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nr- 30 April 2005 . AGE-NC Project No 96-0232 Page 3 of 9 bottles without a preservative and into 40-m1 EPA-approved volatile organic analysis (VOA) vials containing 0 5 ml 18% hydrochloric acid as a sample preservative Care was taken to ensure that visible air bubbles were not present in the vials after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain of custody form,placed in a chilled container and transported to a California DHS-certified laboratory for analysis for • TPH-g and TPH-d by EPA Methods 50301318015Cm and 3510C/8015C, respectively, • Benzene, toluene, ethylbenzene and xylenes (BTEX) by EPA Method 8260, • Tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether (ETBE),tert amyl methyl ether (TAME) and methyl-tertiary butyl ether (MTBE), Methanol and Ethanol by EPA Method 8260B a 24 FINDINGS Ground water elevation, flow direction and gradient were determined from field data collected on 28 March 2005, the contaminant impact to ground water was quantified by laboratory analysis of water samples collected on 28 and 29 March 2005 2 4 1 Ground Water Elevation and Gradient The depths to ground water were measured at between 8 34 feet(MW-18)and 12 64 feet(MW-9C) below the tops of the well casings on 28 March 2005, ground water elevations were calculated to be between 0 82 feet (MW-20B) and 3 24 feet (MW-5) above mean sea level (MSL) Ground water elevation data collected from Flag City Chevron wells MW-9 (A-C),MW-11 (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 28 March 2005 is depicted on cross section C-C' (Figure 3), by determining the difference between ground water elevations (dh) and dividing by the difference of the screen interval midpoints (dl), the vertical gradient between adjacent screen intervals was calculated Generally, near neutral vertical gradients were observed between the First Zone, Second Zone, Rocky's Upper Zone and Secondary Aquifer Zone, pronounced downward vertical gradients were • observed between Secondary Aquifer Zone and Primary Aquifer Zone (Figure 3) Advanced GeoEnvironmental,Inc