2014-05-28_REPORT - C1982056 (4)

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TC had covered approximately 35 acres. Expansion of the refuse pile footprint will add an additional 140 acres to the refuse pile area (see TR09 -67). Other associated satellite TC support facilities contribute an additional 10 to 15 acres. The Fish Creek Tipple site is located approximately 15 miles southwest of Steamboat Springs at the northeast end of Twentymile Park, covering an area of approximately 15 acres. Foidel Creek flows eastward, and is located adjacent to the TC Foidel Creek Mine surface facilities. Foidel Creek receives treated effluent from a series of sediment ponds established at the facility. Mine site drainage is controlled through seven (7) sediment ponds (NPDES Ponds T, B, C, D, E, F, and G — see Figure 2 in Map Pouch at back of report). The Fish Creek drainage is located north of the Foidel Creek Mine surface facilities area and overlies tracts, which have been longwall mined. Fish Creek runs through the Twentymile Park syncline area. Mine water was historically discharged into Fish Creek via the Fish Creek Borehole (FCBH) pump and sodium hydroxide treatment pond facility (discharge site 115), however that practice ceased in early 2005. In 2005, an electro- coagulation treatment system was constructed re -using the FCBH pump. Treated mine water was directed back underground for dust suppression. Electro - coagulation treatment assists in minimizing pipe scaling underground. No discharge to Fish Creek from site 115 occurred in 2013. Mine water is currently dewatered from wells located at the former Fish Creek vent shaft in the old Western Mining District (WMD) and the TORT well located in the old Eastern Mining District (EMD). The wells discharge into the Area 1 Pit. The Pit supplies water to the new Wash Plant. If the Pit overflows, it runs through a flume (site 7) into Pond D. Pond D (site 84) discharges to Foidel Creek. Spoil springs (sites 303 -1, 303 -2, and 303 -3) from the former surface operations at the Fish Creek Tipple site (east of the TC Foidel Creek Mine and Twentymile Park area) also discharge to Fish Creek at surface site 62. The southwest area of TC (Eckman Park area), has been reclaimed and has been released from bond. In addition, the former surface mine area referred to as Area 1 was released from bond in January 2002. As a result, the Colorado Department of Public Health and Environment (CDPHE) subsequently approved eliminating Ponds A (Eckman Park) and H (Area 1) from our ongoing NPDES monitoring program in 2002. Surface coal mining has been conducted in the area since the 1960's. The Fish Creek Tipple site was constructed in 1974, and ceased operation in 1983. The Foidel Creek Mine underground operation was later established in 1983, and has been an on -going operation using a longwall mining process since 1989. This is a form of underground mining where a 1000 foot long wall is mined in a single slice (typically 1 -2 m thick). The block of coal being mined, known as the longwall "panel ", may be on the order of 12,000 feet long. The gate road along one side of the wall is called the main gate, while the other side is called the tail gate. The end of the block that includes the longwall equipment is called the "face ". Air is provided by ventilation fans and associated bleeder vent shafts from the surface. The advantage of longwall mining is that over 80 percent of the coal is recovered, compared with about 50 percent for the traditional pillar method. In addition, subsidence is immediate, allowing for better planning by the mining company. The Foidel Creek Mine portals are faced -up in the down dip high- wall of the strip mine. 2