2018-11-05_GENERAL DOCUMENTS - C1981044

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Williams Fork Mines Prepared by: R. Reilley M.S. GISP C1981044 5 November 2018 29 The applicant disposed of underground development waste within the existing No. 9 Portal Excavation. These portals have been sealed. The approved reclamation plan calls for the backfilling of the existing excavated incline. The applicant will utilize the excavation to dispose of waste. Because there would be no elevated embankment, slope stability is not a concern. Minimal ground waters might invade the unencapsulated waste but are projected to produce insignificant amounts of leachate. A monitoring well will be installed at the No. 9 Mine Portal Excavation to monitor potential ground water within 90 days of final grading of the No. 9 Mine Portal Excavation. A plan for post-mining topography was approved as a portion of original Permit No. C-1981-044 for the Williams Fork Strip Pit No. 2. The approved configuration requires the regrading of approximately 240,000 cubic yards of spoil. The applicant was allowed to postpone final grading, because the installation of a second set of portals for the No. 9 Mine was proposed at this location. These portals, Nos. 9A, were never installed. Backfilling and grading of the Williams Fork Strip Pit No. 2 commenced August 10, 1987. Initial seeding occurred that fall. VIII. Revegetation Pre-mine vegetation information is provided in Section 2.04.10. Additional information is provided in Exhibit 14, Supplemental Vegetation Information. Vegetation communities are shown on Map 20 - Vegetation Map. Section 2.05 of the permit application describes the revegetation methodology and revegetation standards for each type of disturbed area. The Williams Fork Strip Pit revegetation plans and revegetation success criteria are given in Exhibit 24, Williams Fork Strip Pit Reclamation Plan. The Reclamation Plan Map (Map 29a) indicates the planned post-mine uses (vegetation types) and the reference areas for the reclaimed areas. A vegetation inventory was conducted at the Williams Fork Mines in July of 1981. The operator sampled three undisturbed big sagebrush stands adjacent to the surface disturbance. The vegetation sample areas were similar in aspect, elevation, and soils to the disturbed areas. The information collected in that study is located in Section 2.04 of the permit application. No threatened and/or endangered plant species were identified within the disturbed area during the vegetation inventory. Roughly one-third of the permit area is covered by croplands. MCM has divided the croplands into two categories: 1) irrigated hayfields in the Williams Fork River bottom areas, and 2) dryland wheat, found on cleared hillsides which were once sage-dominated. Productivity data is provided for the irrigated hayfields on Table 69 of the permit application. Wheat production is given in Table 70. The approved reclamation plan calls for reclaiming the surface disturbed areas to the following three post-mining land uses: rangeland/wildlife habitat, cropland, and pastureland. The Division has previously approved a revegetation plan and revegetation success standards.