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1 coologicit7echnky1". Page 3 Groundwater Monitoring Report Project No. 989.2 November 14,2003 ' • Gasoline range petroleum hydrocarbons (TPH-G by EPA method 8020/8015(m)) 0 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 2 of Appendix A. A Chain of Custody was ' completed for all samples collected and tracked to ensure sample integrity. On October 27, 2003, the laboratory data were submitted electronically to GeoTracker as ' required under AB2886. The confirmation number for the electronic submittal is 6739973425. 2.0 FINDINGS AND DISCUSSION 2.1 Hydrology of Site On September 2, 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 7.35 feet below the top of casing to a low of 9.04 feet below the top of casing. The average depth to water was 8.26 feet below the top of casing and the average groundwater elevation at the site is 1.20 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 N38°W at 0.0051 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 treasured between N05°W and N45°W at the site and the slope historically averages 0.0067 ft/ft. Vertical groundwater gradients were calculated for the site using the MW-1/MW-101 well pair and found to be negative (Table 4). The site-specific vertical groundwater gradient is - ' 0.4042 ft/ft. 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. The vertical gradient ' calculated for the September 2003 monitoring event is two orders of magnitude greater than the horizontal gradient. i ' Historical groundwater bearing and slope are summarized in Table 1 and a summary of vertical groundwater is included as Table 4 of Appendix A. A Rose Diagram is attached as Figure 4. As required under A132886, the depth to groundwater data was submitted electronically to GeoTracker on October 27, 2603, with confirmation number 1550735294.