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Onsite and Offsite Assessment Report 5 <br /> •%owl The Southland Cor <br /> poration,2725 Country Club Boulevard Stockton California November 30 1998 <br /> TBA,MTBE, DIPE, ETBE,and TAME by EPA method 8260. At the request of Mr. Infurna of the <br /> SJCPHS,two samples(from the northern and southern edges of the Southland site)were also <br /> analyzed for halocarbons by EPA Method 8010(samples GP-10W and GP-16W). <br /> 'r Following groundwater sample collection,each boring was grouted with neat cement and topped with <br /> cold patch asphalt to match the existing surface grade. <br /> 3.0 RESULTS <br /> 3.1 Results of Soil and Groundwater Sample Analyses <br /> All of the samples collected on the Patmon Property were non-detectable for hydrocarbon constituents <br /> with the exception of 39 mg/kg MTBE(detected by EPA Method 8020)found in groundwater in boring <br /> OSGP-6@W. This boring is located northeast(downgradient) of the USA/Exxon site. Concentrations <br /> 60 of 0.011 total xylenes were found in soil at 4 feet below grade in boring OSGP-21 4'. This boring is <br /> located northwest of the USA/Exxon site, and north of the Southland facility. <br /> 6r Onsite results indicate maximum soil hydrocarbon concentrations were found near to the former UST <br /> area. Total petroleum hydrocarbon levels were highest(42,900 mglkg) at 15 feet below grade in <br /> boring GP-15, located adjacent to the former tank location. Concentrations in this same area <br /> +� decreased with depth to non-detectable TPH-g at 20 feet below grade. Benzene levels in the former <br /> tank pit area were less than 0.01 mg/kg, and MTBE was not detected. <br /> ` Soil hydrocarbon data from borings GP-7, GP-8, and GP-16 indicated that the soil hydrocarbon plume <br /> is delineated to the west and southwest of the former tank pit area;there were no detectable <br /> hydrocarbon concentrations in borings GP-7 or GP-8, and soil from boring GP-16 contained only up to <br /> 0.0052 mg/kg benzene,with no detectable levels of TPH-g or MTBE. <br /> �. In between the new and former tank pit areas,soil hydrocarbons were found in boring GP-14 at levels <br /> of up to 1.88 mg/kg benzene, 741 mg/kg TPH-g, and 234 mg/kg MTBE. Concentrations decreased <br /> with depth to non-detectable levels of TPH-g and MTBE at 30 feet below grade, and benzene levels of <br /> �,. less than 0.01 mg/kg. Soil in boring GP-17 (located south of boring GP-14 between the two tank pit <br /> areas) contained up to 12.5 mg/kg benzene, 704 mg/kg TPH-g, and 32.4 mg/kg MTBE. <br /> Concentrations of MTBE decreased with depth to non-detectable levels at 20 feet below grade. <br /> 14117mr.rpt <br /> t.. FLUOR DANIEL GTI <br /> L,i <br />