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15 July 2002 AGE -NC Project No 96-0232 Page 14 of 21 A total volume of approximately 13,972,813 gallons of MTBE -impacted water has been treated at the site since the start-up period in November 2000 (Table 8) • Dissolved MTBE was detected (utilizing EPA Method 826OM) in water samples collected from extraction wells EW -4, EW -5, EW -6, EW -8 and EW -10 at concentrations between 1 4 µg/1(EW-6) and 29 µg/1(EW-4), the greatest MTBE -impacted water was collected from extraction well EW -4 near the southwest corner of the site From the March 2002 to the June 2002 sampling events, the laboratory reported subtle decreases m MTBE concentrations from wells EW -4, EW -5, EW -6, 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 19 µg/1 and 33 µg/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 27 March 2002 and 16 April 2002, the mass of MTBE -impacted ground water processed during operation of the pump and treat system was calculated to be 3,084,915 pounds Multiplying the average MTBE concentration (22 5 µg/1) by the pounds of MTBE - extracted water yielded a mass of approximately 0 07 pounds of MTBE removed from the extracted ground water (Table 8, Appendix D) Between 16 April 2002 and 22 May 2002, the mass of MTBE -impacted ground water processed during operation of the pump and treat system was calculated to be 2,398,697 pounds Multiplying the average MTBE concentration (30 5 µg/1) by the pounds of MTBE - extracted water yielded a mass of approximately 0 07 pounds of MTBE removed from extracted ground water (Table 8, Appendix D) • Between 22 May and 13 June 2002, the mass of MTBE -impacted ground water processed during operation of the pump and treat system was calculated to be 3,484,499 pounds Multiplying the average MTBE concentration (23 5 µg11) by the pounds of MTBE -extracted water yielded a mass of approximately 0 08 pounds of MTBE removed from extracted ground water (Table 8, Appendix D) • A plot of cumulative ground water pump and treat mass removal versus time and a plot of influent ground water MTBE concentrations versus time suggest a continued trend of decreasing MTBE concentrations (Appendix E) The results from the water level measurements performed on 30 April and 22 May 2002 are as follows • Ground water elevation at the site varied between 197 feet and 2 42 feet below mean sea level (MSL) on 30 April 2002 and between 3 01 feet and 4 03 feet below MSL on 22 May 2002 Advanced GeeEnvironmental, Inc