Laserfiche WebLink
largely consisting of clay fines with a noticeable amount of carbonaceous material. Refuse and <br />colluvium were tested for geotechnical modeling purposes, as reported in Section 2. Test results were <br />used to establish HELP model input parameters. Soil material types and characteristics used in <br />modeling are identified in Table 5. <br />Modeled Waste Rock Pile Configurations <br />The following assumptions for land use were calculated in the HELP model based on soil type, slope, <br />and slope length: <br />• Reclaimed Waste Rock Pile at 40 percent Slope (2.5H:1V) - CN=88 for a clay soil material <br />with a fair stand of vegetation and a slope length of 150 -feet <br />• Reclaimed Waste Rock Pile at 3 percent Slope - CN=87 for a clay soil material with a fair <br />stand of vegetation and a slope length of 150 -feet <br />• Unreclaimed Waste Rock Pile at 40 percent Slope (2.5HA V) - CN= 74 for compacted waste <br />rock pile with no vegetative cover and a slope length of 150 -feet <br />• Unreclaimed Waste Rock Pile at 3 percent Slope - CN= 71 for compacted waste rock pile <br />with no vegetative cover and a slope length of 150 -feet <br />The 40 percent slope was modeled as a representation of the north face of the RPEE waste rock pile. <br />The 3 percent slope was modeled as a representation of the working pad and finished top of the waste <br />rock pile, both of which will slope gently to the south to tie into the existing ground to the south. <br />3.1.2 Model Parameters <br />The RPEE waste rock pile was modeled for eight different conditions. The conditions included <br />reclaimed and unreclaimed surface conditions, slope grades for top of pile slope and north face slope, <br />and refuse thickness depths to understand potential conditions at maximum refuse pile depth and <br />average pile depth. The assumed waste rock pile design has a maximum waste rock thickness of 140 <br />feet and an average thickness of 70 feet. The final graded surface has slopes at 40 percent on the <br />north face and 3 percent on the working pad and finished top. The slope of the drainage layer is <br />estimated at 40 percent toward the thalweg of the existing No Name Gulch with an average slope <br />length of 300 feet. The reclaimed refuse conditions include a 24 -inch -thick cover soils layer with <br />vegetation and the refuse layer. The unreclaimed refuse conditions include the refuse layer only. <br />15 <br />PAMpls\06 CO\26\06261003 MCC Refuse Pile Site Review & Permit\WorkFiles\Permit Application\2014 Revision\Exhibit 82 2014-05- <br />29.docx <br />