2017-02-03_REVISION - C1980004 (6)

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McClane Canyon is located in the Book Cliffs area just north of the Grand Valley. This area is northeast of the Garmesa Anticline and on the southern flank of the Piceance Basin. Local strata strike north-northwest and dip to the northeast into the Piceance Basin at between 2 and 3 degrees. The surface geology of the permit area is made up of the Mesa Verde Group of Upper Cretaceous Age, the Wasatch Formation of Lower Tertiary Age, and alluvium and colluvium of Quaternary Age. All local coal seams are in the Mount Garfield Formation of the Mesa Verde Group. The Mount Garfield Formation consists of fine grained to medium grained sandstones, gray shales, and coal bearing zones. The Sego Sandstone underlies the Mount Garfield Formation. Overlying the Mount Garfield Formation is the Hunter Formation which contains massive cliff -forming sandstones that outcrop along the canyon walls of East Salt Creek. The Mount Garfield Formation contains four coal zones; the Loma, Carbonera, Cameo, and Palisade zones. The Cameo seam is mined at the McClave Canyon Mine. The occurrence of ground water within and adjacent to the McClane Canyon Mine permit area is controlled primarily by the combination of local topography, stratigraphy and geologic structure. Drilling has indicated that the Cameo seam becomes increasingly saturated downdip (northeast) from its outcrop along the side slopes of the East Salt Creek drainage basin. This is depicted on Figure 4.2-3 of Volume II of the permit application. As can be seen on the figure, the saturated zone extends downdip towards the northeast along a northwest -southeast trending line. The outcrop line of the coal as well as the East Salt Creek drainage, run roughly north -south in the vicinity of the permit area. Recharge to the Cameo coal seam occurs in an area where the coal seam subcrops in the East Salt Creek alluvium approximately two miles north of the McClave Canyon Mine permit area. The subcrop of the coal seam along East Salt Creek was created as the stream gradually cut through the sedimentary strata to the point where the stream channel intersected the Cameo coal seam. The underground workings of the McClave Canyon Mine extend roughly eastward into the Cameo seam from a point where the coal seam outcrops in McClave Canyon. McClave Canyon is a small tributary canyon to the East Salt Creek drainage. In addition to the saturated portions of the Cameo seam, some local lenticular strata of limited extent situated above the Cameo seamhave been found to contain ground water perched within the strata. Saturation of the Cameo seam occurs at about 5580 ft. elevation. East Salt Creek is an intermittent stream tributary to the Colorado River. The East Salt Creek Valley has been designated as an alluvial valley floor (AVF), with both undeveloped rangeland and irrigated hayland mapped on the AVF in the vicinity of the mine. Existing and proposed surface disturbances associated with the mine are located in the McClave Canyon drainage basin upstream from the AVF boundary, with the exception of office trailer facilities and the lower portion of the access road, which are situated within the boundaries of the AVF. The climate in the region is semi -arid. Prevailing winds at or near ground level at the mine are dictated by the orientation of the deeply incised McClave Canyon. The annual average precipitation within the permit area increases with elevation from approximately 10 inches along East Salt Creek, up to 15" on the ridges above 7000 feet. Soils in the permit area are well drained to excessively well drained and have formed in alluvial or colluvial sediments. Soils are deepest in the valley bottoms and become shallower along the canyon sideslopes where they intersperse with bare rock. Most of the soils are rated fair to good as sources 13