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F. Upgradiet Environmental Clonsultants w _ I � December 14, 1998 • Mr Tom Nicholas 1 20 Magnolia Realty 3911 Waynesboro Ct Stockton, CA 95219 Subject Preliminary Environmental Assessment Electro Delta Co 821 S Wilson Way Stockton, CA Dear Mr Nicholas Upgradient Environmental Consultants has completed the scope of work authorizes under project no. 98036 and is pleased to transmit herewith the results of our investigation The investigation centered around an underground gasoline storage tank that was used b} previous owners of the property to fuel company vehicles When that 500-gallon taiik was removed in 1985, a soil sample was collected from beneath it and lead was detected at a concentration of 407 mg/kg (parts per million {ppm)) in the sample In the Stockton area, the normal background concentration of lead in the soil from non-petroleum source, is between 10 and 20 ppm Hence,the elevated concentration suggested that the tank may have leaked leaded gasoline In order to determine whether the lead is soluble in water and could contaminate groundwater beneath the site, San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD), directed Upgradient to drill c,ne boring through the former tank pit in order to collect a sample at a depth of 15 feet PHS/EHD further directed that the sample should be analyzed for soluble lead using the Cal-WET test Upgradient submitted a work plan and drilling permit to PHS/EHD i I early October, and the work was performed on November 25 Mitchell Drilling Environmental of Rancho Cordova used a truck-mounted CME-7` hollow-stem auger drilling ng I examined samples of the soil during drilling, and recorded my observations on the attached boring log Near the surface, the soil is rec - brown sand, but clay becomes more common downward Below 8 feet, the soil is sticky brown clay and silty clay An odor of gasoline was evident below 12 feet and in the sample collected at the bottom of the hole(15 feet) Therefore, with the concurrence of Ms Carol Oz of PHS/EHD, I directed the laboratory to analyze the sample for bent ne, toluene,ethylbenzene, xylene (BTEX), methyl-tertirary-butyl ether(MTBE)and gasaline (purgeabie hydrocarbons) using EPA methods 8020 and 8015 as well as for soluble dead The laboratory report is attached to this report Gasoline was detected at a concentration of 4,890 ppm, toluene was detected at 236 ppm, ethylbenzene was detected at 110 ppm, and xylene was detected at 433 ppm The rel Ative concentrations of the latter three compounds and the absence 6,f the volatile and easi y- • removed benzene indicate that the gasoline is partly degraded ("weathered" gas accc rding 9 Stockton PO Box 8002, Stockton, CA 95208 (209) 772-3520 Cameron Park 3369 Kimberly Road, Cameron Park, CA 95682 (916) 677-3055