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Mr. Mark Heffner - 2 - June 5, 1989 Item 7: It is apparent from your responses in items 6 and 7 that the southern drainage crossing could be removed and its disturbance reclaimed before construction of the north crossing commences. To minimize impacts to the existing watershed and drainage systems, please commit to not constructing the northern crossing until the southern crossing is removed and reclaimed or discuss why this would not be feasible. Item 8: Your response more fully answered my second question than my first. I had previously asked "What measures will be implemented to assure that mining does not exceed the proposed Phase III mining limits?" Although part of your answer was "in all areas where there is no mining-created barrier to protect the land from rockfall, there is a setback of the mining area from the permit boundary of 50 to 200 feet.", I am still concerned with the South Peak and LJest Thumb areas. As no fence currently demarcates the western property boundary, the possibility of affecting acreage beyond the proposed permit area to the west still exists. How will this be minimized? Will there be, for example, a line of highly-visible stakes to make equipment operators aware of the property boundary? Please address. Secondly, please define "the high degree of instability already existing on the east side of Williams Canyon" that was noted in your response. Will this instability continue after mining? What is proposed to eliminate the problem of instability (if necessary)? Third, although mining from the east side of South Peak westward to the west boundary of the proposed permit area will produce a "mining-created barrier" preventing material from falling outside of the permit area, material dislodged within the permit area could fall into the three steeply-dipping, west-sloping drainages situated north and south of the West Thumb and southwest of South Peak. It is conceivable that material falling into these drainages could continue falling out beyond the permit boundary. After reviewing these concerns will MLRD Senior Reclamation Specialist Steve Renner, it is recommended that the western excavation limit be changed to accommodate a radial setback of 100 feet from the points where the western property line crosses the center of each of these drainages. Please commit to these setbacks or discuss why this would not be feasible while proposing an alternative solution. Item 9: No additional response is necessary. Thank you. Item 10: In your response, you state that the formation dip of the rock to be mined is "between 10 and 15 degrees to the southeast." On page 12 of the amendment application you state "As a rule, walls in sedimentary rock are roughly perpendicular to the dip." As such, it is apparent that the final bench surfaces will dip 10 to 15 degrees southeast and that the backwalls will overhang into the pit 10° to 15°. Can these overhangs and bench slopes be corrected so that the benches dip slightly toward (into) the hillside and the highwalls away from the pit? Achieving this would provide for greater slope stability, water retention, and a lower possibility of material sloughing off the walls onto the benches and hindering revegetation. Please address.