As the smell of sagebrush gives way to the acrid smell of burning coal, smoke begins to rise from the scorched ground.
“Once you smell it, you never forget it,” Campbell County Fire Division Chief Dale Izatt said. “Even if you’re out here fighting a fire, you can distinguish the coal smell from the other smells of burning grass and burning trees.”
The burning coal comes from two partially buried seams, extending more than 50 feet along a hillside about two miles into the Burnt Hollow Management Area, an 18,000-acre tract of BLM land about 20 miles north of Gillette.
The Fire Department discovered the seams after hunters called in a timber fire at the end of September. When firefighters came out to the area, they realized that the smoke was coming from below ground rather than from burning trees.
“We keep discovering new seams,” Izatt said. “It just seems like this area is really prone to them.”
These two coal seams peek out around tree roots and where overlying sediment has slid down the steep hillside. The ground above the burning seams is warm and often collapses after the coal below burns away.
“I hate walking along the seams because the ground feels strange and is unstable,” Izatt said.
Lightning strikes, above-ground fires and spontaneous combustion can ignite the coal, and then, the fire slowly spreads underground.
Because the Powder River Basin coal seams are so close to the surface, underground coal fires have likely happened since the coal formed millions of years ago. The Powder River Basin coal deposits are among the largest in the world, so once coal seam fires start, they can spread across large areas and have enough fuel to smolder for hundreds of years.
“They can start in one place,” said William Haines, who works for the BLM in Buffalo, as he indicated a nearby smoke column. “And then, they can spread underground, popping up in another place,” he said, pointing to smoke about 20 feet away.
Because the Fire Department doesn’t usually find the seams until after they’re burning, there is often no way to know when they ignited nor how far the fires extend.
Haines and Izatt mapped what they know of the two new seams, but they could be larger than is visible from the surface and are likely expanding slowly along the hillside.
“There is just a lot out here that we can’t know until we see smoke rising from the ground,” Izatt said.
When the seams burn, they melt snow, kill plants and bake the above sediment, turning it red. This red sediment — called scoria or clinker — is resistant to erosion and forms many of the hills in Campbell County.
“On a winter day, you have to get in an airplane and look out at the snow covering the county,” Izatt said. “You’ll see just how many coal seam fires we have because where the coal seams are burning will be the only bare spots around.”
Now that Izatt knows about these two coal seams, he will visit the hill each spring to monitor them.
“All we can do is check on them and know where they are, so we can be prepared for when they start above-ground fires,” he said.
Occasionally, the Fire Department digs up the coal seams to extinguish the fires, but it is often futile because the seams are so thick.
During the Great Depression, the Civilian Conservation Corps came to Campbell County, digging up dozens of coal seams and putting out fires. In the decades since, ranchers and firefighters have fought timber and grass fires sparked by coal seams and have discovered new seams as they start burning.
“This is just a fact of life out here,” Haines said.