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iii iiuiiiiiiiii <br />_ _ STATE OF COL._,~.~u.~ <br />MINED LAND RECLAMATION DIVISION o4 ~o,o <br />Department of Natural Resources Q~= },~> <br />~~ o <br />1313 Sherman SL, Room 215 , -~y ~ n , <br />Denver, CO 80203 , ~~,._-~. <br />303 866-3567 `re ia• <br />RA%~ 303 8328106 <br />Roy Romer, <br />Gavemar <br />Michael B. Long. <br />Division Direnor <br />March 25, 1992 <br />Mr. Ranvir Singh <br />Chief, Federal Lands Branch <br />Office of Surface Mining Reclamation and Enforcement <br />Brooks Towers <br />1020 15th Street <br />Denver, CO 80202 <br />RE: Colowyo Coal Company Excess Spoil Fills {C-81-019) <br />Dear Mr. Singh: <br />we received your letter of March 16, 1992 regarding the adequacy of <br />plans for the two proposed excess spoil fills at the Colowyo mine. <br />In that letter, two items of concern were mentioned. <br />The first item was a request for the operator to expand the <br />explanation of construction practices,. including method of <br />placement of material, equipment used and how these methods meet <br />MLRD's horizontal lift requirement. In a submittal dated March 9, <br />1992, Colowyo submitted responses to MLRD adequacy questions in <br />which they expanded on construction methods. Those responses <br />apparently had not been received by the Western Support Center at <br />the time the March 16 letter was generated. MLRD believes that the <br />information in Exhibit 19 of the MRP (CTL Thompson's designs) and <br />the March 9 submittal from Colowyo adequately demonstrates that the <br />fills will be constructed in horizontal compacted lifts, as <br />required by Rule 4.09.2(3) of the Colorado regulations. <br />The second item of your letter involved concerns with prevention of <br />formation of voids in the spoil fill and achieving densities to <br />assure mass stability. Colowyo has indicated that the inspection <br />procedures for the fill will be amended to include documentation of <br />spoil grading as a result of placement in 50-100 foot lifts and to <br />verify whether voids are observed in active faces of the fill. <br />Based on past investigations of spoil sorting at other northwest <br />Colorado mines, performance of the Streeter fill at the Colowyo <br />Mine and information supplied by CTL Thompson in the plans for the <br />two new proposed fills, MLRD feels that the questions of void <br />formation in the spoil and mass stability have been adequately <br />addressed. <br />