The proposed development area is located in the Powder River Basin (PRB), a part of the Northern Great Plains that includes most of northeastern Wyoming and a smaller portion of southeastern Montana. The Absaloka Mine and the South Extension are located near the northwestern edge of the PRB, in an area consisting primarily of dissected rolling hills, plateaus, and ridges of moderate to low relief that formed in the near-flat lying sedimentary strata. Resistant sandstone and clinker beds cap most of the upland areas and form steep cliff escarpments and isolated knobs. Elevations range from about 3,500 to 3,790 feet above sea level, slopes range from nearly flat on the valley bottoms and ridge tops to around 40 and 50 percent on the flanks of the surrounding ridges and hilltops, and approximately 61 percent of the surface has a slope of 10 percent or less.

The three lowermost coal seams of the Tongue River Member of the Fort Union Formation are the Rosebud, McKay, and the Robinson. In the Absaloka Mine area, all younger, stratigraphically higher coal seams have been removed by erosion. In parts of the current mine area, the Rosebud and McKay seams are joined into a single seam referred to as the Rosebud-McKay, which averages 32 feet in thickness. Mining within the proposed development area would be limited to the Rosebud and McKay coal seams. Where not affected by erosion or oxidation, the Rosebud and McKay seams are relatively consistent in thickness throughout the ........

The Absaloka Mine is a 10,427 acre permitted, single-pit surface mine complex located near Hardin, Montana and the Crow Indian Reservation. The coal reserves are leased from the Crow Tribe of Indians. The Absaloka Mine was expressly developed to supply Powder River Basin coal to a group of Midwestern utilities, including Xcel Energy’s Sherburne County Station near Minneapolis, Minnesota. Over the years, it has also sold coal to several other upper Midwest utilities. Coal is shipped via a 38-mile rail spur to the main line of the Burlington Northern Santa Fe Railroad near Hysham, Montana.

The Absaloka Mine has the present capacity to produce up to 7.5 million tons of coal annually.

The first step of the mining process is soil salvage using rubber-tired scrapers. Soil is salvaged in two lifts: the first lift being the “A” horizon topsoil, and the second lift being the “B” horizon subsoil. During initial box cut development, soil is placed in temporary stockpiles for later use in final pit closure and reclamation. Once the pit has advanced far enough to establish room for regrading of dragline spoils, soil is hauled directly from salvage areas and redistributed on regraded areas.

After soil salvage operations are complete, blast holes are drilled down through the overburden to the top of the Rosebud coal seam. The drill holes are then loaded with explosives (ANFO) and detonated to fragment the overburden to facilitate dragline excavation.
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