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GtolagiralTechnics lnc Page 3 Groundwater Monitoring Report Project No 989 2 March 29,2004 1.2 Laboratory Analyses The groundwater samples collected on February 12, 2004, were delivered to Sherwood Labs (Department of Health Services Certification No 1400), of Hilmar, California, for the ' following analyses • Benzene, toluene, ethylbenzene and xylene(BTEX by EPA method 8020/8015(m)) • Gasoline range petroleum hydrocarbons (TPH-G by EPA method 8020/8015(m)) ' • MtBE by EPA method 8021B (positive results confirmed by EPA method 8260) ' The detection limits for these compounds are listed in the laboratory data sheets included in Appendix C and summarized in Table I of Appendix A A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity On March 22, 2004, the laboratory data were submitted electronically to GeoTracker as required under AB2886 The confirmation number for the electronic submittal is 7037221729 2.0 FINDINGS AND DISCUSSION 2.1 Hydrology of Site ' On February12, 2004 the depth to groundwater was measured in all of the p g wells prior to ' purging Depths to groundwater, in the water table wells, ranged from a high of 7 57 feet below the top of casing to a low of 9 01 feet below the top of casing The average depth to water was 8 19 feet below the top of casing and the average groundwater elevation at the ' site is 147 feet below mean sea level The wells are screened at 5 feet bgs and groundwater surface continues to be below the tops of the screens in the nine shallow monitoring wells ' Site-specific groundwater gradient was calculated using MW-3, MW-7 and MW-9, and found to be N22°W at 0 0038 ft/ft The calculated groundwater gradient is displayed on the groundwater gradient map, Figure 3 Previous groundwater gradient calculations show a ' consistent bearing of north-northwest, averaging N30°W at 0 0066 ft/ft Vertical groundwater gradients were calculated for the site using the MW-1/MW-101 well ' pair and found to be negative (Table 3) The site-specific vertical groundwater gradient is - 0 0105 ft/ft The vertical groundwater gradients are generally one order of magnitude greater than the horizontal groundwater gradients MW-1 is screened from 5 to 25 feet bgs ' and MW-101 is screened from 29 5 to 42 feet bgs Vertical groundwater gradient calculations have been performed at regular intervals since the installation of MW-101 on July 30, 2002 I