Laserfiche WebLink
<br />iii iiiiiiiiiiiiiiu <br />999 <br />c~~us <br />~ Orchard Valley <br />Cyprus Orchard Valley Mine <br />P.O. Box 1299 <br />Paonia, CO 81428 <br />Phone: 303-527-4135 <br />Fax: 303527-2234 <br />November 20, 1992 <br />L, ~ ?._ ~ <br />Mr. Steve S. Shuey DEC l 8 1992 <br />Reclamation Specialist <br />Division of Minerals and Geology ~. .._ . <br />1313 Sherman Street, Room 215 MltvctiALS a i,~~` _ <br />Denver, N 80203 <br />RE: PF~II'P NO. C-81-038; '~~TCAL REVISICH~I 92-20; SMALL TRF7~ sxn~vrr~ <br />Dear Mr. Shuey: <br />Cyprus Orchard Valley Coal Corporation (COVCC) is requesting a technical <br />revision to the above referenrzd permit. The revision incorporates <br />doclmlentation into the permit required under Rule 4.05.2(3)(a) demonstrating <br />sedimentation porr9s and treatment facilities are not necessary for drainage <br />from certain disturbed areas within the permit area to meet applicable <br />effluent sr~r>da~a. The attached application is resubmitted with additional <br />materials as requested in the Division's "Inccmlplete De*a*-a+;*~tion" of July <br />13, 1992. <br />Five area-specific demonstrations, developed utilizing the Sedcad+ Hydrology <br />aril Sedimentology modelling program, are provided. The five areas addressed <br />through modelling by this application are as follows: 1) Orchard Valley West <br />Mine Fill Slope (Southern Exposure); 2) Orchard Valley West Mine Fill Slope <br />(Northern Exposure); 3) Orchard Valley West Mine Vent Shaft & Fan Site; 4) <br />Orchard Valley Mine Training Trailer Area Outslopes; and 5) Orchard Valley <br />Mine Silo Area Railroad outslopes. The training trailer and silo area <br />outslopes were modeled using a representative slope segment maximizing slope <br />and slope length. Other areas were modeled in their entirety. All <br />demonstrations illustrate the maximum allowable settleable solids <br />concentration for runoff from precipitation events less than to or equal to <br />the 10-year, 24-hour event (i.e. 0.5 ml/1) is not exceeded. <br />Each demonstration illustrates that runoff generated from the l0-year, 24-hour <br />precipitation event can be effectively treated by established grass filters at <br />the toe of each slope. Existing vegetation, modelled as a grass filter within <br />the Sedcad+ program, in all five instances provides adequate treatment to meet <br />effluent stand?T-r7e for settleable solids. In addition, several areas are <br />equipped with hay bale or silt fence sediment traps which, though not <br />accounted for in the modelling, further reduce sediment concentrations in <br />runoff water. The areas so equipped include: 1) Orchard Valley West Mine <br />