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I ' 31 August 2004 • AGE-NC Project No 95-0173 ' Page 2 of 10 ' site were outlined in Work Plan Addendum, dated 16 May 2000 and conform to ground water monitoring guidelines issued by the San Joaquin County Environmental Health Department (SJCEHD) As built construction details of all monitoring wells are summarized in Table 1 2 1 WELL MONITORING AND EVACUATION PROCEDURES On 19 March 2004, the depth to ground water was measured at each well from the tops of the well casings to the nearest 0 01-foot, utilizing a Solinst water level meter Ground water elevation at the ' site was calculated by subtracting the measured depth to ground water from the surveyed well 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 1/4to 93/4 gallons of ground water(a minimum of three casing-water volumes per well) were evacuated (purged) from single-level monitoring wells MW-1 through MW-12,and air sparge wells AW-1 A and AW-2A utilizing disposable polyethylene bailer,only%gallon of water was purged from MW-11 before the well was purged`dry' Multi-level • monitoring well MW-13 (A-C) and air sparge wells AW-1B and AW-2B were purged by lowering and raising a 3/s-inch or Y2-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 II pump equipped with a mechanical arm was utilized to surge the polyethylene hose Approximately 21/4 and 3'/4 gallons of ground water(a minimum of three casing-water volumes per well) were purged from multi-level wells MW-13A and MW-13B, respectively, and I approximately 15 and 20 gallons were purged from air sparge wells AW1-B and AW-2B, respectively, only I gallon of water was purged from MW-13C before the well was purged `dry' 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 Purged ground water from the above wells was transferred to 55-gallon drums and stored on-site in an area ' lacking general public access Due to discrepancies with previous analytical monitoring data, well MW-13C was re-sampled on 09 Apri 12004 utilizing the above mentioned Watera-Hydro-Lift IT pump equipped with a mechanical arm and polyethylene hose Approximately 4 gallons of ground water(a minimum of three casing- water volumes per well) were purged from multi-level well MW-13C • Advanced GeoEnvironmental,Inc