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i 20 July 1998 AGE-NC Project No 95-0137 ' Page 6 of 8 The gradient for this quarter was calculated to be 0 001 ft/ft, with an approximate flow direction of N 81' W on the northern portion of the RFS site and was calculated to be 0 01 ft/ft, with an approximate flow direction of N 13° W on the monitored portion of the Jimeo portion of the site Historically,ground water flow direction at the site has vaned from northwest to south,consistently at a low gradient ' Figure 3 -Relative Ground Water Elevation illustrates the contoured relative ground water elevations as measured on 29 May 1998 3 4 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in wells MW-1 though MW-8 at concentrations as high as 5,900 parts per billion(ppb,reported as micrograms per liter) TPH-d was detected in wells MW-1 through MW-8 ' at concentrations up to 2,200 ppb (MW-2) TPH-g was detected in the soil vapor wells (VW-1 and VW-2), with screen interval to 20 feet bsg at concentrations of 12,000 and 4,700 ppb, respectively ' Benzene was detected in the sample from wells MW-2, VW-1 and VW-2 at concentrations of 850 ppb, 2,000 ppb and 30 ppb, respectively Toluene was detected at a maximum concentration of 61 ppb in well VW-1 Ethylbenzene and xylenes were detected at maximum concentration in samples ' collected from well VW-1 at 720 ppb and 800 ppb, respectively Low concentrations ( less then 3 ppb) or lack of detectable BTE&X compounds was demonstrated in wells MW-1 and MW-3 through MW-8 DIPE was detected onlyin the sample from well MW-8 at 6 1 b TBA was detected in the samples P PP P from wells MW-1, MW-4, MW-8 and soil vapor well VW-2 at concentrations of 23 ppb, 20 ppb, ' 22 ppb and 35 ppb, respectively TBA was detected in the samples from ias spargmg wells VW-1 and VW-2 at concentrations of 7 1 ppb and 5 2 ppb, respectively MTBE, ETBE and TAME were ' not detected in any of the wells sampled Analytical results of ground water samples for each monitoring event analyzed by EPA methods ' 8015m and 8020 are summarized m Table 2 Analytical results for ground water samples analyzed by EPA methods 8260m are summarized in Table 3 The laboratory report (MAI Lab ID Numbers 89899 through 89910), quality assurance and quality control (QA/QC) and chain-of-custody are tincluded in Appendix E ' Advanced GeoEnvironmcntal,Ine