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I _ __ <br />~. ~I • • III III III III IIII III <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Departmem of Naluml Resources <br />1J13 Sherman BI., Room 215 <br />Denver, Colorado 80203 <br />Phone: (3071 866-3567 <br />FA?(: (303) 832-8106 <br />Date: February 21, 1995 <br />To: Tony Waldron ~ <br />From: Kent Gorham( <br />CC: David Berry <br />I~~~~ <br />DEPAR'TMENT' OF <br />NATURAL <br />RESOURCES <br />RoY Ramer <br />Governor <br />lames 5. L«hhead <br />Executive Director <br />Michael B. Long <br />Division D~reUO. <br />RE: Bear Creek Portal Area Technical Revision, Somerset Mine, #C- <br />81-022 <br />As per your request, I reviewed the information submitted by Bear <br />Coal Co. for the Bear Creek portal area. <br />General Comments <br />I am not sure if you need the road fill material for reclamation of <br />the portal area but keep in mind that road fill slopes do not have <br />to be reclaimed to AOC. (Rule 4.03.1(7)) However, the fill slopes <br />have to be rounded, reduced, or shaped and terraces should be <br />constructed as necessary to prevent excessive erosion and to <br />provide long-term stability. <br />The operator provided no horizontal scale on the map of cross- <br />sections. <br />The operator is proposing to leave post-mining slopes of 53, 51, 50 <br />45 and 29 degrees, compared to 37, 37, 34, 2.5, and 11 degrees, <br />respectively. In addition to this dramatic difference, Bear Creek <br />is immediately adjacent to all of these steep slope areas, making <br />undercutting and accelerated erosion a distinct possibility. <br />Furthermore, it appears that Bear Creek is currently routed under <br />a portion of the fill in this area, although no culverts are <br />represented. Depending on the size of the watershed above this <br />area, a demonstration of the suitability for a permanent culvert at <br />this location would be necessary. <br />The USLE equation is flawed in one critical way with regard to the <br />control factor. The operator has represented the pre-mining <br />condition of the vegetation as consisting of mostly weeds. This <br />would not be representative of the natural vegetative cover in this <br />area. The calculation should be rerun using the same canopy <br />percentages but instead use the assumption of aground cover of grass. <br />