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1 04 January 2002 AGE-NC Project No 95-0137 Page 5 of 6 Depths to ground water ranged from 20 02 to 21 04 feet below the well casing tops of the on-site wells The relative ground water elevations on the RFS site ranged from 78 27 feet to 78 58 feet There was an average decrease of the relative ground water elevation at the site of 1 5 feet over the last quarter The ground water elevations are shown on Figure 3 and contour ed to depict the local ground water flow direction A ground water depression appears at the remediation area and ground ' water appears to be near equal-gradient north and east of the remediation area The average gradient of the ground water flow on-site was 0 001 feet/feet The hydraulic gradient may have been slightly steeper west of the former UST and remediation area 35 ANALYTICAL RESULTS OF GROUND WATER SAMPLES 1 TPH-g was detected In four of the five ground water samples collected from the site, at concentrations ranging fiorn 270 �tg/l in sample MW-1 to 3,800 pg/l in samples MW-2 TPH-d was detected in all five ground water samples at concentrations i angrng from 180 gg/l in samples MW-4 to 3,300 [Ig/l In MW-3 Benzene was detected in four of the five samples collected from the monrtonng wells at concentrations as high as 180 µg/l(MW-2) Toluene, ethylbenzene and total xylenes were reported in sample MW-2 at concentr atlons of 6 2 µg/l, 180 µgrl and 180 µg/1, respectively The other ground water samples contained detectable concentrations of BTEX below 3 9 µg11,the maximum detection of xylene in the sample from well �VfW-1 ' MTBE was not detected above reporting limits In any of the samples utilizing EPA method 8020 Utilizing EPA method 8260,MTBE was detected in sample MW-3 at a concentration of 1 6 µg/l and TBA was detected In sample MWA at 32 µg/l DIPE was detected in sample MW-2 at a concentration of 1 2 µg/1 The other fuel additives were not reported in any of the samples The analytical results are summarized m Tables 5 and 6 A copy of the laboratory report (MAT Lab ID Numbers 80461 through 80465),quality assurance and quality control(QA/QC)report and chain- of-custody harn- ofcustody form ate included in Appendix D 4 0. SUMMARY AND CONCLUSIONS ' Based on the data collected from the site, AGE finds Ile • The ground water elevation decrease approximately 1 6 feet between 10 April and 04 October 2001, exposing additional Impacted-sort to the SVE system • Hydrocarbon concentrations in ground water increased slightly over the quarter,yet remained I well below the highest concentrations detected and average concentrations detected Advanced GeoEnvironmentaL Inc