Montana agency seeks input on air permit for Arch Coal’s Otter Creek mine project

The Montana Department of Environmental Quality is taking comment until June 10 on a draft air permit for the Otter Creek Coal LLC unit of Arch Coal (NYSE: ACI) for the new Otter Creek surface mine.

Otter Creek Coal (OCC) has combined coal lease interests at Otter Creek in Powder River County for a total of approximately 17,900 contiguous acres. This area is divided into three tracts (Tract 1, 2 and 3). OCC propose to operate a coal mine in the area that comprises the major portion of Otter Creek Tract 2. The maximum coal production under the draft permit would be limited to 35 million tons per rolling 12-month time period.

OCC will develop Tract 2 for (approximately) the first 17-19 years and Tract 3 during years 19-41. Tract 1 development is proposed from (approximately) year 40 to year 55. The necessary permits, baseline studies and mining and reclamation plans must be developed and approved for OCC to mine Tracts 1 and 3 in the future.

The OCC mine will be operated in keeping with a typical western surface coal mine and extraction facility, the department noted. Development will begin with construction of an access road from Highway 484 across the Otter Creek valley, then branching to the area to the northeast and southward parallel to Otter Creek. This road, with excavated sediment ponds, will serve as sediment control during initial construction and pit development, and provide access to the primary crusher and dragline erection sites. Simultaneously, a rail loop, live storage silos and train loadout will be constructed west of Highway 484, opposite the mine access road at the terminus of the Tongue River Railroad.

A realignment of the long-planned Tongue River Railroad, which is now part owned by Arch Coal, is working its way through the U.S. Surface Transportation Board. This new rail segment would allow the coal to move to a BNSF Railway interconnection at Colstrip, Montana.

Initial development activity of the new mine will focus on construction of the access roads, rail loop, silos and train loadout, crushing and conveying system, and shops and office facilities. As the transportation and coal handling systems near completion, boxcut development and dragline erection will initiate at mid-pit. The boxcut will be developed using mobile equipment – trucks and a shovel. When the dragline is operational, it will begin by stripping overburden and casting spoil into the empty boxcut. As mining advances to the east, dragline spoil will be cast into the previous empty cut.

As coal is exposed by overburden stripping, the uncovered coal seam will be drilled and blasted. A shovel or front-end loader will load the broken coal into haul trucks that will deliver the coal to the truck dump via graded haul roads. The truck dump and the primary crusher will be located near the pit. From the truck dump the coal will be dumped into a hopper that will feed the primary crusher which will be located below grade. From the primary crusher the coal will be sent via an enclosed overland conveyor to a secondary crusher. From the secondary crusher the coal will be sent to the silos via an enclosed overland conveyor. Screening will occur in association with both the primary and secondary crushing operations. The primary and secondary crushers, screens and conveyors will run off electric land power and will be controlled by a fogging dust suppression system. The coal will be loaded into railcars from the silos and shipped via rail to market.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.