SITE INFORMATION AND CORRESPONDENCE FILE 1

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D/0�k_ R- 1 62 10 May 2007 AGE-NC Project No. 0 -0769 Page 7 of 8 4.0. SUMMARY AND CONCLUSIONS Based on data collected during the January 2007 ground water monitoring event, AGE concludes : • Ground water elevation at the site ranged from 11 .37 feet to 13 .01 feet below MSL during the January 2007 monitoring event. Depth to ground water was between 23 . 16 feet and 26. 79 feet below the tops of the well casings . Graphs illustrating trends in depth to ground water measurements and ground water elevation are included in Appendix F. • In HU- 1 , inferred ground water flow directions are predominantly northeast and southeast (Figure 3). In HU-2, inferred ground water flow direction is generally towards the northeast and south-southeast (Figure 4). In HU-3 , inferred ground water flow directions are outward from well MW-4C (Figure 5) . In HU-4, inferred ground water flow directions are predominantly northeast and northwest (Figure 6). • The most highly impacted groundwater appears to be located near the former USTs, detected in wells MW4 , MW-2, MW- 3 , MW-4, and MW-5 . Laterally, analytes of concern were detected in all wells, except well MW-9; while this was the fourth quarter since December 2003 that contaminants have been detected in multi-level well MW-8 and the third quarter since March 2005 that contaminants have been detected in MW-2A. Vertically, hydrocarbon-impacted groundwaterwas detected in all wells except multi-level well MW-9; although contaminant levels generally decline with depth, well MW-41) (160 feet to 175 feet bsg) continued to contain major increases with depth since September 2004. Graphs illustrating concentration trends of TPH-g in the wells are included in Appendix F. • The lateral and vertical extent of petroleum hydrocarbon-impacted ground water have not been defined, especially due east and north ofthe site. The vertical extent of the fuel additive 1 ,2-DCA is not defined; the lateral extent of 1 ,2-DCA appears to be fairly well-defined except to the southeast, though the plume appears to be somewhat unstable. • BTEX compounds and 1 ,2-DCA are present in on-site monitoring wells at concentrations that exceed the DHS 's Maximum Contaminant Levels (MCLs) for these contaminants in drinking water. • Significant concentrations of TPH-g and BTEX compounds were once again detected in samples collected from MW-8 north of the site, which until April 2005 defined the northwest edge of the site. 5.0. RECOMMENDATIONS I Based on this and previous site investigations, AGE recommends: Adrnuced GeoEnviron nental, Inc.