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15 July 2002 AGE -NC Project No 96-0232 Page 7 of 21 The volume of extracted water between 22 May and 13 June 2002 was equal to 417,956 gallons, which equates to a mass of 3,484,499 pounds of water Multiplying the average MTBE concentration (assumed to be 23 5 µgll based on the average of the 22 May and the 13 June 2002 influent grab water samples) by the pounds of extracted MTBE -impacted ground water yields approximately 0 08 pounds of MTBE removed from MTBE -impacted ground water during this period (Appendix D) During the second quarter, an estimated 0 22 pounds of MTBE was extracted from ground water, to date, the ground water treatment system has removed a total of approximately 10 25 pounds of MTBE from extracted ground water (Table 8) Second quarter mass -volume calculations of MTBE - impacted ground water extracted from the ground water pump -and -treat system are presented in Appendix D Plots of cumulative ground water pump and treat mass removal trends and influent ground water MTBE concentrations versus time are in Appendix E 3.0. GROUND WATER MONITORING AND SAMPLING On 13 and 14 June 2002, ground water monitoring and sampling were performed at 30 ground water monitoring wells (MW -I through MW -13D), at eight ground water extraction wells (EW -2 through EW -8 and EW -10), one domestic drinking water well located at 14749 Thornton Road (DW -1) and two San Joaquin County service area No 31 municipal water wells (CSA -1 and CSA -2), extraction well EW -9 was not sampled due to a pump malfunction 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 SJCEHD by letter dated 24 February 1998 As -built monitoring well construction details are summarized in Table 9 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 tabulated ground water elevation results are in Appendix F In addition to the water level measurements conducted during the June quarterly monitoring event, monthly water level measurements were collected in April and May in accordance with a RWQCB letter dated 28 February 2002 3 1 WELL MONITORING AND PURGE PROCEDURES On 30 April, 22 May and 13 June 2002, 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 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 4) Ground water elevation and Advanced GeoEnvironmental, fnc.