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1 <br />' 25 March 2004 <br /> AGE-NC Project No 97-0249 <br />' Page 3 of 7 <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 a California Department of Health Services (DHS)-certified laboratory for analysis <br /> for <br />' • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, <br /> respectively) by EPA Methods 5030/8015Cm, <br />' • Benzene, toluene, ethylbenzene and xylene (BTEX) by EPA Method 8021B, <br /> • 1,2-Dichloroethane (1,2-DCA), ethylene dibromide (EBD), tertiary butanol (TBA), di- <br /> isopropyl ether(DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and <br />' methyl-tertiary butyl ether (MTBE) by EPA Method 8260E <br /> I3.0. FINDINGS <br /> Ground water elevations, general flow direction and the estimated gradient were determined from <br /> field data collected on 08 December 2003, the contaminant impact to ground water was quantified <br /> by laboratory analysis of water samples collected on 08, 09 and 10 December 2003 <br /> 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> The 08 December 2003 ground water elevation at wells MW-1 through MW-12 were calculated by <br /> subtracting the measured depth to ground water from the surveyed casing elevation The ground <br /> water elevation data collected from the site was plotted for the Informal hydrogeologic flow units <br /> as defined in AGE's CPT Site Investigation - Fourth Quarter 2001 (dated 15 March 2002) The <br /> depth to ground water measurements varied from the purged wells between 10 62 feet(MW-6) and <br /> 13 97 feet (MW-2) below the top of well casings, ground water elevation was calculated to be <br /> between 3 85 feet(MW-6)and 4 32 feet(MW-1 OF)below mean sea level Generally,ground water <br /> elevation at the site Increased an average 107 feet between the September 2003 and the December <br /> 2003 ground water monitoring events <br /> Ground water elevation data collected from Flag City Chevron wells MW-9 (A-C),MW-11 (A-D), <br /> MW-13 (A-D), MW-16, MW-17, MW-18 and Three B's Truck Plaza wells MW-6, MW-9 (A-E) <br /> and MW-10 (A-F) on 08 December 2003 was depicted on cross section C-C' (Figure 3), by <br /> determining the difference between ground water elevations (dh) and dividing by the difference of <br /> I the screen interval midpoints (dl), the vertical gradient between adjacent screen Intervals was <br /> calculated <br /> Advanced GeoEnvironmental,Inc <br />