Western North Dakota contains an estimated 1.3 tillion tons of lignite, the single largest deposit of lignite known in the world. North Dakota also contains an estimated 25 billion tons of economically
mineable coal, enough to last for over 800 years at the present rate of 32 million tons per year. The recorded history of lignite mining goes back to 1873 when small mines sprung up along the main routes
of transportation in western North Dakota. At least 73 mines were operating in the state by 1900. Many of these were small, seasonal mines that removed coal from the face of the outcrop. They were called wagon mines
because area farmers and ranchers would often bring their own wagons to the site to be filled with coal. Still, other mines were large operations employing hundreds of men with underground workings extending for thousands
This photograph of the Bob Miller mine near Williston was taken in 1902 or 1903. (Photo courtesy of the State Historical Society of North Dakota).
By the early 1920s, there were approximately 250 mines operating in the state, with an equal number of underground and surface strip mines. The advent of the steam shovel increased the profitability
of the surface mines and the last underground mine ceased operation in 1966. Underground mines have caused problems in many areas where the collapse of the mine tunnels have created sinkholes at the surface.
The North Dakota Public Service Commission has spent a considerable amount of time and money attempting to rectify this sinkhole problem by digging out the old mine workings where they are close to the surface
and by pumping grout into the deeper workings in an attempt to stabilize them. A portion of the current severance tax on coal goes to a fund to support the reclamation of these old mines. In several areas of the
state (Dickinson, Minot, and Beulah), these underground workings are present beneath highways or county roads and have been grouted in order to stabilize the road. It is interesting to note that as early as the 1920s,
geologists for the North Dakota Geological Survey were noting collapse features of underground mines and warning that these underground workings were going to be posing an increasing problem for the future.
Aerial photograph of spoils northeast of Beulah. Prior to 1969, the state of North Dakota did not require reclamation of surface mines. As a result, approximately 6500 acres of spoil piles
and surface cuts dot the countryside of western North Dakota. (Photo by E. Murphy, NDGS).
The amount of vegetation on the spoil surfaces varies considerably from mine to mine and often within a given mine. It is more difficult for vegetation to establish itself on spoils
that consist largely of clayey till or claystone. The steep, long slopes of spoils that were created in the 1960s with the large draglines are also commonly only sparsely vegetated.
(Photo by E. Murphy, NDGS).
The North Dakota Geological Survey obtaining sediment cores from spoils in the Noonan mine. The spoils in this part of the mine were created in the mid-to late 1940s. There has been some interest
expressed in leveling the old spoil piles that occur throughout western North Dakota, especially some of the larger mines. A study of the groundwater conditions and the natural salts within the spoil
piles in the early 1980s recommended that they be left as they are because leveling of these areas would adversely impact the quality of the underlying groundwater. In addition, these mines provide
cover, albeit sometimes sparse, for wildlife. In fact, portions of several of these old mines are managed by the North Dakota Game and Fish Department. (Photo by E. Murphy, NDGS).
All of the economic or mineable coal in North Dakota is found within the lower Fort Union Group in western and central North Dakota and is Paleocene in age. That is to say that the peat from which this
lignite formed was deposited in swamps 55 to 65 million years ago. Judging from the number and the lateral extent of some of these beds, swamps covered a large portion of the western half of North Dakota
during this time period. We are not able to determine what was occurring in the eastern part of the state at this time because rocks of this age are missing.
The top 15 feet of the Harmon coal is exposed along East River Road north of Amidon, Slope County. The Harmon and Hansen beds are stacked together in this area and consist
of about 40 feet of coal. The Harmon bed extends over an area of at least 5,500 square miles in Bowman, Adams, Slope, and Golden Valley counties and has been mined in eastern Bowman
County since 1925. (Photo by E. Murphy, NDGS).
Seven thin coals are present within a 30 foot interval of the Bullion Creek Formation exposed along the Little Missouri River in northern Billings County.
The repetitive, thin coals indicate that changing environmental conditions such as fluctuating water depths or clastic input was causing peat deposition to increase and
decrease across this interval. (Photo by E. Murphy, NDGS).
Currently, there are six operations mining 32 million tons of coal annually in western North Dakota. Four operations (the Freedom Mine north of Beulah, the Knife River mine south of Beulah,
the BNI mine at Center, and the Falkirk mine north of Washburn) are mining coal to feed steam boilers for electric generating plants in North Dakota. Two smaller operations (GeoResource's mine
at Williston and the American Colloid mine at Haynes) are mining Leonardite (oxidized lignite) to be used in soil stabilization and as drilling fluid additives.
The Freedom Mine is currently the largest mine in the state mining approximately 16 million tons of coal annually, equalling the total of all of the other mines combined.
About one third of the coal mined at the Freedom Mine is supplied to the Great Plains Synfuels Plant for coal gasification. (Photo by E. Murphy, NDGS).
The Antelope Valley electric generating plant is in the foreground and the Dakota Gasification Company's (DGC) plant is in the background. The DGC plant currently has the capability
to produce 170 million standard cubic feet of gas per day along with several marketable byproducts. (Photo by E. Murphy, NDGS).
The GeoResource operation just east of Williston is mining 6 to 15 feet of leonardite. The leonardite is overlain by till on the left side of the photo and by both outwash and till on the
right side of the photograph. (Photo by E. Murphy, NDGS).
Selected References for North Dakota Coal
Babcock, E. J., 1901, Report of the North Dakota Geological Survey; Coal: North Dakota Geological Survey First Biennial Report, 103 p
Brant, R.A., 1953, Lignite resources of North Dakota: United States Geological Survey Circular 226, 78 p.
Groenewold, G.H., Hemish, L.A., Cherry, J.A., Rehm, B.W., Meyer, G.N., and Winczewski, L.M., 1979, The geology and geohydrology of the Knife River Basin and adjacent
areas of west-central North Dakota: North Dakota Geological Survey Report of Investigation No. 64, 402 p.
Leonard, A.G., Babcock, E.J., and Dove, L.P., 1925, The lignite deposits of North Dakota: North Dakota Geological Survey Bulletin No. 4, 240 p.
Moran, S.R., Cherry, J.A., Fritz, Peter, Peterson, W.M., Somerville, M.H., Stancel, S.A., Ulmer, J.H., 1978, Geology, groundwater hydrology, and hydrogeochemistry of a proposed surface
mine and lignite gasification plant site near Dunn Center, North Dakota: North Dakota Geological Survey Report of Investigation No. 61, 263 p.
Oihus, C.A., 1983, A history of coal mining in North Dakota 1873-1982: North Dakota Geological Survey Educational Series No. 15, 100 p.
Pollard, B.C., Smith, J.B., and Knox, C.C., 1972, Strippable lignite reserves of North Dakota: United States Bureau of Mines Information Circular 8537, 37 p.