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CaalMetSane Drainage Prajeet- Panek 16-24 Wert E(k Mine • Page 2-11 concurrently with construction or maintenance activities. These structures shall be maintained for the duration of the project and shall not be removed, without approval, prior to reclamation of the disturbance. Any culverts will be sized to safely pass the runoff from a 25-year event and to withstand flows from a 50-year event. The USFS will approve culvert sizes and lengths. Filter material will be installed below drainage outlets and downslope From rolling dips. Riprap will be installed below culvert outlets when directed by the USFS. 9) At road intersections with existing drainages, which cannot be easily tamed by use of a temporary culvert, riprapped crossings will be established. The approaches to any crossing shall be armored by placing a minimum 8-inch depth of 1- to 3-inch clean crushed rock, 14 feet wide fox a distance of 20 feet on each side of the drainage to minimize siltation, bank rotting, and erosion. Crossings will be constructed perpendicular to the flow line. When access is no longer needed, any temporary culverts, associated fill, and crushed rock shall be removed. Silt fences or appropriate sediment control devices shall be utilized to prevent siltation into existing drainages, ponds, or associated riparian areas. 10) The road surface will be constrocted with an in-slope of 2 percent and the surface width shall not exceed 14 feet except in locations that require curve widening, or those designated for turnouts. These locations must be identified on the ground and approved by [he responsible USFS official. Side-casting will not be permitted where sideslopes exceed 40 percent. , c- 71) Sections of temporary roads with roadway gradient in excess of 12 percent or soft areas which exhibit noting in excess of 3 inches shall be stabilized by placing an adequate depth of 3-inch minus clean crushed rock. The surface of the road shall be maintained to minimize ruts and provide for sheet drainage across the roadway. 12) All classified roads will be surfaced with 3-inch minus dean crashed rock. The USFS officer may also require surfacing of temporary roads where just[Fed by conditions or traffic volumes. 2.4.2 Road Operations 13) With the exceptions of the Minnesota Creek, Dry Fork, and Horse Gulch roads, the project area will be closed to public motorized vehicle use for the duration of the project except under the Public ATV Access Option (refer to Section 2.3.7). Locked gates and signs meeting USFS MUTCD requirements will be provided, installed, and maintained by MCC at the intersections of the Horse Gulch and West Flatiron roads, the Dry Fork and Long Draw Saddle roads, the Dry Fork and Upper Deep Creek roads, and any other locations designated by the USFS of£cial. Motorized use on dosed roads within the project area will be restricted to administratively approved traffic. 14) MCC will be responsible for erecting a temporary closure device on snow-plowed roads to prevent public access on the road. This closure must meet MUTCD requirements. 15) Off-road motorized vehicle travel is prohibited 16) If snow is removed from the Minnesota Creek and Dry Fork Roads, removal must be performed in compliance with MCC's Road Use Pemtit. MCC will be responsible for signing the closure gates on the Dry Fork Road warning snowmobiles of mixed traffic. MCC will constmct a snowmobile passage. Public snowmobile use will not be pemutted on other project roads. Snow shall be compacted to 4 inches, then allowed to freeze before hauling loads where GVW would exceed 10,000 pounds. I W.PP/Mwr GG/EA/U..p IN/OIE~UJFf ~/f/oz.m EnvifonmentalArreument