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t <br />' • 13 February 2003 <br /> AGE-NC Project No 99-0624 <br />' Page 2 of 5 <br /> 2 2 GROUND WATER SAMPLING <br /> IFollowing well purging, ground water levels from each well achieved a minimum of 80 percent <br /> recharge prior to sample collection Ground water samples were collected from the purged wells <br />' utilizing new,disposable polyethylene bailers and transferred into 40-m1 EPA-approved VOA vials <br /> containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was taken to ensure that <br /> visible air bubbles were not present 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 />' 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 McCampbell Analytical, Inc (MAI), a California Department of Health Services <br /> (DHS)-certified laboratory for analysis for <br />' • Total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 8015C <br /> Modified, , <br />'• Benzene,toluene,ethyl benzene and xylene(BTEX)and methyl-tertiary butyl ether(MTBE) <br /> by EPA Method 8021B, and <br /> • Tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert butyl ether(ETBE), tert amyl <br />' methyl ether (TAME) and MTBE by EPA Method 8260B <br />' 3.0. FINDINGS <br />' Ground water elevation, flow direction and gradient were determined from field data collected on <br /> 29 November 2002,the contaminant impact to ground water was quantified from the laboratory data <br />' 3 1 GROUND WATER ELEVATION AND GRADIENT <br />' During the 29 November 2002 monitoring event, depths to ground water in wells MW-1 through <br /> MW-4 were measured at between 53 45 and 54 58 feet below the tops of the well casings, ground <br />' water elevations were calculated to be between 15 08 feet (MW-4) and 15 24 feet (MW-2) below <br /> mean sea level (MSL) Ground water elevation at the site decreased an average 1 25 feet between <br /> the May 2002 and the November 2002 ground water monitoring events(Table 2) The ground water <br />' elevation data for MW-1 through MW-4 during the November 2002 ground water monitoring event <br /> . is depicted and contoured in Figure 3 <br />' Advanced GeoEnviron mental,Inc <br /> I <br />