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Ms. Candace Thompson <br /> November 26 , 1986 <br /> Page - 7 <br /> distances to be graded. In any case, our total cost calculations <br /> only vary by $200. 00. <br /> With respect to the rock tunnel to preparation plant <br /> backfilling and grading plan, two areas that have not been <br /> adequately covered in our previous cost estimations are the <br /> rock tunnels portal and the glory hole bin pad. With respect <br /> to the rock tunnels portal, our calculations earlier in this <br /> submission for returning 13 ,500 cu. yds of pad expansion fill <br /> to the highwall area as well as the demolished building <br /> materials should, when added to other excess materials on and <br /> near the portal bench, adequately backfill the bench area. <br /> Provisions are required for the backfilling of the bin pad. The <br /> approved plan calls for pulling up 63, 000 cu. yds. of material <br /> from the downslope by dragline to accomplish this task. Our <br /> estimated cost calculations are as follows : <br /> Utilizing an HC-48A Dragline with a 1 yard capacity <br /> clamshell bucket 120 CYH can be retrieved under optimum <br /> conditions. Accepting realistic correction factors that <br /> would reduce the actual production by 40% , we will use 72 <br /> CYH which is a very conservative figure. <br /> 63 , 000 Cu. Yds <br /> 72 CYH = 875 Hours <br /> 875 Hours x $128 $112 , 000 <br /> MLRD' s comment on dozer production for backfilling <br /> the preparation plant area is partially acceptable to <br /> Mid-Continent. As covered previously in this letter a <br /> D-8 dozer has proven to be very efficient in Coal Basin, <br /> particularly in the general level terrain at the preparation <br /> plant, rather than the 47% efficiency factor proposed by <br /> MLRD that would increase the cost by $7 ,432 , we believe a more <br /> realistic figure would be 75% efficiency which would ,increase <br /> the cost by approximately $2 , 500. <br /> Topsoiling. <br /> With respect to the MLRD comment on "locally <br /> available" topsoil, we are referring to good A and B horizon <br /> materials that exist, after 30 years of mining, on previously <br /> disturbed areas throughout the permit area. Over a 30 year <br /> period portions of the mine benches and preparation plant <br /> areas have developed fairly sizeable quantities of good A and <br /> B horizon topsoil through normal sloughing, flooding and <br /> other natural phenomenon. Portions of these materials not <br /> required in their present locations should be retreived and <br /> placed on adjacent backfilled areas . All topsoil stockpiles <br />