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<br />' The proposed mine area is not known to have experienced any earthquakes <br />within recorded history. Some earthquakes of a magnitude of up to 5.3 <br />' have occurred in the area northeast of Denver, approximately 150 miles <br />from the project site. Earthquakes of this size at such distances would <br />' not have a significant effect on the slope stability. The mine blasting, <br />however, could have an effect on the pit slopes. The dynamic loading from <br />the mine blasting is generally assumed to be less than 5 percent of the <br />' gravity force (0.05 g); however, stability analyses are performed fora <br />range of assumed seismic coefficients in order to show the influence of <br />' that parameter on slope stability. <br />B. PROPOSID MINE LAYOUT <br />' Although the exact mining plan has not yet been finalized, we are advised <br />that the approximate mining development for the period 1976 to 1983 will <br />' be as shown on Figure II-1. <br />' It is our understanding that mining to the "F" seam has been proposed, and <br />that waste dumps from the initial mine cuts will be located to the north- <br />' east of those cuts in the topographic depression known as Streeter Canyon <br />or Streeter "Draw." <br /> <br /> C. SECTIONS <br />1 <br /> Typical cross section perpendicular to the mine are shown on Figure II-2 <br />' for the two initial cuts shown es "Boxcu[" and " Cut 1" from Figure II-1. <br /> We can see that, at the east end of the mine, in the vicinity of Section <br />' A-A, the "F" seam outcrops and thus the initial exca vation is a three- <br /> sided cut into the hillside. At the west end of the mine, however, in the <br /> vicinity of the Section B-B, the "F" seam does not outcrop; and therefore, <br />' the initial excavation is a four-sided cut. <br />1 <br />i <br />WAWAHLEH Project 0823 II-2 <br />& ASSUCW6 <br />