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The first step in reclaiming the vent holes will consist of digging down four to six feet deep around <br />each hole and cutting the casing off from three to four feet below the ground surface. It is assumed that <br />an 80-horsepower tracked hydraulic excavator will require about 20 minutes at 3 to 4 miles per hour <br />(mph) to tram between the two locations and that the trench around each casing could be excavated in <br />45 minutes. Based on this scenario, 2 hours were allotted toward excavating around the 2 vent holes <br />plus an additional 1 hour for traveling from the portal area to the initial excavation. <br />After the casing is cut off, a steel plate will be welded over the opening and structural steel (i.e., small <br />I-beams and rebar) will be welded over the top of the steel plate to form asix-inch-thick, reinforced <br />square cover. Concrete will be poured between the I-beams and around the rebar to complete the <br />installation. A minimum of three feet of soil will be placed over the cover. The cost estimate assumes <br />that a welder and laborer can cut the casing and weld together a cover in six hours and that two <br />laborers can hand mix and pour the concrete for each cover in four hours. Materials are based on <br />average cover dimensions of six feet by six feet. <br />• Each shaft area is assumed to have a maximum disturbance of 100 feet wide x 100 feet long or 10,000 <br />square feet. This includes any short two-track roads built to access the shaft area. After shaft sealing, <br />the topsoil which was previously stockpiled at each shaft location will be replaced and graded. The <br />area will then be seeded and mulched. Assuming an average topsoil depth of 12 inches, approximately <br />370 cubic yards of topsoil will be placed. <br />As explained in Section 14 and 17 of Exhibit D -Mine Plan, two cased holes will serve as power <br />drops into the mine workings. The power cable will be removed from these holes and then the casing <br />will be cut off at a depth of three to four feet below the surface using an acetylene torch. The cased <br />opening will be sealed with an expansion foam plug and the excavated soil will be placed back over <br />the sealed hole. <br />The proposed pad areas for the Whirlwind and Packrat power drops encompass 0.23 acre and 0.41 <br />acres respectively, for a total acreage of 0.64 acres. Using the same cost assumptions as specified <br />above for the vent shaft pads, this will require regrading of 370 + 659 cubic yards = 1029 cubic yards <br />of topsoil. <br />• <br />Whirlwind Mine 07 (rev. April 08) E-6 <br />