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BLM at the time of closure for their review and approval. For reclamation costing purposes, the • following traditional reinforced metal and concrete design is assumed. The first step in reclaiming the vent holes will consist of digging down four to six feet deep around each hole and cutting the casing off from three to four feet below the ground surface. It is assumed that an 80-horsepower tracked hydraulic excavator will require about 20 minutes at 3 to 4 miles per hour (mph) to tram between the two locations and that the trench around each casing could be excavated in 45 minutes. Based on this scenario, 2 hours were allotted towazd excavating azound the 2 vent holes plus an additional 1 hour for traveling from the portal azea to the initial excavation. After the casing is cut off, a steel plate will be welded over the opening and structural steel (i.e., small I-beams and rebaz) will be welded over the top of the steel plate to form asix-inch-thick, reinforced square cover. Concrete will be poured between the I-beams and azound the rebaz to complete the installation. A minimum of three feet of soil will be placed over the cover. The cost estimate assumes that a welder and laborer can cut the casing and weld together a cover in six hours and that two laborers can hand mix and pour the concrete for each cover in four hours. Materials aze based on • average cover dimensions of six feet by six feet. The total cost for each ventilation shaft is $5,500. Two shafts result in a total cost of $11,000. Each shaft area is assumed to have a maximum disturbance of 100 feet wide x 100 feet long or 10,000 square feet. This includes any short two-track roads built to access the shaft azea. After shaft sealing, the topsoil which was previously stockpiled at each shaft location will be replaced and graded. The azea will then be seeded and mulched. Assuming an average topsoil depth of 12 inches, approximately 370 cubic yards of topsoil will be placed. This earthwork will be done at an estimated cost of $1.50 per cubic yazd, therefore the cost per shaft is $555. Seeding and mulching costs aze estimated to be $1,500 per acre, allowing fora 50% reseeding rate. Therefore, reseeding costs per shaft are $150. The cost for regrading and seeding is $705 per shaft resulting in a total estimated cost of $1,410 for two shafts. As explained in Section 13 and 15 of Exhibit D -Mine Plan, two cased holes will serve as power drops into the mine workings. The power cable will be removed from these holes and then the casing will be cut off at a depth of three to four feet below the surface using an acetylene torch. The cased • 1 opening will be sealed with an expansion foam plug and the excavated soil will be placed back over l the sealed hole. Plugging costs aze estimated at $500 per hole or $1,000 total. Whirlwind Mine June 07 E-6