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1' 18 August 1997 • AGE-NC Project No. 95-0185 Page 3 of 5 ' The ground water flow direction determined from the data collected during the March 1997 sampling event was toward the west, at a hydraulic gradient of 0.00025 ft/ft. The relative ground water elevations at the site are contoured on Figure 3 -Relative Ground Water Elevation. The ground water flow direction measured from the data collected during the June 1997 sampling event was toward the east, at a hydraulic gradient of 0,00033 ft/ft. The relative ground water ' elevations at the site are contoured on Figure 4 -Relative Ground Water Elevation. Ground water at the site has a very low gradient. At such a low gradient, normal measurement error can equal or even surpass the differences between wells, and can greatly influence the inferred ground water flow direction determination. The regional ground water flow direction is generally southwest. The mapped flow direction on the site has been a variation from the regional trend, but may be off in part due to minor measurement error. 3.2. ANALYTICAL RESULTS OF PURGED WATER SAMPLES Detectable concentrations of TPH-g or BTE&X were not present in the sample collected from the barrels of purge water stored on-site. However, MTBE was detected at 24 parts per billion (ppb, reported as micrograms per liter) and TPH-d was also detected at 260 ppb. The laboratory report ' (MAI Laboratory I.D. No. 74065), chain-of-custody and QA/QC report are included in Appendix B. J.3. LABORATORY RESULTS OF GROUND WATER SAMPLES - TPH-d was detected in ground water samples collected on 27 March 1997, from monitoring wells MW-1, MW-3 and MW-4 at concentrations of 1,900 ppb,_190 ppb and 2,600 ppb,respectively. TPH- g was detected in the ground water sample from MW-1" at a concentrations of 160 ppb. BTE&X compounds were detected in samples collected from MW-1 and MW-4 at concentrations as high as 5.5 ppb (xylenes, MW- 1). Benzene was detected in the water sample from MW-1, near the former ' UST area, at 0.65 ppb. Analytical results of monitoring well ground water samples are summarized in Table 2 -Analytical Results of Ground Water Samples. The laboratory report (MAI Laboratory I.D. Nos. 71805 to 71808), and chain-of-custody form are included in Appendix B. -- TPH-d was detected in ground water samples collected on 06 June 1997; from monitoring wells MW-1, MW-3 and MW-4 at concentrations of 6,000 ppb, 220 ppb and 220,000 ppb, respectively. ' TPH-g was detected in ground water samples from MW-1 and MW-4 at concentrations of 200 ppb • and 390 ppb , respectively. BTE&X compounds were detected in samples collected from MW-1 and MW-4'at concentrations as high as 5.4 ppb (xylenes, MW- 1). Benzene was detected in the water Advanced GeoEnvironmental,Inc. 1 -