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t Geological Technics Inc. Page 3 Groundwater Monitoring Report Project No.989.2 April 30,2003 1.2 Laboratory Analyses ' The groundwater samples collected on November 19, 2002, 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)) • Volatile Organic Compounds by GC/MS Fuel (MTBE, DIPE, ETBE, TAME, TBA, 1,2- DCA and EDB by EPA method 8260) ' The volatile organic compound samples were submitted by Sherwood Labs to Entech Analytical Labs of Santa Clara, California(DHS # 2346). ' The detection limits for these compounds are listed in the laboratory data sheets included in Appendix C and summarized in Table 2 of Appendix A. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. On March 3, 2003, the laboratory data were submitted electronically to GeoTracker as required under AB2886. The confirmation number for the electronic submittal is 5936293482. 2.0 FINDINGS AND DISCUSSION ' 2.1 Hydrology of Site On February 14, 2003, the depth to groundwater was measured in all of the wells prior to purging. Depths to groundwater, in the water table wells, ranged from a high of 7,09 feet below the top of casing to a low of 8.48 feet below the top of casing. The average depth to water was 8.08 feet below the top of casing and the average groundwater elevation at the site is 1.02 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 N30°W at 0.0046 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. Bearings have been measured between N05°W and N45°W at the site and the slope historically averages 0.0050 ft/ft. Historical groundwater bearing and slope are summarized in Table 1 of Appendix A and are plotted on a Rose Diagram, Figure 4. i