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1 - , . 20 July 2004 AGE-NC Project No 99-0657 ' Page 2 of 4 ' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each purged well using new disposable plastic bailers after ' - allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into one 1-liter amber bottle without sample preservative and 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 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,ethylbenzene and total xylenes(BTEX)and the fuel additives di-isopropyl ether(RIPE),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 3.0. FINDINGS Ground water elevation, flow direction, and gradient were determined from field data collected on 12 January 2004 The contaminant impact to ground water was quantified from the laboratory analytical data 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the January 2004 sampling event, depths to ground water ranged from 35 03 (MW-7) feet to 37 08 (MW-6) feet below the tops of the well casings Ground water elevation at the site averaged approximately 5 36 feet above mean sea level (MSL) which indicates an increase in elevation of approximately 0 77 feet since the October 2003 monitoring event (Table 1) During this monitoring event, the ground water levels In the wells were at least four 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 towards the southwest with an average hydraulic gradient of 0 003 foot/foot This flow direction remains consistent with the previous monitoring events Figure 3 illustrates the contoured ground water elevations as measured on 12 January 2004 Iand also includes a rose diagram showing ground water directions from previous monitoring events Advanced GeoEnvironmental,Inc