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watersheTs were determined from maps of the area provided by WFC. The +~ <br />C hydrologic parameters utilized in the: simulation are presented on Table 1. <br />The curie number of 80 for the undisturbed areas (subwatersheds :L and 2> is <br />the valie presented by the SCS for forested land with poor cover and belonging <br />to hydr:~logic soli group C. A curve number of 90 is typically used for <br />compacted spoil materials and is thought. to be representative of the compacted <br />waste m+iterlal. Times of concentration travel times. and routing coefficients <br />were es-:imated using the overland flow method as outlines by Barfield, et al. <br />(198I). <br />Table 1. <br />Hydraulic-Tnput Values for Subwatersheds <br /> Sub- Time Routing <br /> Water Area Curve of Travel Coefficients <br /> shed Number Conc. Time K X <br /> (acres) (hr) (hr) (hr) <br /> ---- <br />1 <br />10.90 - <br />80.00 - <br />.490 <br />0.000 --- <br />0.000 - <br />0.00 <br /> 2 12.60 80.00 .400 0.000 0.000 0.00 <br /> 3 9.2^ 90.00 .176 .130 .130 .40 <br /> 4 11.20 90.00 .150 .110 .110 .40 <br /> 5 5.60 90.00 .140 .L10 .110 .40 <br /> 6 8.00 90.00 .130 .100 .100 .40 <br /> 7 14.90 90.00 .110 .040 .^'v .41 <br /> 8 3.30 90.00 .080 .030 .030 .42 <br /> 9 2.60 90.00 .060 .020 .020 .42 <br /> LO 2.20 90.00 .050 .020 .020 .42 <br /> 11 2.10 90.00 .050 .020 .020 .42 <br /> 12 1.70 90.00 .030 .010 .010 .42 <br /> 13 .80 90.00 0.000 0.000 0.000 0.00 <br /> To estiaate the total volume of water that woul d result from a 10 year, 24 <br /> hour rainfall event. SEDIt+gT II was used with a ~nul l~ structure at the <br /> location of the proposed Sediment pond. The 10 year, 24 hour precipitation <br /> depth 1n the vicinity of the New Elk mine i s approx imately 2.9 inches based on <br /> examination of NOAA maps for Col orado (NOAA, 1973). The resulting total <br /> volume of runoff from the draina ge bas in in its final configuration is <br /> approximately 12 acre feet. A po nd was then des igned to hold approximately ' <br /> T <br /> this volume of water. <br />he resulting design is pres ented on Figure 4. The dam <br />