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Section 2.05.3(4)Page 3 April 2024 (TR-25) <br />the runoff from a 25-year, 24-hour or larger event, as required by the DRMS regulations. <br />In accordance with Rule 4.05.9(9), the faces of all embankments and surrounding areas will be <br />vegetated to protect against erosion. Where water will be impounded, the upstream faces of all <br />embankments will also be vegetated to protect against erosion from water or sudden drawdown. <br />Vegetation will occur in accordance with one of the approved temporary seed mixtures. The <br />sediment storage capacity of the sedimentation ponds will be periodically monitored to ensure that <br />sediment storage is available beneath the principal spillway inlet. When adequate capacity is no <br />longer available, corrective actions will be taken to restore adequate sediment storage capacity to <br />the pond. Corrective action to restore adequate sediment storage capacity will include removal of <br />accumulated sediment from the pond. The excavated material suitable for topsoil will be salvaged <br />in a stockpile used for reclamation. The excavated material that is not suitable for a topsoil-like <br />medium will be graded into the surrounding topography within the disturbance area, topsoiled and <br />revegetated in accordance with the NHN approved reclamation plan. All sedimentation ponds will <br />be inspected quarterly under the supervision of a registered professional engineer and reported to <br />the DRMS. <br />Erosion Control Plan <br />New Horizon Mine will use various types of structures to control the runoff from disturbed areas <br />within the permit boundaries. In addition, surface mining activities will be planned and conducted <br />to minimize disturbance of the prevailing hydrologic balance in both the mine plan and adjacent <br />areas in order to prevent long-term adverse changes in the hydrologic balance. If rills and/or gullies <br />of limited areal extent form which disrupts the approved post mining land use or the <br />reestablishment of the vegetative cover they will be mitigated as soon as practical. Repairs will <br />also be performed in accordance with Rule 4.15.7(5)(a), which means they will be limited to no <br />more than five percent of the acreage initially revegetated during any one year. If a rill or gully <br />feature is identified, NHN will utilize appropriate manpower and equipment depending on the <br />ground conditions and the extent of the erosion. This shall include but is not limited to small track <br />dozers, blades and rubber tired farm tractors. Equipment will be utilized to repair the areas with a <br />minimal footprint as possible. <br />Should an area need repaired that requires a more long term control method, NNH may employ <br />additional measures including erosion control blankets, straw wattles, silt fences, silt fence like <br />products, small riprap structures, mulches, small check dams, small rock structures including rock <br />basket(s) to reduce runoff volume. If repairs are required, all areas that have been mitigated will <br />be seeded with an appropriate approved seed mixture. If any of the above mentioned sediment <br />control measures are employed, they will be used inside the primary sediment control systems or <br />in conjunction with small area exemptions (SAE). These measures, if necessary, will also not be <br />implemented on any designed structures (i.e. conveyance ditches or sediment ponds).