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Camille M. Farrell <br />February 13, 1989 <br />Page 2 <br />8. From the question, there is apparently some confusion regarding <br />the angle of the pit walls, suggesting that a discrepancy exists in the <br />plans. There is no discrepancy. The original plans submitted give a range <br />in slopes for the backwalls between benches (65 to 75 degrees), and for an <br />overall pit slope as measured from the outermost edge of the benches (45 to <br />55 degrees). <br />Subsequent to the original submittal of the application, the Division <br />requested additional information regarding pit wall stability. Figures 3 <br />and 4 contained in a report prepared by Schnabel Engineering Associates <br />dated November 15, 1988, and submitted to the Division along with other <br />responses contained in a letter dated December 6, 1998, illustrate design <br />cross-sections of typical pit slopes per slope orientations described in <br />the body of the report. The pit slopes are within the range described in <br />the original application but specify slope gradients and bench widths for a <br />particular orientation of slope. <br />Additionally, in response to your most recent set of inquiries, the <br />proposed slopes for the upper weathered zone have been revised to address <br />stability in the less competent rock relative to offsite property. Details <br />of these revisions are given in the attached correspondence submitted by <br />Schnabel Engineering Associates. Also, as shown on Figure 1 of the <br />Schnabel document, the uppermost safety bench proposed in the origi-,a1 <br />application would then be modified to develop a slope and bench instead of <br />the bench and warning drop. <br />A. ENTECH <br />a.,b. Information addressing these two items is provided in the <br />attached correspondence from Schnabel Engineering Associates. <br />B. SCHNABEL <br />a. Information addressing these two items is provided in the <br />attached correspondence from Schnabel Engineering Associates. <br />C. SUMhLARY <br />As you know, on January 18, 1989, Gordon Matheson of Schar.:~el <br />Engineering Associates met with Steve Renner and you to discuss <br />geotechnical concerns pertaining the pit. I believe that it was resolved <br />that further work regarding pit slope stability, for the purposes of <br />developing a :actor of safety value, is not necessary. <br />13. a.,b.,c.,d. Information regarding provisions fer she plunge <br />pools, post-mining channels, drop structures and culverts is provided in <br />the attached letter from Water and Environmental Systems Technology, Inc. <br />