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, . 30 July 1999 <br /> AGE-NC Project No 95-0144 <br /> Page 2 of 4 <br /> approved drums on-site <br /> ' 2 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each purged well using new disposable bailers Samples were <br /> ' transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a <br /> sample preservative Due to sampling error, 1-liter amber bottles were not collected during filling <br /> 1 of VOAs Samples were transferred into 1-liter amber bottles without preservative on the morning <br /> of 05 May 1999 The samples were labeled, stored on ice and transported under chain-of-custody <br /> to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified <br /> analytical laboratory Each sample was analyzed for <br /> ' • Total petroleum hydrocarbons quantified as gasoline (TPH-g), diesel (TPH-d) and motor oil <br /> (TPH-mo) in accordance with EPA Methods 5030/8015m <br /> • Volatile aromatic hydrocarbons (benzene, toluene, ethylbenzene and total xylenes, BTEX) <br /> with methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 8020/602 <br /> • Oxygenated compounds (di-isopropyl ether [DIPE], ethyl tertiary-butyl ether [ETBE], <br /> MTBE,tertiary-amyl methyl ether [TAME] and tertiary butanol [TBA]) in accordance with <br /> ' EPA Method 8260 modified <br /> t3.0. FINDINGS <br /> Ground water elevation and flow direction were calculated from field data, hydrocarbon-impact to <br /> ground water was inferred from laboratory analysis of the ground water samples <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> ' The elevation of ground water in each well was calculated by subtracting the depth to water from <br /> the surveyed casing elevation (Table 1) Between February and May 1999, ground water elevation <br /> increased an average of 0 72 feet in monitoring wells MW-1913, MW-20B and MW-21 B, screened <br /> ' below a clay layer Ground water elevation increased an average of 0 76 feet in the remaining wells <br /> The approximate hydraulic gradient for the May 1999 monitoring event was calculated to be 0 002 <br /> ft/ft with a northerly flow direction Ground water elevation contours derived from data collected <br /> on 04 May 1999 are depicted in Figure 3 Ground water was between approximately 2 and 5 feet <br /> above the screened interval in monitoring wells MWA, MW-2, MW-4 and MW-13 Groundwater <br /> ' Ad►anced GeoEnwConmental,Inc <br /> 1 <br />