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Federal water quality standards for receiving streams, and also due to the fact that <br />no mixing of surface drainage with a discharge from underground workings will <br />occur (4.05.2(3)(b)(i). <br />B. Diversions, Conveyance of Overland Flow, and Stream Channel Diversions <br />The segment of McClave Canyon affected by mine surface facilities extends <br />approximately 3000 feet from a box canyon at its upper end to its junction with East <br />Salt Creek. Five tributary drainages come together at the upper end of the canyon to <br />form the main ephemeral drainage. The mine portal facilities are situated at this <br />location, and four of the five tributary drainages have been diverted via culverts <br />beneath the mine bench. The culverts are adequately sized for the design event and <br />have functioned well for over 25 years, with the exception of a couple occasions when <br />they were overwhelmed by 100 year magnitude cloud burst type storm events in late <br />summer. One ephemeral drainage on the south side of the portal bench is ditched <br />around the shop building at the base of the cut slope, and is directed to the <br />sedimentation pond. A temporary diversion ditch to the south of the sediment pond <br />routes flow from three small ephemeral drainages around the pond, sediment drying <br />area, topsoil stockpile and construction material stockpile. Berms in the office <br />facilities area divert overland flow around the site. <br />An additional diversion of the McClane Canyon stream channel occurred when the <br />access/haul road was constructed in the spring of 1977. The point of diversion was <br />between the riprap storage area and the office area, where the road was constructed <br />across the channel. Due to the placement of road fill in the original channel, the flow <br />in McClave drainage was diverted for many years. The diversion channel flowed <br />generally straight west to East Salt Creek. Lower segments of the diversion channel <br />developed into a steep sided gully, deeply incised into the colluviaValluvial deposits, <br />as is typical of ephemeral stream channels in the region. In 2006, Haul Road Culvert <br />'T" was installed as approved by TR -14, which re -connected the upper segment of <br />McClane Creek with its original lower segment. <br />Upon final reclamation, all temporary diversion ditches, berms and culverts will be <br />removed, and ephemeral drainages will be reconstructed in their approximate original <br />locations. Fill embankments in locations where the haul road crosses McClave Creek <br />will be removed and the approximate original channel configurations 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. Applicable maps and <br />tables are 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 <br />ephemeral stream channels. This measure is proposed to be approved by the <br />Division, since the riprap lining is necessary to control erosion, and the lined <br />channels will be stable and will require infrequent maintenance (4.05.4(2)(a)). <br />22 <br />