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12 May 2004 AGE-NC Project No 01-0827 Page 3 of 4 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION On 26 March 2004, depths to ground water in monitoring wells MW-1 through MW-6 and vapor wells VW-1, VW-2d, VW-3 and VW-5d ranged from 21 79 to 23 85 feet below the tops of the casings (btoc), the water table was approximately 10 feet above the screened intervals of wells VW-2d and VW-5d and 35 feet above the screened interval of well MW-6 (Table 1) The ground water elevations and gradient were calculated and determined from depths to ground water data from monitoring wells MW-1 through MW-6 The ground water elevations at the site ranged from 11 89 feet (MW-5) to 13 09 feet (MW-2) below mean sea level (MSL) The ground water flow direction was Inferred to be east to southeast at a gradient of approximately 0 006 ft/ft at the former UST area (Figure 3) 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected 1n the ground water samples from wells MW-6 and VW-2d at concentrations . of 400 micrograms per liter (µg/1) and 1,900 µg/1 Various BTEX compounds were detected in samples MW-6 and VW-2d at maximum concentrations of270µg/l benzene,31 µg/1 toluene,39 µg/l ethylbenzene and 46 µg/1 xylenes, all detected in sample VW-2d The fuel additive MTBE was only detected in ground water sample VW-2d at a concentration of 27 4g/1 The analytical results are summarized in Tables 2 and 3 A copy of the laboratory report (CTEL Project No 214-0403215) and chain-of-custody form are included in Appendix B 4.0. SUMMARY AND CONCLUSIONS Based on the data collected from the site, AGE finds • During the March monitoring event, ground water was encountered at a depth of approximately 23 5 feet btoc At the former UST area, ground water flow was inferred to be generally towards the east under a gradient of 0 006 ft/ft Except for wells VW-1 and VW-3, all site wells are"drowned" and analytical data from these wells may not be representative of shallow-water conditions, analytical data from monitoring well MW-6, screened from 60 to 65 feet bsg, may be representative of deeper ground water conditions • The maximum concentrations of petroleum hydrocarbon and BTEX compounds in ground water were detected in the ground water sample collected from on-site vapor well VW-2d However, the current distribution of contaminates is limited MTBE was detected in the sample from the drowned vapor well VW-2d Advanced GcoEnviron mental,Inc