Laserfiche WebLink
(c) Provide a nonclogging dewatering device or conduit spill- <br />way to remove water storage resulting from inflow. The dewatering <br />device shall not be located at a lower elevation than the maximum <br />sediment storage volume. Dewatering shall be achieved in accordance <br />with applicable State law; and <br />(d) Provide for an appropriate combination of principal and <br />emergency spillways to discharge safely the runoff from a 25-year, <br />24-hour precipitation event, or larger event specified by the Divi- <br />sion, plus inflow from any underground mine or water pumped from the <br />pit. The elevation of the crest of the emergency spillway shall be <br />a minimum of 1.0 foot above the crest of the principal spillway. <br />Emergency spillway grades and allowable velocities shall be approved <br />by the Division. <br />(e) There shall be no out-flow through the emergency spillway <br />during the passage of runoff resulting from the 10-year, 24-hour <br />precipitation events through the sedimentation pond, regardless of <br />the volume of water and sediment present from any underground mine <br />or water pumped from the pit if any, during the runoff, <br />Fesponse: The conceptual design detention basin is presented on <br />Figure 4a, Middle Creek Mine Conceptual Detention Basin Design. As <br />shown on Table A, Detention Basin Design Parameters, the detention <br />basin will provide adequate storage for the runoff and sediment <br />yield from a 10-year, 24-hour storm event. Accumulated sediment <br />will be removed when surveys indicate that leas than 40 percent of <br />the design sediment storage volume exists. The pond is to be equip- <br />