Laserfiche WebLink
Technical Revision 90-06 <br />• Civil Engineering Handbook, Urquhart L.C.; 1959, and Barfield, Warner, Hahn Applied <br />Hydrology and Sedimentology of Surface Mine Land. The equations utilized are noted in the <br />design calculations. <br />The sedimentation control structures have been located to minimize disturbance, ensure <br />collection and control of disturbed area runoff, limit the distance of the structure from mining <br />disturbance and the receiving drainage, and facilitate construction, operation, and final <br />reclamation. The configuration of the pond embankment, the impoundment area, and the inlet <br />and outlet structures, is consistend with the general design criteria, ensures effective flood <br />routing, and is designed to prevent short circuiting within the pond. <br />Diversion Ditch/Inlet Desion <br />Diversion or inlet ditches for the sedimentation control structure are designed to safely pass <br />• the peak flows from the 10-year, 24 hour storm event with a minimum freeboard of 1.0 foot <br />between the maximum flow elevation and the top of the ditch. Ditch design is abased upon <br />the Manning equation for open channel stability and the limiting velocity approach for open <br />channel capacity. See attached Ditch Design Reference. <br />Outlet Design <br />Outlet design considerations have been incorporated in the design of primary outlet structures <br />and emergency spillways. <br />Culvert Desion <br />Drainage culverts are located throughout the Mine to route surface runoff under roads and <br />• prevent excessive erosion. Culvert design based on the SCS method of calculating peak flows <br />TR 90-06 Exhibit 3 - 11 Revised 11/16/90 <br />