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i j4 22 August 2000 �• AGE-NC Project No 95-0144 Page 6 of 8 32 ANALYTICAL RESULTS OF WATER SAMPLES ' During the May 2000 monitoring event, TPH-g was detected in samples from monitoring wells MW-21A and MW-21 B,both centered on the former UST No 8 site, at concentrations of 3,900 µg11 ' and 1,400 µg/1, respectively BTEX compounds were detected in samples from wells MW-21A and MW-21B at concentrations as'high as 210 µgll (benzene, MW-21A) TPH-d was detected in wells MW-19A, MW-20A, MW-21A, MW-20B and MW-21B at concentrations ranging from 150 µg/1 ' b to 2,400 µg/l TPH-mo was detected in monitoring well samples MW-19A, MW-21A and MW- 2 113 W2113 at concentrations of 320 µg/l, 300 4g/1 and 360 µg/l, respectively Hydrocarbon concentrations in the remaining wells generally remained low or non-detect MTBE was detected In ground water samples from well MW19A and MW19B ata concentration of 1 5 µg/1 (EPA Method 8260M) Ground water sampled from MW-21A contained MTBE at a concentration of 25 0µg/l(EPA Method 8260M) Other oxygenates were not detected in the samples collected at the site during the May 2000 monitoring event Historically, only low concentrations of MTBE and TBA have been detected intermittently at the site Analytical results for May 2000 are summarized on Table 2 Analytical results of recent and historical ground water samples are summarized on Tables 2 and 3 The laboratory report(MAI Laboratory I D Nos 37694-37703) and • , chain-of custody forms are included in Appendix C 4.0 SUMMARY/CONCLUSIONS Based upon data collected from the site, AGE concludes ' • Ground water elevation increased approximately 1 7 feet at the site since the previous ground water monitoring event Ground water remained above the screened interval in nine of the ' shallow wells sampled during the current quarter Ground water elevations in wells completed beneath the clay layer were lower than in wells completed within first ground water tPetroleum hydrocarbons were detected in five of the ten wells sampled during the May 2000 monitoring event Average concentrations of TPH-g and TPH-d have increased between the ' February 2000 and May 2000 monitoring events The average concentration of TPH-mo has decreased between February 2000 and May 2000 • The plume of ground water impacted by TPH-g is appears to be confined to the area centered ' on the former UST No 8 pit, and does not extend more than 40 feet southwest of the pit of more than 50 feet northeast of the pit • The plume of ground water impacted by TPH-d is larger than the TPH-g plume, extending at least 40 feet to the southwest of the former UST No 8 pit to MW-19 and more than 50 feet Advanced GeoEnvironmental,inc