Laserfiche WebLink
Waste rock will be transported to the top of the pile via conveyor and will be <br /> spread with heavy equipment that will access the top of the pile from existing <br /> roads leading to the top of the mesa from the northeast. A constructed road that <br /> traverses the pile and the north hillside and terminates on the top of the waste <br /> pile will provide access for light duty vehicles. The road will initially be <br /> constructed as shown up to the point where it attains its highest elevation on the _ <br /> north hillside. Then it will gradually drop back down toward the valley floor as it <br /> heads east, upvalley. As the pile volume increases in elevation it will <br /> progressively cover this portion of the road until the maximum volume is reached <br /> and the road will appear as shown on the plans. This will give continuous access <br /> as the pile grows with time. <br /> Stability Analysis <br /> A limit equilibrium analysis for plane surfaces was used to assess the stability <br /> of the design configuration. The analysis is appropriate for simple geometries <br /> with plane failure surfaces. Because of the very shallow depth to bedrock a <br /> circular failure plane is unlikely and a plane failure surtace paralle+�to-the bedrock <br /> is expected. Static equilibrium equations were derived for the specific geometry <br /> oecu rring at this site. <br /> The limit equilibrium stability analysis is dependent on three soil propertres: <br /> effective cohesion, effective friction angle and the unit weight of the material. To <br /> determine fa+d estimates of these-properties, soil samp+es artd testing were <br /> completed by Lambert and Associates, Inc. (Consulting Gaotechnical Engineers <br /> aneF Materia+Testing)-. A ho4bw stem auger was used to�drill through the entire <br /> thickness of the existing pile. Samples were extracted at various depths and <br /> used to estimate the soil properties. <br /> Direct shear tests ware peroormed to determine the effective cohesion and <br /> friction angle. The result of these tests covered an exceptionally wide range and <br /> thus a triaxial shear test was performed to confirm the appropriate values. The <br /> unit weight of the material was determined during compaction tests. Test results <br /> are reported in the properties table shown above. <br /> Safety factors computed using these parameters ware from t.5 to 2. The <br /> analyses included pore water effects, which lowers the safety factor resulting in a <br /> conservative estimate. The requiretl safety factor must be equal to or greater <br /> than t.5. <br /> Gonstruction <br /> The waste pile will ba constructed in stages, progressively extending up the <br /> drainage as needed. Prior to development of a new stage, the topsoil will be <br /> removed and stockpiled. All vegetation will be removed prior to stripping of the <br /> topsoil. <br /> January 1998 <br />