharger indicate concentrations of aluminum in the final effluent are less than 200 gg/L(ppb). The Basin Plan does not provide a numeric water quality objective for aluminum. However,the USEPA has recommended, as freshwater 6bient water quality criteria for aluminum, a CCC of 87 gg/L (ppb) and a CMC of 750 gg/L(ppb) expressed in terms of total recoverable metal in the water column. Given that toxic conditions have been identified in French Camp Slough, and concentrations of aluminum exceeding USEPA recommended criteria have routinely been identified in French Camp Slough and the SSJID Canal, this Order requires acute toxicity monitoring of the effluent and chronic toxicity monitoring of the effluent and receiving water to ensure the discharge is not contributing additional toxicity to the receiving waters. This Order also requires the Discharger to collect additional effluent data for aluminum of sufficient quality for comparison with appropriate water quality criteria. This Order may be re-opened if data indicate the effluent is contributing toxicity, or if concentrations of aluminum are or may be discharged at a level which will cause or have the reasonable potential to cause or contribute to an in-stream excursion above the USEPA aquatic life ambient water quality criteria. 28. The pesticide Bromacil has been detected in the effluent of the three GWTPs at maximum concentrations of 5.2 gg/L (ppb) (North Balloon GWTP, 8/4/1998), 4.1 gg/L(ppb) (Central Area GWTP, 8/7/2001), and 7.6 gg/L (ppb) (South Balloon GWTP, 8/8/2000). No MCL has been established for Bromacil. The USEPA has published a drinking water health advisory, or Suggested No-Adverse Response Level (SNARL) of 90 gg/L (ppb). The Basin Plan does include an objective for Pesticides, stating in part: "Pesticide concentrations shall not exceed the lowest levels technically and economically achievable". This Order requires the Discharger to evaluate concentrations of Bromacil in the effluent and provide information on the lowest effluent levels which may be technically and economically achievable. This Order requires continued effluent and receiving water monitoring for Bromacil.