A U.S. Bureau of Land Management office in Wyoming is taking public comment until Jan. 25 on an environmental assessment on a proposal by Bridger Coal Co., which is co-owned by PacifiCorp and Idaho Power, to expand an existing federal coal lease by 320 acres for underground mining.
The additional 320 acres of BLM-administered land is in the checkerboard region of mixed public-, private- and state-owned land. The modified lease is adjacent to the current Bridger mine permit boundary. The permit area covers approximately 26,691 acres of land, located roughly 35 miles northeast of Rock Springs, Wyo. In addition to the federal lease modification request, the company is proposing to conduct underground coal mining on connecting private land.
Bridger Coal operates the Jim Bridger Coal Mine complex, which includes surface, underground, and highwall mining, with coal production moving to the nearby Jim Bridger power plant, also co-owned by PacifiCorp and Idaho Power. The annual production for this mine complex is approximately 6 million tons.
The Jim Bridger surface mine has been supplying the majority of the coal requirements for the power plant over the past 38 years. The underground mine began full production in 2007, at a rate of about 3.5 million tons per year, and is now providing the majority of the overall production, with the surface mine and coal from other sources in the region supplementing the annual requirements to the power plant. The coal produced by underground mining methods replaces coal previously produced by surface mining methods, with no resulting change in total annual coal production.
The proposed lease addition tract borders coal mining activity on three sides: to the east is the Bridger underground mine, on the north and south the lands are leased to Bridger Coal for underground mining. To the west there are no further underground mineable coal reserves. The proposed lease modification would support future expansion on the western side of the deep mine. The coal reserves contained within this lease tract are estimated at about 5.7 million tons of mineable coal.
The underground mine utilizes continuous miners and retreat longwall mining. Approximately 85%-90% of the coal recovered from the underground mine is achieved by the longwall, the EA noted. The underground mine is developed with continuous miners developing main and sub-main entries with gateroads to access and support a series of longwall mining panels.
“Coal mined at the Jim Bridger Mine is used to generate electricity at the Jim Bridger Power Plant,” said the EA. “The power plant is capable of generating 2,120 megawatts (MW) of electricity and is the largest coal-fired power plant in PacifiCorp’s or Idaho Power’s system. The power plant is connected to the western power grid through a series of transmission lines.”