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Mr. George A. Holcomb <br /> April 18, 1985 <br /> Page 2 <br /> The N34°W striking, 43°SW dipping joint set was observed at several locations <br /> in the quartz latite but was not adversely affecting slope stability. These <br /> joint sets can be clearly seen in the attached computer developed schmidt <br /> plots of Call's outcrop data. Two potentially adverse wedges have been delineated <br /> by Call's data, and are shown on an attached diagram (.Joints A-C,and A-D). <br /> The joint data from the detail lines will define the potential hazards. <br /> The physical testing will permit calculation of stability and the test slopes <br /> will prove the accuracy of stability predictions. <br /> I believe it should be possible to use 60-ft high benches. This may well <br /> permit wider catch benches and steeper overall final pit slopes. Wider catch <br /> benches should provide more safety against ravel. Consideration should be <br /> given to using inclined blastholes at the final pit perimeter. This should <br /> enhance the stability of the joint controlled bench faces on the southwest <br /> facing pit walls. <br /> All in all conditions appear favorable for steeper slopes. I believe a <br /> case can be made for such an increase in overall slope angle without jepardizing <br /> slope stability. <br /> Call with your questions. <br /> Sincerely, <br /> )/aLq. aLle,e) • <br /> John F. Abel, <br /> Colorado P.E. 5642 <br /> cc: Steve Anderson <br /> • <br /> • <br />