SITE INFORMATION AND CORRESPONDENCE_1993-2003

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INFORMATION SHEET • • 19 WASTE DISCHARGE REQUIRMENTS ORDER NO. R5-2002-0213 U.S. DEPARTMENT OF DEFENSE DEFENSE LOGISTICS AGENCY DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN SHARPE GROUNDWATER REMEDIATION SYSTEM SAN JOAQUIN COUNTY Trace metal objectives in this table are dissolved concentrations. 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. Toxicity At p.III-9.00 the Basin Plan provides that relative to toxicity : "All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human,plant, animal, or aquatic life." At page 1, the USEPA's Technical Support Document for Water Quality- based Toxics Control (TSD)provides that"Where States have not developed chemical specific numeric criteria, States may interpret their narrative standards for specific chemicals by using EPA criteria updated with current quantitative risk values." The TSD further states on page 1 "The integrated approach must include the control of toxics through implementation of the "no toxics"criterion and/or numeric criteria for the parameter of toxicity, the control of individual pollutants for which specific chemical water quality criteria exist in a state's standard, as well as the use of biological criteria. Reliance solely on the chemical specific numeric criteria or the narrative criterion or biological criteria would result in only a partially effective State toxics control program." Under the CWA Section 304(a), EPA has developed methodologies and specific criteria guidance to protect aquatic life and human health. These methodologies are intended to provide protection for all surface waters on a national basis. The methodologies have been subject to public review, as have the individual criteria guidance documents. Water quality criteria developed under Section 304(a) of the CWA are based solely on data and scientific judgments on the relationship between pollutant concentrations and environmental and human health effects. Section 304(a) criteria do not reflect consideration of economic impacts or the technological feasibility of meeting the chemical concentrations in ambient water. Section 304(a) criteria provide guidance to States in adopting water quality standards that ultimately provide a basis for controlling discharges or releases of pollutants. USEPA's ambient water quality criteria have been used as a means of supplementing the integrated approach to toxics control, and in some cases deriving numeric limitations to protect receiving waters from toxicity as required in the Basin Plan's narrative standard prohibiting the discharge of toxic constituents in toxic amounts. 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 (micrograms per Liter), 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 SKID Canal and French Camp Slough. Results of receiving water monitoring in the SKID Canal from 7 July 1998 through 11 October 2001 indicate aluminum concentrations ranged from less than 200 µg/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