2010-02-09_PERMIT FILE - C1982056A (6)

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relevant. • RESPONSE Descriation of Surface Drainaees The Twentymile Park structural basin controls surface as well as ground water movements in the general azea. All surface areas within the Twentymile Park Basin drain to Trout Creek. The headwaters area for Trout Creek is in the Dunkley Flat-Tops south of the Foidel Creek Mine Plan Area, on the northern edge of the White River Plateau. From its headwaters, Trout Creek flows in a northeasterly dvection approximately 32 miles to its confluence with the Yampa River near Milner, Colorado. The upper Trout Creek drainage is gcegraphically and hydrologically separated from the proposed area of mining. Foidel Creek and Fish Creek, as shown on Map 13, Twentymile Park Hydrology, drain the pemtit and adjacent aeeas, and areas to be affected by mining and related operations are contained within these watersheds. Discharges of disturbed area runoff from sedimentation ponds are to Foidel Creek and Fish Creek (Fish Creek Tipple area only). Controlled discharge of Veated mine water to Fish Creek occurs on an intermittent basis during high flow periods. Foidel Creek is tributary to Middle Creek, and Fish Creek and Middle Creek are tributary to the lower portions of Trout Creek. Both Fish Creek and Trout Creek are perennial streams, while Middle Creek and Foidel Creek are intemtittent sVearns, which flow ordy in response to snowmen and major storm events. Due to the semi-arid climate, site topography, and soil and vegetation conditions, surface runoff from disturbance areas within the mine permit area is ephemeral. Disturbed area runoff is intercepted by collection ditches and duected to sedimentation ponds designed to contain and treat the runoff from a 10-year, 24-hour precipitation event prior to discharge. Mine water discharge from the Fish Creek Borehole can be recycled back to the mine for use in dust control sprays, routed to the wash plant for make-up water, or Vlated and discharged. The majority of the mine water discharge is recycled. Any excess mine water discharge is Veated with caustic soda and routed through a series of three settling ponds, which are designed to allow excess iron to precipitate and settle-out prior to discharge. • The headwaters of Foidel Creek are in the mountainous area to the southwest of the Foidel Creek Mine Permit Area. Foidel Creek flows to the northeast, joining lower Middle Creek at a point about 1.5 miles above the confluence of Middle Creek with Trout Creek. Foide] Creek receives limited disturbed area runoff discharge from the Foidel Creek Mine following retention and settling of suspended solids in the designed sedimentation ponds. Foidel Creek also receives discharge from sedimentation ponds associated with the adjacent reclaimed Eckman Park surface mine, including limited flows from backfill seeps and runoff from distwbed and reclaimed areas. Middle Creek begins in a headwater area south of the proposed mining azea and flows northeastward for a distance of approximately 15.6 miles to its confluence with Trout Creek, approximately 1.5 miles north of the Middle Creek Shop building. The Middle Creek drainage Iies immediately to the south of the Foidel Creek drainage and is separated from Foide] Creek and the mine plan area by a drainage divide, as shown on the Twentymile Park Hydrology Map (Map 13). Middle Creek will not be directly disturbed or affected by discharge from distwbed aeeas or underground operations associated with the Foidel Creek Mine. Foidel Creek is a tributary to Middle Creek, so there is the potential that any effects on Foidel Creek could indirectly affect lower Middle Creek. The Fish Creek headwaters are in the Dunkley Flat-Tops area southwest of the mine plan area. Fish Creek flows in a northerly direction, then turns northeastward, joining Trout Creek approximately 22.5 miles from its headwaters. The Fish Creek drainage lies north of the Foidel Creek drainage and is isolated from the Foidel Creek drainage by a surface drainage divide, however given its location and the dip of the synclinal basin, it does receive ground water recharge from the Foidel Creek basin. As previously noted in the ground water hydrology description, the Wadge overburden ground water aquifer discharges to the lower Fish Creek drainage under artesian conditions in the center of the Twentytnile Park Basin. It is estimated that discharge from the Wadge overburden aquifer alone provides about 0.5 percent of the streamflow in Fish Creek during low flow periods. r~ U TR06-52 2.04-30 02/1 °b106 0