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19 April 1999 <br /> AGE-NC Project No 96-0229 <br /> Page 2 of 5 <br /> 2 2 GROUND WATER SAMPLING <br />' <br /> Following well purging, ground water levels in monitoring wells MW-1 through MW-10 achieved <br /> a minimum of 80 percent recharge prior to sample collection Ground water samples were collected <br /> from the purged wells utilizing new, disposable polyethylene bailers and three 40-nil EPA-approved <br /> VOA vials containing 0 5 ml 18%hydzochloric acid as a preservative Care was taken to ensure that <br /> I visible air bubbles were not piesent in the vials after filling and capping Ground water sample <br /> containers were labeled with the well designation, date, time, and sampler's initials <br /> 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> Each ground water sample was logged on a cliain-of-custody form, placed in a chilled container and <br /> transported to a CaIifoinia Depaitment of Health Services (DHS)-certified laboratory for analysis <br /> in accordance with <br /> • EPA Method 8015M for total petroleum h diocarbons quantified as gasoline (TPH- <br /> g), <br /> • EPA Method 8020 for volatile arornaties benzene, toluene, ethyl benzene and xylenes, <br /> (B 17EX) with methyl-tertiary butyl ether (MTBE), and <br /> • EPA Method 8260 for fuel oxygenated compounds tertiary butanol (TBA), di-isopropyl <br /> ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and MTBE <br /> 30 FINDINGS <br /> Fiom the field data, AGE was able to determine the ground water flow direction and gradient <br /> Laboratoiy analysis of eleven ground water samples detected either petroleum hydrocarbons, volatile <br /> aromatics or oxygenated fuel additives in nine ground water samples <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> Duinlg the April 1999 monitoring event, deptlis to ground water fiom wells MW-I through MW-10 <br /> weic measured bethveea 22 67 and 24 50 feet below the tops of well casings, ground water elevations <br /> were calculated to be between 12 10 feet and 13 21 feet below mean sea level GY ound water <br /> elevation at the site incieased an dveldge 3 68 feet between the January 1999 and the Apiil 1999 <br /> groundwater inonitonng events The ground water elevation data for MW-1 tluough MW-10 dui ing <br /> the January 1999 ground water monitoring event is depicted in Figure 3 <br /> ,4r1i rrncerl GcoEin iron nuntel,IE1c <br />