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1 ' 07 February 2003 .. ; AGE-NC Project No. 98-046$ •; , Page 2 of 4 measured at regular intervals using an Oakton Water Analyzer. The field data sheets are included ' in Appendix A. Purged water was stored on site in 55-gallon drums. ' Water sampling tools were cleaned prior to utilization at each well location. Wash and rinsewater generated from decontaminating the equipment was placed in properly labeled DOT-approved model 17H 55-gallon drums and stored on-site. 2.1.2. Collection and Analysis of Ground Water Samples After allowingthe wells to achieve a minimum 80%recovery of thepre-purge water volume,water r5' . samples were collected from wells MW-3 through MW-8 utilizing a dedicated,disposable bailer and from wells MW-9 to MW-10 using the Wattera pump system. The samples were transferred into 40-m1 EPA-approved vials containing 0.5 ml 18%hydrochloric acid as a sample preservative. The sample containers were then labeled with the monitoring well designation, date, time of sampling ' and the sampler's initials. The samples were subsequently transported'in a chilled container under: chain-of-custody to McCampbell Analytical Inc. (MAI), a Department of Health Services (DHS)- certified laboratory-in Pacheco, California. The ground water samples were analyzed for: ; . ' Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary butyl.ether (MTBE) in accordance with EPA Method 8260 Modified. 3.0. FINDINGS Ground water elevation, flow direction and gradient were determined from field data collected on ' 24 December 2002. The contaminant impact,to ground water was assessed from the laboratory analyses of the monitoring well ground water samples., �. 3.1. GROUND WATER GRADIENT AND FLOW DIRECTION ' Depths to ground water during the fourth quarter 2002 ranged between 10.33 and 13.80 feet below the tops of.the well casings(btoc) of water table wells and ranged between 12.07 and 18•.06 feet btoc in the deep-screened.wells. The ground water elevations of the five surveyed wells MWA ' through MW-5"ranged from 3.44 feet below mean sea level'(MSL)in MW-3 to 4.58 feet below MSL in MW-4; ground water elevation decreased in four. wells (MW-1, MW-2, MW-4.and MW-5) an average of 0.23 feet, and increased by 0.05 feet in well MW-3. ' • elevations from wells MW-1 through MW-5. Based on ground water e e g , ground water flow direction IS inferred to be toward the northeast at a gradient of 0.022 (Figure 3). Advanced GeoEnvironmentai,"Inc.