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Runoff over the face of the pile is controlled by a series of benches <br />• that slope back toward the pile at a rate of 1v:20h. The benches are <br />pitched to drain toward either side of the refuse pile where runoff is <br />carried to the sediment pond at the toe of the fill. The outslope of <br />the pile between terraces is 24 degrees, resulting in an average slope <br />of 20 degrees for the face of the pile. Details of the refuse pile <br />configuration are shown on Drawing D-4-12. <br />Runoff will be diverted around the refuse pile by permanent diversions <br />D-7, D-9, and D-10, all have been designed for the 100-year, 24-hour <br />event. Design calculation for these ditches are in Appendix 4-B, "final <br />Design Calculations". <br />The diversions drain into the refuse disposal pond. A description of <br />the foundation for the pond, source and properties of the material, <br />and compaction methods is found in Appendix 4-B, "Chen and Associates <br />Geotechnical Report," under Construction Considerations. A discussion <br />on the cutoff trench to limit seepage is included in Appendix 4-B. <br />• Because less than 5 feet of the outlet pipe is the saturation zone <br />(due to the low riser design), antiseep collars are not justified and <br />will not be used. <br />Snowmass Coal requests an authorization from the Division allowing the <br />proposed embankment, and pledges to fulfill all the requirements of <br />section 4.05.18(1) (a ), (b), and (c) concerning mining activities <br />closer to a perennial stream than specifically allowed by the <br />Division. <br />Refer to sheet numbers 1 of 2 and 2 of 2 of Refuse Pond and North <br />Thompson Creek in Appendix 4-6 under final Design Calculations for the <br />following discussion. <br />U <br />4-22 <br />