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located in the pond, will be used to monitor sediment accumulation. <br />• Given the gravel cover of the permit area, the actual sediment <br />yield is expected to be minimal, and therefore, the calculated <br />sediment volumes are conservatively high. The pond and berms will <br />all be constructed with 2h:ly slopes. <br />u <br />LJ <br />There will be no operational spillway, only an emergency spillway. <br />Water collected in the pond during runoff events will be pumped <br />from the pond and used for dust suppression, if necessary, or left <br />to evaporate. Pump capacity will allow dewatering the pond within <br />48 hours after the 10-year event. Design features of the pond are <br />provided in Appendix 9.2-1. <br />Sediment cleaned from the pond, either after unusual precipitation <br />events or during annual cleaning, will be hauled by truck back to <br />the mine permit area and added to the refuse slurry system for <br />disposal as described in Permit C-89-065, 1990 Permit Revision. <br />4.2.9.2 Diversions and Culverts <br />As described above, a Clearwater diversion system exists outside of <br />the permit area diverting all runoff around the permit area (Figure <br />9.2-3). Appendix 4.2-1 provides an analysis of the ditch and <br />culvert capacities, as well as the expected runoff during 10-year <br />and 25-year, 24-hour events. The present system will successfully <br />divert the 10-year, 29-hour event around the permit area. The <br />addition of a small berm along the diversion ditch north of the <br />permit boundary will be required to pass the 25-year, 24-hour event <br />through the culvert beneath the access road to the permit area. <br />D&RG has agreed to make this modification to the their existing <br />system. <br />NCIG - Load Out Revision <br />4-7 <br />ABC/1145/910531 <br />~/s/41 <br />