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I 1 ^ x 4 , 12 March 1999 AGE-NC Protect No 95-0121 Page 4 of 7 each SVE/IAS well head to control vacuum and compressed air flow A utility sand was utilized to ' backfill the IAS and SVE pipe system in the trench to 6 inches bsg,the remaiiung void trench space was backfilled with stockpiled soil generated from trenching activities The SVE/IAS,piping system is depicted in Figure 5 ' 2 3 MONITORING WELL PURGE PROCEDURES Depths to ground water were measured from the top of each well casing at the site to the nearest 0 01 ' foot utilizing a Solinst water level meter Ground water elevations in each well at the site were calculated by subtracting the measured depth to ground water from surveyed casing elevations (Table 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 6) After water levels were measured, approximately twelve to sixteen gallons of ground water (a minimum of three well volumes per well) were removed (purged) from wells MW-1 through MW-9 ' utilizing a two-stage submersible pump, the first two gallons were removed utilizing a teflon bailer } and new rope Temperature, pH and conductivity were measured for stabilization at regular purge volume intervals from each well using an ICM Model 52200 water analyzer Field data and logs are included with Appendix D Purged ground water was containerized in 55-gallon drums and was stored on-site in an area lacking general public access 2 3 1 Ground Water Sampling Prior to sampling wells MW-1 through MW-9, ground water levels achieved a minimum of 80 percent recharge Ground water samples were collected from the purged wells utilizing new, disposable polyethylene bailers, and were transferred into one-liter amber bottles and four 40-m1 EPA-approved 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 filling and capping ' Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 2 3 2 Laboratory Analysis of Ground Water Samples 1 Each ground water sample was}logged on achain-of-custody form,placed in a chilled container and transported to Castle Analytical Laboratory and McCampbell Analytical Inc ,California Department ' of Health Services (DHS)-certified laboratories for analysis in accordance with • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline and diesel AdvancedGeoEmironmental,Inc i