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INFORMATION SHEET <br /> • is <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 /> Study must still be completed to ensure the protection of French Camp Slough. Upon completion <br /> of the Study, this Order may be reopened and alternative final effluent limitations considered. If <br /> this Study is not completed, this Order includes a final monthly average effluent limitation for <br /> arsenic of 10 Rg/L (ppb) consistent with the new USEPA primary MCL and effective 23 January <br /> 2006 <br /> This Order retains the 40 Rg/L (ppb) monthly median effluent limitation and daily maximum <br /> effluent limitation of 50 Rg/L(ppb) for arsenic from the previous Order as interim limitations until <br /> the study required by this Order is completed. Previous Order No. 95-258 included a receiving <br /> water limitation for arsenic of 10 Rg/L(ppb) in French Camp Slough based upon the water quality <br /> objectives for trace elements in the Delta, as provided in Table III-1 of the Basin Plan. Footnote a <br /> of Table III-1 provides in part that "Metal objectives in this table are dissolved concentrations." <br /> Since domestic and municipal supply is a beneficial use of French Camp Slough, this Order <br /> includes a 10 Rg/L(ppb) receiving water limitation and monitoring requirement for total <br /> recoverable arsenic in French Camp Slough for protection of the municipal and domestic supply <br /> beneficial use of French Camp Slough. <br /> Hexavalent Chromium <br /> Previous Order No. 95-258 included a monthly median effluent limitation for hexavalent <br /> chromium of 11 Rg/L (ppb). The basis for this limitation as described in the Order was that the <br /> limitation was consistent with other NPDES permits issued in the area, and was technically <br /> achievable. The air stripping GWTPs utilized by the Discharger are not designed for removal of <br /> hexavalent chromium. As summarized in Attachment C,results of effluent monitoring of the three <br /> GWTPs indicates the maximum effluent concentration's (MECs) of hexavalent chromium in the <br /> final effluent were less than 10 Rg/L(ppb). The data indicate final effluent does not have the <br /> reasonable potential to exceed the minimum CTR/NTR aquatic life CCC water quality criterion for <br /> hexavalent chromium of 11 Rg/L(ppb). Effluent data summarized in Attachment C represents <br /> new information which was not available at the time of adoption of previous Order 95-258. <br /> Considering these facts,the monthly median effluent limitation for hexavalent chromium from <br /> previous Order No. 95-258 has been removed from this Order(new information). This Order does <br /> require continued effluent and receiving water monitoring for hexavalent chromium, and may be <br /> re-opened if hexavalent chromium is or may be discharged at a level that will cause or have the <br /> reasonable potential to cause or contribute to an in-stream excursion above the CTR/NTR criteria. <br /> Lead <br /> Previous Order No. 95-258 included a weekly average effluent limitation for total lead of 3.2 Rg/L <br /> (ppb). Previous Order No. 95-258 indicates this limitation was based upon a receiving water <br /> hardness of 100 mg/L(ppm) as CaCO3,however the final effluent limitation does not account for <br /> changes in the hardness of the receiving water. As noted previously, hardness levels of the SKID <br /> Canal have been reported as low as 28 mg/ (ppm) as CaCO3. As shown in Attachment C, results <br /> of effluent monitoring of the three GWTPs indicates the MECs of total lead in the final effluent <br />