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r. n <br /> STATE OF CALIFORNIA , GEORGE DEUKMEJIAN,Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— v � <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTIER ROAD <br /> SACRAMENTO.CA 95827-3098 <br /> '7 <br /> 21 December 1987 CERTIFIED MAIL <br /> #.' .t��� '. 1 , N0. P111 907 449 <br /> RkfiC <br /> Mr. Dave Lei•ns <br /> Southland Corporation <br /> P.0. Box 404 <br /> Pleasanton, CA 94566-0040 <br /> 7-11 GROUND WATER CONTAMINATION AT 9110 THORNTON ROAD. .STOCKTON <br /> We have reviewed your November 1987 Project Update Report for this site <br /> and discussed the apparent analytical discrepancies in the local wells with <br /> Laurie Cotulla of the San Joaquin Local Health District. Groundwater <br /> Technology, Inc. (GTI), your consultant, has provided data that show <br /> some xylene in off-site wells, requiring that the property owners be <br /> placed on bottled water. Now GTI says that sampling and/or laboratory <br /> errors were made which mean that the well users can be taken off <br /> bottled water. However, GTI has not resampled the wells to substantiate <br /> their claim. <br /> In addition your report shows that free product has been found consis- <br /> tently in MW-1 ( maximum 1.8 feet on 18 September 1987) and that some <br /> wells have gone dry. Our concerns are that free product is not being <br /> removed properly and that the wells have not been constructed to <br /> accomodate local fluctuating ground water levels. According to State <br /> regulations, in this case, the well screens should be 5 feet above and 20 <br /> feet below the highest and lowest anticipated ground water levels, respec- <br /> tively- or, at a minimum, 15 feet below the bottom of the tank (Section <br /> 2647 (c) (d), and (g) of the California Underground Tank Regulations). <br /> We also are concerned about the time needed to stabilize your site. . We <br /> agreed with your interim remediation plan to provide bottled water to <br /> ground water users while establishing the extraction-hydrocarbon <br /> stripping system. However, at this time, it appears that the system has <br /> been inadequate to contain the plume and the remediation has been of <br /> limited success. <br /> Therefore, we believe that Southland Corporation should consider- the <br /> following: <br /> All wells on and off-site be resampled on the same day for <br /> the constituents of concern. Proper QA/QC protocal for both <br /> field sampling and laboratory analyses are to be used. <br />