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Exhibit L: Reclamation Costs <br /> Black Mountain Sand Weld LLC(Black Mountain) plans to construct and operate the Lost Creek Mine, a 2.4 <br /> million ton per year(Mtpy) industrial proppant sand production facility in Weld County, Colorado. It will consist <br /> of an open pit mining operation, sand wash processing plant, and associated loadout facility. See Exhibit D for <br /> details of the mining process. <br /> As mining areas of the project are completed, Black Mountain will commence ongoing reclamation operations. <br /> See Exhibit E for details of the reclamation process. In addition,final closure operations will commence upon <br /> cessation of all mining. For conservatism,the 'worst case'closure scenarios, assuming premature closure in <br /> either the initial 10 years of mining(Scenario 1) or the remainder of the life-of-mine (Years 11-35,Scenario 2) <br /> have been proposed, and are summarized in Table L1. <br /> Cost estimates provided here assume that all closure operations would be performed by Black Mountain, using <br /> their own mining equipment and the workforce available at the time of closure. <br /> Notes to Table L1 are provided below: <br /> Scenario 1, Years 1-10 <br /> Handling Backfill Stockpile <br /> 'Worst-case' assumes the entire larger out-of-pit backfill stockpile is at its largest anticipated size and all needs <br /> to be re-handled within Phase 1.A unit cost of$1.35/cubic yard (cyd) is estimated assuming the use of the <br /> operation's mining equipment, such as; 7 cyd-class front end loaders (matched with 40 ton-class mining <br /> trucks; and support from 3.5 cyd—class excavators and 300hp—class tractor dozers.The average haul would <br /> be approximately 1.4 miles,with the majority of the haul on level,well-established haul roads. Some minor <br /> sections (i.e.,stockpile and pit access)would require ramping at a general slope of 8% (not exceeding a 12% <br /> slope for any significant distance). <br /> Regrade Disturbed Areas <br /> It is assumed that the disturbed areas would require regrading to a maximum 5:1 slope,with an average cut <br /> depth of 6" over the entire area to be cut by a tractor dozer, and final regrading by a motor grader. Dozer costs <br /> are estimated at$0.35-0.40/cyd,while grader costs are estimated at approximately$55/acre of regrading. <br /> Topsoil Redistribution <br /> 'Worst-case' assumes that the entire topsoil stockpile is to be redistributed at a similar cost to backfill re- <br /> handling by the mining equipment(see above). <br /> Vegetation and Erosion Control <br /> Estimated costs are based on industry average costs for reseeding and rehabilitation operations for Years 1- <br /> 10,assuming a 'worst case'scenario that no previous reclamation had been accomplished. <br /> Scenario 2, Years 11—35 <br /> Handling Backfill Stockpile <br />