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GEOMATRIX <br /> previously measured. Based on current data and historical data(i.e., 1998) from the <br /> existing monitoring wells, groundwater flows to the east;which is consistent with <br /> previously collected data. <br /> • MW-1 contained approximately three-inches of separate-phase petroleum, which is <br /> slightly less than the amount previously measured. <br /> • Petroleum hydrocarbon-affected soil was identified in two areas on the site: <br /> (1)within the currently defined area north of the former pump house(i.e., area of <br /> MW-1) and (2)within an area further east that is currently defined by one soil <br /> boring SB-14 (Figure 4). The lateral extent of petroleum (i.e., crude) affected soil <br /> has been delineated in the area of MW-1 as part of previous investigations and by <br /> advancing borings SB-9 through SB-12 during this investigation. The vertical <br /> extent of petroleum hydrocarbon-affected soil at the site is defined by boring SB-9. <br /> in SB-9, affected soil was identified in field observations at a depth of <br /> approximately 81 feet bgs. In SB-14 the affected soil was identified in field <br /> observations and confirmed with laboratory results at a depth of at least 45 ft bgs. <br /> The presence of petroleum hydrocarbon-affected soil in this area may be due to <br /> operations of the actual pipeline within the right-of-way. <br /> • Groundwater samples collected in crossgradient wells MW-3 and MW-4 did not <br /> contain petroleum hydrocarbons. Samples collected downgradient of the previously <br /> defined petroleum hydrocarbon-affected soil (MW-2 and SB-13) had detections of <br /> TPHd (without silica gel preparation procedure). Ager treatment with silica gel, <br /> concentrations were less than 140 µg11. These concentrations are less than the WQQ <br /> as presented by the Central Valley RWQCB.2 Grab groundwater samples from <br /> SB-13 also had low detections of toluene and PAHs (i.e., less than 1 µg11). <br /> The water quality objective utilized by the Central Valley Regional Water Quality Control Board for diesel fuel <br /> in 100µg11 and based on secondary criteria(i.e.,taste and odor threshold). <br /> �-\t)w Safe\5000s15UIIMIgtcporilsoiIand Gw Repor doc 10 <br />