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<br />1 <br />1 <br /> <br />1 <br />1 <br />1 <br />t <br />1 <br /> <br />1 <br /> <br />1 <br />In the event of a flood resulting from an extreme precipitation event, it is likely <br />that additional dewatering equipment would be mobilized to lower the wate~• level in the <br />pond. The dam stability analysis indicates that ample time would be available to install <br />portable diesel driven pumping equipment and temporary pipelines to augment the <br />capacity of the decant spillway system if necessary. <br />Bvaass System Oceration <br />The upper bypass system, consisting of the Ute Creek Reservoir Bypass, the <br />Horseshoe Bypass, and the East Branch Reservoir Bypass, generally consists of trash <br />rack protected inlets to buried pipelines. It is likely that these systems would not suffer <br />significant damage from the PMF; however, the inlets would most likely require <br />cleaning. <br />The existing interceptor canal around the tailing basin does not inclu~je overflow <br />spillways at the several small tributary crossings. It is likely that during the PMF the <br />canal would wash out at the crossings and would require repair. It is anti~;ipated that <br />this repair would be a high priority in the days following the PMF. This repair could be <br />accomplished using equipment and personnel at the mill and/or outside contractor <br />equipment and labor. It is expected that overtopping outside of the tributary crossings <br />would be fairly well diffused because of the very flat grade of the canal and .access road <br />(0.1 foot of fall in 100 feetl. Floodwater flow with the highest erosion potential would <br />be focused on the crossings. Other excess water would overtop with modest erosive <br />' energy. If the canal were damaged by the flood, it is expected that this darnage would <br />occur at isolated areas that could be quickly repaired. <br />Tailing Pond Embankment Stability <br />' The stability of the Henderson tailing pond embankment under high water level <br />conditions was evaluated by URS Corp. Their geotechnical report that addresses this <br />' issue is included herein as Appendix B. The results of the stability analysis, which are <br />described in more detail in the URS report, indicated that the factors of safety <br />1 <br /> <br />9 <br />