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I 07 January 2000 AGE-NC Project No 95-0130 ' Page 2 of 5 I22 GROUND WATER SAMPLING Following well purging, ground water levels in monitoring wells MW-1 through MW-5, VW-1 C, VW-2A and VW-3A achieved a minimum of 80 percent recharge prior to sample collection Ground water samples were collected from the purged wells utilizing new, disposable polyethylene bailers and three EPA-approved 40-m1 VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was taken to ensure that visible air bubbles were not present in the vials after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 23 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain-of-custody form, placed in a chilled containei and I transported to a California Department of Health Services (DHS)-certified laboratory for analysis for - Total petioleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 8015M, Volatile aromatic compounds (benzene, toluene, ethyl benzene and xylene BTEX) with methyl-tertiary butyl ether (MTBE) by EPA Method 8020, and Tertiary butanol (TBA), di-isopropyl ether (DIPS), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and MTBE by EPA Method 8260M 30 FINDINGS AGE determined that ground water flow direction was towards the northeast at a gradient of 0 006 ft/ft from the field data collected on 13 October 1999 Laboratory analysis of the eight ground water samples detected TPH-g and MTBE in four samples and BTEX compounds in six samples 3 1 RELATIVE ROUND WATER ELEVATION AND GRADIENT The depths to ground water from wells MW-1 through MW-5, VW-1C, VW-2A and VW-3A were measured between 38 54 and 39 68 feet below the tops of the well casings Ground water elevations at the site were calculated to be between 22 79 feet and 23 32 feet below mean sea level, ground water elevations are depicted in Figure 3 Ground water elevation at the site decreased an average 1 92 feet between June 1999 and October 1999 ground water monitoring events The general ground water gradient at the site was calculated to be approximately 0 006 ft/ft or approximately 32 feet per Advarreed GeoEn%tronmental,Inc