SITE INFORMATION AND CORRESPONDENCE_1988-1991

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MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION Phone: (916) 361-5600 3443 Routier Road, Suite A ATSS Phone: 8-495-5600 Sacramento, CA 95827-3098 TO: Antonia K. J. Vorster FROM: Camilla Williams Senior WRC Engineer Engineering Geologist MAR 2 7 9"1y�w.'4&'wo DATE: 8 March 1991 ENVIRONMEI� AL H.CALS NATURE: PERIVIIT/SERVICES SUBJECT: REMEDIAL INVESTIGATION REPORT, DEFENSE DISTRIBUTION REGION WEST (DDRW), SHARPE SITE, SAN JOAQUIN COUNTY I have reviewed the Draft Final Remedial Investigation Report for the Defense Distribution Region West, Sharpe site. My review revealed that although the collection of data is adequate, the data analysis needs to be improved and many of the conclusions and recommendations are questionable. Of the most concern is that basic hydrogeologic principles have not been applied, some of the hydrogeologic data has been misinterpreted and frequently the presentations are constructed with so many flaws that the conceptual model of the site may not be accurate. Specifically, my review revealed that the basic elements of the hydrogeologic analysis, such as the cross-sections, ground water level contour maps and water quality typing, were performed inaccurately or not at all , so that conclusions drawn from the data are in question. Because the capture zone analysis is dependent on the conceptual model of the site and because Sharpe has not been able to demonstrate complete plume capture, it is important that the basic elements of the hydrogeologic analysis are revisited and revised, if necessary. My review of the Report resulted in so many questions that I recommend a meeting be held to discuss specific technical issues. I have listed my responses to each of the findings listed in Chapter 9 of the Report. I have also enclosed a preliminary summary of the basic problems with the hydrogeologic analysis and presentations (refer to the Enclosure) . The Enclosure also provides recommendations for work products which could be generated to verify whether or not the current conceptual model is accurate. I have also responded to each of the recommendations found in Chapter 10 of the Report. Of particular concern, is that there were no recommendations for the installation of additional monitor wells. It appears that additional monitor wells will need to be installed to define the lateral and vertical extent (especially in the D zone) of contamination. The lateral and vertical extent of the plumes may continue to be defined during the feasibility study. The problem with inaccurate and incomplete hydrogeologic analysis is a long standing problem at this site. Our correspondence dating back to 1988 indicates that ample amounts of data had been collected for the hydrogeologic analysis but repeatedly required that the appropriate data interpretation and presentations be made. However, the interpretations and presentations of the hydrogeologic data historically have been inadequate. To finalize the remedial investigation with these deficiencies in the hydrogeologic analysis would ultimately have detrimental effects on the ground water cleanup. It is imperative that the analysis of the remedial investigation data be accurate and complete enough so that cleanup, in turn, will be effective.