2019-09-13_PERMIT FILE - M2018051 (17)

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'Worst-case' assumes that an open pit that has not been backfilled for the previous two years and is to be re- filled to the general regrade topography,at average costs for truck-loader operations. A unit cost of $1.35/cubic yard (cyd) is estimated assuming the use of the operation's mining equipment, such as; 7 cyd - class front end loaders (matched with 40 ton-class mining trucks; and support from 3.5 cyd—class excavators and 300hp—class tractor dozers.The average haul would be approximately 1.4 miles,with the majority of the haul on level,well-established haul roads. Some minor sections (i.e.,stockpile and pit access)would require ramping at a general slope of 8%(not exceeding a 12%slope for any significant distance). Regrade Disturbed Areas It is assumed that the disturbed areas would required regrading to a maximum 5:1 slope,with an average of a depth of 6"over the entire area to be cut by a tractor dozer, and final regrading by a motor grader. Dozer costs are estimated at$0.35-0.40/cyd,while grader costs are estimated at approximately$55/acre of regrading. Topsoil Redistribution 'Worst-case' assumes that sufficient topsoil to cover disturbance of two years of mining is to be redistributed at a similar cost to backfill re-handling by the mining equipment(see above). Vegetation and Erosion Control Estimated costs are based on industry average costs for reseeding and rehabilitation operations for Years 11- 35,assuming a 'worst case'scenario that no previous reclamation had been accomplished. Plant Facility Demolition At the end of mine life,the processing facility will be demolished. Equipment will be cleaned as needed with water and reused and recycled as much as possible. This will include the sand wash processing plant and equipment,conveyors,silos,water storage tanks, and loadout facilities. Warehoused materials and fuel will be removed as part of the demolition of the site. Fuel will be removed from the storage tanks at the warehouse and fueling station,and the tanks will be cleaned thoroughly before being dismantled. Materials that cannot be recycled will be disposed in the process water pond and slurry pond. The liners will be cut to prevent water ponding within the disposal area.The materials to be disposed will include pavement, some concrete foundation materials,siding,supports, unused raw plant feed or product and other materials that cannot be recycled.The ponds will be filled and compacted and regraded to conform to surrounding contours. Stormwater will be directed around the construction material disposal. No outside material will be accepted for disposal. All mat slab foundations and footings will be removed (approximately 7,000 cubic yards of material) and all deep foundations will be buried in place. The office and warehouse buildings will remain in place for use in subsequent rangeland operations at the site. Pavement to those buildings will remain in place.