The proposal covers the plan to expand the existent Jim Bridger surface mine underground to access at least 160 million tons of coal reserves.

The mine, currently owned by Bridger Coal Company, supplies coal to the Jim Bridger Power Plant. The expansion will supply the plant with fuel for an additional 10 to 15 years.

The switch from surface to underground will occur gradually as the mine follows the Deadman seam in a northeasterly direction into the adjacent leases, company spokesman Kimball Hansen told Associated Press.

Bridger has been experimenting with longwall mining in the northern area of the mine in anticipation for the underground move.

The Bureau of Land Management is accepting written public comments on the proposal through early March.