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• Thln and Thlck Overburden <br />The Nucla Mine does not meet the requirements of either the thick or thin overburden regulations <br />as shown by the following calculations. <br />65.0' Max., stripping depth <br />(Area No. 1) 47.8' Avg. OVl3. <br />1.7' Upper Dakota <br />8.2' Parting <br />5.2' Lower Dakota <br />At the average stripping depth <br />47.8' overburden <br />1.7' coal <br />8.2' parting <br />5.2, coal <br />82.9' material excavated <br />at 15°,6 swell <br />• 1.15 x (47.8' + 8.2') =64.4' material replaced <br />64.4' - 62.9' = 1.02 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 />65.0' overburden <br />1.7' coal <br />8.2' parting <br />5.2' coal <br />80.1' material excavated <br />at 15% swell <br />1.15 x (65.0' + 8.2') = 84.2' material replaced <br />84.2' - 80.1' = 1.05 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 />• <br />20-2 <br />