2023-05-15_PERMIT FILE - C1983059 (2)

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2.04.6 Geology Description The permit area of TCC facilities is located adjacent to the North Fork of the Gunnison River within eastern Delta County, Colorado. The area is characterized by the drainage to the North Fork of the Gunnison River and deep canyons which separate the adjacent steep table lands of both north and south of the river. The area is deeply dissected by tributary streams to the North Fork of the Gunnison River and is bounded on the south and east by an arc of intrusions of igneous rock which forms the rugged mountains inherent with the Gunnison National Forest. Stratigraphy The rocks exposed in the vicinity of the permit area are Upper Cretaceous in age. Three different sedimentary units are present. Due north of the permit area, the Mesaverde formation contains several sequences of coal bearing rocks. The rocks present in the area cf the Terror Creek site are of Mancos Shale formation. Within the North Fork • of the Gunnison River Vally, Quaternary Age alluvial deposits are found. Severe erosion of the 14esaverde formation, sandstones, shales and coals, has occurred which in turn has covered the Flancos Shale slopes of the permit area. A colluvial fan deposit, which has been graded to its current configuration by farming, overlies the FP1ancos Shale. Faterial which will be intersected at TCC consists of this colluvial fan deposit. This material characteristically consists of large angular shaped boulders with a poorly consolidated matrix of fine material resulting from weathering~of shales, siltstones and sandstones materials. The unconsolidated and poorly sorted nature of the colluvial material indicates that it was placed by gravitational mass wasting from the adjacent steep slopes. Some transport by overland flow of surface waters is also evident. The unconsolidated nature of the material lends itself to deep weathered zones and infiltration of surface water. Because of the loose unconsolidated nature of the material, little or no groundwater is found above the level of adjacent intermittent or perennial streams. 2.04-8