ARCHIVED REPORTS_XR0002530 - Laserfiche WebLink

Home Browse Search

' 10 September 2002 • AGE-NC Project No 95-0184 ' Page 2 of 5 ' 2 2 COLLECTION AND LABORATORY ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each monitoring well using new disposable bailers after allowing ' the wells to achieve a minimum 80% recovery of the pre-purge water volume Each water sample was transferred Into laboratory-supplied 40-m1 VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative, the sample from MW-4 was also transferred Into a 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 and diesel (TPH-g and TPH-d) in ' accordance with EPA Method 8015m, • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether ' (MTBE) In accordance with EPA Method 602/8020, • The fuel oxygenates di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE, tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), and other volatile organic ' • compounds (VOCs) by GC/MS (full-scan 8260) ' 3.0. FINDINGS ' Ground water elevation and flow direction were Inferred from field data, hydrocarbon-Impact to ground water was quantified by laboratory analysis of the ground water samples ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION ' The elevation of ground water In each well was calculated by subtracting the depth to 73MC water r the surveyed casing elevations (Table 1) Depths to ground water ranged from et to y r4\-R) 3� feet below the tops of the well casings, however, ground water levels are as high as ' approximately 22 feet above the screened Interval Ground water elevations at the site ranged from -19 15 feet In MW-7 to -20 53 feet In VW-5C relative to mean sea level ' The ground water appears to flow generally northeast across much of the site at a gradient of approximately 0 005 ft/ft (Figure 2), however, an apparent northeast finger In the northern quarter ' of the site separated the flow pattern Into a northwesterly flow direction (gradient from 0 008 to R • 0 013 ft/ft) and a southeasterly flow direction (gradient of about 0 005 ft/ft) Advanced GeoEnvironmental,Inc