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I ' 12 July 2006 • AGE-NC Project No 95-0130 ' Page 2 of 14 ' • 28 February 2006 - Quarterly ground water monitoring event performed at wells MW-1 through MW-3, MW-5 through MW-8, VW-1C, VW-2A and VW-3A • 14 March 2006-Monthly monitoring event performed on P&T and SVE remediation system 1 ' 2.0. GROUND WATER MONITORING PROCEDURES A quarterly ground water monitoring event was performed at the site on 28 February 2006 Ground ' water monitoring procedures for the site were outlined in the Work Plan Addendum - June 2001, dated 11 June 2001 and approved by the San Joaquin County Environmental Health Department (SJCEHD) by letter dated 07 July 2001 2 1 WELL MONITORING AND PURGING ' On 28 February 2006, depth to ground water was measured in each well from the top of the well casing to the nearest 0 01-foot utilizing a Solinst water level meter Ground water could not be ' recovered from wells MW-6A and MW-7A and the monitoring location was subsequently reported as `dry', a tubing obstruction was encountered from well MW-7E and adequate purging of the well ' was not feasible, however, enough sample was obtained to fill sample containers, well MW-4 was inaccessible due to a parked car and could not be sampled The ground water elevation at wells MW-1,MW-2,MW-3 and MW-5 through MW-8 were calculated by subtracting the measured depth ' to ground water from the surveyed casing elevation As-built monitoring well construction details are summarized in Table 1 Ground water elevations were plotted and contoured on scaled site maps depicting First Zone and Second Zone ground water elevations (Figures 3 and 4, respectively) ' After water levels were measured, approximately 6 to 18 gallons of ground water (a minimum of three casing-water volumes per well) were purged from wells MW-1, MW-2, MW-3, MW-5 and MW-8 by lowering and raising a dedicated 3/S-inch diameter, length-discrete polyethylene hose equipped with a ball-valve water tip through the specific water-charged screened section Approximately 1/3 to 3'/4 gallons of ground water (a minimum of three casing-water volumes per ' well) were purged from wells MW-6 and MW-7 by lowering and raising a disposable 3/8-inch diameter,length-discrete polyethylene hose equipped with a ball-valve water tip through the specific water-charged screened section A Watera Hydro-Lift lI pump equipped with a mechanical arm was ' utilized to surge the polyethylene hose Temperature, pH and conductivity were measured for stabilization at regular purge-volume intervals from each well using the Oakton water analyzer Field data and logs are in Appendix A The purged ground water was transferred to the interim ground ' water pump-treat remediation system holding tank for treatment and disposal i Advanced GeoEnvironmental,Inc