2019-06-28_REVISION - M1977004 (9)

Home Browse Search

Homestake Mining Company May 10,2019 Regular(112d)Operation Reclamation Permit Application Package In the future, this water may be treated using a semi-passive (ETC approach as described in Section 4.3. The engineered treatment cell or cells would be installed adjacent to Indian drainage along the stretch between the North Pit and the Mine Shop within the Water Management System OU, which includes the current engineered treatment cell pilot location on the IRD. The design and reactive media mixture will be contingent on the results of current ETC pilot testing. • The Southeast Wall Buttress will be placed over the marginally stable portion of the southeast pit wall, as a means of stabilization, above the historic Pinnacle Adit. This will be implemented by constructing fill in lifts from the Northwest Pit Wall Layback and sloping the outer face to the designed grade. The preliminary design of this buttress is anticipated to require approximately 400,000 cy of fill, as shown on Exhibit F Map F-01 B. The following reclamation activities are proposed within the Landslide Crest Mitigation area: • The upper east slope will be logged and clear-cut to allow for grading and revegetation. See paragraph 5.1.1.4 for the description of spreading slash from the cutting. • Slash from logging operations on nearby areas of the Mine will be spread on the slopes, to create small animal habitat, reduce erosion, and introduce seed from pine cones to the new surface of mineral soil. • Tension cracks above the eastern crest of the North Pit will be graded to mitigate infiltration. Sloping toward or around the pit will be performed to facilitate overland flow and minimize channelization. Existing roads and drainage features within this operable unit are located on private property and will remain open to accommodate general site access and erosion control. The North Pit will be regraded to the final topography shown on Exhibit F Map F-01 B, with sections presented on Exhibit F Map F-01 C. 5.2. Operable Unit 2: South Pit The current topography for the South Pit is shown on Exhibit F Map F-02A. 5.2.1. Previous Reclamation Previous reclamation activities include regrading the majority of the South Pit to final slopes, terracing, and reseeding. In addition, the Pinnacle Adit was plugged in 1995 (DMG, 1995a), and the underground mine workings are considered reclaimed. 5.2.2. Proposed Reclamation The following reclamation activities are proposed within the Landslide Remediation area of the South Pit: • Regrading (excavation of loose fill and placement of engineered fill)will be required on the area of the Landslide Remediation. • The East Diversion Ditch will be re-established to convey runoff into the existing Diversion Ditch further south. The ditch be lined with a GCL to minimize infiltration and seepage along its alignment. EXHIBIT E-RULE 6.4.5(AMENDED RECLAMATION PLAN) Page 68 HOMESTAKE MINING COMPANY