The U.S. Bureau of Land Management field office in Rock Springs, Wyo., is taking public comment until May 2 on what should be covered in a planned environmental assessment report on a proposal by Bridger Coal to expand a coal lease by 320 acres for underground mining.
The additional 320 acres of BLM-administered land is in the “checkerboard” region of mixed ownership of public, private and state owned land, BLM said in an April 3 announcement. The modified lease is adjacent to the current Bridger permit boundary. The permit covers about 26,691 acres of land the company has under lease. In addition to the federal lease modification request, the company is proposing to conduct underground coal mining on connecting private land.
Bridger Coal, which is jointly owned by PacifiCorp and Idaho Power, operates the Jim Bridger Coal Mine complex, which includes use of surface, underground, and highwall mining methods. The underground longwall mine is a relatively new operation developed last decade to supplement waning surface production. This coal moves to the neighboring Jim Bridger power plant, which is also co-owned by PacifiCorp and Idaho Power.
Heat content an issue for Bridger coal
PacifiCorp d/b/a Rocky Mountain Power, filed a general rate case request in February with the Utah Public Service Commission. The initial PacifiCorp rate case testimony dealing with coal supply issues came from Cindy Crane, Vice President, Interwest Mining and Fuel Resources for PacifiCorp Energy.
Crane testified that total Bridger Coal deliveries to the Jim Bridger plant from the surface mine decreased from 1,609,150 tons in the prior case to 1,214,785 tons, a reduction of 394,365 tons; however, deliveries out of the longwall mine have increased from 4,396,850 to 4,697,215 tons, or 300,365 tons.
During the test period ending in June, the heat content of the Bridger coal deliveries from the underground mine is projected to average 9,492 Btu/lb. The heat content in the next test period ending May 2013 is forecast at only 9,262 Btu/lb. That 230 Btu/lb decrease in heat content is the result of increased ash content in the coal. Increased out-of-seam dilution associated with the current sandstone roof has caused the ash content of the deep mine to increase from 11.79% in the prior period to 13.67% in the May 2013 ending test period, Crane noted.
Bridger is a captive mining operation controlled by the Jim Bridger power plant owners, while the nearby, non-captive Black Butte Coal mining operation also supplies the power plant. Though test period delivered costs of the Bridger Coal and Black Butte coals are similar, Black Butte has no additional production capacity and therefore no ability to ship extra coal to Jim Bridger, Crane noted. The company was even forced due to production shortfalls to purchase about 130,000 tons of Black Butte coal from the Valmy power plant owners during the last half of 2011 to supplement the current year Jim Bridger plant coal supply.