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General Grading Requirements <br /> Final Graded Slopes. Postmining slopes will not be uniform but will approximate the <br /> general nature of the premining topography. All highwalls will be eliminated and graded <br /> to a 5:1 slope or flatter. <br /> Terraces. Terracing in the final reclamation is not proposed at the Nucla Mine. <br /> Small Depressions. Small depressions are not proposed at the Nucla Mine. See Exhibits <br /> 20-3 and 20-10 for the postmining topography. <br /> Steep Slopes. Nucla Mine does not have steep slopes as defined in the regulations. <br /> Final Grading. Final grading and preparation of the backfilled material before <br /> placement of topsoil material will be done along the contour to minimize subsequent <br /> erosion and instability. If such grading is hazardous to equipment operators, then <br /> grading will be done in a direction other than generally parallel to the contour. <br /> Final Pit Backfilling. In order to eliminate any final highwalls and to achieve the <br /> approximate original landform, some highwall material will be pushed or dozed into the <br /> mined area. Exhibits 20-4 and 20-11 show typical cross sections of the fill material <br /> placed into the mined pits. Material above the final highwall may be blasted or ripped <br /> and then graded to blend into the surrounding topography. <br /> Thin and Thick Overburden <br /> The Nucla Mine does not meet the requirements of either the thick or thin overburden <br /> regulations as shown by the following calculations. <br /> 65.01 Max., stripping depth <br /> (Area No. 1) 47.8' Avg. OVB. <br /> 1.71 Upper Dakota <br /> 8.2' Parting <br /> 5.2' Lower Dakota <br /> 20-2 Revised 05/24/91 <br />