2013-05-01_REVISION - M2002004 - Laserfiche WebLink

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2. Topsoil (A, E and AC- horizons) will be removed, handled and stockpiled as a separate layer from the area to be disturbed. This salvaged topsoil will be hauled and placed on an appropriately located and designed topsoil stockpile. 3. If the native topsoil is less than 6- inches thick, Rio Grande will remove the topsoil and the unconsolidated AC and /or B- horizon material immediately below the topsoil and treat the entire 6 inch mixture as topsoil. Suitable AC and /or B- horizon subsoil will be managed as subsoil to be removed and stockpiled. 4. Stripping of topsoil from the bottom of drainages should be given first priority to prevent contamination of topsoil by disturbed runoff. It may be necessary to strip drainage corridors to establish proper drainage prior to additional topsoil removal. 5. Suitable subsoil (AC and B- horizons) will be removed, handled and stockpiled as a separate layer from the area to be disturbed. This salvaged subsoil will be hauled and placed on an appropriately located and designed subsoil stockpiles. Subsoil suitability discussions for each soil series are contained in Exhibit I — Soils Information. 6. Topsoil and subsoil will be separately stockpiled in areas shown on Exhibit D -1. 7. The soil removal crew will be provided with a detailed map showing the stripping depths, and a qualified individual will ensure that soil is removed to the specified depth. Topsoil identification for equipment operators is most successful if related to soil mapping location, depth, color, structure, texture and salt and /or calcium carbonate deposition. Soil Stockpile and Erosion Control Plan. Topsoil will be stockpiled in such a manner so as to minimize wind and water erosion and unnecessary compaction. The primary methods of erosion control for soil stockpiles are timely revegetation and /or the use of temporary erosion control measures such as surface roughening, surface mulches, berms, ditches, or small sediment traps. All soil stockpiles will be constructed with 2.5h:1v or flatter slopes, and a ring ditch will be bladed around the base of each stockpile. All A- horizon topsoil stockpiles will be identified by a "Topsoil" sign having 6 -inch lettering. All B or AC- horizon subsoil stockpiles will be identified by a "Subsoil" sign having 6 -inch lettering. Stockpiled soil will be seeded with the stabilizing revegetation mixture during the first appropriate season. A sterile cover crop (Triticale) may be utilized as a nurse crop and stubble mulch. Temporary Soil Stockpiles. In limited situations, topsoil and /or subsoil materials may be temporarily stockpiled or windrowed near active operations rather than placed in permanent stockpiles. These situations would occur when the salvaged soil is needed for current reclamation, but the area is not immediately ready for soil to be respread. Temporary soil stockpiles will be seeded as soon as possible after stockpile construction and clearly identified with appropriate signs. A berm will be placed around the toe of the stockpile to contain sediment produced from the stockpile. Upon reclamation, the surface elevation in the mined area will be lowered from 20 to 30 feet due to removal of the limestone (except when the limestone layer thickness is minimal, caused by ancient weathering and erosion), assuming approximately a 15 to 20% swell factor for the replaced shale and unconsolidated material. The physical extent of the lowering in surface elevation is controlled by the thickness of the unconsolidated material, shale, and limestone and underlying sandstone removed, and the actual swell of the excavated and replaced materials. The proposed reclamation sequence and status of each stage of reclamation at the end of the first eight -years of mining activities is illustrated on Figure D- TR 4 with Markup April 26, 2013 D -7