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<br />' 3-03. EXISTING SLOPE CONDITIONS <br />~ ' Within the subject area in the southeastern corner of the central pit, the benches at the pit wall were <br />~ backf'illed with soil overhurdeh. Over time some of these benches failed thereby allowing loll and <br />rock debris to move downslope. This debris presently covers nearly the entire failed slope, with the <br />' exception of the highest bench at the north end of the slope failure and several rock outcrops. It is <br />likely that some benches or portions of benches remain hidden below the debris but it is not possible <br />to distinguish individual benches based on visual observations. <br />' The surface of the slope is comprised primarily of soil and rock debris with a few rock outcrops <br />exposed. Cross sections based on a laser profile survey of the pit slope reveal a relatively uniform <br />' slope with an angle of between 40 and 44 degrees from horizontal. <br />At the top of the slope there is a natural ridge which is relatively Flat on top and slopes steeply down <br />' Farther to the east. The flat and low angle ridge top is approximately 50 to 80 R wide. The highwall <br />defining the limits of mining is located approximately at the western edge of the ridge top. <br />' Tension cracks and near-vertical scarps associated with the slide are present throughout the ridge top <br />area, but do not in general extend into the steeper slope to the east. Individual cracks are arch-shaped <br />and combine into a system of cracks parallel with the slope and extending for approximately 400 R. <br />The cracks have vertical offsets of as much as six feet and are open by as much as three feet. The <br />' location of the scarps are dictated by factors effecting slope stability such as the original slope <br />geometry and rock mass properties; the fact that the scarps extend to near the eastern edge of the <br />ridge top is coincidental. The scarps define the limits of the sliding mass, and their location is a <br />critical factor in determining the limits of the proposed interim configuration cut. On the western side <br />of the slope, soil and rock debris obscures observations of cracks and therefore the western extent of <br />the cracks is not known. <br />' The tension cracks and scarps observed near the top of the slope likely extend down through the rock <br />mass and exit somewhere near the toe of the slope, defining the limits of the unstable mass. <br />' However, at the present time there is no visual evidence, such as bulging, that can be used to identify <br />the existence or location of the downhill limits of the unstable mass. The fact the downhill limits of <br />the unstable mass are not evident is primarily due to the presence of debris on the slope and is not <br />' necessarily related to movement, or the lack of movement, at the slope toe. <br />I <br />' 3-04. EXISTING MINING PLAN AND OPERATIONS <br />Present pit operations are based on permanent benches at pit walls (exterior benches) 40 R wide and <br />' with 80 R highwalls. Rock is drilled, blasted and removed in 44-ft-deep cuts. <br />'i'he general slope reclamation plan to he implemented at the completion of mining calls for placement <br />of soil on exterior benches at a slope of approximately 1.5: 1 to support vegetation. <br />1 <br /> <br />~ f~-~>~ <br />