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<br />' slope declines to near the angle of repose. The wedge type <br />stability analysis was run using a 3:1 slope to 3.5:1 (horizontal <br />' to vertical) slope. A safety factor of 2.95 was determined for <br />these parameters and with no seismic acceleration. The gravel <br />' pit extension is in a seismic zone one which is a low potential <br /> earthquake zone. Seismic acceleration is generally assumed to be <br />' between 0.10 to 0.20. California <br />i uses a value <br />f t <br />i <br />i of 0.25 where <br />h <br />h <br />k <br /> gh and the <br />earthquake potential is h ntens <br />ty o e eart <br />qua <br />es <br /> are large. With a seismic acceleration value of 0.10 the above <br />' discussed wedge has a safety factor of 2.68. The safety factor <br /> is above unity and is adequate for the temporary slope. Using <br />' California's much more intense value of acceleration the factor <br />of safety would be 2.36. In addition, these slopes were analyzed <br />' with overburden material being piled in a berm in the worst case <br />scenario, directly on they edge of the pit, 8' high. A safety <br />' factor of 2.54 was determined with no seismic acceleration. The <br />safety factor reduces to 2.31 with a value of 0.10 seismic <br />acceleration, and 2.03 with a value of 0.25. <br />Numerous soils experts, including the Bureau of Reclamation in <br />' their Earth Manual, recommend excavated slopes for this type <br />operation to be 1:1 on a standard basis. Some small slough is <br />' expected to occur with time due to vibration or wetting from <br />rainfall or snow and from frost heave. These same sources <br />' recommend 1.5:1 slopes for permanent borrow pit and reservoir <br />area back slopes. However, they do recommend the slopes be <br />increased where the public has access. Therefore, it should be <br />' determined that the proposed 3:1 mining and reconstruction slopes <br />are more than adequate for this type of operations, even when <br />' intense seismic acceleration values are factored in. <br />' Conclusion <br />In conclusion, the proposed mining and reconstruction slope is <br />' adequate for this mining operation. The 200 foot separation from <br />County Road 44 and the buried utility lines under or beside it is <br />' 12 <br />