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i 03 February 2004 • AGE-NC Project No 98-0500/04-1127 Page 2 of 6 I A set of dedicated Waterra inertial bailers or dedicated disposable bailerwere used to purge between 15 5 and 16 gallons of ground water from wells MW-18 and MW-21,between 23 and 25 5 gallons of ground water from wells MW-22 through MW-24,6 5 gallons of ground water from wells MW-25 I and MW-26, and approximately 20 to 41 gallons of ground water from wells MW-27 through MW-34 Temperature,pH and conductivity were measured for stabilization at regular purge-volume intervals using an Oakton water analyzer/meter Field data and logs are provided in Appendix B I Purged ground water was containerized in 55-gallon drums and was stored on-site,pending proper disposal 2 2 GROUND WATER SAMPLING Water samples were collected from each monitoring well using dedicated disposable or dedicated Waterra bailers after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume The samples were transferred into three 40-m1 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 VOA vials after filling and capping The ground • water sample containers were subsequently labeled with the well designation, date, time, and sampler's initials 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain-of-custody form,placed in a chilled container and shipped to McCampbell Analytical,Inc (MAI),a California Department ofHealth Services(DHS)- certified analytical laboratory Selected samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline and stoddard solvent (TPH-g and TPH-ss) in accordance with EPA Method 8015 Modified, • Volatile organic compounds(VOCs),including benzene,toluene,ethylbenzene and xylenes (BTEX) and the fuel additives 1,2-dibromoethane (EDB), 1,2-dxchloroethane (1,2-DCA), tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME), methyl tertiary-butyl ether (MTBE)by EPA Method 8260B 3.0. FINDINGS Ground water elevation,flow direction and gradient were determined from field data collected on 29 • and 30 December 2003 The contaminant impact to ground water was assessed from the ground water laboratory data IAdvanced Geo Environmental,Inc