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underground mine waste rock extracted over the life of the King I and II Mines. The <br />material is composed of dense, medium grained sandstone with occasional shale and <br />carbonaceous shale partings. <br />The valley fill waste pile is located east of the King I Mine entrance, beginning just <br />east of the shop building and extending up the east side drainage approximately 900 <br />feet. A limit equilibrium static analysis was performed using effective stresses to <br />assure long term stability of the bank. A relatively flat 2.Sh :1 v slope is used for the <br />face of the waste pile. This analysis provided a range of factors of safety between 1.85 <br />and 2.74, well above the required 1.5. An intercept channel was constructed at the top <br />of the bank to divert flow originating above it away from the bank and into the east <br />side drainage. Similarly, a channel was constructed at the bottom of the waste bank to <br />intercept runoff from the pile. An under drain system was constructed beneath fill and <br />drains into the east side drainage (4.04.8(3)). <br />B. The applicant has demonstrated that disposal of such materials will not adversely affect <br />water quality or flow, vegetation, public health, or stability of the disposal area based <br />on hydrologic, geotechnical, physical, and chemical analyses. The waste pile designs <br />exceed the minimum safety factor of 1.5. The new designs for the expanded waste pile <br />were approved February 9, 1998. <br />C. The disposal area will be inspected on a regular basis by a qualified professional <br />specialist under the direction of a professional engineer, experienced in construction <br />of similar earth and waste structures. Inspection by this person has been approved by <br />the Division as appropriate (4.10.2(1)). <br />VIII. Backfilling and Grading <br />The previously approved plan for backfilling and grading of disturbed areas is described in <br />Section 2.05.4 of the permit application. Maps King I-011 and King II-010 show approved <br />post-mining contours. <br />At the end of the King I Mine's life, NKC will backfill the disturbed bench azeas of this <br />mine to a stable configuration that blends with the surrounding topography. Based on <br />information provided by NKC, pre-mining contour maps of the King I Mine do not exist <br />due to the length of time the mine has been in operation (>50 years). Backfilling of the <br />King I Mine will involve reducing all mine bench highwalls and the bench outslope crest to <br />approximately 1.5 h: l v and inmost azeas to 2.Sh :1 v, or less, to blend in with surrounding <br />azeas. The portal area of the King II Mine and all other disturbed areas on this mine will be <br />reclaimed to approximate original contour. <br />20 <br />