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Ms. Lori Duncan <br /> June 12,2007 <br /> CONESTO-OA-ROVERS <br /> &ASSOCIATES <br /> Two domestic wells were'.identified from the DWR's records within 2,000'feet of the site. The closest <br /> well is located approximately 1,300 feet southwest of the subject site. - <br /> Surface Water Bodies: Cambria reviewed United States Geologic Survey topographic map for Tracy to <br /> identify surface water bodies within the surveyarea. Nosurface water bodies were identified within a- <br /> 2,000-foot radius of the site. <br /> Conclusions: It is unlikely that any of the receptors identified in this survey would be impacted by site <br /> activities. The groundwater flow direction has.been predominantly toward the north over the last six <br /> monitoring quarters. . None of the receptors identifie& during this survey are .located directly <br /> downgradient of the site. The wells are located approximately 1,300,feet and 1,900 feet from the site. <br /> Given these conditions, it is unlikely that tither of these receptors would be impacted by,MTBE from this <br /> site. a <br /> EXTENT OF HYDROCARBONS IN SOIL_ <br /> The vertical and lateral extent of TPHg and BTEX in soil is defined by non-detect results in soil samples <br /> collected from well borings MW=5 through.MW-7, boring SB-1; and several soil samples collected-- <br /> beneath the dispensers at.the site. The lateral extent of MTBE-in shallow soil at the site has been defined, <br /> by non-detect results in soil samples collected from well borings MW-5 through MW77, and from boring <br /> SB-1. The vertical extent of MTBE in soil beneath the site is defined. <br /> EXTENT OF HYDROCARBONS IN GROUNDWATER <br /> Groundwater analytical data suggests that the lateral and vertical: extent of TPHg and BTEX-,iri ' . <br /> groundwater beneath this site is delineated. TPHg and BTEX are typically not detected-in the wells at <br /> this site, and historically have only sporadically been detected at low levels. y <br /> The lateral extent of MTBE in shallow groundwater has not been defined north of the site. MTBE has <br /> been detected in downgradient wells MW-1, MW-5, MW-6, and MW-7. . However, Interstate 205 is <br /> located immediately downgradient of the site and further investigation is not feasible. MTBE has also <br /> been detected in well MW-4, located upgradierit.of the underground storage tanks(USTs) and is likely <br /> indicative of an offsite source. Thc'vertical;extent of MTBE in groundwater has'becn defined-by <br /> depth-discrete grab groundwater samples collected during,the installation of a deep`boring SB-1, . <br /> downgradient of the USTs and dispensers at the site. No MTBE was' detected in grab groundwater <br /> samples collected from 52, 72, and 82 fbg. <br /> 1667 .3 <br /> worldwide Engineering,Env--ironmental,Construction,and IT Services <br />