2003-06-10_REVISION - M1977342 - Laserfiche WebLink

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With the approval of amendment AM-04, certain buildings and associated infrastructure at the Henderson Mine will remain in place following mine closure. These facilities will be put to a beneficial industriaUcommercial post mining land use. The reclamation cost estimate for the Henderson Mine has been revised accordingly. The following revised and new cost estimating spreadsheets were generated relative to the revised reclamation plan for the mine site. The new spreadsheets are enclosed. Task Ola: The estimate for demolition costs has been revised for the mine site. The costs estimated for demolition of the office/dry building and for the surface shop/warehouse have been deleted from the estimate, as have the costs estimated for demolition of the potable water facilities, the sewage treatment plant, and the fire water building. Asphalt paving removal costs have been revised to allow for removal of 17.4 acres of pavement (20 acres industriaUcommercial, 2.4 acres covered by the buildings that will remain) compared to the previous estimate to remove 35 acres. In the previous reclamation cost estimate processed at the time of approval of technical revision TR-12, it was assumed that 1 percent of the demolition debris may not meet the definition of inert material, and would have to be hauled to a suitable off site dump. The volume of potentially non-inert debris has been revised considering the volume of the buildings to remain for industriaUcommercial use. Likewise, the estimated costs to conduct chemical testing on the debris has been revised downward from the cost to conduct 20 TCLP tests to a cost to conduct 12 TCLP tests given the reduction in debris volume caused by leaving certain structures in place. These changes to the estimate result in estimated direct costs being lowered by $607,174. Task Oln: The estimated cost to finish grade the mine site was reduced by $2054 in consideration of the reduction in acres to be graded from 120 acres to 100 acres. Task 01 q: The estimated cost to mix biosolids and wood chips into the regraded surfaces was reduced by $13,448 in consideration of the reduction in acres to be revegetated from 120 acres to 100 acres. Task O1 r: DMG originally estimated that 70 acres of the 120 acres of affected land at the mine site would require drill seeding at the time of reclamation. With the reduction of acreage to be revegetated at the mine to 100 acres, the number of acres to be drill seeded were reduced proportionately to 60.4 acres. The reduction in acreage results in a lowering of the estimated direct drill seeding cost of $7880. Task Ols: DMG originally estimated that 50 acres of the 120 acres of affected land at the mine site would require hydroseeding at the time of reclamation. With the reduction of acreage to be revegetated at the mine to 100 acres, the number of acres to be hydroseeded were reduced proportionately to 44.1 acres. The reduction in acreage results in a lowering of the estimated direct hydroseeding cost of $11,575. Task Olt: DMG originally estimated that the entire 120 acres of affected land at the mine site would require tree and shrub planting at the time of reclamation. With the reduction of acreage to be revegetated at the mine to 100 acres, the number of acres to be planted with trees and shrubs was reduced. The reduction in acreage results in a lowering of the estimated direct tree and shrub cost of $33,421.