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17 June 1996 AGE-NC Project,No 95-0121 Page 4 of 6 ' 4 0. FINDINGS 41 RELATIVE GROUND WATER ELEVATION AND GRADIENT 1 The depths to ground water in wells MW-1 through MW-9 ranged between 20 40 and 22 03 feet ' below the top of each well casing, and on the average rose approximately 129 feet between February 1996 and May 1996 Currently, ground water is between 2 to 11 feet above the top of the screen intervals in the nine ' ground water monitoring wells t ' Ground water flow direction at the site is generally toward the northeast at a, gradient of approximately 0 0016, or 9 feet per mile (Figure 3 -Surface Ground Water Elevation Contour Map) 42 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in water samples from MW-1 through MW-4, MW-6, and MW-7 at concentrations as high as 29,000 ppb(parts per billion reported as micrograms per liter), TPH-d was detected in samples from MW-1 through MW-4,and MW-6 through MW-9 at concentrations as high ' as 34,000 ppb Benzene was detected in samples from MW-1 through MW-7 at concentrations up to 7,800 ppb Toluene was detected in samples from MW-1 through MW-3, MW-6, and MW-7 at concentrations up to 1,300 ppb Ethyl benzene was detected in water samples from MW-i through MW-5, and MW- 7 at concentrations as high as 1,400 ppb Xylenes were detected in water samples from MW-1 through MW-7 at concentrations up to 1,600 ppb The analytical results for soil samples are summarized in Table 2 The laboratory report (CAL, Laboratory Batch Nos 764-1) and chain-of-custody forms are included in Appendix B f 5.0. CONCLUSIONS & RECOMMENDATIONS [ 51 CONCLUSIONS I Ground water flow direction has remained relatively constant at the site over the past two years Monitoring wells MW-6 and MW-9 continue to be up-gradient of the former UST area, while monitoring wells MW-8 and MW-5 continue to be down-gradient r I