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B. Diversions,Conveyance of Overland Flow,and Stream Channel Diversions <br /> The segment of McClane Canyon affected by mine surface facilities extends approximately 3000 <br /> feet from a box canyon at its upper end to its junction with East Salt Creek. Five tributary <br /> drainages come together at the upper end of the canyon to form the main ephemeral drainage. The <br /> mine portal facilities are situated at this location, and the tributary drainages were diverted via <br /> culverts beneath the mine bench when the bench was constructed. The culverts are adequately <br /> sized for the design event and have functioned well for over 25 years, with the exception of a <br /> couple occasions when they were overwhelmed by 100 year magnitude cloud burst type storm <br /> events in late summer. A temporary diversion ditch to the south of the sediment pond routes flow <br /> from three small ephemeral drainages around the pond, sediment drying area,topsoil stockpile and <br /> construction material stockpile. Berns in the office facilities area divert overland flow around the <br /> site. <br /> An additional diversion of the McClane Canyon stream channel occurred when the access/haul <br /> road was constructed in the spring of 1977. The point of diversion is between the riprap storage <br /> area and the office area,where the road was constructed across the channel. Due to the placement <br /> of road fill in the original channel, the flow in McClane drainage is now routed through a small <br /> drainage which flows directly west to East Salt Creek for a distance of approximately 600 feet, <br /> rather than to the southwest for approximately 800 feet as it originally did. The diversion channel <br /> is approximately four to six feet deep and ten to twelve feet wide at its upper end, underlain by <br /> sandstone bedrock, and similar in dimension and appearance to the natural McClane channel <br /> immediately above. Lower segments of the channel have the appearance of a steep sided gully, <br /> deeply incised into the colluvial/alluvial deposits, as is typical of ephemeral stream channels in the <br /> region. There has apparently been no significant downcutting or associated slumping of gully <br /> sides for many years, as there is a mature cover of big sagebrush and greasewood along both edges <br /> of the gully for its entire length. <br /> Upon final reclamation, all temporary diversion structures will be removed, and ephemeral <br /> drainages will be reconstructed in their approximate original locations. The road fill across the <br /> lower segment of McClane Drainage will be removed and the approximate original channel <br /> configuration will be restored. <br /> Diversion design is addressed in Sections 2.4.1 and 2.4.4 of the application. Channel <br /> reconstruction is discussed in Section 3.5 of the application. Existing configuration of the lower <br /> McClane Creek temporary diversion and plan for restoration of the original channel is addressed <br /> under "McClane Creek Temporary Diversion" in Appendix M. Applicable maps and tables are <br /> referenced in the cited text sections. <br /> The following specific approval is required by Rule 4. <br /> 1. Rock riprap lining is proposed for use to control erosion in certain reclaimed ephemeral <br /> stream channels. This measure is proposed to be approved by the Division, since the riprap <br /> lining is necessary to control erosion, and the lined channels will be stable and will require <br /> infrequent maintenance(4.05.4(2)(a)). <br /> 14 <br />