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• <br />n <br />U <br />I • <br />Appendix D <br />Safety Factor Analysis for Sediment Pond <br />General <br />A soil sample representative of the embankment construction material, collected at the <br />embankment location, was submitted to Trautner Geotech in Durango, Colorado, to determined <br />average cohesion and internal friction angle values. <br />Safety factors in this report were determined by a rotational shear analysis using the Hoek <br />Method, Hoek & Bray, "Rock slope Engineering", 1981. This method uses a series of standard <br />charts to determine the safety factor based on a given set of parameters, including slope height, <br />slope angle, soil density, cohesion, and internal friction angle. <br />The following assumptions are used in these calculations: <br />(1) The material forming the slope is assumed to be homogeneous; <br />(2) The shear strength of the material is characterized by a cohesion (c) and a <br />friction angle (~); <br />(3) Failure is assumed to occur on a circulaz failure surface which passes through <br />the toe of the slope; <br />(4) A vertical tension crack is assumed to occur in the upper surface of the face <br />of the slope; <br />(5) The location of the tension crack and failure surface aze such that the factor of <br />safety of the slope is a minimum for the slope geometry and groundwater <br />conditions considered. <br />The proposed sediment pond is shown on the following drawings: Watershed Map 1 of 3, <br />Sediment Control Plan 2 of 3, and Proposed Sediment Pond 3 of 3. The pond will be located <br />neaz an existing drainage and will be partly incised into the natural ground. The existing channel <br />will be filled and compacted. This newly created azea will be used for the storage of topsoil. <br />Undisturbed storm runoff, that would normally pass through this drainage, will be diverted past <br />the sediment pond site by a 72 inch culvert. <br />The proposed pond bottom will be at an elevation of 7227 feet and will have an embankment of <br />I 1 feet. The embankment elevation is scheduled to be at 7238 feet. Embankment slopes within <br />the pond are proposed to be a maximum of 2H:1 V. The exterior of the embankment will be at a <br />slope of 3H:1 V. See Figure 1 Sediment Pond Dam Cross Section. <br />Nationd Xing Cod, LLC. <br />King Mine l7 <br />April 2006 <br />