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a . <br /> � r <br /> CHAPTER 4 <br /> HELD AND ANALYTICAL RESULTS <br /> This chapter presents the field and analytical results of the October 1990 Site Investigation <br /> at ARCO Products Company Station 2093,'Fracy, California. 'Clic soil and groundwater samples <br /> collected during this investigation were analyzed at Brown and Caldwell Analytical Laboratory, <br /> Emeryville, California. <br /> Soil Results <br /> Soil samples collected from the boreholes were measured in the field for organic vapors <br /> using an organic vapor meter. Table 4-1 presents organic vapor field readings according to the <br /> depth of tite sample. <br /> Soil samples collected from the boreholes were analyzed for benzene,ethylbenzene,toluer:r, <br /> and xylene (BET},`), and total petroleum hydrocarbons (TPH), using the U.S. Environmental <br /> Protection Agency (EPA) Modified Method 8015 with extraction by EPA Method 5030. <br /> 'fable 4-2 presents a summary of the analytical results of the soil samples collected during this <br /> investigation. A full laboratory report for the soil analyses is included as Appendix E. <br /> Soil BETX Results. One soil sample was collected from each of the five boreholes except <br /> t TEX-1 for laboratory analysis. /,lone of the soil samples collected from the Off site boreholes <br /> contained detectable concentrations of BTEX based on a laboratory detection limit of 0.5 <br /> milligrams per kilogram (mg/kg). Both soil samples collected from the boreholes drilled near <br /> the underground storage tanks (USTs) (BH-1 and BH-2) conutined detectible concentrations of <br /> xylene but not benzene, ethylbenzene or toluene based on a laboratory detection-limit of 50 <br /> mg/kg, The laboratory detection limit was set higher for the on site borehole samples than the <br /> off-site borehole samples because hydrocarbons were anticipated in these samples based on field <br /> observations. <br /> Soil TPH Results. Based on a laboratory detection limit of 5.0 mg/kg, none of the soil <br /> sarnplesXrom the off site wells contained detectible concentrations of TPH. <br /> Based on the,analytical results of the soil samples collected during this and previous <br /> investigations, hydrocarbon affected soil is present beneath the site with the highest <br /> concentrations occurring in the UST area• <br />