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' 27 May 2004 AGE-NC Project No 96-0229 Page 2 of 7 ' prepared Work Plan Addendum -June 1998, dated 10 June 1998, and approved by the San Joaquin County Environmental Health Department (SJCEHD) by letter dated 24 June 1998 2 1 GROUND WATER MONITORING PROCEDURES On 25 November 2003, 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 Ievel meter The ground water elevation in each well was calculated by subtracting the measured depth to ground water from the surveyed ' casing elevation(Table 2) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) ' After water levels were measured, approximately 3'/4 to 10% 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, however, approximately 9'/2 gallons of water were purged from MW-1 and 6 gallons from MW-2 before the well was purged"dry" 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 with Appendix A Purged ground water was containerized in 55-gallon drums and was stored on-site in an area lacking general public access ' Approximately 1'/4 to 3 gallons of groundwater(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/a-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 Watera-Hydro-Lift H 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 with Appendix A Purged ground water was containerized in 55-gallon drums and was 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 I - of 80 percent recharge prior to sample collection, however, 80% recharge was not achieved from wells MW-13A and MW-l3D 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-m1 EPA- approved volatile organic analysis(VOA)vials containing 0 5 ml 18%hydrochloric acid as a sample • preservative Care was taken to ensure that visible air bubbles were not present in the vials after f Advanced CeoEnvironmental,Inc