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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />- 16 - <br />pile will be less than 50 feet. <br />For a pile of this size, the use of terraces to stabil- <br />ize the face and/or control surface runoff should not be <br />necessary. Uniform slopes of 1.0 (v) 2.25 (h) should <br />terminate at a 15 foot wide bench along the crest of the <br />pile. The recommended section is illustrated on Plate 4. <br />The stability analyses have been performed assuming a <br />foundation inclined at 1.0 (v) 20.0 (h). The stability of <br />the foundation could be affected if significant cuts are <br />excavated in the vicinity of the pile. For this reason, we <br />recommend that no cuts greater than 10 feet in height be ex- <br />cavated within 100 feet of the pile without careful evaluating <br />of the foundation stability. <br />We understand that no mining is planned beneath the <br />initial waste rock storage pile. This should eliminate the <br />possibility of instability due to subsidence. <br />4.3 SUP.FACE DRAINAGL~ <br />An interceptor ditch should be constructed upslope of <br />the pile to prevent surface runoff from entering the area. The <br />ditch should be stabilized and designed to pass a 100-year, <br />24-hour precipitation event. The ditch should be located at a <br />sufficient distance from the toe of the pile to enable access <br />between the ditch and the pile. <br />After final grading and covering of the pile, the sur- <br />face of the upper bench should slope outwards at a slope not <br />exceeding 1 (v) 20.0 (h). There should be no depressions on <br />the surface of the pile where ponded water could accumulate. <br />r,EaNwoo coNSUinHC, iNC. <br />