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21 September 2000 <br />' AGE-NC Project No 99-0624 <br /> Page 2 of 4 <br /> 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES <br /> A total of four water samples were collected from monitoring wells MW-1, MW-2, MW-3, and <br /> MW-4 using new disposable bailers, after allowing the wells to achieve a minimum 80%recovery <br /> of the pre-purge water volume The samples were transferred into laboratory-supplied 40-m1 <br /> EPA-approved VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative The <br /> sample vials were then labeled with the monitoring well designation,date,time of sampling and the <br /> sampler's initials The samples were transported in a chilled container under chain of custody to <br /> McCampbell Analytical, Inc (MAI:), a California Department of Health Services (DHS)-certified <br /> analytical laboratory for analysis The samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 5030/8015 Modified, <br />' • Volatile aromatic compounds, including benzene, toluene, ethylbenzene, and total xylenes <br /> (BTEX)with methyl tertiary butyl ether(MTBE)in accordance with EPA Method 8020,and <br /> • Fuel oxygenates,including tertiary butanol(TBA),di-isopropyl ether(DIPE),ethyl tert-butyl <br /> ether(ETBE), tert-amyl methyl ether(TAME), and MTBE in accordance with EPA Method <br /> 8260M <br /> 3.0. FINDINGS <br /> Ground water elevations were determined by subtracting the measured depths-to-water from the <br /> surveyed casing elevations and are presented in Table 1 Ground water flow direction was <br /> Idetermined by contouring the ground water elevations on a scaled site plan (Figure 3) <br /> Hydrocarbon-impact and MTBE-impact to ground water was assessed from laboratory analysis of <br /> the ground water samples <br /> 3 1 GROU14Di WATER ELEVATION AND GRADIENT <br /> Monitoring data from MW-1, MW-2, MW-3, and MW-4 was combined to infer the site-specific <br />' ground water elevation and flow direction Ground water elevation was measured at approximately <br /> 9 50 feetFbelow mean sea level(MSL) Ground water flow direction was inferred to be southerly at <br /> approximately S 2' W with a gradient of 0 004 ft/ft Figure 3 depicts the ground water elevation <br /> contours and approximate flow direction for 17 May 2000 <br /> Advanced GeoEnvironmental,Inc <br />