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<br />October 30, 1981 <br />~I~ II~II~II~IIIIII~ <br />STATE OFCOLORADO RiC HARpD LA1d1d Governor 99g <br />DEPARTMENT OF NATURAL RESOURCES <br />D. Monte Pascoe, Executive Director <br />MINED LAND RECLAMATION <br />423 Centennial Building, 1313 Sherman Street <br />Denver, Colorado 80203 Tel. (303) 866-3567 <br />David C. Shelton <br />Director <br />TO: Dan Mathews ~~_~ <br />FROM: Jim Pendleton <br />RE: Western SI Ca rbo s~Coal Processing Waste Pile <br />Having reviewed the materials forwarded by you and having visited the site <br />of the coal processinq waste pile, I forward the following comments regazding <br />the permitting of that pile. <br />t Having examined the relatively flat site, I no longer consider slope stability <br />~ to be a critical issue in the case of this particular coal processing waste <br />pile. Flowever, the structure must conform with the construction requirements <br />of Rule 4.10.4. If [Jestern Slope Carbon places the coal processing waste <br />in conformance with the 2 foot maximum Ii ft and 90'a compaction requirements <br />of Rule 4.10.4(3), the resulting waste pile should be stable and a stability <br />analysis will not be necessary. If, however, Western Slope Carbon prefers <br />not to conform with the construction requirements of Rule 4.10.4(3), they <br />should then prepare a simplistic Homographic-type stability analysis based <br />upon field determinations of material density being achieved at present and <br />laboratory testing of t/~e shear .strength of the actual coal processing <br />waste at that placement density. <br />In addition, because of the apparent possibility of entrapment of water within <br />the containment berm of Pit 6, it is important that an appropriate diversion <br />structure be designed, approved and installed in order to minimize the <br />collection of water within the waste material. Impoundment of water in contact <br />with the coal processing waste could result in ground water and surface water <br />pollution, as well as destabilization of the waste pile. In addition, you <br />will have to resolve the required non-toxic cover material requirements of <br />Rule 4.10.9(4). <br />.~ <br />/mt <br />cc: Fred Banta <br />