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' 01 October 2004 • AGE-NC Project No 97-0333 ' Page 4 of 11 Laboratory analysis of extraction and treatment effluent grab water samples did not detect any constituents of concern Analytical results are summarized in Table 1, laboratory reports are in Appendix A iUtilizing a Blue-White Industries F-2000 flow meter,total flow(totalizer)was recorded between 26 December 2003 and 10 March 2004(Table 5) During this time,the extraction and treatment interim ground water remediation system was in operation for approximately 75 days Based on the total of approximately 280,576 gallons of water recorded during this time, AGE estimated that an average 3,741 gallons of water was discharged per day during this time 2 6 MASS-VOLUME REMOVAL CALCULATIONS Between 26 December and 10 March 2003,an estimated 13 56 pounds of MTBE was extracted from ground water (Table 5), since the system was initiated on 21 January 2002, a total mass of 233 90 pounds of MTBE has been removed The December 2003 to March 2004 mass-volume calculations of MTBE-impacted ground water extracted from the ground water extraction and treatment system are presented in Appendix B Plots of cumulative ground water 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 Between 31 March and 02 April 2004, ground water monitoring and sampling were performed at 46 ground water monitoring wells (MW-1 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 April 2002 As-built monitoring well construction details are summarized in Table 6 3 1 WELL MONITORING AND PURGE PROCEDURES ' On 31 March 2004 the depth to ground water was measured at each momtonn well from the to p 1� g p of each well casing to the nearest 0 01-foot utilizing a Solinst 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 Advanced GeoEnvironmental,Inc i