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i. Channel Aligninent <br /> Gold Basin during volunteer reclamation and final DRMS permitted mine disturbed areas will be <br /> reclaimed with slopes equal to or less than 2.5H: 1 V using drainage channels to stabilize and <br /> revegetate land features. The altered drainage prior to 1950 as approved by DRNIS maybe return <br /> to approximate pre-mine location as illustrated on. Figure F-3. <br /> ii. Channel Gradient <br /> Stream gradients will be designed to approximate pre-mine gradients(Exhibit E-Attachment C) <br /> with channels designed and constructed to safely convey to the peak flow from the 100 year-24 <br /> hour storm. <br /> iii. Geomorphic Channel Configuration <br /> Rosgen geomorphic channel design (USDA, 1973)concepts have been incorporated in post mine <br /> channel configuration. According to Rosgen(Table 11-2), Cache Creek is As+-A stream type <br /> which is characterized as being steep,deeply entrenched debris transport, torrent streams. High <br /> energy/debris transport associated with depositional soils. The channels are very stable if <br /> bedrock or in boulder dominated channels. The entrenchment ratio are characterized as being <br /> less than 1.4 with a width/depth ration of less than 12 and sinuosity ranges from 1.0 to 1.1. <br /> Where deemed possible, passive restoration techniques will be adopted including rock built drop <br /> structures,rip rap,minimizing stream channel gradients in areas prone to erosion, installing <br /> natural channel stabilization methods and establishing effective biological erosion control <br /> techniques. <br /> A concept considered in designing channel reconfiguration includes; <br /> Stream type <br /> Valley type <br /> • Channel dimensions <br /> • Channel profile <br /> Geologic controls <br /> iv. Channel Stabilization <br /> Channel structures are illustrated on Exhibit D Figure D-1 (mine plan)and figure F-2 (post mine <br /> reclamation plan). Stabilization methods include silt fences, wattles, rock barriers,fiber mats,rip <br /> rap, drop structures, vegetation strip buffers,and riparian vegetation. (See Exhibit E-Attachment <br /> B), <br /> December 28,2014 <br /> Colorado Division of Reclamation Mining and Safety <br /> Gold Basin Mine,Inc. <br /> Gold Basin Mine <br /> Granite,Colorado <br />