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Mr. George A. Holcomb <br />April 18, 1985 <br />Page 2 <br />The N340w striking, 430Sw dipping joint set was observed at several locations <br />in the quartz latite but was not adversely affecting slope stability. These <br />joint eats 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 -Cyaud 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 teat 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 />John F. Abel, Jr. <br />Colorado P.E. 5642 <br />cc: Steve Anderson <br />