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_ _- s,.:� - rte=---;s,, r�z.err _ _ _ ... � •v <br /> OWNs <br /> I <br /> PropomW Work Phn ior---Aatfon of <br /> 7trm On S11e Weft and RtrsaPrpart <br /> 1605 South Ei Oorado,Stockton.G4ilorma <br /> }:cu. <br /> SITE DESCRIPTION <br /> The Exxon Service Station, RAS#7-0137, located at 160 South EI Dorado in the City of <br /> Stockton, San Joaquin County, California, is presently an active station. The store retails E <br /> regular-leaded, regular-unleaded, and extra-unlead es. The station facilities <br /> include a building,three dispenser islands and hree 10 000- allon nderground storage <br /> tanks (USTs) with associated product piping. a ree s are located immediately <br /> north of the dispenser islands on the northern half of the site, see Figure 2. The type of <br /> construction and the installation dates-2f the USTs are unknown. j <br /> SITE BACKGROUND AND HYDROGEOLOGY <br /> Can February 22, 1991, a pre-tank replacement site assessment was performed by Aegis, <br /> which included the advancement oft~ borin s (30 degrees from vertical)adjacent <br /> to and underneath the existing USTs. The laboratory results reported total purgeable <br /> petroleum hydrocarbons (TPPH) at 16,000 milligrams per killigram (mg/kg)/parts per <br /> million (ppm) from a soil sample collected at approximately 35 feet below grade. A <br /> duplicate analysis of this sample indicated a concentration of 14,000 mg/kg (ppm). The <br /> laboratory results for benzene,toluene,ethylbenzene,and xylenes (BTEX) were reported <br /> at 66 ppm, 1,300 ppm, 360 ppm, and 2,000 ppm in the same soil sample, respectively. <br /> The remainder of the TPPH, al-EX,and 1,2-dichlorcethane (EDC) concentrations ranged <br /> from below detection limit to 0.33 ppm in samples collected from approximate depths of <br /> 18 to 30 vertical feet below grade. Total lead ranged from 3.4 to 7.5 ppm and ethylene <br /> dibromide (EDB) was below detection limit in all samples analyzed. <br /> A saturated water horizon was encountered at depth 49 and 48.5 vertical feet below <br /> grade in borings SB-1 and SB-2, respectively. Based on fieg o servations and the soil <br /> types encountered, the groundwater is inferred to be under unconfined conditions. <br /> SITE PLAN <br /> For the purposes of this work plan, a project site plan map is included as Figure 2. The <br /> layout includes the location of the three existing USTs, dispenser islands, product Unna' <br /> and the proposed three on site monitor wells. <br /> 57-044A.RPr 'p_ - - <br />