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1 ' 05 September 2003 AGE-NC Project No 97-0333 ' Page 4 of 10 ' recorded during this time,AGE estimated that an average 1,745 gallons of water was discharged per day during this time 2 6 MASS-VOLUME REMOVAL CALCULATIONS ' Between 12 December 2002 and 27 March 203, an estimated 8 36 pounds of MTBE was extracted from ground water (Table 5), since the system was initiated on 21 January 2002, a total mass of 197 67 pounds of MTBE has been removed The December 2002 to March 2003 mass-volume ' calculations of MTBE-Impacted ground water extracted from the ground water pump-and-treat system are presented in Appendix B Plots of cumulative groundwater pump and treat mass removal trends and Influent ground water MTBE concentrations versus time are in Appendix C 3.0. GROUND WATER MONITORING AND SAMPLING I ' On 27 and 28 March 2003, ground water monitoring and sampling were performed at 47 ground water monitoring wells(MW-I through MW-13) Quarterly ground water monitoring procedures for !. the site were outlined in the AGE-prepared Work Plan Addendum, dated 03 April 2002,prepared by AGE and approved by San Joaquin County Environmental Health Department(SJCEHD)by letter ' dated 12 Apnl 2002 As-built monitoring well construction details are summarized in Table 6 3 1 WELL MONITORING AND PURGE PROCEDURES On 27 March 2003, the depth to ground water was measured at each monitoring well from the top ' of each well casing to the nearest 0 01-foot utilizing a Sollnst water level meter The ground water elevation in each monitoring well was calculated by subtracting the measured depth to ground water from the surveyed casing elevation(Table 2) Ground water elevation and vertical gradient data for ' wells MW-11, MW-12 and MW-13 are depicted in cross section F-F' (Figure 3), ground water elevations were plotted In plan view for the Informal First Zone, Second Zone, Third Zone and Primary Aquifer Zone hydrogeologic flow units as defined in AGE's Cone Penetrometer Testing Site ' Investigation -Fourth Quarter 2000, dated 07 February 2001 (Figures 4 through 7) On 27 and 28 March 2003, approximately 6 to 13 gallons of ground water (a minimum of three casing-water volumes per well)were evacuated(purged)from wells MW-1 through MW-6 utilizing disposable polyethylene bailers Temperature,pH and conductivity were measured for stabilization at regular purge-volume intervals from each well using an Oakton water analyzer Field data and logs are provided in Appendix D The purged ground water was transferred to the ground water interim remediation system holding tank for treatment and disposal ' Advanced GeoEnvironmental,Inc