2022-07-19_REVISION - M1987026 (22)

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Black Obsidian Pit—Permit M-1987-026 112c Conversion Application (rev 7/15/22) Rule 6.4.12 '4i ' '!`('i=�. �ION Exhibit L °1V�1i tii ` Reclamation Costs Reclamation Overview The mining plan of this site is to create the bench and highwall pit configuration as mining progresses, and to carry out as much early-stage concurrent reclamation of the site as possible, by shaping and revegetating all surfaces that are in their final configuration,and which will not be redisturbed. The mining of this pit is based on demand. Obsidian that is blasted from the highwalls is moved to the pit floor,and from there is hauled to the processing pad,then exported from the site. Since there will not be excessive amounts of product stockpiled on the site,there will be minimal amount of stockpiled obsidian onsite to be backfilled in the pit during final reclamation. The pit will be mined in three segments, in part to minimize the amount of new disturbance to be reclaimed,and to help minimize the bond amount. The Mining and Reclamation Maps show the three segments,which are equal in size. Mining will begin in Segment 1,the central segment,which is adjacent to the existing 110 permit highwall. Mining there will finish with the deepening of the pit floor. At that time, backfill of the pit floor will be carried out, bringing it up to 8011 feet final elevation. Then mining will commence in Segment 2, and proceed in similar fashion. When reclamation backfilling is completed in Segment 2, mining will begin and proceed in Segment 3. Upon completion of pit floor backfilling in Segment 3,the entire floor should be up to 8011 feet elevation. This elevation does not ensure the pit will be free-draining, since the adjacent operations pad is 8024 feet in elevation. A drainage channel will be cut into the operations pad,down to the necessary depth,to allow for the pit to drain freely. The channel will have 3:1 side slopes and rock check dams to control sediment transport. Material generated in constructing the channel will be moved to the pit floor,and graded smooth. Most of the material to be employed in pit floor backfilling will be the stripped and stockpiled overburden. Most of the stockpiled overburden will be utilized as fills for pads, or backfilled into the pit floor and benches. Portions of the pit benches and pit floor will be reclaimed during the mining stages, as explained below. At the end of reclamation, it is not anticipated that there will be any excess overburden; all stockpiled overburden should be needed for reclamation: on pit benches and pit floor backfill. If mining ceases before the pit is fully mined,there will be unneeded overburden still in the stockpile. Because there will be a portion of it that is not needed for backfilling, it will remain permanently in the stockpile area. As such, it will be graded with 3:1 slopes,capped with 6 inches of topsoil,and seeded. Topsoil will be placed on portions of the pit benches and the sloped overburden area above the pit during the mining stages. Any topsoil remaining in the stockpiles at the start of the last stage of final reclamation is expected to be needed: placement on the last segment of the pit benches,the full pit floor, and (after removal of product stockpiles and equipment)on the various pad areas. If mining ceases before the pit is fully mined, all topsoil will still be replaced on disturbed areas for seeding.