2010-04-16_PERMIT FILE - C1996083

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3.0 GEOTECHNICAL FRAMEWORK 40 In this section, the geological setting of the Terror Creek crossing area is reviewed, followed by a description of extensive rock mechanics testing program and joint surveys within the North Fork Valley. Procedures suggested by ISRM are used to characterize rock mass quality for the entire overburden, which indicates mostly fair-to -good rock types capped by semi - consolidated colluviums. 3.1 Geologic Setting The Somerset Coal Field is located on the southeastern margin of the Piceance Basin, which lies north of the Gunnison Uplift; west of the Elk Mountains, east of the Uncompahgre Uplift; and south of the White River Uplift. There are six primary coal seams within the Somerset Coal Field, ranging from 10 ft thick on a single bench of coal to over 20 ft where one or more seams merge (Maleki and others 1997) (figure 2). There is an estimated 1.5 billion tons of bituminous coal within the Somerset field. Coal seams B, C, D, E, and F have been mined historically in this basin. The coal seams contain a very well developed cleat set oriented at N58° to 75° E (Carroll 2003). The regional structural dip of the Mesa Verde Formation is 3° to 5° to the north- northeast. The predominant jointing of sedimentary rocks is N 68° E to N 74° E in the basin, with secondary jointing at N 18° W (Carroll 2003) to N 35° W. Regional jointing patterns are mapped by Tifft 1995, and Carrol 2003. BRL geologic staff has studied faulting near the existing longwall panels. Faulting is divided into three systems based on strike, sense of shear, and maximum offset. The four largest faults possess normal or reverse offsets of up to 50 ft and are visible at the surface. One longwall block (shown in figure 1) is bounded to the northeast by a N 45° W- trending fault (West Mains fault), a part of this system. Oblique -slip movement indicators are common along this fault. • Maleki Technologies, Inc. Page 9