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i. Channel Aligrunent <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: IV using drainage channels to stabilize and <br />revegetate land features. The altered drainage prior to 1950 as approved by DRMS 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 I.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). r1__ <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 />