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09 June 1998 <br /> .� AGE-NC Project No 95-0104 <br /> Page 2 of 4 <br /> 22 GROUND WATER SAMPLING <br /> Following purging, the monitoring wells were allowed to recover for a minimum of one hour prior <br /> to sample collection Ground water samples were collected from the four purged wells utilizing new, <br /> disposable polyethylene bailers and new nylon rope Sufficient sample was collected fiom each well <br /> to fill three 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloiic acid as a sample <br /> preservative Care was taken to ensure that visible air bubbles were not piesent in the vials after <br /> filling and capping Giound water sample containers were labeled with the well designation, date, <br /> time, and sampler s initials <br /> 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> Each ground water sample was togged on a chain-of-custody fo <br /> rm, placed in a chilled container and <br /> transported to a California state-certified laboratory for analysis in accordance with EPA Methods <br /> • 8015M foi total petroleum hydrocarbons quantified as gasoline (TPH-g), and <br /> • 8020 for volatile aiomatics (benzene, toluene, ethyl benzene and xylene BTE&X) with <br /> methyl-tertiary butyl ether (MTBE) <br /> The laboratory ieport (Alpha Analytical Laboratories Inc Batch No 98-0310) and chain-of-custody <br /> forms aie piesented in Appendix B <br /> 30 FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The depths to giound water from wells MW-1 through MW-6 and VW-1 weie measured at 60 26 <br /> Iand 61 55 feet below the top of well casings Between September 1997 and March 1998, ground <br /> water elevation increased an average 9 42 feet at the site The ground water ele, ation data foi MW-I <br /> I through MW-6 and VW-I during the March 1998 ground water monitoring event is depicted in <br /> Figure 3 <br /> During the March 1998 monitoring event, ground water was approximately 1 89 feet and 6 41 feet <br /> above the top of the screened intervals of monitoring wells MW-2 through MW-6 As a result the <br /> screened intervals from these wells are completely submerged, and may not yield water samples <br /> fully representative of ground water conditions near the top of the saturated zone wheie fuel <br /> hydrocarbons would be expected to have the greatest impact <br /> Advanced GcoEn ironnicnlal,Inc <br />