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25 January 2005 AGE-NC Project No 01-0827 IPage 4of5 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES Based on analysis of the 03 December 2004 ground water samples,TPH-g was only detected in the I ground water sample collected from well VW-2d at a concentration of 910 micrograms per liter (µg/1) BTEX compounds were also detected in the ground water sample collected from well VW-2d at concentrations of 57µg/1 benzene, 4 5 µg/1 toluene, 7 5 µg/1 ethylbenzene and 10 6 µg/1 xylenes I The fuel additive MTBE was detected only in sample VW-2d at a concentration of 16 µg/1 (Tables 2 and 3) No additional analytes were detected at or above laboratory reporting limits in the samples analyzed ' The analytical results are summarized in Tables 2 and 3 A copy of the laboratory reports (CTEL Project No CT214-041031), quality assurance/quality control and chain of custody forms are I included in Appendix B GeoTracker confirmation pages of the submitted laboratory electronic deliverable format (EDF) files are included in Appendix C ' 4.0. SUMMARY AND CONCLUSIONS Based on the data collected from the site, AGE finds I • On 03 December 2004, ground water was encountered at a depth of approximately 24 feet btoc, which is a decrease of approximately 0 5 feet since the August sampling event • The ground water flow direction was inferred to be towards the east on-site, at a gradient of Iapproximately 0 01 ft/ft on-site • With the exception of wells VW-1 and VW-3, all wells are"drowned" and analytical data ' from these wells may not be representative of the shallow ground water conditions • The only detections of TPH-g and BTEX compounds were in the ground water sample ' collected from deep vapor well VW-2d,MTBE was the only fuel additive detected also from sample VW-2d The concentrations of MTBE and benzene are above their respective DHS Maximum Containment Levels (MCL) for drinking water ' • Low ORP values,detected in the source area,demonstrate the presence of generally reduced environment in the saturated zone near the source area Ideally, the introduction of oxygen rich air (ozone air sparging) in the source area should produce an oxidizing environment which will lead to a reduction in contaminant levels Dissolved oxygen concentrations collected from wells at the site, since operation of the ozone air sparge system commenced, indicate an adequate migration of ozone-rich sparged air into the subsurface • Generally, since the initiation of operation of the ozone-spargmg system, dissolved concentrations of TPH and BTEX compounds have decreased While upward fluctuations Advanced CeoEnv►ronmental,Inc I