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• 30 April 2005 AGE-NC Project No 99-0624 Page 2 of 4 I2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each purged well using a Watera hydrolift pump and dedicated tubing after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into three 40-m1 volatile organic analysis(VOA)vials containing 0 5 ml 18%hydrochloric acid as a sample 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 State of California Department of Health Services-certified analytical laboratory The samples were analyzed for ' a Totaletroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA P Methods 8015M, ' 0 Benzene, toluene, ethylbenzene and total xylenes(BTEX)in accordance with EPA Method 8260B, and ' 9 Fuel additives di-isopropyl ether(DIPS), ethyl tertiary-butyl ether(ETBE),methyl tertiary- butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), . 1,2-dichloroethane (1,2-DCA) and ethylene dibromide (EDB) in accordance with EPA ' Method 8260B ' 3.0. FINDINGS ' Ground water elevation, flow direction, and gradient were determined from field data The contaminant impact to ground water was quantified by the laboratory analytical data ' 3 1 GROUND WATER GRADIENT AND DIRECTION At the time of the February 2004 sampling event, depths to ground water ranged from 53 87 feet to 55 11 feet below the tops of the well casings (toc) Ground water elevations at the site ranged from 15 53 feet below mean sea level (MSL) in well MW-6 to 16 85 feet below MSL in well MW-5 ' (Table 1) During this monitoring event,the ground water levels in wells MW-1 through MW-6 were at least ten feet below the tops of the well screens, indicating that the wells are screened properly to ' yield representative shallow ground water samples The ground water elevation at the site increased approximately 1 36 feet between the November 2004 and February 2004 monitoring events ' The ground water was inferred to be flowing towards the south at a calculated gradient of 0 006 foot . per foot (ft/ft) Figure 3 illustrates the contoured ground water elevations as measured on 17 February 2005 ' Advanced GeoEnvironmental,Inc