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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 />February 26, 2014 <br />William A. Bear <br />Bowie Resources, LLC <br />P.O. Box 483 <br />Paonia, CO 81428 <br />Re: Bowie No. 2 Mine (Permit No. C- 1996 -083) <br />Technical Revision No. 85 (TR- 85) <br />Gob Pile #2 Temporary Drying Area <br />Dear Mr. Bear: <br />COLORADO <br />ID I V I S I O N O F <br />RECLAMATION <br />MINING <br />SAFETY <br />John W. Hickenlooper <br />Governor <br />Mike King <br />Executive Director <br />Loretta E. Pineda <br />Director <br />The Division has reviewed the response provided by J.E. Stover & Associates, Inc. on behalf <br />Bowie Resources, LLC (BRL) to the Division's adequacy concerns with TR -85 for the Bowie No. 2 <br />Mine. The revision proposes to establish a gob drying area on Gob Pile #2 during the winter <br />months of 2013 -2014. We have the following comments and questions regarding the <br />application. <br />Rules 4.10.1 and 4.10.4 <br />1. Buckhorn has responded that a compacted coal mine waste wet density of 104.6 pcf will <br />be used for stability analyses. This item has been addressed. <br />2. a) Buckhorn provided two new stability analyses in the 04- Feb -2014 response. The first <br />evaluated the stability of Gob Pile #2 with an assumed phreatic surface at the top <br />surface of the compacted coal mine waste. The computed FOS (block failure) for this <br />analysis was 1.319, which is less than the 1.5 required by Rule 4.10.4(2). A minimum <br />FOS of 1.5 must be maintained in the pile at all times. If the pore pressures reported for <br />VWP -06 and -08 dictate that the phreatic surface be modeled at the top of the <br />compacted waste, then it appears that storage of uncompacted waste at this location <br />cannot be approved. <br />In a second stability analysis, Buckhorn evaluated a circular failure plane, using the same <br />model conditions. The failure surface occurred within the uncompacted coal mine <br />waste (U -CMW), and no information was provided about the effects of the U -CMW on <br />the stability of the pile as a whole. The Division suggests an alternate approach would <br />be useful, i.e. the volume of U -CMW could be replaced by a distributed static load of <br />comparable magnitude so that the lower shear strength of the U -CMW does not mask <br />an evaluation of the stability of the pile as a whole. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />