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• design and performance requirements of the Colorado Mined Land Reclamation <br />Division while utilizing as much of the existing structure and topography <br />as passible. <br />HYDROLOGY <br />The hydrology of each watershed was analyzed utilizing the SEDIMOT II <br />computer program. In performing this analysis, the characteristics of the <br />minesite and reclamation procedures along with on-site sediment control <br />procedures were considered. Addendums A and B contain complete listings <br />of the SEDIMOT II inputs and outputs for the 10-year and 25-year design <br />storms. Table 1 is a summary of these results. <br />TABLE 1 <br />Design Hydrology and Sedimentology Summary <br />Structure 001 <br />• <br />DESCRIPTION 10-yr-24hr 25yr-24hr <br />Precipitation Depth 1.60-in. <br />Inflow Routed Volume 6.67-ac-ft <br />Pond Volume At Peak Stage 10.08-ac-ft <br />Peak Stage 9.12-ft <br />Peak Inflow Rate 27.33-cfs <br />Peak Discharge Rate 0.81-cfs <br />Basin Trap Efficiency 100.00 % <br />Detention of Flow (Sediment) 49.70-hr <br />Detention of Hydrograph Centers 15.22-hr <br />1.80-in. <br />9.63-ac-ft <br />12.97-ac-ft <br />10.67-ft <br />48.26-cfs' <br />0.88-cfs E <br />• <br />In determining the hydrology parameters to be used as input to the <br />SEDIMOT II computer program, each major watershed was subdivided into <br />logical junctions, branches, structures, and subwatersheds. The basis <br />of the subwatershed were drainage boundary, similar soil and vegetation <br />type, and similar land use. The drainage area for this sediment pond <br />was measured on 1-inch equals 400-feet and I-inch equals 2000-feet <br />topographic maps (see Exhibit 13-4 and Exhibit 13-6, respectively). <br />In some instances, the mining will cause the drainage area to change <br />during the life of the sediment structure. When the pit moves into the <br />watershed, runoff is intercepted by the pit and diverted away from the <br />2 <br />