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t► DISCUSSION: \ MTBE was detected in groundwater samples collected from wells MW-1, MW-3 through MW-8, and MW-10. TPHG (18,000 µg/1) and benzene (9,500 µg11) were detected in the sample collected from well MW-4. TPHG (30,000 µg11) and benzene (15,000 µg11) were also detected in the sample collected from well MW-8. 1,2-DCA was detected in the samples collected from wells MW-9 (17 µg/1) and MW-10 (0.73 µg/l). DIPE (3.1 µg11)was detected in the sample collected from well MW-9. Toluene, ethylbenzene, xylenes, ETBE, TBA, and EDB were not detected in any of the samples. These analytical data are generally consistent with previous sampling events. Groundwater elevations were generally unchanged since the previous sampling.event (December 2001). The groundwater flow direction on February 22, 2002, was calculated to be variable, but generally towards the east-northeast at a low gradient. The groundwater flow direction between wells MW-8 and MW-7 was calculated to be towards the south-southeast at a gradient of 0.0064 ft/ft. The groundwater flow direction between wells MW-8 and MW-4 was calculated to be towards the west at a gradient of 0.0032 ft/ft. The groundwater flow direction between wells MW-2 and MW-7 was calculated to be towards the north at a gradient of 0.0026 ft/ft. Groundwater flow directions have predominantly been toward the northeast and east during previous monitoring events. ATTACHMENTS: O Table 1 Groundwater Monitoring Data C Table 2 Groundwater Analytical Results for Oxygenates and Additional Compounds 0 Figure 1 Site Location Map G Figure 2 Groundwater Elevation Contours (First Quarter 2002) C Figure 3 Groundwater Analytical Summary(First Quarter 2002) C Appendix A Field Data Sheets G Appendix B Sampling and Analysis Procedures Appendix C Certified Analytical Reports and Chain-of-Custody Records P:\ARCO\5469\QuarterlyMO2\Arco-5469—IQ02.doc Delta