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drying the watershed to an index of watershed wetness below average <br />or more closely representing AMC I. <br />To convert a CN with AMC II to a CN with AMC I involves <br />multiplication by a conversion factor which decreases the CN value. <br />For example, a AMC II, CN = 80 is equal to a AMC I, CN = 63. <br />Therefore, by definition, Colowyo should convert all CN's from AMC <br />I3 to AMC I to accurately reflect mine site characteristics in <br />accordance with Rule 4.05.6(3)(a). <br />Treatment/Reclamation ProceduresJSite Sediment Control Practices <br />A quote of a statement made by Mike Lonq, director of CMLRD, <br />at the Colorado Mining Association Annual Convention, is reflective <br />of Colowyo's reclamation philosophy: <br />"Sediment control without sediment ponds is <br />the direction in which Colorado needs to go". <br />Once again, recall Colowyo's numerous awards for "exemplary <br />reclamation performance". Additionally, remember that runoff is <br />equal to precipitation minus all abstractions, ie, losses. Another <br />major abstraction from precipitation on reclaimed land at Colowyo, <br />is surface storaae of water. Surface storage is defined as "the <br />volume of water required to fill depressions and other storages <br />before surface runoff begins". <br />-• A standard reclamation practice at Colowyo is to cut contour <br />furrows perpendicular to the reclaimed slope. These furrows are <br />cut into the topsoil by either a farm tractor or dozer equipped <br />with plow shears. Each furrow is approximately two feet wide by <br />one foot deep, spaced approximately 6.5 to 10 feet apart, with <br />variable lengths that are not continuously connected. These <br />furrows serve the dual function of a surface storage water trap and <br />as a sediment trap. The water trap serves to irrigate the root <br />zone of the reclaimed slope below it while the sediment trap keeps <br />topsoil from being lost. Rills and gullies are prevented from <br />forming also. <br />In discussing contour furrows with Dr. Warner, he stated that <br />the CN value will be lower due to the entrapment of rainfall in the <br />contour furrow where it is lost to surface runoff. Actual <br />measurements of surface storage are difficult to make, but none- <br />the-less, surface storage of water and sediment is a valid factor <br />to be recognized in the design of sediment storage ponds. <br />Therefore, in accordance with Rule 4.05.6(3){a), Colowyo <br />should receive consideration when determining runoff volume, due to <br />contour furrows being used in reclamation procedures and as an on <br />site sediment control practice. <br />• <br />