2008-08-20_REVISION - C1980004 (2)

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Mike Boulay -3- August 19, 2008 13. DRMS: The Division requested further narrative, location, and design information addressing Light Use Roads #1, #2, and #3, as well as a narrative status update regarding the reclaimed light use road constructed in 2005 along the North Fork of Munger Creek to a remote drill site. Updated narrative was provided on amended page 2-32. Light Use Roads #1 and #2 are depicted and labeled on amended Map Figure 2.2-2, however Light Use Road #3 is (apparently erroneously) not depicted or labeled on the map figure. Please provide amended map Figure 2.2-2, with Light Use Road #3 depicted and labeled. CAM: Light use Road #3 is shown on amended Figure 2.2-2. Rule 2.05.3(4) Ponds, Impoundments, Other Treatment Facilities and Diversions 14. Item Resolved. 15. Item Resolved. 16. DRMS: The Division concurs that the new sediment pond embankment is not a Class B or C dam and failure will not cause serious property damage or loss of life. However, a stability analysis is required for all impoundment embankments. In accordance with 4.05.9(8)(b), any impoundment not meeting the size or other criteria of 30 CFR 77.216(a), and located where failure would not be expected to cause loss of life or serious property damage, shall have a minimum static safety factor of 1.3 for a normal pool with steady state seepage saturation conditions. Please provide a stability analysis for the proposed new impoundment that demonstrates compliance with 4.05.9(8)(b). CAM: Attached as Appendix S are stability analyses demonstrating compliance with Rule 4.05.9(8)(b). 17. Item Resolved. 18. Item resolved. 19. DRMS: it is still unclear how the new sediment pond will be operated (manually versus passively discharged). The revised SEDCAD demonstration shows that the pond will discharge through the primary spillway during the 10- year, 24-hour precipitation event. Yet the operator has indicated in their response to Item 20 below that the pond is designed to contain the 10-year event. The Elevation-Capacity-Discharge Table provided for the 10-year event does not show the top of sediment storage elevation. There is also no Structure Summary provided showing the peak settleable solid concentration out of the pond, which