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' 26 February 2004 AGE-NC Project No 98-0448 ' Page 2 of 10 ' 2 1 WELL MONITORING AND EVACUATION During both December 2003 and January 2004 monitoring events, depth to ground water measurements were collected in monitoring wells MW-1 through MW-8 from the top of the well ' casing to the nearest 0 01-foot utilizing a Solinst water level meter Due to a parked vehicle, ground water measurements were not collected from MW-3 on 29 December 2003 The ground water ' elevation in each well was calculated by subtracting the measured depth to ground water from the surveyed casing elevation(Table 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) ' After water levels were measured, approximately 6%2 to 15 gallons of ground water(a minimum of three casing-water volumes per well)were evacuated(purged)from wells MW-1,MW-2,MW-4(A ' and B) and MW-6 utilizing either a polyethylene disposable bailer or a stainless steel bailer 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 provided in Appendix A Purged ground water was contamenzed in properly labeled Department of Transportation (DOT)- approved 55-gallon drums and was stored on-site in an area lacking general public access 2 2 GROUND WATER SAMPLING ' Following well purging, the ground water level in each of the purged wells was allowed to achieve a minimum of 80%recharge prior to sample collection Ground water samples were collected from the purged wells utilizing new, disposable polyethylene bailers and transferred into 40-mi 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 filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials I23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain-of-custody form,placed in a chilled container and transported to-Castle Analytical Laboratory (CAL), a California Department of Health Services (DHS)-certified laboratory for analysis for I • Total petroleum hydrocarbons quantified as gasoline (TPH-g)by EPA Method 5030/8015, ' • Benzene, toluene, ethylbenzene and xylene (BTEX) and methyl tert butyl ether(MTBE)by • EPA Method 8020, and Advanced GeoEnvironmental,Inc