ARCHIVED REPORTS_XR0010175 - Laserfiche WebLink

Home Browse Search

1 ' 08,July 2004 i AGE-NC Project No. 97-0343 ' Page 2 of 4 ' 2.2. COLLECTION OF GROUND WATER SAMPLES Water samples were collected from wells MW-2,MW-3,MW-4,MW-5 and MW-7 using disposable ' plastic bailers and from MW-8 using dedicated tubing after allowing the well to achieve a minimum 80% recovery of the pre-purge water volume. The water samples were transferred into three 40-milliliter(ml)volatile organic analysis(VOA)vials containing 0.5 ml 18%hydrochloric acid as a sample preservative and into one 1-liter amber bottle without added 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 Department of Health Services-certified laboratory. The ground water samples were analyzed for: I 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 the fuel additives methyl- tertiary butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), 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 18 March 2004. The contaminant impact to ground water was quantified from the laboratory analytical data. I3.1. GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the March 2004 sampling event, depths to ground water in wells MW-1 through MW-5,MW-7 and MW-8 ranged from 53.40 feet to 54.47 feet below the well heads; ground water elevations ranged from 25.74 feet below mean sea level (MSL) in well MW-1 to 26.21 feet below MSL in well MW-7(Table 2). The average ground water elevation at the site this quarter was 26.00 feet below MSL. The average .ground water elevation at the site increased 4.86 feet between the August 2003 and March 2004 sampling events. Based on the elevation contours, the ground water flow direction was inferred to be flowing generally to the south at an average hydraulic gradient of 0.01 feet/feet. Figure 3 illustrates the contoured ground water elevations as measured on 18 March 2004. i Advanced GeoEnvironmental,Inc.