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25 February 2005 . AGE-NC Project No 01-0827 ' Page 7 of 10 the coarse sand and gravel encountered from 25 to 30 feet bsg 1 ' 5.0. GROUND WATER MONITORING RESULTS Between December 1998 and December 2004, 35 ground water monitoring events were performed ' on monitoring well MW-1,while a total of 18 monitoring event were conducted at vapor well VW-2, to measure dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient on the site ' Since initiation ofround water monitoring in December 1998,ground water elevations have ranged g g at the site from approximately 9 to 34 feet below mean sea level as depicted In Table 1 ' (Appendix A) The ground water flow direction at the site had been dominantly east to northeast,at the former UST area ' Laboratory analysis of shallow ground water monitoring well samples(between 25 and 30 feet bsg) historically detected TPH-g and BTEX compounds in water samples collected from wells MW-1, ' VW-1 and VW-2, the highest dissolved concentrations were detected 1n wells MW-1 and VW2 during their first sampling events on 22 December 1988 and 26 November 1997, respectively The highest concentrations of TPH-g was 34,000 micrograms per liter(µg/1)from well VW-2d,followed ' closely in magnitude by 33,700 µg/l in well MW-1 and 32,000 µg/1 or 29,000 µg/1 in vapor well VW-5s and VW-1,respectively TPH-g and BTEX compound concentrations generally declined at well MW-1 and the former UST area during the declining ground water table elevation of the early 1990's The TPH-g detections then rebounded to a high concentration in October 1996 during which time water rose to 30 feet bsg or within the mayor coarse sand and gravel layers at the site, and/or the water table was five feet above the top of the MW-I well screen BTEX compounds have been ' detected as great as 6,100 gg/l benzene, 4,900 µg/1 toluene, 2,300 µg/1 ethyl-benzene and 6,100 xylene (VW2d) Analytical results of ground water samples are summarized in Table 3 However,all these concentrations decreased after the initial sampling TPH-g and BTEX,along with fuel additive concentrations decreased in vapor wells and the monitoring wells,during SVE and IAS remediation near the former UST area Monitoring well MW-1,vapor wells VW-I and VW5d have ' declined to non-detect levels, since July of 2003 The concentration trends of TPH-g and BTEX detections in the samples from well VW-2d, at the former UST area, is depicted in Appendix A ' Laboratory analysis of samples from well MW-6, representing the deeper ground water, have detected TPH-g as high as 1,000 µg/1 in the July 2003 sample Concentrations of TPH-g in well ' MW-6 have steadily declined to a non-detect level during six sampling events, over 18 months Additionally, BTEX compounds had been observed in the samples from well MW-6 at • concentrations up to 62 µg/1 of benzene, 7 4 µg11 of toluene, 31 gg/l of ethyl-benzene and 19 µg/1 ' Advanced GeoEnvironmental,Inc 1