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1 - ' 13 April 2001 AGE-NC Project No 96-0232 ' Page I 1 of 14 ' treat system did not detect any constituents of concern • Dissolved MTBE was detected in water samples collected from the extraction wells at ' concentrations between 20 and 540µg/I, the greatest MTBE-impact water was detected at extraction well EW-4 near the southwest portion of the site • Dissolved MTBE was detected from grab samples collected at the influent-end of the ' treatment system at concentrations between 101 and 240µg/l • Between 06 December 2000 and 03 January 2001, the mass of MTBE-impacted ground ' water processed from operation of the pump and treat system was calculated to be 5,706,685 pounds Multiplying the average MTBE concentration (345 ,ug/l) by the pounds of MTBE- extracted water yielded a mass of approximately 1 97 pounds of MTBE removed from ' extracted ground water (Table 8, Appendix E) • Between 03 January and 02 February 2001, the mass of MTBE-impacted ground water ' processed from operation of the pump and treat system was calculated to be 6,595,109 pounds Multiplying the average MTBE concentration(195 µg/1)by the pounds of MTBE- extracted water yielded a mass of approximately 1 29 pounds of MTBE removed from extracted ground water (Table 8, Appendix E) • Between 02 February and 08 March 2001, the mass of MTBE-impacted ground water processed from operation of the pump and treat system was calculated to be 8,383,012 pounds Multiplying the average MTBE concentration (126 µg/1)by the pounds of MTBE- extracted water yielded a mass of approximately 1 06 pounds of MTBE removed from Iextracted ground water (Table 8, Appendix E) The results from the ground water monitoring and sampling events performed in March 2001 are as follows • Generally, depth to ground water at the site vaned between 9 and 12 feet bsg • First Zone ground water flow direction at the site appeared to be oriented northeast, east and southeast toward the area of MW-1 and MW-6A at an approximate gradient of 0 002 fUft or less (Figure 3), Second Zone ground water flow direction at the site appeared to be oriented toward the area of MW-1 and EW-2 radially inward in all directions at an approximate gradient of 0 02 ft/ft or less (Figure 4) Outside the area of influence of MW-1 and EW-2, Ithe ground water flow direction in Secondary Aquifer Zone and Primary Aquifer Zone appeared to oriented east at an approximate gradient of 0 001 ft/ft or less (Figures 5 and 6) • First and Second Zone ground water flow direction and gradient during the Flag City Chevron monitoring event appeared to be influenced by ground water extraction from wells EW-2, EW-4, EW-6 and EW-9 (south trench-line) I Advanced GeoEnvironmentai,Inc