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GROUND ZERO ANALYSIS,INC. <br /> 1714 Main Street <br /> Escalon,California 95320-1927 <br /> Telephone: (209)838-9888 ' <br /> Facsimile: (209)838-9883 <br /> April 10,2001 r' <br /> Ms. Lori Duncan <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject: Workplan for Groundwater Monitoring Well Installation <br /> 8709 N. Davis Road, Stockton, California <br /> Dear Ms. Duncan: <br /> Ground Zero Analysis,Inc. (Ground Zero)is submitting this workplan on behalf of North Stockton Auto in <br /> response to your directive dated March 30, 2001. This Workplan describes the proposed methodology to <br /> install and sample one groundwater monitoring well at the subject site. A survey to locate and identify all <br /> wells within 2,000 feet of the site is currently underway. <br /> BACKGROUND INFORMATION <br /> Previous Investigations <br /> The site currently is an automotive service center and is owned by Mr. Ed Niemann, et.al. The location <br /> of the property is shown on Figure 1. One 550-gallon UST was previously utilized for storage of <br /> waste oil. The UST was removed under permit from San Joaquin County Public Health Services <br /> Environmental Health Division (PHS/EHD) on May 26, 2000. A soil sample collected from beneath <br /> the tank contained elevated levels of petroleum hydrocarbons and chlorinated hydrocarbons. Analytical <br /> results are summarized in Table 1. <br /> On September 11, 2000, five soil borings were advanced at the site to investigate the lateral and <br /> vertical extent of soil contamination, as well as the potential impact to groundwater. Analytical results <br /> of soil samples collected from the borings indicated soil contamination was present at shallow depths <br /> within the former tank pit location; however, no analytes of concern were detected in any perimeter <br /> borings nor at a depth of 17 feet below grade in the central boring (SBI). Soil boring locations are <br /> shown on Figure 2. Analytical results are summarized in Table 2. <br /> On November 8, 2000, approximately 165 cubic yards of soil was excavated in the vicinity of the former <br /> tank pit in order to remove contaminated soil from the subsurface; document the completeness of the <br /> removal effort with confirmation soil samples, and further investigate the vertical limit of <br /> contamination. Confirmation soil samples collected from the floor and sidewalls of the excavation pit <br /> indicated that contamination did not extend beyond the limits of the excavation boundaries. The <br /> excavation location is depicted on Figure 2. Analytical results are summarized in Table 3. <br /> F:Oma\GROUNBZEINSAU)OIREPORTSXWORKPLAN 1MW.doc <br />