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CjeoCagual7echnicsTnc Page 8 <br /> Soli Groundwater Investigation Report <br /> George s Service <br /> PtojectNo 425 2 <br /> November 311, 1998 <br /> 3 MW-105 contains trace concentrations of Benzene and Total Xylene <br /> 4 MW-107 did not detect contamination <br /> 5 The plume appears to be vertically defined in the area of MW-105 and MW-107 <br /> 6 MW-202 tested positive for low levels of BTEX and TPH-G in the groundwater at 80 feet <br /> bgs All soil samples collected between 50 and 80 feet bgs were non-detect It is <br /> possible that the low levels of BTEX and TPH-G in the groundwater are a result of <br /> drilling artifacts and will slowly dissipate over time Further monitoring will determine if <br /> the vertical extent of the plume has been defined in area of the former USTs <br /> 7 The groundwater plume associated with the former UST's has not migrated to the north <br /> to MW-7 or MW-107, which is 75 feet from the former UST's Neither has it migrated <br /> far enough to impact MW-6 or the domestic wells <br /> 8 Free-floating product has been observed in MW-2 during the fall or winter monitoring <br /> events since 1996 <br /> 5.2 Recommendations <br /> Geological Technics Inc makes the following recommendations based on the conclusions <br /> outlined above <br /> 1 Groundwater monitoring of the existing monitoring wells and domestic wells should be <br /> continued on a quarterly basis to evaluate groundwater quality at the site and determine if <br /> the initial groundwater monitoring results are reproducible A monitoring event took <br /> place on November 13, 1998 These results will be submitted shortly The next <br /> monitoring event will take place in February <br /> 2 Water levels should be collected on a monthly basis for a 12-month period to track the <br /> effects of pumping of the adjacent wells and to determine if the site experiences vertical <br /> groundwater flow <br /> 3 It is recommended that a limited soil excavation be performed at the site to remove the <br /> highest concentrations of petroleum hydrocarbons in the soil This would serve to reduce <br /> continued leaching into the groundwater and would also add oxygen to the subsurface to <br /> aid in natural attenuation The excavation would be approximately 500 cubic yards <br />