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4.0 FINDINGS <br /> 4.1 SOIL <br /> CRA summarizes the soil chemical analytical data in Table 1. Figure 3 presents the <br /> TPHg,TPHd,benzene,MTBE,and TBA soil analytical results. The analytical laboratory <br /> reports are included in Appendix E. <br /> 5.0 DISCUSSION <br /> Twenty two air sparge points were installed during this investigation to facilitate the <br /> installation of a previously proposed AS/SVE system at the site. Soil samples collected <br /> from the borings contained up to 3,600 mg/kg TPHg, 4,400 mg/kg TPHd, 4.0 mg/kg <br /> benzene, 8.9 mg/kg MTBE, and 3.2 mg/kg TBA. The highest petroleum hydrocarbon <br /> concentrations were observed in soils samples collected in borings AS-8, AS-9, AS-11, <br /> and AS-16 located south or east of the Truck Loading Rack.at depths ranging from 5 to <br /> 15 fbg and the highest MTBE and TBA concentrations were detected in boring AS-9 <br /> located east of the Truck Loading Rack. Elevated petroleum hydrocarbon <br /> concentrations were also observed in borings AS-2, AS-4, and ASS located east of the <br /> Tank Farm. Soil samples collected from other areas of the site generally contained low <br /> to moderate petroleum constituent concentrations. <br /> Subsequent to this investigation and as discussed in our November 30,2011 letter to the <br /> RWQCB, CRA recommended preparing a CAP to evaluate current site conditions and <br /> re-evaluate site remedial alternatives. The RWQCB approved submittal of a CAP in <br /> their January 13,2012 letter to Shell. The CAP will be submitted under separate cover. <br /> 247729(37) 4 CONESTOGA-ROVERS&ASSOCIATES <br />