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i <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> PpUIN SAN JOAQUIN COUNTY <br /> �o.•_�.coG Unit Supervisors <br /> Donna K.Heran,R.E.H.S. <br /> ". ..Z� 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. <br /> Director <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins, S.,R.D.I. <br /> - Douglas W.Wilson, <br /> R.E.H.S. <br /> Cq`'FORa�P Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> APR 2 9 2002 <br /> STEPHEN VALENTINE <br /> STEVE & GENES SERVICE <br /> 6232 HEMET AVE <br /> STOCKTON CA 95207 <br /> RE: STEVE& GENES SERVICES SITE CODE: 2080 <br /> 2315 N ELDORADO ST <br /> STOCKTON CA 95204 <br /> San Joaquin County Environmental Health Department (EHD) has reviewed Additional Site <br /> Characterization (the report) dated November 30,2001 and 4'6 Quarter 2001 Groundwater <br /> Monitoring Deport dated March 15,2002 prepared by Geological Technics, Inc. (GTI). The <br /> newly installed deep monitoring well #201 (MW-201) is screened at 148 feet below surface <br /> grade (bsg) to 150.5 feet bsg. Analytical results of the first quarterly groundwater sample <br /> from MW-201 were 13.8 micrograms per liter (µg/1) benzene and 1,140 µg/l total petroleum <br /> hydrocarbons as gasoline (IPH-g). Analytical results of the next deepest monitoring well, <br /> MW-101, screened at approximately 92 feet bsg to 97 feet bsg,were 1.9 µg/l benzene and <br /> 139 µg/l TPH-g. <br /> The extent of the vertical contamination in groundwater has not been defined. EHD agrees <br /> with GTI that cross-contamination may have occurred in MW-201 and contributed to the <br /> contamination detected in the groundwater samples. EHD recommends an extended round <br /> of re-development of both GT-101 and GT-201 to remove potentially contaminated silt <br /> from the casings and the filter packs to reduce the potential for cross-contamination in <br /> future quarterly samplings. In a telephone conversation on April 18,2002, GTI agreed to <br /> perform this task before or during the upcoming second quarterly monitoring event of 2002. <br /> EHD requests that the investigation of both the vertical and horizontal extent of the <br /> contamination be combined under the same scope of work in order to minimize the <br /> number of mobilizations. EHD requests submission of a workplan that would assess the <br /> vertical extent of the groundwater contamination first,and based on these results, establish <br /> the minimum required depth for the borings or wells for the lateral investigation. Submit <br /> the workplan to EHD by July 1,2002. <br /> Please include a site conceptual model with geological cross-sections and a discussion of <br /> how the proposed work will test and refine the model. Sufficient soil data should be <br /> obtained to put GT-201 in a site conceptual model context. EHD would also like to have <br /> an analysis and discussion in the next quarterly report on the apparent concentration <br /> switches between MW-4 and MW-5 between 12/97 and 9/99; could this be an effect of <br />