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t <br /> 27 January 1999 <br /> AGE-NC Project No 96-0232 <br /> Page 2 of 5 ° <br /> 22 GROUND WATER SAMPLING <br /> t 4 Prior to sampling wells MW-1, MW-2 and MW-4 through MW-7, ground water levels achieved a <br />' minimum of 80 percent recharge Ground water samples were collected from the purged wells <br /> utilizing new, disposable polyethylene bailers, and were transferred into one-liter amber bottles and <br /> four 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a sample <br />' preservative Care was taken to ensure that visible air bubbles were not present in the vials after <br /> filling and capping Ground water sample containers were labeled with the well designation, date, <br />' time, and sampler's initials <br /> e f lh <br />' 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES _ ;A <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 (DHS)-certified laboratory for analysis <br /> in accordance with <br /> • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline and diesel <br /> (TPH-g and TPH-d, respectively), <br />' • EPA Method 8020 for volatile aromatics '(benzene, toluene, ethyl benzene and xylene E <br /> BTEX) with methyl-tertiary butyl ether (MTBE), and <br /> • EPA Method 8260 for tertiary butanol TBA di-isopropyl' <br /> i-iso ro 1 ether DIPE , ethyl tert butyl <br />' r}' (TBA), P PY ( ) Y Y <br /> ether (ETBE), tert'amyl methyl ether (TAME) and MTBE <br /> 3.0. FINDINGS <br />' From the field data, AGE was able to determine the ground water flow direction and gradient <br /> Laboratory analysis of seven ground water samples detected total petroleum hydrocarbons in two <br /> of the seven samples, MTBE was detected in all seven ground water samples <br />' 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> t <br /> t <br /> During the Novemiber 1998 monitoring event, depths to ground water from wells MW-1,MW-2 and <br />' MW-4 through MW-7 were measured between 10 00 and 1146 feet below the top of well casings, <br /> ground water elevations were calculated between-1 64 and-1 85 feet below mean sea level' Ground <br /> water elevation at the site decreased an average 1 14 feet between the June 1998 and the November <br /> 4 <br /> Advanced GeoEmironmental,Inc <br /> I ` <br /> t <br />