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Cu 4 30 October 2004 AGE-NC Project No 96-0232 Page 6of14 Between 15 June and 17 August 2004, an estimated 0 35 pounds of MTBE was extracted from groundwater,to date,the groundwater treatment system has removed a total of approximately 13 33 pounds of MTBE from extracted ground water (Table 5) Third quarter 2004 mass-volume calculations of MTBE-Impacted ground water extracted from the ground water pump-and-treat system are presented in Appendix C Plots of cumulative groundwater pump and treat mass removal trends and influent ground water MTBE concentrations versus time are in Appendix D 3.0. GROUND WATER MONITORING AND SAMPLING On 13 and 14 September 2004,ground water monitoring and sampling were performed at 37 single- or multi-level ground water monitoring wells (MW-1 through MW-19) Quarterly ground water monitoring procedures for the site were outlined in the AGE-prepared Work Plan Addendum, dated 28 January 1998, and approved by the San Joaquin County Environmental Health Department (SJCEHD) by letter dated 24 February 1998 As-built monitoring well construction details are summarized in Table 6 • A coordinated effort was made with Three B's Truck Plaza (14749 Thornton Road, Lodi CA) to conduct ground water monitoring activities concurrently, the Three B's Truck Plaza ground water elevation results and analytical results are In Appendix E 3 1 WELL MONITORING AND PURGE PROCEDURES On 13 September 2004, 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 Solmst 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-9,MW-11,MW-13,MW-16,MW-17,MW-18 and Three B's Truck Plaza wells MW-6, MW-9 and MW-10 are depicted in cross section C-C'(Figure 3), ground water elevations were plotted for the Informal First Zone,Second Zone,Secondary Aquifer Zone and Primary Aquifer Zone hydrogeologic units as defined In AGE's Final Remediation Plan (Figures 4, 5, 6 and 7, respectively) On 13 and 14 September 2004, approximately 33/4 to 15% gallons of ground water (a minimum of three casing-water volumes per well) were evacuated (purged) from wells MW-1 through MW-5, MW-6 (A and B), MW-7 and MW-16 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 F The purged ground Advanced GeoEnvironmental,Inc