SITE INFORMATION AND CORRESPONDENCE

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STATE OF CALIFORNIA PETE WILSON, Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— CENTRAL VALLEY REGION 3443 ROUTIER ROAD, SUITE A SACRAMENTO, CA 95827-3098 ��"'aw^`.� PHONE: (916) 361-5600 FAX: (916) 361-5688 "4 'd3M k 15 R.re Fg� ,,yiz Fqi la'�.i �i' NxYn SEP 3 29 August 1991 ENVIRONMENTAL HEALTH PERMIT/SERVICES Mr. Abel Haines Director, Environmental Protection Office Defense Distribution Region West, Tracy Tracy, CA 95367-5000 PROVE-OUT PHASE REPORTS FOR THE INTERIM REMEDIAL MEASURE, DEFENSE DISTRIBUTION REGION WEST (DDRW) , TRACY, SAN JOAQUIN COUNTY We have reviewed the reports for the Prove-Out Phase of the Interim Remedial Measure (IRM) submitted on 10 July 1991 for DDRW, Tracy. The reports were required by Waste Discharge Requirements (WDRs) Order No. 90-275 and were prepared by Ensotech, Inc. for the Corps of Engineers. Our detailed comments and concerns can be found in the enclosed memorandum. Our review of the Prove-Out Phase Reports indicated that the Potable Water Start- Up and the Prove-Out Phases were performed in accordance with the WDRs. Therefore, we approve of the start-up of the IRM for the Full-Scale Operations. However, we are concerned that there appears to be a lack of an exchange of technical information between the contractors for the IRM and the Remedial Investigation/Feasibility Study (RI/FS) . An exchange and integration of technical data between the contractors needs to be implemented by Tracy so that the final ground water remedial design will be based on all of the available information at the site. We are concerned that the performance of one of the injection wells, IW-2, was significantly less than that of the other two injection wells. An evaluation of this well is necessary to avoid similar problems with future injection wells and to optimize the final ground water remedial design. Our review also revealed that there was insufficient rationale presented in the reports for the placement and design criteria of the extraction and injection wells and that the hydrogeologic cross-sections are inadequate for future reference. Therefore, we request that Tracy submit a report to the regulatory agencies which responds to our comments on the Prove-Out Phase Reports and which includes an evaluation of the poor performance of injection well IW-2. We suggest that Tracy provide this information in the Technical Report required under Provision D. 5.