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3.0 ANALYTICAL METHODS <br /> e<:s <br /> SPL Laboratories, a state-certified analytical laboratory, analyzed the soil and groundwater <br /> samples using standard test methods of the U.S. Environmental Protection Agency (EPA). <br /> The soil and groundwater samples were analyzed for the following: <br /> • Total petroleum hydrocarbons as gasoline (TPH-G) using EPA Methods 5030/8015 <br /> • Benzene, toluene,ethylbenzene, and total xylenes (BTEX) and methyl t-butyl ether <br /> (MTBE) using EPA Methods 5030/8020 <br /> • MTBE, di-isopropyl ether (DIPE),ethyl t-butyl ether (ETBE), t-butyl alcohol (TBA) and <br /> tert-amyl methyl ether (TAME) using EPA Method 8260. <br /> Laboratory results for water and soil samples are summarized in Tables 1, 2, and 3, and the <br /> laboratory reports and chain of custody records are included in Appendix G. The results of <br /> groundwater analysis are shown on Figure 4. Graphs showing the concentrations of MTBE and <br /> BTEX in Monitoring Wells MW-2 and MW-3 over time are presented in Figure 5. Chemical <br /> concentrations in Wells MW-2 and MW-3 were selected for graphical depiction because both are <br /> closest to the USTs and dispenser islands and have the highest reported concentrations of <br /> petroleum hydrocarbons and MTBE. <br /> 4.0 SENSITIVE RECEPTOR AND WATER WELL SURVEY <br /> A sensitive receptor survey was conducted to identify surrounding facilities or features that <br /> may be affected by or may have an effect on a petroleum release originating from the site. The <br /> potential receptor survey form is presented in Appendix H. <br /> The nearest school,Lathrop School,is approximately 4000 feet northeast of the site. Inspection <br /> of buildings and structures in the vicinity of the site revealed no basements or subways within a <br /> 300-foot radius of the BP Oil site. Properties in the immediately vicinity of the BP Oil site are <br /> either commercial businesses,residential, or vacant. <br /> 4.1 Utility Survey <br /> Subsurface utilities in the vicinity of the site were identified,based on review of public record <br /> and site inspections, to locate underground features which may provide potential conduits for <br /> the migration of the petroleum release. The following agencies were contacted to obtain <br /> information and construction drawings,if available,on subsurface utilities. <br /> • City of Lathrop <br /> • Pacific Gas and Electric Company <br /> • Pacific Bell <br /> • West Valley Sanitary District <br /> • San Joaquin County Department of Public Works <br /> 6 R/4111\1� <br />