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i <br /> 7.0 SUMMARY <br /> Petroleum hydrocarbons were not detected in soil samples collected <br /> from on-site soil boring MW-7 and off-site boring MW-8. This is <br /> consistent with previous work which indicated soil contamination <br /> was largely confined to the northeast corner of the property. <br /> Gasoline hydrocarbons were detected in groundwater samples <br /> collected from on-site monitoring wells MW-6 and MW-7, and off-site <br /> well MW-8 . Diesel hydrocarbons were not detected in groundwater <br /> t samples collected from on-site monitoring wells MW-6 and MW-7, and <br /> off-site well MW-8. 112-Dichloroethane was detected in groundwater <br /> I samples collected from on-site monitoring wells MW-6 and MW-7. <br /> Tetrachloroethene (PCE) was detected in groundwater samples <br /> collected from on-site monitoring well MW-7. Chlorinated <br /> hydrocarbons were not detected in groundwater samples collected <br /> from off-site monitoring well MW-8, however this may be due to the <br /> unusually high method detection limits. <br /> The direction of groundwater flow beneath the site on September 26, <br /> 1994 was to the northeast; the hydraulic gradient magnitude was . 01 <br /> ft/ft. <br /> i <br /> 8.0 CONCLUSIONS <br /> i <br /> The horizontal and vertical extent of soil impacted by gasoline <br /> hydrocarbons is defined in the northwest portion of the site and <br /> appears to be limited to soil adjacent to borings TB5 and SB22 to <br /> a depth of approximately 25 feet bgs. These residual gasoline <br /> hydrocarbons may have impacted groundwater beneath the site at <br /> times of higher groundwater level. <br /> f Soil samples collected from boring TB7 and from the sidewalls of <br /> the former UST excavation located near the central portion of the <br /> site (whish may have been located incorrectly relative to the <br /> actual tank locations) indicates an additional shallow soil boring <br /> is warranted in the area southwest of the former USTs and the <br /> existing excavation. <br /> i <br /> Soil samples collected from boring TB9 drilled into native soil <br /> f beneath the area of the former UST located along the southern <br /> property boundary indicates sources gasoline hydrocarbons did not <br /> impact soil beneath the former UST located along the southern <br /> property boundary. <br /> Groundwater at the site and downgradient off-site has been impacted <br /> by gasoline hydrocarbons. The lateral extent of gasoline <br /> hydrocarbons in groundwater has not been delineated. <br /> Off-site environmental investigations being conducted for the <br /> gasoline service station directly upgradient of the site to the <br /> west indicates petroleum hydrocarbons could be migrating towards <br /> 7 <br /> r <br />