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i I21 May 2001 . AGE-NC Project No 95-0173 ' Page 2 of 7 Approximately 1% gallons of ground water were removed from well MW-11 and 14 gallons from I MW-13 before being pumped "dry" Temperature, pH and conductivity of purged water were measured from each well for stabilization at regular purge-volume intervals using a water analyzer Field data and logs are included in Appendix A Purged ground water was contamenzed in 55-gallon drums and was stored on-site in an area lacking general public access 2 2 GROUND WATER SAMPLING I I Following well purging,ground water levels in the wells achieved a minimum of 80 percent recharge prior to sample collection Ground water samples were collected from the purged wells utilizing new, disposable polyethylene bailers and three 40-m1 EPA-approved VOA vials containing 0 5 ml I 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 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES IEach ground water sample was logged on a chain-of-custody form, placed in a chilled container and transported to a California Department of Health Services (DHS)-certified laboratory to be analyzed ' for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Methods 5030/8015M, t • Volatile aromatic compounds - benzene, toluene, ethyl benzene and xylene (BTEX) and -methyl-tertiary butyl ether(MTBE) by EPA Method 8020, • Fuel oxygenated compounds - tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and MTBE by EPA Method 8260 Modified 3.0. SOIL VAPOR EXTRACTION/IN-SITU AIR SPARGE PROCEDURES Between 01 January and 31 March 2001 (first quarter 2001), a SVE remediation system was continually operated at the site by applying an induced vacuum to wells VW-1, VW-2, VW-3, VW- 4, VW-5, VW-6 and VW-7 utilizing a Solleco Ecat 250 catalytic converter vapor extraction system, during this time, IAS remediation was continued at the site by air sparging at wells MW-1, MW-2, MW-3,AW-1,AW-2, AW-3,AW-4, AW-5, AW-6 and AW-7 SVE and IAS procedures for the site were described in Remedial Action Work Plan dated 30 December 1998, prepared by AGE, and IAdvanced GeoEnvironmental,Inc I