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21 June 2004 S AGE-NC Project No 97-0249 Page 3 of 7 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES ' Eachound water logged on a chain-of-custody form,placed in a chilled container and �' sample p was gg transported to McCampbell Analytical Inc , a California Department of Health Services (DHS)- certified laboratory for analysis for • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, respectively) by EPA Methods 5030/8015Cm, • Benzene, toluene, ethylbenzene and xylene (BTEX) by EPA Method 8021B, • 1,2-Dichloroethane (1,2-DCA), ethylene dibromide (EBD), tertiary butanol (TBA), di- isopropyl ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether(TAME) and methyl-tertiary butyl ether(MTBE) by EPA Method 8260B I ' 3.0. FINDINGS Ground water elevations, general flow direction and the estimated gradient were determined from ' field data collected on 15 March 2004, the contaminant impact to ground water was quantified by laboratory analysis of water samples collected on 15, 16 and 17 March 2004 I3 1 GROUND WATER ELEVATION AND GRADIENT I The 15 March 2004 ground water elevation at wells MW-1 through MW-12 were calculated by subtracting the measured depth to ground water from the surveyed casing elevation The depth to ground water measurements vaned from the purged wells between 7 36 feet(MW-6)and 10 75 feet (MW-8F)below the top of well casings, ground water elevation was calculated to be between 0 57 feet(MW-9B) and 1 27 feet(MW-1 OF)below mean sea level Generally,ground water elevation at the site increased an average 3 28 feet between the December 2003 and the March 2004 ground Iwater monitoring events The ground water elevation data collected from the site was plotted for six informal hydrogeologic flow units as defined in AGE's CPT Site Investigation - Fourth Quarter 2001 (dated 15 March 2002) Hydrologic Units 1, 2 and 6 at Three B's Truck Plaza are laterally equivalent to Flag City's First Zone, Second Zone, and Primary Aquifer Zone, respectively, with the exception of minor interpretational differences in location ofhydrostrati graphic boundaries,Three B's Hydrologic Units 3 and S are laterally equivalent to Flag City's Rock Upper Zone and Secondary Aquifer Zone, respectively Ground water elevation data collected from Flag City Chevron wells MW-9 (A-C),MW-ll (A-D), • MW-13 (A-D), MW-16, MW-17, MW-18 and Three B's Truck Plaza wells MW-6, MW-9 (A-E) and MW-10(A-F)on 15 March 2004 was depicted on cross section C-C'(Figure 3),by determining Advanced GeoEnvtronmental,Inc I