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Chapter IV <br /> All sediment ponds will be examined quarterly for the following: <br /> - Seepage from the downside of the embankment. <br /> - Erosion of embankment slopes. <br /> - Obstructions to emergency and/or principal spillways. <br /> - Properly cleaned and maintained dewatering devices. <br /> - Sediment storage volume. <br /> - Sloughing, tension cracks, piping, etc. <br /> Sedimentation ponds will be removed after disturbed areas have been <br /> restored and revegetated, following mine closure, in accordance <br /> with the post-mine reclamation plan. Each pond will be removed, <br /> unless approved for retention as part of the post mining land use, <br /> and the area disturbed by the pond will be regraded, topsoiled and <br /> revegetated. <br /> Reclamation of sedimentation ponds will be accomplished following <br /> mine abandonment, although ponds approved for retention in support <br /> of the postmining land use plan will remain. They will be removed <br /> after the disturbed areas have been restored and revegetated in <br /> accordance with the postmining reclamation plan. The reclamation <br /> of the ponds will be accomplished when the drainages meet <br /> applicable water quality standards. When the sedimentation pond is <br /> removed, the disturbed area will be regraded, topsoiled and <br /> revegetated. <br /> Small area exemption have been approved for the following areas: <br /> Technical Revision 19 Technical Revision 20 <br /> S/E corner No. 4 mine bench S/W end No. 3 Mine pad <br /> Mine No. 3 lower coal storage pad Outslope - rock tunnel pad <br /> Mine No. 3 upper storage paid 016 pond topsoil pile <br /> Mine No. 3 lower coal storage bin pad S/E end bathhouse berm <br /> Mine No. 1 powder magazine No. 1 Mine substation <br /> Mine No. 4 powder magazine South portal - No. 1 Mine <br /> Adit/Rock Tunnel area powd r magazine <br /> 7. Discharge Standards. <br /> The sedimentation ponds have been designed to provide a minimum <br /> sediment storage of 0.1 acre feet of sediment per acre of disturbed <br /> land, or designed to contain the 3 year sediment storage from the <br /> disturbed area using the Universal Soil Loss Equation (USLE) . The <br /> designed retention time of the ponds is 24 hours, with dewatering <br /> devices of either a valve activated or T-culvert discharge system <br /> or unlined impoundment natural filtration. <br /> Revised 7/91 <br /> 20 <br />