2016-08-05_PERMIT FILE - C2010089A

Home Browse Search

outside the permit area due to mining disturbance. In accordance with Rule 4.05.6(3) each sedimentation pond is designed, constructed, and maintained to: a) Provide storage for the runoff or inflow entering the pond as a result of a 10 -year, 24- hour precipitation event and to meet all applicable State and Federal regulations for all effluent limitations before discharge from the permit area. The characteristics of the mine site, reclamation procedures, and on site sediment control practices are also considered in the design. b) Provide adequate sediment storage volume in compliance with the DRMS regulations. c) Install an appropriate non -clogging dewatering device to maintain a 10 -year, 24-hour storage volume. d) Install appropriate combinations of principal and emergency spillways to safely discharge the runoff from a 25 -year, 24-hour precipitation or larger event, as required by the DRMS' regulations. Pond NHN-001 The design information for Pond NHN-001 can be found in Appendix 2.05.3(4)-1, and the as - built for Pond NHN-001 can be found in Appendix 2.05.3(4)-6. Pond NHN-002 The design information for Pond NHN-002 can be found in Appendix 2.05.3(4)-8, and the as - built for Pond NHN-002 is located in Appendix 2.05.3(4)-8. The specific designs for Pond NHN- 002 replace any designs contained in Appendix 2.05.3(4)-1. Pond NHN-003 The design information for Pond NHN-003 can be found in Appendix 2.05.3(4)-1. In accordance with Rule 4.05.9(9), the faces of all embankments and surrounding areas will be vegetated to protect against erosion. Where water will be impounded, the upstream faces of all embankments will also be vegetated to protect against erosion from water or sudden drawdown. Vegetation will occur in accordance with the approved seeding plan. The sediment storage capacity of the sedimentation ponds will be periodically monitored to ensure that at least 40% of designed three years of sediment storage is available as designed. When 40% of the designed sediment storage capacity is no longer available, sediment removal will be taken to restore sediment storage capacity to at least 80% of the designed three year sediment storage capacity. The excavated material suitable for topsoil will be salvaged in a stockpile used for reclamation. The excavated material that is not suitable for a topsoil -like medium will be graded into the surrounding topography within the disturbance area, topsoiled, and revegetated in accordance Section 2.05.3(4) Page 4 April 2016 (TR -13)