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f , <br /> - GROUND ZERO ANALYSIS INC. <br /> 1714 Main Street <br /> Escalon,California 95320-1927 <br /> a Telephone:(209)838-9888 <br /> Facsimile:(209)838-9883 <br /> February 28, 2006 <br /> # Mr. Harlin Knoll <br /> San Joaquin County Environmental Health Department <br /> 304 East Weber Avenue, Third Floor ' <br /> Stockton, CA 95202 <br /> Subject: Workplan for Vertical Groundwater Investigation and i <br /> Bench Test for In-situ Oxidation <br /> 7835 Thornton Road, Stockton, CA (APN#077-490-27) <br /> Dear Mr. Knoll: <br /> CW This Workplan is submitted on behalf of the Harold and Dena Knowles Family Trust to present a , <br /> proposed scope of work for further subsurface investigation at the subject site (Figure 1) pursuant <br /> to correspondence from San Joaquin County Environmental Health Department (EHD) dated <br /> ' December 28, 2005. <br /> The workplan describes the proposed methodology to drill and install a deep well to investigate the " <br /> vertical extent of groundwater contamination, and to conduct a bench scale test to evaluate the <br /> feasibility of in-situ oxidation as a remediation alternative for the site. All field work will be <br /> conducted in accordance with Ground Zeros Site Health and Safety Plan and QA/QC Protocol on <br /> file at EHD. <br /> BACKGROUND AND SUBSURFACE INVESTIGATIONS <br /> The site previously operated as a retail gasoline facility, which distributed regular, unleaded, and <br /> premium unleaded gasoline. The fuels were stored onsite in four 6,000-gallon and two 12,000- <br /> gallon underground fuel storage tanks. All buildings, pump islands, underground fuel storage <br /> tanks, and associated product lines were removed on or before March 17, 1987. Figure 2 presents a <br /> site plan showing former site features. <br />{ Groundwater Technology, Inc. (GTI) performed the initial subsurface investigation. On April <br /> 10, 1987, GTI collected confirmation soil samples from beneath tanks 5 and 6 at depths of 30 to <br /> L34 feet. Analytical results indicated the presence of low levels of petroleum hydrocarbons. <br /> i <br /> G:IGROUNDZEIKNOWLES.HA"REPORTSI WKPLAN_deepwel l_hench2.doc <br />