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I04 November 2005 . AGE-NC Project No 02-0950 ' Page 2 of 4 sample was transferred into three laboratory supplied, 40-milliliter (ml) volatile organic analysis I (VOA)vials containing 0 5 ml 18%hydrochloric acid solution as a preservative,and into one 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) and diesel (TPH-d) in accordance with EPA Method 8015 Modified, ' • Benzene,toluene,ethylbenzene,and total xylenes(BTEX)and fuel additives methyl tertiary- butyl ether(MTBE),tertiary-butyl alcohol (TBA),di-isopropyl ether(DIPE), ethyl tertiary- butyl ether(ETBE),tertiary-amyl methyl ether(TAME), 1,2-dichloroethane(1,2-DCA),and ' 1,2-dibromoethane (EDB) in accordance with EPA Method 8250B ' 3.0. FINDINGS ' Ground water elevation, flow direction, and gradient were determined from field data collected on 12 September 2005 The contaminant impact to soil and ground water was quantified from laboratory analytical data 1 ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the September 2005 sampling event, depths to ground water ranged from 18 22 feet ' (MW-5)to 18 70 feet(MW-2)below the tops of the well casings Ground water elevation at the site averaged approximately 10 71 feet below mean sea level (MSL), indicating an overall average decrease in ground water elevation of 128 feet between June 2005 and September 2005 (Table 1) ' During this monitoring event, the ground water levels in all wells were below the tops of the well screens,indicating that the wells are screened properly to yield representative shallow ground water samples IGround water was inferred to be flowing east to northeast on the northern portion of the site and east to southeast on the southern portion, under a hydraulic gradient of approximately 0 004 foot/foot ' (ft/ft) Figure 3 illustrates the contoured ground water elevations as measured on 12 September 2005 Ground water directions and gradients can vary greatly, as they are influenced by seasonal changes to the static water table 1 • ' Advanced GeoEnvironmental,Inc