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' 20 December 2001 • AGE-NC Project No 99-0624 ' Page 2 of 4 ' 22 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each monitoring well using new disposable bailers after allowing ' the wells to achieve a minimum 80%recovery of the pre-purge water volume The samples were transferred into laboratory-supplied 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative The sample vials were then labeled with the monitoring ' well designation,date,time of sampling and the sampler's Initials The samples were transported in a chilled container under chain of custody to McCampbell Analytical, Inc (MAI), a California ' Department of Health Services(DHS)-certified analytical laboratory for analysis The samples were analyzed for ' • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 5030/8015 Modified, • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and methyl tertiary butyl ether (MTBE) in accordance with EPA Method 8020, and • Fuel oxygenates - tertiary butanol (TBA), di-isopropyl ether (RIPE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and MTBE in accordance with EPA Method 8260M r 3.0. FINDINGS The ground water elevation in each well was determined by subtracting the measured depths-to- water from the surveyed casing elevations and are presented in Table 1 Groundwater flow direction was determined by contouring the ground water elevations on a scaled site plan (Figure 2) Hydrocarbon-impact and MTBE-impact to ground water were assessed from laboratory analysis of the ground water samples 3 1 GROUND WATER ELEVATION AND GRADIENT Depths to ground water ranged from 54 33 feet to 55 40 feet below the tops of the well casings Ground water elevations at the site ranged from 15 90 feet (MW-4) to 16 14 feet (MW-2) below Imean sea level The top of the saturated zone occurred witlnn the screened intervals of all the morutonng wells IThe ground water flow direction was determined by contouring the ground water elevation data The • ground water underlying the site was inferred to have an average gradient of 0 003 ft/ft, the flow Advanced GeuEnvironmental,Inc