2022-07-19_REVISION - M1987026 (3)

Home Browse Search

stockpiles themselves, will be seeded in a timely manner with the approved revegetation seed mix at the approved rates. Any excess topsoil that remains in the stockpile area will be shaped and seeded to remain stable in that permanent location. Pit Benches and Floor The pit walls will be developed in portions of approximately one-third of the overall pit expansion,as explained in Exhibit D Mining Plan. The pit benches, being roughly level,will ultimately all be revegetated, and will be carried out one portion at a time. Within each portion, overburden will be placed on the pit benches, at a depth of approximately one foot(12 inches) or more. Topsoil will be placed at a depth of at least 6 inches on top of the overburden on the benches. Broadcast seeding and dragging will follow topsoiling. The pit will be mined in segments, as stated above,which will include deepening that related portion of the pit floor. (The entire pit floor will not be deepened at one time,only segment by segment.) Concurrent reclamation of these pit segments will include the backfilling of the relevant portion of the pit floor. At the conclusion of mining,with the completion of the last portion of the pit,the last of the pit floor will be backfilled with salvaged overburden. Backfill material will be moved to the floor by scraper or truck/loader teams,and appropriately compacted during spreading by dozer. The final elevation of the pit floor will be 8011 feet. This is not sufficiently elevated to allow free drainage, since the operations pad will be higher than the backfilled floor. A drainage trench will be cut into the pad to a sufficient depth to provide for positive drainage from the pit. Estimating that the pad will be about 8024 feet in elevation (13 feet higher than the floor), a 13-foot deep channel will be cut into the pad,with 3:1 sideslopes,and for an estimated distance of 280 feet. The volume of this material exceeds 5,000 CY, and will be spread in the pit as part of the backfill material. The channel will allow the pit to drain, and water will be directed to the sediment pond. The surface of the overburden will be graded and ripped,then capped with 6-12 inches of topsoil,then revegetated. No areas of the pit floor will be steeper than 3H:1V. The entire site will be monitored for erosion and sedimentation,during mining and reclamation, and especially on disturbed areas in final reclamation. Any problem areas will be addressed in a timely manner. Revegetation Seeding, Fertilizer, Mulch Revegetation seeding will be carried out on all disturbed surfaces,with the exception of some roadways and exposed obsidian on the pit highwalls. Mulch will be spread after seeding,and fertilizer will be applied as needed after seed germination. Seed Mix: Seed Name Variety Pounds of PLS/Ac Western wheatgrass Arriba 9.6 Arizona fescue Redondo 0.9 Blue grama Hachita 1.4 Blue flax Lewis 0.2 Total pounds PLS/Ac 12.1