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- <br /> S <br /> 11 November 1998 <br /> AGE-NC Project No 95-0121 <br /> Page 2 of 5 ` <br />' 2 2 GROUND WATER SAMPLE COLLECTION <br /> F <br /> ,The ground water levels in monitoring wells MW-1 through MW-9 achieved a minimum of 80 <br /> percent recharge prior to sample collection Ground water`samples were collected from wells MW-1 <br /> I' through MW-9 utilizing disposable polyethylene bailers, one-liter amber bottles and EPA-approved <br /> 40-m1 VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was taken <br />' to ensure that visible air bubbles were not present in the VOAs after filling and capping Ground <br /> I water sample containers were labeled with the well designation, date, time, and sampler's initials <br /> I , <br /> F 2 3 LABORATORY ANALYSIS OF GROUND WATER 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 Department of Health Services-certified laboratory for analysis in <br /> accordance with <br /> a <br /> • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline and diesel <br /> (TPH-g and TPH-d, respectively), <br /> In <br /> • EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene <br /> BTE&X)with methyl-tertiary butyl ether(MTBE), and <br /> • EPA Method 8260 for tertiary butanol (TBA), dl-isopropyl ether (DIPS), ethyl tert butyl <br /> ether(ETBE), tert amyl'methyl ether(TAME) and MTBE <br /> 3.0.' FINDINGS i <br /> I <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT i <br /> In August 1998,,the,depths to ground water in monitoring wells MW-1 through MW-9 were <br /> measured at 13 91 to 16 01 feet below the tops of the well casings Between May 1998 and August N <br /> 1998, ground water elevation has decreased an average 1 15 feet atsthe site During the monitoring <br /> event, ground water was between 8 09 and 17 54 feet above the screened Intervals`in monitoring <br /> wells MW-I through MW-9, therefore, the wells are "drowned", and may not yield samples fully <br /> representative of ground, water conditions near the top of the saturated zone,- where fuel <br /> hydrocarbons would be expected to have the greatest impact The ground water elevation data for <br /> MW-1 though MW-9 during the August ground water monitoring event is depicted in Figure 3 <br /> In August 1998, the gradient was calcillated to be 0 002 ft/ft, or approximately 10 feet per mile ' <br /> 4 <br /> Advanced GcoEnvlronmOntal,Inc. <br /> r <br /> t , <br />