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I I 13 August 2003 • AGE-NC Project No 99-0624 IPage 2 of 5 2 2 GROUND WATER SAMPLING Following well purging, ground water levels from each well achieved a minimum of 80 percent recharge prior to sample collection Ground water samples were collected from the purged wells ' utilizing the techniques described above in purging each well Ground water samples were transferred into 40-m1 EPA-approved volatile organic analysis (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 IEach ground water sample was logged on a chain-of-custody form,placed in a chilled container and transported to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified laboratory for analysis for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 8015Cm, • Benzene,toluene,ethyl benzene and xylene(BTEX)and methyl-tertiary butyl ether(MTBE) by EPA Method 8021B, and • Tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert butyl ether(ETRE), tert amyl Imethyl ether(TAME) and MTBE by EPA Method 8260B 3.0. FINDINGS Ground water elevation, flow direction and gradient were determined from field data collected on 04 March 2003, the contaminant impact to ground water was quantified from the laboratory data 3 1 GROUND WATER ELEVATION AND GRADIENT During the 04 March 2003 monitoring event,depths to ground water in wells MW-I through MW-4 were measured at between 52 59 and 53 67 feet below the tops of the well casings, ground water elevations were calculated to be between 14 17 feet(MW-4)and 14 41 feet(MW-1)below mean sea level (MSL) Ground water elevation at the site increased an average 0 88 feet between the November 2002 and the March 2003 ground water monitoring events (Table 2) The ground water elevation data for MW-1 through MW-4 during the March 2003 ground water monitoring event is Ile depicted and contoured in Figure 3 Advanced GeoEnvironmental,Inc