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a November 17, 1987 AGS Job No. 87048-2 Page 2 iced storage for transport to the laboratory. A Chain of Custody Record was initiated by the sampler and accompanied the samples to the analytical laboratory. Copies of the Chain of Custody Record and the laboratory Record of Analysis are attached. The results of the recent analyses are summarized in Table 1. They indicate that ground water sampled from monitoring wells MW-1 and MW-4 are within maximum concentration levels, commonly termed "action levels, " for drinking water recommended by the California Department of Health Services. Ground water sampled from MW-2 contained 0.438 parts per million (ppm) of benzene which is significantly above the action level, and the sample from MW-3 showed 0.0010 ppm of benzene, which is slightly above the state action level for that compound. The distribution of contaminants suggests that the source of contamination is surface water directed toward the two "dry wells" located at the southeast margin of the site (Generalized Site Plan, Plate P-2) . Relatively clean water from MW-1, MW-3 , and MW-4 implies that the product storage tanks are not a source of ground-water contamination. It is our understanding that Sharbob has destroyed or intends to destroy the dry wells. We recommend that quarterly monitoring of the ground-water wells be continued for at least two more sampling intervals to generate a full year of data for the subject site and obtain information on the levels of benzene contamination after the two dry wells are destroyed. Further recommendations will be provided after the year-long monitoring program has been completed. Copies of this letter and Applied GeoSystems Report No. 87048-1, which was previously submitted, should be forwarded to Laurie Cotulla of the San Joaquin Local Health District, P. O. Box 2009, Stockton, California 95201 and to Gordon Boggs of the California Regional Water Quality Control Board, Central Valley Region, 3443 Routier Road, Sacramento, California 95807-3018. , 0,01ied GeoSystems