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Revised April, 1984 <br />• computing runoff volumes and rates. Precipitation data were obtained <br />from NOAH Atlas 2, Volume III for Colorado. Soil types were obtained <br />from Map 19, Mine No. 3 Soils. Although mining activities within each <br />watershed in the permit area will create changing hydrologic <br />conditions, the designs are based on the assumption that topsoil has <br />been removed from the entire area to be disturbed by mining within <br />each tributary watershed. Dndisturbed and reclaimed areas were <br />assummed to have the same hydrologic characteristics. Area-weighted <br />calculations were performed to derive representative curve numbers for <br />each tributary watershed. Runoff from any undisturbed area which is <br />to be diverted by ditches away from a disturbed area was not <br />considered in the impoundment designs. <br />• Short-circuiting will be prevented by effecting proper design <br />considerations. All ponds will be constructed so that the outlet is <br />located as far away as practical from the major point of inflow. All <br />of the above design considerations will be used to achieve the proper <br />detention time and prevent short-circuiting. <br />Construction Schedule <br />The Mine No. 3 Detention Basin is an eais[ing structure which <br />will be modified to the specifications proposed in Exhibit 3, Sediment <br />Control Plan. The modification consists of filling the basin with <br />approximately 100,000 cubic yards of backfill material, in accordance <br />with the spoil grading plan proposed under Section 2.05.3(2). The <br />• final configuration of the pond will resemble that show on Figure 3 <br />of Exhibit 3, Energy Mine No. 3 Detention Basin Stage-Storage Diagram. <br />2.05-22a <br />