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08 June 1998 <br /> AGE-NC Project No 95-0173 <br /> Page 2 of 7 <br /> beneath two of the three removed USTs at depths of approximately 17 to-181 feet below <br /> surface grade (bsg) <br /> • On 25 and 26 July 1996,preliminary site assessment activities were conducted by advancing <br /> six soil borings (B1, B2, MW-1 through MW-4) near the former UST area to maximum <br /> depths of 60 feet bsg, borings MW-1 through MW-4 were converted into 2-inch diameter <br /> PVC ground water monitoring wells Total petroleum hydrocarbons quantified as gasoline <br /> and diesel (TPH-g and TPH-d, respectively) and volatile aromatics (benzene, toluene, <br /> ethylbenzene and xylenes BTE&X) were detected in both soil and initial ground water <br /> samples collected from B1, B2 and MW-1 through MW-4 <br /> • On 19 and 20 December 1996, site assessment activities included advancing six soil probe <br /> borings (B3 through 138) downgradient of the former UST area to maximum depths of 40 <br /> feet bsg TPH-g, TPH-d and BTE&X were detected in soil samples collected from 133, B4 <br /> and B6 TPH-g, TPH-d and BTE&X were detected in grab ground water samples collected <br /> from B3, B4, B6 and B7, ground water samples were not collected from B5 and B8 <br /> • On 16, 17 and 18 June 1997, five ground water monitoring wells (MW-5 through MW-9) <br /> and two soil vapor extraction wells (VW-1 and VW-2)were installed on and off-site as part <br /> of site assessment activities TPH-g, TPH-d and BTE&X were detected in soil samples <br /> collected from MW-6,VW-1 and VW-2,TPH-g,TPH-d and BTE&X were detected in initial <br /> ground water samples collected from MW-6, MW-8 and MW-9 <br /> • On 14 July 1997, an eight-hour soil vapor extraction (SVE) pilot test was performed to <br /> provide data to assess SVE as a component of the final remediation system <br /> • On 3 and 4 November 1997, two in-situ air sparging (IAS) wells (AW-1 and AW-2) were <br /> dual-completed at the site to delineate the vertical extent of petroleum-impact and to seive <br /> as remediation wells TPH-g, TPH-d and BTE&X were detected in soil and initial ground <br /> water samples collected from AW-1 and AW-2 <br /> • On 13, 14 and 15 January 1998, a 72-hour IAS pilot test was performed to assess feasibility <br /> of IAS as a remediation technique <br /> Additional background information is summarized in Quarterly Reports submitted to PHS-EHD <br /> (prepared by AGE) between August 1996 and January 1998 <br /> 3.0, SCOPE OF WORK <br /> Based upon a letter dated 16 October I997,the PHS-EHD is requiring the installation of additional <br /> ground water monitoring wells to further assess the dissolved petroleum hydiocarbon plume The <br /> scope of work for this investigation initially includes the advancement of three single-completed <br /> Advanced GeoEnvtronmental,Inc <br /> 4 <br />