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08 November 2002 AGE-NC Project No.02-0918 Page 8 of 9 4.4. GROUND WATER ELEVATION,FLOW DIRECTION AND GRADIENT Depth to ground water at the site ranged from 40.83 feet to 41.54 feet below the monitoring wells casing tops. The ground water elevations at the site ranged from 25.35 feet (MWI) to 25.41 feet (MW3)below mean sea level (MSL). The ground water flow direction and gradient were calculated from the well elevation data. The ground water flow was directed toward the southeast at a gradient of 0.00 15 ft/ft.Figure 4 illustrates the contoured ground water elevations as measured on 02 July 2002. 5.0. SUMMARY AND CONCLUSIONS Based on the data collected from the site, AGE finds: • Silt occurred under most of the site; sand units were encountered in the former UST area at depths of approximately 10, 20 and 50 feet bsg. • Petroleum hydrocarbons were detected in the soil samples analyzed from boring B1, advanced within, the former UST excavation, and MW2 and MW3, located north and southeast,respectively,of the former UST.The highest concentrations of TPH-g and BTEX compounds were detected at 20 and 30 feet bsg in boring B 1. • The highest concentrations of MTBE in soil was detected in sample B1-40, located on the eastern portion of the former UST area. • Ground water occurred at approximately 40 feet bsg during the July 2002 monitoring event The ground water flow direction was inferred to be southeast at a gradient of 0.0015 ft/ft. • With the exception of ethylbenzene in ground water sample B1,TPH-g,BTEX and MTBE concentrations were significantly above 1,000 µg11 in ground water samples B 1,MW2 and MW3; much lower concentrations of TPH-g and MTBE and no BTEX compounds were detected in MW L • With the exception of ethylbenzene in ground water sample B1, BTEX compounds and MTBE present in the ground water samples all exceeded the DHS's Maximum Contaminant Levels for drinking water. • The vertical extent of petroleum hydrocarbons-and MTBE-impacted soil and ground water and the lateral extent of impacted ground water have not been delineated. Advanced GeoEnvironmental,Inc.