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The Division proposes to grant small area exemptions (SAE's) from use of sediment ponds <br />for the office facility area (SAE-1, .78 acres), the topsoil stockpile (SAE-2, .39 acres), and <br />the construction dirt stockpile (SAE-3, .30 acres) due to the limited size of the areas and due <br />to the fact that the operator has demonstrated that ponds and treatment facilities are not <br />necessary for the drainage to meet the effluent limitations of Rule 4.05.2 and applicable State <br />and Federal water quality standards for receiving streams, and also due to the fact that no <br />mixing of surface drainage with a discharge from underground workings will occur <br />(4.05.2(3)(b)(i). <br />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 four of the five tributary drainages have been <br />diverted via culverts beneath the mine bench. The culverts are adequately sized for the design <br />event and 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 summer. <br />One emhemeral drainage on the south side of the portal bench is ditched around the shop building <br />at the base of the cut slope, and is directed to the sedimentation pond. A temporary diversion <br />ditch to the south of the sediment pond routes flow from three small ephemeral drainages around <br />the pond, sediment drying area, topsoil stockpile and construction material stockpile. Berms in the <br />office facilities area divert overland flow around the 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 was 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, [he flow in McClane drainage was diverted for many years. <br />The diversion channel flowed generally straight west to East Salt Creek. Lower segments of the <br />diversion channel developed into a steep sided gully, deeply incised into the colluvial/alluvial <br />deposits, as is typical of ephemeral stream channels in the region. In 2006, Haul Road Culvert "P" <br />was installed as approved by TR-14, which re-connected the upper segment of McClane Creek <br />with its original lower segment. <br />Upon final reclamation, all temporary diversion ditches, berms and culverts will be removed, and <br />ephemeral drainages will be reconstructed in their approximate original locations. Fill <br />embankments in locations where the haul road crosses McClane Creek will be removed and the <br />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 tables are <br />referenced in the cited text sections. <br />The following specific approval is required by Rule 4. <br />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 />