2022-07-19_REVISION - M1987026 (11)

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then extended out to those stripped limits. Under the proposed 112 plan,the mined area will be expanded as follows: The extent of the economically mineable deposit within the limits of the 112c permit will be further defined and delineated, while also accounting for the depth of overburden lying above the obsidian. With the extent of the obsidian deposit to be developed now defined,the topsoil and overburden above the entire footprint of the deposit will be affected, during the early mining stage. Topsoil and overburden will be stripped and the residual overburden along the margins of the stripped area will be sloped back, away from the top of the obsidian ore body. In other words,the margins of the mined area will be expanded to include the area of the overburden that is left in place,that is sloped back. Within this delineated area the operator will strip all topsoil and stockpile it for reclamation,then strip the overburden and separately stockpile it for reclamation. The topsoil that is stripped from all the mining-disturbed areas will be placed in the topsoil stockpile area or windrowed along the edges of the areas of activity(to facilitate reclamation),shaped with sideslopes of no steeper than 3H:1V, and seeded to reduce erosion. Once the upper slopes around the expanded quarry are established,the operator plans to spread topsoil and seed the slopes. Initial removal of the topsoil and overburden materials will disturb the full "footprint" of the expanded quarry area at an early stage in the life of the mine. However, it will allow the final sloped areas above the expanded quarry to be reclaimed far earlier than at the point when mining terminates. This reclaimed sloped area is not expected to be redisturbed. Stockpile the Overburden to Backfill a Deeper Pit The average depth of the overburden that will be stripped to expose the top of the obsidian is estimated to be about 18 feet(estimate based on drilling around site). The quarry footprint is 12 acres (including the current 3-acre pit);the sloped overburden around the pit will be about 7 acres. The volume of overburden to be stripped above the pit is estimated to be 261,360 cubic yards;The volume of overburden to strip in the 7-acre sloped area around the pit is estimated to be 101,640 CY. The total of these two figures is 363,000 CY. Most of it(330,000 cubic yards)will be placed in the stockpile area north of the pit. Approximately 33,000 cubic yards of it will be moved directly to construct the new operations pad, onsite roadways,the processing and product stockpile area,and earthen berms for stormwater controls. These areas will be constructed with the overburden during the initial stages of the overburden stripping. The majority of the overburden will be placed in the 2.7-acre stockpile area, to a depth of approximately 25 feet. Sideslopes will be about 3H:1V, and seeded to reduce erosion. The lowest point of the existing pit floor is currently about 8000 feet elevation, and the adjoining process pad is about 8020 feet. The operator plans to deepen the floor of the expanded pit to a final mined elevation of 7981 feet. At the end of mining,this will create a situation to potentially impound water in the final pit, if conditions were left unreclaimed. The operator plans to reclaim the pit so that it drains freely, by backfilling the stockpiled overburden into the final pit, up to an elevation of 8011 feet. If the operations pad is higher than the backfilled pit floor, a drainage channel will be cut into the operations pad so that there is no long-term impoundment of water. Approximately 320,000 cubic yards of overburden will be pushed into the mined pit to create the free-draining pit. Please see the cross sections included in Exhibit F. Other Areas of Mining-Related Disturbance The proposed expansion of the quarry necessitates that the staging and stockpile areas will be moved from their present locations to adjacent, undisturbed areas, as shown on the maps in Exhibit C. Topsoil