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CAMB R IA <br /> i <br /> at 10 ppb No other fuel oxygenates were detected in groundwater samples collected from the <br /> wells <br /> The groundwater chemical analytical data are summarized in the well concentrations table in <br /> Blaine's report (Appendix Q and in Table 3 Benzene and MTBE results are presented on <br /> Figure 3 Laboratory analytical data are included in Blaine's report (Appendix Q <br /> REVISED SITE CONCEPTUAL MODEL <br /> Cambria updated the site conceptual model, originally submitted in April 2002, for this site and <br /> included it as Appendix G <br /> CONCLUSIONS <br /> Soil sample analytical results from well borings MW-8 through MW-10 further delineate the <br /> lateral extent of fuel oxygenates in soil west, southwest, and south of the subject site Based on <br /> current and historical soil sample analytical data, the lateral and vertical extent of petroleum <br /> • hydrocarbons and fuel oxygenates are defined in all directions surrounding the site The lateral <br /> and vertical extent of TPHg and benzene in soil are defined by borings SB-2 through SB-5, the <br /> vertical extent of fuel oxygenates in soil is defined by borings CPT-1 and CPT-2, and the lateral <br /> extent of fuel oxygenates in soil is defined by well borings MW-5 through MW-10 <br /> TPHg and BTEX were not detected in groundwater samples collected from the wells, although <br /> some reporting limits were elevated MTBE and TBA have been detected in groundwater <br /> beneath the site Wells MW-6 and MW-8 through MW-10 delineate the lateral extent of MTBE <br /> in groundwater (at 10 ppb) northeast, northwest, southwest, and south of the USTs Wells <br /> MW-5 through MW-10 delineate the lateral extent of TBA in groundwater in all directions <br /> surrounding the site Deep well MW-11 contained Iow concentrations of MTBE and TBA, <br /> which may be a result of drilling activities <br /> RECOMMENDATIONS <br /> Cambria recommends gauging and sampling all site wells quarterly to determine if there are <br /> seasonal fluctuations in the observed groundwater elevations and chemical concentrations and to <br /> confirm a predorrunant east/southeast groundwater flow direction As approved by SJCEHD in <br /> September 9, 2003 correspondence, the groundwater samples from all wells will be analyzed <br /> quarterly for fuel oxygenates and annually for TPHg and BTEX until site conditions change <br /> 0955 8 <br />