Colorado Has an Underground Fire That's Been Burning for Over 100 Years
Crews have begun a long-awaited project to extinguish a coal seam fire that has been burning underground on Marshall Mesa, south of Boulder, Colorado, for over a century.
The fire, a remnant of the region's coal mining history, has raised concerns about potential surface fires and threats to nearby communities, especially after the devastating 2021 Marshall Fire .
In the coming months, the Colorado Inactive Mine Reclamation Program will lead the effort to eliminate this stubborn underground blaze, which is 30 feet underground, KUNC recently reported. Crews will excavate down to the coal seam that is 6 to 8 feet thick, bringing the smoldering material to the surface. There, they will mix the coal with cooler soil to prevent reignition before reburying it.
"This is an attempt to completely excavate and extinguish all areas where we've seen previous fire activity and where there's additional coal that's unburned," Jeff Graves, director of Colorado's Inactive Mine Reclamation Program, told Boulder Reporting Lab.
The project, expected to take three to four months, will also include renovations and expansions to the Marshall Mesa trailhead and parking lot, as well as the installation of a 20,000-gallon cistern to improve fire resilience for nearby homes.
Newsweek contacted Colorado's Division of Reclamation, Mining and Safety, which is running the Inactive Mine Reclamation Program, via email for an update on the progress of the excavation.
Colorado has around 40 other underground coal fires, remnants of the state's mining legacy. The Marshall Mesa fire is one of the more accessible and manageable sites, making it a priority for extinguishment.
"There's a lot of different methods that the coal can ignite. One of the biggest is probably spontaneous combustion, and that just occurs over time as that coal gets exposed to oxygen, it heats up and then can result in combustion of the coal," Graves told KUNC's In The NoCo show.
Other ways the fires can start include miners in the past tipping over candles, lightning strikes and wildfires at the surface. Once lit, the underground coal fires can reach temperatures of up to 1,000 degrees and can spark surface fires in return, as happened at a coal seam in 2005.
There was some speculation that the 2021 Marshall Fire, which destroyed more than 1,000 homes in the area, could have been sparked by an underground coal fire. An investigation by the Boulder County Sheriff's Office and District Attorney's Office determined this was likely not the case, though it couldn't be completely ruled out.
"It's in an area that has high risk to infrastructure and is one of those fires that's relatively easy to attack and hopefully extinguish," Graves said.
Once the Marshall Mesa fire is extinguished, Boulder County will have no remaining underground coal fires, as the state recently completed a similar project near the intersection of Cherryvale and Marshall roads.
