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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />August 6, 2009 <br />COLORADO <br />D I V I S I ON OF <br />RECLAMATION <br />MINING <br />SAFETY <br />Bill Ritter, Jr. <br />Governor <br />Harris D. Sherman <br />Executive Director <br />Mr. Jerry Nettleton Ronald W. Catt <br />Division Director <br />or <br />Environmental Supervisor Natural Resource Trustee <br />Twentymile Coal Company <br />29515 Routt County Road 27 <br />Oak Creek, CO 80467 <br />Re: Foidel Creek Mine, Permit No. C1982-056, TR67 Proposed CRDA 20 MM cu. yd. Expansion Adequacy <br />Concerns <br />Dear Mr. Nettleton: <br />The Division has reviewed Twentymile Coal Company's (TCC) application for a technical revision for <br />expansion of the existing Coal Refuse Disposal Area (CRDA). Rule 4.10.1(1)(a) requires that Coal mine waste <br />disposal areas be designed and constructed in accordance with Rules 4.09.1, 4.09.2, 4.10 and 4.11. The <br />Division finds that location and design of the CRDA expansion does not qualify as a Valley Fill (4.09.2) or <br />Head of Hollow Fill (4.09.3). Rule 4.09.1(10) requires keyway cuts or rock toe buttresses if the slope in the <br />disposal area is steeper than 2.8H:1 V. The final grade of the outslope of the CRDA is proposed to be 3.0H:1 V. <br />So the requirement for a rock toe buttress does not appear to be necessary for this refuse disposal area. <br />The Division has identified the following concerns: <br />1. Cover for the CRDA needs to be non-toxic and non-combustible (Rule 4.10.4(5) & Act 129(2)(k)). <br />TCC is proposing to use the backfilled spoil from the reclaimed slope for the cover material. TCC needs <br />to provide evidence that the spoil material is non-toxic and non-combustible. <br />2. TCC provided Exhibit 26C: NWCC report. On page 10 of Exhibit the surface area of the disturbance <br />footprint is greater than the final surface area of the pile. The table on the bottom of this page indicates <br />that the surface area of the completed pile will be less than the footprint of the pile. The west side of the <br />pile abuts the existing RDA. Only a portion of the RDA has received cover material and topsoil. It is <br />not clear, based on the provided cross-sections, how the surface of a 20 million cubic foot refuse pile, <br />extending approximately 200-250 feet above the current topography will have a smaller surface area <br />than its footprint. Please provide an explanation or additional cross sections to demonstrate this. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />?4.