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FF 1'0 <br /> . GROUND ZERO ANALYSIS, INC. <br /> 1714 Main Street <br /> Escalon,California 95320-1927 `� Pti 12. Sri <br /> Telephone: (209)838-9888 <br /> Facsimile: (209)838-9883 <br /> November 14, 2000 <br /> Mr Harlin Knoll <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 3 04 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject Subsurface Investigation and Quarterly Groundwater Monitoring Report <br /> Knowles Property, 1140 W Hammer Lane, Stockton, California <br /> Dear Mr Knoll <br /> Enclosed is your copy of the Subsurface Investigation and Quarterly Groundwater Monitonng <br /> Report for the subject site The report details site activities conducted during the third quarter <br /> 2000, including routine quarterly groundwater monitoring and sampling, and additional <br /> subsurface investigation north of well MW5 The report concludes that the lateral extent of the <br /> dissolved contaminant plume has been defined to the north and is roughly bounded by non-detect <br /> concentrations in wells MW8, MW4, MW2, MW3, and boring SB 1 X The plume has remained <br /> very stable and chemical concentrations have been declining :n each well since their respective <br /> historic highs were recorded <br /> Since receiving a letter from the UST Cleanup Fund in November 1997 stating that the Fund was <br /> evaluating whether or not the site should be closed, Ground Zero Analysis, Inc (Ground Zero), <br /> on behalf of Mr Carl Knowles, has worked closely with San Joaquin County Public Health <br /> Services, Environmental Health Division (PHS/EHD) to gather sufficient data to determine if site <br /> closure is warranted Based upon a meeting at PHS/EHD offices on January 29, 1998 and as <br /> requested in correspondence from PHS/EHD dated March 9, 1998, Ground Zero conducted <br /> additional soil and groundwater sampling south of well MW5 in July 1998 Ground Zero <br /> concluded that gasoline contamination in soil attenuated with depth and the vertical hnuts have <br /> been essentially defined TPHg levels in the soil between approximately 35 and 45 feet below <br /> ground surface (bgs) were in the several thousand part per million range and very low levels were <br /> detected to approximately 100 feet in the vicinity of the former USTs Soil contamination at <br /> depth is likely attributable to the relatively high concentrations in groundwater The gasoline <br /> hydrocarbon concentrations detected in the groundwater grab samples were consistent with levels <br /> historically detected in nearby well MW5 <br /> Pursuant to a written request from PHS/EHD (July 8, 1999) requesting additional investigation <br /> north of MW5 to delineate the plume and determine if soil contamination is present north of the <br /> Knowles ham/reports/3gm2000 doc <br />