landowner, CSLB. The request from the landowner for the portion of ditch to remain as a
<br /> permanent structure is found in Volume 2A, Exhibit 1B in the Colowyo Permit Application
<br /> Package (PAP). Map 1 of the SL-17 application, as well as Figure 1 of this document, show the
<br /> portion of the South Collection Ditch being requested for bond release. The bond release area is
<br /> located in the Colowyo Mine's Section 16 Pit in portions of Township 3 North, Range 93 West of
<br /> the 6th Principal Meridian, Section 16 — SE 1/4 E 1/2. The permit area can be found on the USGS
<br /> Quadrangle 7.5 Minute Series Maps of Axial and Nine Mile Gap. The permit area and surface
<br /> ownership can be found on Map 1, and the coal ownership can be found on Map 2 of the
<br /> Colowyo PAP.
<br /> Background
<br /> The East Pit and West Pit mining sites lie just west of the northward flowing Goodspring (also
<br /> referred to as Good Spring) Creek, which is paralleled by Colorado Highway 13. The area
<br /> includes gently sloping uplands and valleys that cut into the upland surface. These valleys are
<br /> generally narrow, v-shaped, and about 250 to 500 feet deep. Elevations range from
<br /> approximately 7,650 feet in the upper portion of East Pit reclamation to 6,950 feet near East
<br /> Taylor Pond.
<br /> Mining operations began in 1976 with the East Pit, a multi-seam coal operation that continued to
<br /> move in a southerly direction. Eight coal seams (Y, X, A, B, C, D, E, F)were mined from the
<br /> East Pit, ranging in thickness from two to fifteen feet. The East Pit is nearly 6,000 feet from east
<br /> to west(width), 1,000 feet in breadth (highwall to highwall), and 450 feet deep. Due to the
<br /> number of coal seams, immense size of the pit, and manpower and equipment employed,pit
<br /> progression was slow, with additional disturbances of approximately 40 to 50 acres per year.
<br /> Extraction of coal from the East Pit was terminated in 2006. All reclamation activities have been
<br /> completed in the East Pit and is in the required final revegetation stages.
<br /> The West Pit is located to the west of the East Pit. The method of operation utilized in, and the
<br /> coal seams extracted from, the West Pit were the same as those of the East Pit. The West Pit was
<br /> roughly the same overall size as the East Pit. Mining in the West Pit advanced from the north to
<br /> south,paralleling the movement of the adjacent East Pit. Mining operations in the West Pit were
<br /> completed in 2015. Reclamation activities remaining in the West Pit include backfllling,
<br /> grading, reduction of the highwall, and revegetation.
<br /> Colowyo is continuing to perform reclamation maintenance and activities in the East Pit and
<br /> West Pit. Reclamation in the East Pit and West Pit is expected to conclude in 2029.
<br /> Operations in the South Taylor Pit began after the approval of PR-02 in 2007. This pit is located
<br /> north and west of the northward flowing Good Spring Creek and southwest of the West Pit. It
<br /> lies partially in Rio Blanco County. In the South Taylor Pit, 17 seam and sub-seam complexes
<br /> are mined. The seams are the A, B, C, D, E, F and G seams and their seam complexes (for
<br /> example, the G-Seam is separated into G7, G8 and G9 in the South Taylor Area). At the peak of
<br /> operations, the South Taylor Pit will be nearly 4,000 feet wide, 6,000 feet long, and 550 feet
<br /> Proposed Decision and Findings of Compliance December 18,2019
<br /> Partial Phase I,II and III Bond Release SL-17 Page 2
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