Laserfiche WebLink
aTber 12, 1979 <br /> B , Morrison-Knudsen S tudv C` -)7-101 <br /> M COMIT ENT RES0LIRL""rS, L%. <br /> Coal Basin Mines <br /> Pitkin County, Colorado <br /> ROCK TUNNM SED"= & DRAU:Aa C01= STRUCIUF.ES <br /> The Rock Tunnel is located in Dutch Creek Drainage within Coal Basin <br /> (II-3-App . 7-Att . 4-1) <br /> in Western Pitkin County, Colorado. (Figure 1) The disturbed areas include <br /> the pad area at the portal to the Rock Tunnel called the Yard Area and the <br /> z <br /> site for placement of waste rock fill called the Waste Pile. <br /> (Figure <br /> 2) t t . -2) <br /> The Waste Pile area includes the three sedimentation ponds. Undisturbed areas <br /> adjacent to the disturbed areas are isolated from the disturbed areas by div- <br /> ersion ditches. Mine effluent (I cfs) will be conveyed Lrom the Yard Area to <br /> the sedimentation ponds. <br /> METHODS <br /> Design criteria for the Rock Tunnel site have been developed using U.S. <br /> Soil Conservation Service Methods. References used include; Determination of <br /> Peak Flows within Colorado (1977) , SCS Technical Note 50 aid National Engineer- <br /> ing Handbook Numter 4. <br /> (Section C) <br /> The calculations are described in detail in the attached appendix. Thy <br /> attached 2 plates show design details. (See Exhibit I I-B-A p p . 5-5&6) <br /> DESIGN <br /> The sediment and drainage control structures include the follo-Ang: <br /> 1.) Three sedimentation ponds <br /> 2.) Collector ditch <br /> 3.) Ditch Spill-Tray <br /> 4.) Diversion ditches <br /> 5.) _ Cross-over culvert <br /> 3 <br />