2017-08-09_REVISION - M1980244 - Laserfiche WebLink

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Revegetation: A minimum of six inches of growth medium will be applied over the regraded AGVLF surface including the benches and downgradient reclamation areas. Benches will be used to provide access for top soil and seeding on the south and west slopes. It is anticipated that growth medium from soil storage areas #19 and #13 will be used due their close proximity to the AGVLF. As noted in previous submittals, use of soil storage area #19 will require haul trucks to cross Highway 67 during reclamation. CC&V will work with the Colorado Department of Transportation to construct an appropriate road crossing and traffic control plan during this activity. The replaced growth medium will be spread using dozers. After growth medium placement and grading, soil sampling may be performed to assess the potential need for additional soil amendments to enhance revegetation efforts. Fertilizer and other appropriate soil amendments will be broadcast on the reclamation areas during or after growth medium placement depending on site specific conditions and constraints(e.g., accessibility,moisture content, application rate). Application of the seed mix presented in the attached Table 2 will be broadcast, drilled, or hydro-seeded onto the placed growth medium. This table provides a list of preferred species of seeds and a list of alternative species of seeds in the event the preferred seed is not commercially available. The application rate of the seed mix will be approximately 50 pounds of pure live seed (PLS) per acre if the seed is broadcast. A lower PLS (e.g., 25 PLS) may be used if the seed mix is incorporated into the growth medium using a rangeland harrow, slope chain, or equivalent equipment, as necessary and feasible. Hydro-mulch or other surface treatments will be used to facilitate the revegetation efforts in steep or high-profile areas and generally will be applied at a rate of 2,000 pounds per acre of wood fiber hydro- mulch. A combination of broadcasting of the seed mix presented in the attached table followed by slope chaining or harrowing and/or hydro-seeding/hydro-mulching were used in the financial warranty calculations presented in Section 13.0 of the Project Description, Amendment 11 (February 2017). The addition of soil fertilizer has been estimated for financial warranty calculations at a rate of 400 pounds per acre of a blend of nitrogen, phosphorus and potassium fertilizer product. The results from actual soils analyses and observations of the specific reclamation areas will be used to determine the appropriate fertilizer blend and application rates. After placement, the growth medium will be amended as needed,and seeded. Approximately 89 acres of trees will be planted on the north side of the AGVLF and will cover a portion of the crusher area using a variety of tree and shrub species adapted to the site. See drawing F-1 and F-7 in the attachment for the location of trees on the AGVLF. Approximately 150 trees and/or shrubs per acre will be planted on this north facing slope. The shrubs and trees currently planned for the AGVLF include Gooseberry at about 50 plants per acre, Wood Rose at about 50 plants per acre, Engelmann Spruce at about 25 plants per acre and Bristlecone Pine at about 25 plants per acre. Monitoring: Post-reclamation monitoring will initiate after reclamation has been completed. Monitoring is expected to include: • Review of vegetation success; • Routine inspections for erosion features on side slopes; • Identification of seeps at the toe of the AGVLF; Monitoring is expected to continue for a period of 2 years after reclamation of the AGVLF is complete. Schedule: Closure and reclamation at the AGVLF, including neutralization (approximately six years), physical reclamation (approximately two years) monitoring (approximately two additional years), are scheduled to take up to ten years total after final leaching of ore has been completed. Based on a schedule of active leaching at the AGVLF occurring through 2024, final reclamation of the AGVLF is expected to be completed by approximately 2034 assuming CNWAD removal criteria can be achieved within 6 years.