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' 05 July 2002 . AGE-NC Project No. 98-0520 ' Page 6 of 7 TBA was detected by EPA Method 8260B in groundwater samples from MW-2,MW-3 and MW-4 tat concentrations ranging from 34 µg11 in MW-4 to 150 µg/1 in MW-3. MTBE,EDB and 1,2-DCA were not detected at or above laboratory reporting limits in the ground ' water samples collected. Analytical results of ground water samples are summarized on Table 3. The laboratory report(MAI Lab I.D. No. 0203011-001 through 0203011-010) and chain-of-custody forms are included in. .Appendix F. 4.0. SUMMARY AND CONCLUSIONS ' Based'up on data collected from the site, AGE concludes: • Depth to ground water at the site averaged approximately 18.83 feet bsg on 28 February 2002. • On 28 February 2002 the ground water elevation at the site averaged approximately ' •. 17.73 feet above mean sea level, with a net flow towards the north-northwest under an average gradient of 0.001 ft/ft. ' TRH-g concentrations remainedrelatively stable in ground water samples collected,from MW-1 through MW-5 compared to the previous quarter monitoring. TPH-g and various BTEX compounds were detected in eight of the ten groundwater monitoring wells. • TBA was detected in three of the ten ground water monitoring wells at concentrations as high ' as 150 µg/l. • The vertical extent of petroleum hydrocarbon-impacted ground water has been defined, ' impacted ground water does not extend beyond 45 feet bsg. • The-lateral extent of petroleum hydrocarbon-impacted ground water has only been defined ' toward the north and south of the former UST area. 5.0. RECOMMENDATIONS , Based upon data collected from the site, AGE recommends continued quarterly ground water ' monitoring. The next quarterly monitoring event is scheduled for June 2002. Advanced CeoEnvironmental,Inc.