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03 June 2002 i AGE-NC Project No 99-0657 ' Page 3 of 4 ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in the water samples collected from wells MW1, MW2 and MW4 at a maximum concentration of 8,100 micrograms/liter (µg/1), in the sample from MWI TPH-d was detected in water samples MW 1 and MW4 at a maximum concentration of 960 µg/l (MW 1) I One or more BTEX compound was detected in water samples MW1, MW2 and MW4 The maximum benzene (980 µg/1), toluene (410 µg/1) and xylenes (420 µg/1) concentrations were detected in water sample MW1, the maximum ethylbenzene concentration (42 µg/1) was detected in sample MW4 MTBE was detected by EPA Method 8021 in ground water samples collected from wells MW1, MW2 and MW4 at concentrations of 2,300 pg/l, 400 µ.g/1 and 320 µg11, respectively MTBE was confirmed by EPA Method 8260 in the same samples at concentrations of 2,800 µg/l, 520 gg/l and 370 µg/l, respectively and detected in the water sample from MW3 at a concentration of 8 0 11g/1 1,2-DCA was detected in ground water samples collected from MWI, MW3 and MW4 at concentrations as high as 49 µg/l (MW1) TAME was detected in the water sample collected from MW2 at a concentration of 2 6 µg/1 TBA was detected in the water samples from MW 1 and MW4 at concentrations of 350 µg/1 and 35 µg/l, respectively EDB and the other fuel additives were not detected in the ground water samples The analytical results of water samples collected in April 2002 are summarized on Table 2 The laboratory report(CTEL Lab I D No 0204-035-1 through 0204-035-4),QA/QC report and chain-of- custody form are included in Appendix B 4.0. SUMMARY AND CONCLUSIONS The following conclusions were drawn from the results of this investigation • The ground water elevations ranged from 7 77 to 8 04 feet above MSL Ground water is inferred to be flowing toward the southwest at an average gradient of 0 004 feet/feet The relative ground water elevation at the site increased an average 0 07 feet between the January 2002 and April 2002 monitoring events • Concentrations of dissolved TPH-g,TPH-d,BTEX,MTBE and 1,2-DCA have decreased in all the wells sampled since the last monitoring event in January 2002 The highest concentration of dissolved hydrocarbons occurred in monitoring wells MWI and MW4 which are south and south-southwest and downgradient of the UST area Isoconcentration ' maps depicting the approximate distribution of dissolved TPH-g, benzene and MTBE are presented in Figures 4, 5 and 6 Advanced GeoEnviron mental,Inc