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• 09 May 2002 AGE-NC Project No 96-0232 Page 13 of 18 sampling events,the laboratory reported subtle Increases In MTBE concentrations from wells EW-4, EW-5, EW-8 and EW-10 (Table 5) • Dissolved MTBE was detected from grab samples collected at the Influent-end of the treatment system at concentrations between 12 and 41 gg/l (Table 1) • Laboratory analysis of three grab water samples collected at the effluent-end of the pump and treat system did not detect any constituents of concern(Table 1) • Between 12 December 2001 and 03 January 2002, the mass of MTBE-Impacted ground water processed during operation of the pump and treat system was calculated to be 4,492,826 pounds Multiplying the average MTBE concentration(30 5 µg/1) by the pounds of MTBE-extracted water yielded a mass of approximately 0 13 pounds of MTBE removed from the extracted ground water(Table 8, Appendix E) • Between 03 January 2002 and 04 February 2002,the mass of MTBE-Impacted ground water processed during operation of the pump and treat system was calculated to be 7,025,365 pounds Multiplying the average MTBE concentration (35 µg/1) by the pounds of MTBE- extracted water yielded a mass of approximately 0 25 pounds of MTBE removed from extracted ground water(Table 8, Appendix E) • Between 03 January and 27 March 2002, the mass of MTBE-impacted ground water processed during operation of the pump and treat system was calculated to be 18,440,677 pounds Multiplying the average MTBE concentration(20 5 µg/1)by the pounds of MTBE- extracted water yielded a mass of approximately 0 37 pounds of MTBE removed from extracted ground water (Table 8, Appendix E) The results from the ground water monitoring and sampling events performed in March 2002 are as follows • Generally, depth to ground water at the site varied between 9 and 12 feet bsg • First Zone ground water flow appeared to be inward toward an east-west-trending depression of the water table which extends from the east side of Flag City Chevron towards the west end of Three B's Truck Plaza, ground water gradients range from 0 002 fl/ft at Flag City Chevron to 0 01 ft/fl at Three B's Truck Plaza (Figure 3) • Ground water flow direction In Second Zone ground water at the site was inferred to be bi- directional,from the east and the west towards a south-plunging depression of the water table in the area of MW-6B, at an approximate gradient of 0 002 ft/ft or less (Figure 4) • Secondary Aquifer Zone ground water flow direction was Inferred to be radially inward toward a south-plunging depression of the water table In the area of MW-12C at an approximate gradient of 0 001 ft/fl or less (Figure 5) Advanced GeoEnvj ron mental,Inc