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. Results of the soil sample analyses indicate that soil impacted by greater than 100 mg/kg of <br /> TPH-as-diesel extends up to 40 feet away from the former UST excavation (Figure 4) Due to <br /> the proximity of the former UST to the State Highway 99 right-of-way to the north, the lateral <br /> extent of impacted soil is not defined The greatest concentration of TPH-as-diesel (8,800 <br /> mg/kg) was detected in SB-7 at a depth of 15 feet bgs This sample was collected in close <br /> proximity to the former UST and within the zone of groundwater fluctuation (i e , capillary fringe) <br /> Vertically, the extent of impacted soil is not fully defined The soil sample collected at the total <br /> depth from SB-7 (20 feet bgs) contained 460 mg/kg of TPH-as-diesel <br /> The greatest concentration of petroleum hydrocarbons detected in groundwater during this <br /> investigation was in the groundwater-grab sample collected from SB-7 This sample contained <br /> 13,000 µg/I of TPH-as-diesel, 2,800 µg/l of TPH-as-gasoline and 2 2 µg/I of benzene The fuel <br /> oxygenate MTBE was detected in minor concentrations (up to 1 1 µg/1) in two of the monitoring <br /> wells (MW-1 and MW-3) No other alcohol- or ether-based oxygenate compound was detected <br /> in any of the groundwater samples analyzed <br /> Results of the groundwater-grab samples and groundwater samples from the monitoring wells <br /> indicate that groundwater impacted by petroleum hydrocarbons extends less than 80 feet west <br /> and approximately 100 feet south of the former UST (Figure 5) The lateral extent of impacted <br /> • groundwater is not defined to the east and north (i e , downgradient) of the former UST <br /> i9 <br />