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I 27 September 2004 • AGE-NC Project No 01-0827 Page 3 of 5 ' 2 2 2 Ground Water Sample Collection and Analysis After allowing wells to achieve a minimum 80% recovery of the pre-purge water volume, a water sample was collected using the disposable bailer The sample was transferred into three 40-m1 EPA- approved volatile organic analysis (VOA)vials and a 1-liter amber container without preservative The samples were stored in a chilled container and transported under chain of custody to Cal Tech ' Environmental Laboratories (CTEL) a Department of Health Services (DHS)-certified analytical laboratory The samples were analyzed for ' • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g/d) in accordance with EPA Method 8015 Modified, ' • Benzene, toluene, ethylbenzene and total xylenes (BTEX), and the fuel oxygenated compounds tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), methyl-tertiary-butyl ether (MTBE), ' 1,2-Dichloroethane (1,2-DCA) and ethylene dtbromide (EDB) by EPA Method 8260 ' 30. FINDINGS ' Ground water flow directions and gradients were inferred from the field data collected on 10 August 2004 Contaminant impacts to ground water were assessed from the laboratory analysis of the ground water samples collected The DO concentrations and ORP were determined from field ' data collected on 10 August 2004 (Appendix A) ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION On 10 August, depths to ground water in monitoring wells MW-1 through MW-6 and vapor wells ' VW-1, VW-2d, VW-3 and VW-5d ranged from 23 25 to 24 91 feet below the tops of the casings (btoc) (Table 1) The ground water elevations and gradient were calculated and determined from depths to ground water data from monitoring wells MW-I through MW-5 The August ground water ' elevations at the site ranged from 13 35 feet (MW-5) to 14 38 feet (MW-2) below mean sea level (MSL) The ground water flow direction at the UST release was inferred to be towards the southeast, at a gradient of approximately 0 01 foot per foot (ft/ft) on-site (Figure 3) I I Advanced GeoEnvironmental,Inc I