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i Geologual Technics Inc. Page 4 Groundwater Monitoring Report Project No. 989.2 January 21,2002 • Benzene, toluene, ethylbenzene and xylene (BTEX b EPA method 8020 Y ) • Gasoline range petroleum hydrocarbons (TPH-Gasoline by EPA method 8015(m)) • Fuel oxygenate suite (MTBE, DIPE, ETBE, TAME, and TBA by EPA method 8260) • 1,2-Dibromoethane and 1,2-Dichloroethane (1,2 DCA and EDB by EPA method 8260) The fuel oxygenates, 1,2 DCA and EDB samples were submitted to Entech Analytical Labs of Santa Clara, CA (DHS # 2346). ' A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. Laboratory data sheets with detection limits are included in Appendix C. ' The laboratory data was submitted electronically to GeoTracker as required under AB2886 on January 14, 2002. The confirmation number for the electronic submittal is 6161439180. ' 3.0 FINDINGS AND DISCUSSION 3.11 Hydrology of Site On December 11, 2001, the depth to groundwater was measured in all of the wells prior to purging. Depths to groundwater ranged from a high of 7.66-feet below the top of casing to a low of 9.05-feet below the top of casing. The average depth to water was 8.53-feet below ' the top of casing. The wells are screened at 5-feet bgs and groundwater surface continues to be below the tops of the screens in the 6 monitoring wells. Groundwater elevations were calculated and are summarized in Table 2 of Appendix A. Site-specific groundwater gradient was calculated using MW-1, MW-3 and MW-6, and found to be N24°W at 0.0049 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. The bearings have been measured between N05°W and N45°W and the slope averages 0.0063 ft/ft. Groundwater bearing .and slope are summarized in Table 2 of Appendix A and are plotted on a Rose Diagram, Figure 4. 3.2 Groundwater Analytical Results • Low concentrations of BTEX were present in MW-1 14, ' • Low concentrations of Xylene and Ethyl Benzene were present in MW-3. The levels have increased slightly from the September 2001 monitoring event. • Low concentrations of TPH-gasoline were present in MW-1, MW-3 and MW-4. The ' levels have increased from the September 2001 monitoring event. • • No BTEX or TPH-gasoline were found in MW-2, 5, & 6.