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' 07 August 2002 i AGE-NC Project No 98-0465 ' Page 3 of 4 ' 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g, TPH-d and BTEX were not detected at concentrations at or above the laboratory reporting ' limits in any of the ground water samples MTBE was detected in samples collected from MWI, MW3 and MW4 by EPA Method 8260B at concentrations of 440 µg/l, 10 �ig/l and 2 3 gg/l,respectively No other fuel oxygenated compounds were detected in the ground water analyses Figure 4 illustrates the approximate extent of MTBE- impacted ground water ' Analytical results of water samples collected during January 2002 are summarized on Table 2, the laboratory report(MAI Lab IDs 0207022-001 through 0207022-004), QA/QC report and chain-of- custody form are included in Appendix B ' 4.0. SUMMARY ANIS CONCLUSIONS ' The following conclusions were drawn from the results of this investigation c The ground water elevations ranged from 7 68 to 7 82 feet below MSL Ground water was inferred to flow radially toward the north, varying from northwest to northeast, under an average gradient of 0 002 feet/feet The ground water elevation at the site decreased an average 1 4 feet between the January 2002 and June 2002 monitoring events G MTBE was detected in samples collected from MW-1,MW-3 and MW-4 at concentrations of 440 pg/l, 10 pg/l and 2 3 µg/1, respectively, by EPA Method 8260 G The sample collected from MW-1 during the June 2002 monitoring event contained the highest detected concentration of dissolved MTBE since monitoring began in July 2000 However, the detected concentrations of MTBE in MW-3 and MW-4 have remained ' relatively stable during the same period U The lateral extent of MTBE-impacted ground water has been defined to the northeast of the ' former UST area, but not toward the west to northwest, east or south s Advanced GeoEnvironmental,Inc 1