Laserfiche WebLink
<br />Proposed Decision and Findings of Compliance July 2018 <br />Permit Renewal No. 7 P a g e | 14 <br />4.4 Topography <br /> <br />The East Pit, West Pit and Section 16 Pit mining sites lie just west of the northward flowing Good <br />Spring Creek, which is paralleled by Colorado Highway 13. The area is gently sloping and upland <br />ranging from about 7,640 feet near the southwest corner to 6,560 feet near the northeast corner of <br />the permit area. Valleys that cut into the upland surface are generally narrow (V-shaped) and <br />approximately 250 to 500 feet deep. The topographic surface north of the East Pit, West Pit and <br />Section 16 Pit mining sites is dominated by two ridges approximately two miles long, trending <br />north-northeast and bounded by Good Spring, Taylor Creek and Wilson Creek. <br /> <br />The South Taylor Mining area lies north and west of the northward flowing Good Spring Creek <br />and south-southwest of the other pits. The area is also just south of the northeastward flowing <br />Taylor Creek, which runs adjacent to the Section 16 Pit and West Pit. Much of the area was gently <br />sloping upland rangeland, but the valleys were steeply sloping, with slopes in excess of 20 percent <br />in some areas. <br /> <br />The Collom area occupies the south-central headwaters of the synclinal axial basin along the <br />Danforth Hills and drains to the northeast, eventually into the Yampa River. Elevations range <br />from just below 6,400 feet to approximately 8,550 feet. Upland side slopes range from moderately <br />steep to steep (>35 percent) whereas the areas between drainages generally exhibit flatter slopes <br />with a northeasterly aspect between 1 and 5 percent. <br />4.5 Geology <br /> <br />Geologic information is found in Sections 2.04.6, Maps 7 through 9A, and Exhibit 6 of the PAP. <br />The permit area lies approximately six miles south of the axis of the Axial Basin Anticline, a large <br />northwest-trending fold found in the southern Uinta region of the Piceance Basin. The anticline <br />structure and corresponding Collom Syncline to the south consist of thousands of feet of marine- <br />deposited sediments of Cretaceous age. <br /> <br />To the south of the anticline, the axis of the Collom Syncline, a downward fold, passes directly <br />through the permit area, trending north 70 degrees west and plunging from 0 to 20 degrees to the <br />north. In the southeastern corner of the permit area near the Streeter Fill, the Collom Syncline is <br />influenced by the Elkhorn Syncline which results in strata having an eastward dip and north-south <br />strike (see Map 7 and Figure 1 in the PAP). <br /> <br />There appears to be no evidence of faulting in the permit area; however, linear features that may <br />be fault-related have been observed from aerial photographs. These linear features trend <br />approximately north 70 degrees west, north 45 degrees west and north 30 degrees east, with near <br />vertical inclinations. <br /> <br />The coal-bearing strata of interest to the Colowyo operation are stratigraphically located in the <br />Mesaverde Group within the Williams Fork Formation of the upper Cretaceous age. The Williams <br />Fork consists of alternating beds of sandstone, sandy shale, carbonaceous shale and coal. The coal