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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 /> January 29, 2001 <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: Additional Subsurface Investigation Report— Soil and Groundwater Sampling <br /> North Stockton Auto Service, 8709 N. Davis Road, Stockton, California <br /> Dear Ms. Duncan: <br /> This letter report is submitted on behalf of North Stockton Auto Service to summarize the results of <br /> additional subsurface investigation at the subject site. The purpose of the investigation was to <br /> determine if groundwater has been impacted by an unauthorized release from an underground <br /> waste oil storage tank (UST) formerly located at the facility. Fieldwork was performed pursuant to <br /> • a San Joaquin County Public Health Service, Environmental Health Division (PHS/EHD) directive <br /> dated January 2, 2001. Fieldwork was conducted on January 12, 2001. <br /> BACKGROUND INFORMATION <br /> Initial Investigation and Underground Storage Tank Removal <br /> The site currently is an automotive service center and is owned by Mr. Ed Niemann, et.al. The <br /> location of the property is shown on Figure 1. One 550-gallon UST was previously utilized for <br /> storage of waste oil. The UST was removed under permit from PHS/EHD on May 26, 2000. A <br /> soil sample collected from beneath the tank contained elevated levels of petroleum hydrocarbons <br /> and chlorinated hydrocarbons. Analytical results are summarized in Table 1. <br /> Soil Boring Investigation <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. Boring SBI <br /> was located within the backfilled former UST excavation. Borings SB2 through SB5 were <br /> located around the perimeter of the UST excavation (Figure 2). The borings were advanced to <br /> depths ranging from 16.5 to 17 feet bgs where drilling refusal was met due to a hard pan <br /> formation. Analytical results of soil samples collected from the borings indicated soil <br /> contamination was present at shallow depths within the former tank pit location. Analytes of <br /> concern were not detected in any perimeter borings nor at a depth of 17 feet below grade in the <br /> • central boring (SB 1). Analytical results are summarized in Table 2. <br /> nsauto/reports/addsuhsurtsum.doe <br />