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1 <br /> Ile 21 December 2005 <br /> AGE-NC Project No 99-0624 <br /> Page 2 of 4 <br /> 2 ; COLLECTION AND ANALYSIS OF GROUNDWATER SAMPLES <br /> 1 <br /> Water samples were collected from each purged well using a Watera hydrolift pump and dedicated <br />' tubing after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume <br /> Each water sample was transferred into three 40-m1 volatile organic analysis(VOA)vials containing <br /> 0 5 ml 18%hydrochloric acid as a sample preservative After collection,the samples were properly <br />' labeled, placed in a chilled container and transported under chain of custody to Cal Tech <br /> Environmental Laboratories (CTEL), a State of California Department of Health Services-certified <br /> analytical laboratory The samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Methods 8015M, <br /> rBenzene,toluene, ethylbenzene and total xylenes(BTEX) in accordance with EPA Method <br /> 8260B, and <br />' Fuel additives di-isopropyl ether(DIPE), ethyl tertiary-butyl ether(ETBE), methyl tertiary- <br /> butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), <br /> 1,2-dichloroethane (1,2-DCA) and ethylene dibromide (EDB) in accordance with EPA <br />' • Method 8260B <br /> I3.0. FINDINGS <br /> I Ground water elevation, flow direction, and gradient were determined from field data The <br /> contaminant impact to ground water was quantified by the laboratory analytical data <br />' 31 GROUND WATER GRADIENT AND DIRECTION <br /> At the time of the July 2005 sampling event,depths to ground water ranged from 54 38 feet to 55 53 <br /> feet below the tops of the well casings (TOC) Ground water elevations at the site ranged from <br />' 16 10 feet below mean sea level (MSL) in well MW-4 to 16 42 feet below MSL in well MW-5 <br /> (Table 1) During this monitoring event,the ground water levels in wells MW-1 through MW-6 were <br /> at least ten feet below the tops of the well screens, indicating that the wells are screened properly to <br />' yield representative shallow ground water samples The ground water elevation at the site decreased <br /> approximately 2 37 feet between the May 2005 and July 2005 monitoring events <br />' The ground water was inferred to be flowing towards the south-southeast at a calculated gradient of <br /> 0 002 foot per foot(ft/ft) Figure 3 illustrates the contoured ground water elevations as measured on <br /> 25 July 2005 <br /> Advanced GeoEnvsroomental,Inc <br />