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,, iii iiuiiiiiiiiiiii • S1ATE OF COLORADO MINED LAND RECLAMATION DIVISION of ~a~ Department of Natural Resources ~~_- 4, ~~ ~ 1313 Sherman St., Room 215 Denver C080203 '~^e ~ ~ ~$ ~ ``~ ~T~ , 303 866-3567 , ~s .~ re76 FA%.303 832-8106 Roy Romer, Governor Freo R. Banta. Division Director January 16, 1991 Mr. Mark Heifner 37 E. Colorado Avenue Denver, Colorado 80210 RE: Solberg Pit Adequacy-Bond Calculation-File No. M-81-044 Dear tdr. Heifner: As we discussed by telephone on January 16, 1991, only one issue remains prior to our recommendation to the Board for approval of your conversion application. All of the cost estimates you prcvided in Exhibit 1 - Reclamation Costs are acceptable with the exception of the cost of regrading the major disturbance areas. Our estimate of the cost of this regrading was based on calculating the volume of material which would have to be moved to cut down the maximum length of highwall and fill in the highwall below the cut. The data used for our estimate is as follows: 1. average highwall height 30 ft. (10 yds). 2. maximum-worst case-highwall lengths 1500 ft. (500 yds). 3. distance from base of highwall to toe of fill to create a 3H:IY slope-90 ft. (30 yds). Volume of material to be moved equals 1/2 the length of fill base (distance from highwall to toe of fill) x height of fill (height of fill = 1/2 height of highwall to compensate for cutting down of highwall during "cut and fill') x length of highwall. The volume then calculates as 1/2 x 30 yds. x 5 yds x 500 yds = 37,500 yd3, To move this yardage 100 feet (from the center of the cut area to the center of the fill area, perpendicular to the highwall) will cost 28 cents per cubic yard. This unit cost was derived from the Cat Handbook, Edition 19 based on a 100 foot downhill push using a D-7 dozer. The total cost for the cut and fillwork is therefore 37,500 yd3 x .28 = 510,500,00. The total estimated reclamation cost is therefore estimated as follows: