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S I ' Q ' 15 February 2006 AGE-NC Protect No 95-0184 ' Page 3 of 7 2 2 WELL MONITORING AND PURGING ' n 2005 a Sollnst water level meter was used to measure the depth to ground water O 02 December , in five ground water monitoring wells and five vapor extraction wells relative to the tops of the well ' casings The ground water elevations and gradient were determined from this data(Table 1) ' After recording water level measurements,a Waterra Hydrolift Pump was used to purge monitoring wells MW-1 through MW-4,MW-7, and at the direction of the EHD,vapor wells VW-3,and VW-4 were purged of standing water,dedicated disposable plastic bailers were used to purge wells VW-213, ' VW-5B and VW-5C of standing water The wells were generally evacuated in order of least contaminated to most contaminated, based on previous monitoring data Between 16 5 and 19 gallons of water(a minimum of three casing'water volumes)were purged from monitoring wells MW-1 through MW-4,and between 8 5 and 12 gallons of water were purged from monitoring well MW-7 and vapor extraction wells VW-2B, VW-3, VW-4, and VW-5C ' Approximately 3 5 gallons of water was removed from vapor extraction well VW-5B Ground water temperature,pH,and conductivity were measured at regular intervals during the purge process using an Oakton water analyzer Purged water was stored on-site in properly labeled, Department of • Transportation(DOT)-approved 55-gallon drums The field data sheets are included in Appendix C 23 COLLECTION OF GROUND WATER SAMPLES Water samples were collected from wells MW-1 through MW-4, MW-7,VW-3, and VW-4 with a hose bailer,while dedicated disposable plastic bailers were used to sample the remaining wells after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into laboratory-supplied, 40-milliliter(ml)volatile organic analysis (VOA) ' vials containing 0 5 ml 18%hydrochloric acid solution as a sample preservative, the sample from MW-4 was also transferred into a 1-liter amber bottle without preservative After collection, the ' samples were properly labeled,placed in a chilled container,and transported under chain of custody to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified analytical laboratory, for analysis The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015M, and • Volatile organic compounds (VOCs) benzene, toluene, ethylbenzene, and total xylenes ' (BTEX) and fuel oxygenates di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), methyl tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary-butyl ' alcohol(TBA), 1,2-dibromoethane(EDB),and 1,2-dichloroethane(1,2-DCA)in accordance • with EPA Method 8260B Full Scan _ ' Advanced GcoEnvsronmental,Inc