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ti <br />' 04 .lune 1999 <br /> • AGE-NC Project No 98-0448 <br />' Page 2of5 <br /> 2 2 GROUND WATER SAMPLING <br />' Follow w - MW-4a, W-6 and <br /> Following purging, ground water levels m monitoring wells MW 2, MW-3, M , M <br />' MW-7 achieved a minimum of 80 percent recharge prior to sample collection, ground water levels <br /> in monitoring wells MW-1, MW-4b and MW-5 aclueved between 50 and 80 percent recharge prior <br /> to sample collection Ground water samples were collected from the purged wells utilizing new, <br /> disposable polyethylene bailers and three 40-m1 EPA-approved VOA vials containing 0 5 ml 18% <br />' hydrochloric acid as a preservative Care was taken to ensure that visible air bubbles were not <br /> present in the vials after filling and capping Ground water sample containers were Iabeled with the <br />' well designation, date, time, and sampler's initials <br />' 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 (DHS)-certified laboratory for analysis <br /> in accordance with <br />' • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline (TPH-g), <br /> • EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene <br />' BTEX) with methyl-tertiary butyl ether(MTBE), and <br /> • EPA Method 8260M for tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyI <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 eight ground water samples detected petroleum hydrocarbons in five ground <br /> water samples, BTEX compounds in four ground water samples and fuel oxygenates in one ground <br />' water sample <br />' 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br />' The depths to ground water from wells MW-1 through MW-7 ranged from 15 98 to 18 50 feet below <br /> the top of well casings Between December 1998 and March 1999, ground water elevation increased <br /> an average 1 36 feet at the site Ground water elevation measured from MW-4A (screened 8 to 33 <br /> Advanced GeaEm ironmental,Inc <br />