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C . Morrison-Knudsen Calculations <br /> COAL CREEK MINE AREA <br /> ROCK TUNNEL SEDIMENTATION POND CALCULATIONS <br /> MIDCONTINENT RESOURCES <br /> 1. GENERAL DATA - <br /> Site Location - SW corner, section 10 and NZ, NW,, Section 15 <br /> Township 10S, Range 89 W, 6th P.M. <br /> West Pitkin County, Colorado <br /> Average elevation of site - 8100 feet <br /> Drainage: Dutch Creek which is tributary to Crystal River within Coal <br /> Creek Basin in White River National Forest. Property owned <br /> by Mid Continent Resources, Carbondale, Colorado. <br /> Reference - U. S. Soil. Conservation Service 1977 - Proc. for determining <br /> peak flows in Colorado. <br /> 2. SUB AREA DRAINAGE DATA (Fig. 2) <br /> Elevation <br /> Length Max. Min. Diff. Ave.% Curve <br /> Sub Area ft. ft. ft. ft. Slope Number <br /> a) Yard Area 1 500 8950 8550 400 80 8EY <br /> Yard Area 2 600 8550 8540 10 2 90 <br /> b) Pond & Waste 1 1500 8550 8390 160 60 <br /> Pile 2* 700 8800 8400 400 57 85 <br /> 3 800 8400 8340 60 3 100 <br /> *Flow diverted around Pond via ditch (Fig.2) <br /> 3. PRECIPITATION DATA <br /> STORM 24-HOUR RAINFALL <br /> 100 yr. 3.0 inches <br /> 25 yr. 2.6 inches <br /> 10 yr. 2.0 inches <br /> 5 yr. 1.8 inches <br /> 4. RUNOFF TYPE II STORM <br /> Area Runoff (inches) <br /> Sub Area Acres Sq. Mi. C.N. 25 yr. 10 yr. 5 yr. <br /> Yard 1 4.99 0.0078 85 1.26 0.80 0.65 <br /> 2 5.36 0.0084 90 1.62 1.09 0.93 <br /> . Pond & Waste Pile <br /> 1 12.00 0.0188 60 0.20 0.60 0.03 <br /> 2* 4.77 0.0074* 85 1.26* 0.80* 0.65* <br /> 3 4.80 0.0075 100 2.60 2.00 1.80 <br /> *Flow diverted via ditch <br />