2020-10-27_REVISION - C1981019 (15)

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Colowyo originally applied for a partial Phase 11 Bond Release for 281.4 acres associated with the East and West Pit as shown on Map 1 of the SL-19 application and Figure 1 of this document. After review in the field and office, a total of 238.2 acres are being reviewed as part of the SL-19 bond release process and additional details will be discussed in Section IV — Observations and Findings of this SL-19 Findings Document. The bond release area is located in the Colowyo Mine's West Pit in portions of Township 3 North, Range 93 West of the 6 h Principal Meridian, Section 8— SE'/4 and Section 9 — SW'/4. The permit area can be found on the USGS Quadrangle 7.5 Minute Series Maps of Axial and Nine Mile Gap. The permit area and surface ownership can be found on Map 1, and the coal ownership can be found on Map 2 of the Colowyo Permit Application Package (PAP). Background The East Pit and West Pit mining sites lie just west of the northward flowing Goodspring (also referred to as Good Spring) Creek, which is paralleled by Colorado Highway 13. The area includes gently sloping uplands and valleys that cut into the upland surface. These valleys are generally narrow, v-shaped, and about 250 to 500 feet deep. Elevations range from approximately 7,650 feet in the upper portion of East Pit reclamation to 6,950 feet near East Taylor Pond. Mining operations began in 1976 with the East Pit, a multi -seam coal operation that continued to move in a southerly direction. Eight coal seams (Y, X, A, B, C, D, E, F) were mined from the East Pit, ranging in thickness from two to fifteen feet. The East Pit is nearly 6,000 feet from east to west (width), 1,000 feet in breadth (highwall to highwall), and 450 feet deep. Due to the number of coal seams, immense size of the pit, and manpower and equipment employed, pit progression was slow, with additional disturbances of approximately 40 to 50 acres per year. Extraction of coal from the East Pit was terminated in 2006. All reclamation activities have been completed in the East Pit and is in the required final revegetation stages. The West Pit is located to the west of the East Pit. The method of operation utilized in, and the coal seams extracted from, the West Pit were the same as those of the East Pit. The West Pit was roughly the same overall size as the East Pit. Mining in the West Pit advanced from the north to south, paralleling the movement of the adjacent East Pit. Mining operations in the West Pit were completed in 2015. Reclamation activities remaining in the West Pit include backfilling, grading, reduction of the highwall, and vegetation. Colowyo is continuing to perform reclamation maintenance and activities in the East Pit and West Pit. Reclamation in the East Pit and West Pit is expected to conclude in 2029. Operations in the South Taylor Pit began after the approval of PR-02 in 2007. This pit is located north and west of the northward flowing Good Spring Creek and southwest of the West Pit. It lies partially in Rio Blanco County. In the South Taylor Pit, 17 seam and sub -seam complexes Proposed Decision and Findings of Compliance October 26, 2020 Partial Phase II Bond Release SL-19 Page 2