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-4- SUMMARY Description of the Environment and Description of the Operations and Reclamation Plan Descriotion of the Environment The Snowmass North Thompson Creek Mines and loadout are located in the lower Roaring Fork Dralnage Basin. The loadout is located about a mile below the confluence of the Roaring Fork and Crystal Rivers. The permit area of the North Thompson Creek Mines are located within the North and Middle Thompson Creek Dralnage Basins. These two perennial streams combine to form Thompson Creek, about 2 1/2 miles below the mining facilities. Thompson Creek is a ma,Jor tributary of the Crystal River, which is located about 5 miles downstream of the mining disturbance. The stream valleys of North and Middle Thompson Creeks have steep stream yradtents and have steep valley walls. Elevations within the Thompson Creek drainage basin range from 10,921 feet at Twin Peaks, to 1,600 feet at the mine, down to 6,375 feet at the confluence with the Crystal River. Annual precipitation at the mine is,approximately 22 inches, with upland areas receiving up to 35 inches. Approximately 65X of the annual precipitation occurs as snowfall. The North Thompson Creek Mines and the loadout areas are located along the Grand Hogback monocline. The Grand Hogback forms the steeply dipping eastern edge of the Plceance Basin. The Pennsylvanian through Tertiary Age sedimentary formations which form the Grand Hogback dip 15 to 45 degrees to the west. An unnamed syncline and the Wolf Creek anticline are located to the west of the mines. The Wolf Creek anticline plunges to the north, northwest. The sedimentary beds on the eastern limb of the unnamed syncline (tn the area of the mines) dip 25 to 34 degrees to the west. Most faults along the Grand Hogback are perpendicular to the strike of the strata and trend east-west. The faults in the area of the mines are low displacement normal faults. The displacements of faults increase in ,~ faults located south of the mines. Sedimentary rock units within the permit and adJacent areas of the mines and loadout range 1n age from Pennsylvanian to Tertiary Formation. The formations, in ascending order, are the Maroon Formation, Entrada Formation, Morrison Formation, Dakota Sandstone, Mancos Shale, Iles Formation, Williams Fork Formation, and Wasatch Formation. The most significant sandstones and coals in the permit and adJacent areas of the mines are contained in the Iles and Williams Fork Formations.