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Final Graded Slopes: Post -mining slopes will not be uniform but will approximate pre -mining <br />topography. All highwalls will be eliminated and graded to a 511:1 V slope or flatter. <br />Terraces: Terracing in the fmal reclamation is not proposed at the NHN Mine. <br />Small Depressions: Small depressions are not proposed at the NHN Mine. <br />Steep Slopes: NHN Mine does not have steep slopes as defined in the regulations. <br />Thin and Thick Overburden: The NHN Mine permit area does not meet the requirements of <br />either the thick or thin overburden as shown by the following calculations: <br />96.00' maximum stripping depth <br />55.91' average overburden <br />9.60' Max. Combined Upper and Lower Dakota <br />At the average stripping depth <br />55.91' overburden <br />+ 7.05' coal <br />62.96' material excavated <br />at 15% Swell <br />1.15 x (55.91) = 64.30 material replaced <br />64.30'/62.96' = 1.021 of the initial thickness <br />Therefore, the 0.8 requirement for thin overburden and the 1.2 requirement for thick overburden <br />are not met. <br />At the maximum stripping depth <br />96.00' overburden <br />+ 9.60' coal <br />105.60' material excavated <br />at 15 % Swell <br />1.15 x (96.00') = 110.40' material replaced <br />110.40'/105.60'= 1.045 of the initial thickness <br />Therefore, the 0.8 requirement for thin overburden and the 1.2 requirement for thick overburden <br />are not met. <br />Disposal of Excess Spoil <br />All excavated non -coal material from the mining areas will be used for backfilling the mined pits <br />and blending mined areas into the existing topography to achieve the approximate original <br />landform. Therefore, no excess spoil material will exist. <br />Section 2.05.4(2)(c) Page 2 March 2018 (TR -16) <br />