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s <br /> 12 May 1998 <br /> AGE-NC Project No 95-0121 <br />' Page 2 of 5 i <br /> 22 GROUND WATER SAMPLE COLLECTION <br /> The ground water levels in monitoring wells MW-1 through MW-9 were allowed to recover for a <br />' r minimum of one hour prior to sample collection Ground water samples wei e collected utilizing <br /> disposable polyethylene bailers and new nylon-rope Sufficient ground water sample was collected <br /> from each well to fill a one-liter amber bottle and three EPA-approved 40-m1 VOA vials containing <br /> it 0 5 ml 18%hydrochloric acid as a preservative for the samples Care was taken to ensure that visible , <br /> air bubbles were not present in the VOAs after filling and capping Ground water sample containers <br /> = were labeled with the well designation, date, time, and sampler's initials <br /> f <br /> 23 LABORATORY ANALYSIS OF GROUNDWATER SAMPLES <br /> Each ground water sample was logged on a chain-of-custody form,placed in a chilled container and <br /> transported to a California state-certified laboratory for analysis in accordance with the following <br /> • EPA method 8015M for total petroleum hydrocarbons quantified as gasoline and diesel <br /> (TPH-g and TPH-d, respectively) <br /> • <br /> EPA method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene <br /> BTE&X) with methyl-tertiary butyl ether (MTBE) <br /> IEPA Method 8260 for tertiary butanol (TBA), di-isopropyl ether (DIPS), ethyl tert butyl <br /> ether (ETBE) and tert amyl methyl ether (TAME), and to confirm and quantify MTBE ;f <br /> detected by EPA Method 8020 w <br /> _ r <br /> 30 FINDINGS - <br /> 3 1 RELATIVE GROUND WATER ELEVATION ANDIGRADIENT <br /> f <br /> The depths to ground water in.wells MW-1 through MW-9 were-measured at 14 76 to 16 68 feet - <br /> below the tops of the wells Between November 1997 and February 1998, ground water elevation <br /> increased an average 4 37 feet at the site The ground water elevation data for MW-1 though MW-9 <br /> during February's ground water monitoring event Is depicted in Figure 3 <br /> .. - , l , , 11 f , 4 1, =r 5 - , J I, <br /> During the February 1'998 monitoring event, groiind water was between 7 24 and 17 10 feet above <br /> the screened intervals in monitoring wells MW-'1 through MW-9 Therefore, the wells are <br /> "drowned", and may not yield samples fully representative of ground water conditions near the top <br /> of the saturated zone„where,fuel hydrocarbons would be expected to have the greatest impact <br /> P <br /> Adtianced CeoEnuronmental,Inc <br />