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10 March 2009 AGE-NC Project No. 01-0839 Page 5 of 6 5.0. CONCLUSIONS Based upon the results of the ground water monitoring, AGE presents the following conclusions: • Depth to ground water has steadily decreased since January 2007, when depth to ground water averaged approximately 58.67 feet btoc and now averages 76.50 feet, a 17.83 foot increase in the depth to ground water. • The lateral extent of the dissolved MTBE plume is defined to the west and north of the former UST area bywells MW-1 and MW-2;the dissolved MTBE is somewhat defined east of the site by well MW-5. The dissolved plume extends northeast of well MW-4 (former UST area) toward well MW-5, based on the hydrologic conditions near the site. The dissolved MTBE plume is not yet defined due southeast of well MW-4, which has historically been the most impacted well in the monitoring well network (Figure 4). • The dissolved MTBE plume appears relatively stable, if not decreasing in maximum concentration and size. Concentrations of MTBE have reduced significantly in the ground water samples collected from MW-3 (over 99%decrease)and MW-4(57%decrease)while depth to ground water dropped by an average of 4.80 feet since the October 2008 event. • Historically,reported detections of dissolved TPH-g appear to be due to the dissolved MTBE component(Table 3). • Nearly one year passed between sampling of the ground water monitoring wells. The trends indicate that both MTBE and 1,2-DCA has decreased appreciably during this time frame (Appendix D). • 1,2-DCA has not been reported in ground water samples in wells MW-3 and MW-4 since January 2008 (four events), in well MW-2 since January 2008 (one event), in well MW-1 since 2003 and never in off-site well MW-5 (not sampled this event). • Wells MW-2, MW-4 and MW-5 appear to required re-development. Wells MW-2 and MW-4 are set at a depth of 85 feet bsg, while off-site well MW-5 is set at 80 feet bsg. Field measurements performed this event indicate that sediment is present at the bottom of wells MW-2 (3.2 feet above bottom),MW-4(5.2 feet above bottom)and off-site well MW-5 (2.3 feet above bottom). 6.0. RECOMMENDATIONS Based on the conclusions presented in this report, AGE recommends: • Continuation of semi-annual monitoring and reporting. The semi-annual monitoring event Advanced GeoEnvironmentnl,Inc.