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i ' 17 May 1999 AGE-NC Project No 96-0249 Page 7 of 9 through 08841) and chain-of-custody forms are included in Appendix D 4.0. SUMMARY AND CONCLUSIONS Based on the results of monitoring well Installation, soil sampling, ground water monitoring and Iground water sampling activities performed in March and April 1999, AGE concludes • TPH-g was detected in three soil samples from borings MW-2 and MW-3 at concentrations ranging as high as 920 mg/kg, TPH-d was detected from the same soil samples at concentrations as high as 360 mg/kg • BTEX constituents were detected in eleven soil samples collected from soil borings MW-1, MW-2,MW-3,MW-5 and MW-6 at concentrations ranging as high as 40 mg/kg The highest concentration of benzene was reported in the 10-foot sample from MW-3 at 5 2 mg/kg • MTBE was detected in the 25-foot sample from MW-4 at 0 0063 mg/kg • The estimated extent of petroleum hydrocarbon-impacted soil is illustrated in cross sectional view in Figures 14, 15 and 16 and extends horizontally approximately 160 feet southeast and 130 feet east of the former UST area and extends vertically to depths of 25 feet bsg The vertical and horizontal extent of petroleum hydrocarbon-impacted soil is relatively unknown in all other directions C The site gradient was calculated at 0 02 ft/ft, or approximately 105 feet per mile (Figure 12) Ie Ground water was inferred to be flowing towards the northeast in the area bound by wells MW-3, MW-4, and MW-6, ground water was inferred to be flowing northwest in the area ' bound by wells MW-2, MW-4 and MW-5 • The ground water depths in wells MW-1 through MW-6 were approximately two to five feet below the tops of the well casings Therefore, these wells are "properly screened", and should yield samples representative of shallow ground water conditions • TPH-g was detected in ground water samples collected from wells MWA through MW-6 at ' concentrations ranging from 67 /.zg/l (micrograms per liter) to 24,000 µg11 TPH-d was detected from the same samples at concentrations between 97 µg/l and 6,400 kcgll, respectively, however the laboratory reported that the diesel chromatograms for the samples did not have typical diesel patterns • BTEX compounds were detected in ground water samples collected from wells MW-1 through MW-6 at concentrations ranging as high as 3,400 pg/l (benzene, MW-3) • MTBE was detected in a ground water sample collected from MW-4 utilizing EPA Methods Advanced Geoinvironmentai,Inc I