2018-11-19_PERMIT FILE - C2010089A (3)

Home Browse Search

Topsoil Salvage Depths The available topsoil and salvageable depths for the permit area is shown on Map 2.04.9-3: Topsoil Salvage Map. The overall topsoil balance for the mine was calculated by taking the weighted averages from each mapping unit shown on the map as well as major inclusion areas. Generally, topsoil having a very high percentage of coarse fragments (greater than 20 percent by volume), very shallow bedrock (0 to 10 inches) and shallow ground water (less than 1 to 2 feet), have little suitable topsoil to be salvaged. No topsoil is available to be salvaged from existing roads, ponds, ditches, residences, or farmyards. Topsoil Stripping Before any area at the NHN Mine site other than a topsoil stockpile, light use access road, shallow drainage ditches, power line corridors and other small area exemption areas are disturbed, the suitable topsoil material will be removed. Suitable topsoil will be salvaged from all significant disturbance areas including sediment ponds (includes pond area, embankment and spillway), mining activities, spoil stockpiles, haul roads, access roads, mining areas, facilities area and diversion ditches, which extend below the depth of salvageable topsoil. Prior to topsoil removal, vegetation which is too large for incorporation into the topsoil will be scraped away, placed in the pit, or utilized on Dryland Pasture reclamation areas as habitat should the surface landowner agree with this practice. The remaining vegetation will be incorporated into the topsoil to help increase organic matter levels. To prevent unnecessary contamination, adequate buffer of a few feet shall be salvaged from the edge of a road, embankment, ditch, cut slope and toe of fill between the edges of the disturbance. Since the topsoil map is an estimation based on field data and the salvage depths vary according to the actual topsoil depths observed during topsoil stripping, all topsoil is salvaged to maximize postmining vegetation production. Structural damage can occur to topsoil if they are salvaged while saturated. Therefore, topsoil salvage equipment will generally be limited to the drier areas. Wet areas will be dewatered and allowed to dry prior to salvage. Appropriate adjustments will be made to the recovery rate as dictated by actual field conditions and initial topsoil balance reports. During the preparation of the initial boxcut area, the existing topsoil materials were salvaged in a single lift and hauled to a designated topsoil stockpile shown on Map 2.05.4(2)(d)-2: Topsoil and Overburden Stockpile Locations. During the normal mining sequence as operations advance and there is sufficient graded area behind the pit for reclamation, topsoil may be stripped and direct hauled from the advanced stripping areas to the graded areas behind the pit. On the Garvey property, the Irrigated Pasture/Cropland (IPC) areas corresponding to the more productive Progresso topsoil and REC topsoil will be salvaged separately and stockpiled separately. Stockpile locations are shown on Map 2.05.4(2)(d)-2. Section 2.05.4(2)(d) Page 4 January 2018 (PR -02)