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S TATE OF CALIFORNIA • PETE WILSON, Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION <br /> ! R <br /> 3443 ROUTIER ROAD, SUITE A §F <br /> SACRAMENTO, CA 95827-3098 <br /> PHONE: (916) 361-5600 <br /> FAX: (916) 361-5686 <br /> 24 January 1992 �w <br /> b <br /> Mr. Abel Haines JAN 3 1 1992 <br /> Chief, Environmental Protection Office ENVIRONMENTAL HEALTH <br /> Bldg. , S-4, Sharpe Location PERM IT/SERV,CES <br /> Defense Distribution Region West <br /> P. 0. Box 960001 <br /> Stockton, CA 95296-0250 <br /> THIRD QUARTER 1991 GROUND WATER MONITORING REPORT, DEFENSE DISTRIBUTION REGION <br /> WEST (DDRW), SHARPE SITE, SAN JOAQUIN COUNTY <br /> We have reviewed the Third Quarter 1991 Ground Water Monitoring Report for the <br /> DDRW, Sharpe Site (Sharpe) submitted on 3 January 1992. This Report consisted <br /> of maps of the A, B and C Zones which depicted ground water level elevations and <br /> the extent of the volatile organic constituent (VOC) plumes. <br /> The maps of the third quarter 1991 confirm that the VOC ground water <br /> contamination has migrated laterally and vertically further into the aquifer than <br /> in previous years. Therefore, the extent of the plumes are undefined with the <br /> existing monitoring network. Of particular concern, is the presence of VOCs in <br /> samples from MW-504 and MW-509 clusters. Because of the high VOC concentrations <br /> in this off-site area, we concur with your plan to submit a Work Plan for the <br /> installation of additional monitor wells (refer to your letter dated 23 September <br /> 1991) . The submittal must include plans to revise the ground water monitoring <br /> program. <br /> We anticipated that the Third Quarterly Report would show similar plume <br /> configurations as the Second Quarterly Report because agricultural pumpage should <br /> have continued during the third quarter. However, the Third Quarter 1991 <br /> Monitoring Report does not depict all of the VOC plumes to be as extensive as the <br /> previous quarter. Explanations for the differences between quarterly reports <br /> were not provided. <br /> Because these maps were the first to be produced by the Sharpe Environmental <br /> Protection Office, it is unknown whether the data bases and/or the methods of <br /> data interpretation and presentation are the same as previous quarters. We <br /> question whether the ground water elevations were manually collected during the <br /> quarter, or whether the ground water elevations were collected using the <br /> automated ground water elevation measuring system. We also found that specific <br /> wells were not sampled (such as the MW-518 cluster) during the third quarter. <br /> In addition, the VOC concentrations listed on the maps and the concentrations <br /> listed in the Quarterly Progress Report (submitted on 4 November 1991) are not <br />