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10 01 May 2406 AGE-NC Project No 99-0657 tPage 2 of 4 ' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Ground water samples were collected from each purged well using the Waterra Inertia 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-milliliter (ml) volatile organic analysis (VOA)vials containing 0 5 ml 18%hydrochloric acid solution as a sample preservative and into one ' 1-liter amber bottle without 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(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, and • Benzene, toluene, ethyl-benzene, and total xylenes (BTEX) and the fuel additives di- isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), methyl tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary-butyl alcohol (TBA), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) in accordance with EPA . Method 8260B 3.4. FINDINGS 1 The ground water elevation, flow direction, and gradient were determined from field data collected on 08 February 2006, the contaminant impact to ground water was quantified by the laboratory analytical data 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the February 2006 sampling event, depths to ground water ranged from 34 74 feet (MW-7)to 38 04 feet(MW-9)below the tops of the well casings Ground water elevation at the site ' averaged approximately 7 9 feet above mean sea level (MSL), indicating an increase in average ground water elevation of approximately 18 feet since the last monitoring event In November 2005 During this monitoring event,the ground water levels in the wells were at least 5 feet below the tops of the well screens, indicating that the wells are screened properly to yield representative shallow ground water samples Ground water flow was inferred to be flowing toward the south-southwest under calculated hydraulic gradients ranging from approximately 0 003 foot/foot(ft/ft)to 0 006 ft/ft ' This flow direction remains consistent with the previous monitoring events Figure 3 shows the • contoured ground water elevations as measured on 08 February 2006 tAdvanced GeoEnvironmenfal,Inc