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INFORMATION SHEET -2- <br /> DEFENSE DISTRIBUTION REGION WEST TRACY <br /> INTERIM GROUND WATER CLEANUP SYSTEM <br /> SAN JOAQUIN COUNTY <br /> The Order also requires the Discharger to conduct a waste characterization study <br /> of the extracted ground water during the first three months of the full scale <br /> operation of the IRM system. The objective of the waste characterization is to <br /> determine if the influent to the air stripper contains previously unidentified <br /> constituents of sufficient magnitude to either pose a threat to water quality <br /> and/or affect the treatment effectiveness of the air stripper. If pollutants <br /> that are not treatable by the air stripper system are identified at levels <br /> threatening water quality objectives of the aquifer, then this discharge permit <br /> may be revised. <br /> The objective of the performance evaluation is to determine the ability, <br /> reliability, and associated 0&M costs of the air stripper system in meeting <br /> (1) the 1.0 ppb TCE and PCE effluent limitations in this Order, and (2) the <br /> nondetectable levels of TCE and PCE of 0. 12 and 0.03 respectively (per EPA Test <br /> Method 8010) . Staff has conferred with the Department of Health Services and <br /> determined that the 1 .0 ppb effluent limitation for both TCE and PCE are <br /> sufficiently protective of the potential beneficial uses of the recharged <br /> aquifer. However, in keeping with the Board's policy regarding the high quality <br /> of waters (State Water Resources Control Board Resolution No. 68-16 - Statement <br /> of Policy with Respect To Maintaining High Quality Of Waters In California) <br /> staff, through this performance evaluation, will be determining the best <br /> practicable treatment levels. If levels less than the 1.0 ppb effluent limits <br /> are determined to be practicably achievable with the proposed air stripper <br /> system, then Discharge Specification C.4. (v) will apply and require the <br /> Discharger to operate this system to meet levels less than the prescribed <br /> effluent limitations, in order to maintain the high quality water of the <br /> receiving aquifer. <br /> In addition, this Order also places DDRW upon a time schedule to develop and <br /> conduct a quarterly sampling and analyses of the RI/FS monitoring wells at the <br /> Depot. <br /> This permit is for an interim system only. The final long-term ground water <br /> remedial system will require a new or revised permit. Effluent limitations for <br /> the long-term discharge permit will be reevaluated based upon the performance <br /> capabilities of the interim system. <br /> JJT:jt <br />