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I ' 15 November 2004 AGE-NC Project No 96-0229 ' Page 2 of 6 ' Ground water monitoring procedures for the site were outlined in Work Plan Addendum, dated 11 April 2003, prepared by AGE and approved by San Joaquin County Environmental Health Department (SJCEHD) by letter dated 07 May 2003 2 1 GROUND WATER MONITORING PROCEDURES On 01 June 2004, 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 The ground water elevation in each well ' was calculated by subtracting the measured depth to ground water from the surveyed casing elevations (Table 2) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) ' After water levels were measured, approximately 4 0 to 10 0 gallons of ground water(a minimum of three casing-water volumes per well)were evacuated(purged)from wells MW-1 through MW-12 utilizing disposable 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 included in Appendix A Purged ground water was containerized in 55-gallon drums and stored ron-site In an area lacking general public access ' Approximately 0 3 to 3 0 gallons of ground water(a minimum of three casing-water volumes per well) were purged from multi-level wells MW-13 (A-D), MW-14 (A-D), MW-15 (A-D), MW-16 (A-E), MW-17 (A-C), MW-18 (A-E), and MW-19 (A-C) Each well was purged by lowering and raising a 3/9-inch outer diameter,length-discrete polyethylene hose equipped with a ball-valve water tip through the top chambers into the specific water-charged screened section A Waterra Hydro- Lift II pump equipped with a mechanical arm was utilized to surge each well with a polyethylene ' hose 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 included in Appendix A Purged groundwater was containerized In 55-gallon drums and stored on-site in an area ' lacking general public access 2 1 1 Ground Water Sampling Following well purging, the ground water level from each well was allowed to achieve a minimum of 80% recharge prior to sample collection, however, 80% recharge was not achieved from well MW-I due to a combination of water drawn down nearly to the bottom of the screen section and slow recharge Ground water samples were transferred into 40-milliliter(ml)EPA-approved volatile organic analysis (VOA) vials containing 0 5 ml 18% hydrochloric acid solution as a sample preservative Care was taken to ensure that visible air bubbles were not present in the vials after ' Advanced GeoEnvi ran mental,Inc