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sandstone that will be constructed in- place. Soil material types used in modeling are identified in <br />Table 3. <br />Land Use <br />The following assumptions for land use were calculated in the HELP model based on soil type, slope, <br />and slope length: <br />• Reclaimed Refuse Pile at 40% Slope- CN =88 for a clay soil material with a fair stand of <br />vegetation and a slope length of 150 -feet <br />• Reclaimed Refuse Pile at 3% Slope- CN =87 for a clay soil material with a fair stand of <br />vegetation and a slope length of 150 -feet <br />• Unreclaimed Refuse Pile at 40% Slope- CN= 74 for compacted refuse (gravel) pile with no <br />vegetative cover and a slope length of 150 -feet <br />• Unreclaimed Refuse Pile at 3% Slope- CN= 71 for compacted refuse (gravel) pile with no <br />vegetative cover and a slope length of 150 -feet <br />3.1.2 Model Parameters <br />Eight different refuse pile filling states were modeled that varied reclaimed and unreclaimed surface <br />conditions, slope grades, and refuse thickness depths. The assumed refuse pile design has a <br />maximum refuse thickness of 350 -feet and an average thickness of 130 -feet. The final graded <br />surface has slopes at 40% and 3 %. The slope on the drainage layer is estimated at 54% with a slope <br />length of 820 -feet. The reclaimed refuse conditions include a 24 -inch cover soils layer, the refuse <br />layer, and a 12 -inch drainage blanket layer. The unreclaimed refuse conditions include the refuse <br />layer and a 12 -inch drainage blanket layer. The following eight conditions were used in modeling: <br />Reclaimed Refuse Conditions <br />1. Average refuse depth = 130 -feet and a 40% surface slope <br />2. Average refuse depth = 130 -feet and a 3% surface slope <br />3. Maximum refuse depth = 350 -feet and a 40% surface slope <br />4. Maximum refuse depth = 350 -feet and a 3% surface slope <br />0 Unreclaimed Refuse Conditions <br />5. Average refuse depth = 130 -feet and a 40% surface slope <br />P:\Mpls \06 CO\26 \06261003 MCC Refuse Pile Site Review & Permit \WorkFiles\Permit Application \Text\2010 -04 -19 RPE East Permit Application.docl o <br />