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DEPARTMENT OFtN ATUHAL RESOURCES o. ~nMU. GnV n,~ III III III III IIII III <br />Hams D. Sherman. Executive Director 999 <br />MINED LAND RECLAMA'T10N <br />723 Centennial Building, 7313 Sherman Street <br />Denver, Colorado 80203 Tel. (303) 839-3567 <br />Hamlet J. Barry, II I, <br />Director <br />July 16, 1980 <br />TO: Rick Mills •°"~ '` ~ <br />.• • ~ •E n ~ <br />FROM: Tim Pendleton `+ /_ ,,.s-- ~'~^~'~~~ <br />RE: Certified Inspection Raport for H-G Coal Company's <br />Hayden Gulch Mine"Disposal Plan <br />I have reviewed the certified inspection report for the Hayden Gulch <br />Mine of the H-G Coal Company, prepared by David D. Haas of Morrison- <br />Knudsen Company, Inc. I forward the following comments for your <br />consideration: <br />1) Any certified letter of inspection should be signed by the inspecting <br />professional, and should bear a facsimile of his professional seal. <br />The submitted report bears neither. <br />2) The Engineer, Mr. Naas (Colorado License PE 1/15432), is apparently <br />confused regarding the limitations of the interim regulations placed <br />upon excess spoil pile final slopes. He repeatedly refers to <br />"2.1v: 1h: (36~)" as the maximum allowable slope. The interim <br />regulations refer to 2.8v: 1h (16%) as the maximum allowable natural <br />slope on which an excess spoil pile can be placed. <br />3) The critical determination, as defined in permanent regulatory <br />section 30 CFR 816.71 (f), will be whether the fill achieves a Long- <br />term static safety factor of I.S. Mr. Haas states in section I of <br />his certified report that his preliminary examination indicates <br />that the long-term static safety factor exceeds the required I.S. <br />When H-G Coal submits its permanent program application, it will <br />have to include a final stability analysis der..onstrating that the <br />fill's slopes do attain the required Long-tc~m factors of safety <br />on 1.5 or greater. <br />,.. <br />4) The definition of "valley fill" contained in the interim and <br />permanent regulations differ. It will be necessary for H-G to <br />determine, to our satisfaction, whether this fill classifies as <br />a valley fill under the permanent regulations. If so, under <br />section 30 CFR 816.72, they would be required to place material in <br />horizontal lifts, not to exceed 4 feet in thickness, which they are <br />not, to my knowledge, currently doing. <br />