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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 aze 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 yeaz magnitude cloud bwst 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. Beans 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 similaz in dimension and appearance to the natwal McClane channel <br />immediately above. Lower segments of the channel have the appearance of a steep sided gully, <br />deeply incised into the colluviaUalluvial 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 matwe cover of big sagebrush and greasewood along both edges <br />of the gully for its enfve length. <br />Upon fmal 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 aze <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 />