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GEOMATRIX <br /> 3.6 ANALYTICAL METHODS <br /> Soil samples were collected in July 1998 by Radian were submitted to Core Laboratories of <br /> Pasadena, California, and/or American Environmental Network of Pleasant Hill. California, for <br /> the following analyses: <br /> • BTEX and methyl tertiary-butyl ether(MtBE) using EPA Method 8020 <br /> ■ Polynuclear aromatic hydrocarbons (PAHs)using EPA Method 8270 <br /> • TPHd and TPH as motor oil (TPHmo)using EPA Method 8015M <br /> ■ TPH as gasoline (TPHg) using EPA Method 8015M <br /> The Consistent Technical Approach requires that soil samples be analyzed for petroleum <br /> constituents that could pose a threat to human health (BTEX and PAHs) and for TPH as crude <br /> oil(TPHc) for delineation purposes. In lieu of TPHc data, TPHd and TPHmo data can provide <br /> useful information regarding the presence of QVPL petroleum in soil. The hydrocarbon range <br /> of TPHc (typically Cs to C36) is represented by the combined hydrocarbon ranges of TPHd <br /> (typically Clo to C24) and TPHmo (typically C24 to C36). An analyses of MtBE was not required <br /> because the potential source material (crude oil)would not contain MtBE. The TPHg data <br /> provide limited information because weather crude oil contains low concentrations of purgable <br /> gasoline range hydrocarbons components (typically C4 to C12)- <br /> Groundwater samples were collected by Radian on July 28, 1998, and submitted to Core <br /> Laboratories for the following analyses: <br /> • BTEX and MtBE using EPA Method 8020 <br /> • PAHs using EPA Method 8270 <br /> • TPHd and TPHmo using EPA Method 8015M <br /> • TPHg using EPA Method 8015M <br /> The Consistent Technical Approach requires that groundwater samples be analyzed for <br /> petroleum constituents(i.e.,BTEX and PAHs) that could pose a threat to human health and for <br /> which there are primary water quality objectives (WQCs), such as maximum contaminant <br /> levels (MCLS)or other constituent-specific screening criteria. Additionally, groundwater <br /> samples are analyzed for TPHd and TPHg, which have secondary WQOs (taste and odor <br /> thresholds). The analysis of TPHmo is not required as part of the Consistent Technical <br /> 1\9f31deptdnU\Doc_SafC�Soa0001 1\S1 HKA Rptdoc <br />