BOULDER COUNTY, Colo. — Excavation work is underway to put out an underground coal mine fire that’s been burning in Boulder County for decades.
The mine closed roughly 100 years ago, but still holds areas of hot, smoldering coal, registering below-ground temperatures of more than 200 degrees, according to the state.
Crews with the state’s Division of Reclamation, Mining and Safety began work on the project late last month near the intersection of Highway 93 and Marshall Road to cool that coal down.
“I don’t think most people know this is a problem in the state,” said Tara Tafi, a senior environmental protection specialist with the department.
Tafi said about 40 underground coal fires are known to be burning in Colorado, but this one has gained plenty of public attention following the Marshall Fire. The state does not believe the coal mine played a role in that fire, but Tafi said they’ve decided to excavate this site to prevent possible fires in the future.
“There’s always risk when you have something smoldering underground, that you can have changes that may create a change on the surface. That may be gas emissions, wildfire,” Tafi said. “By excavating, we are able to dig all the way down to the bottom of the coal seam, and we’re able to eliminate that source of potential burning.”
Although the risk to public safety is low, authorities are continuing efforts to control the fire. However, environmental and weather conditions are key factors in the pace of the mitigation work.
“The only thing that slows us down right now is wind. We basically stop all excavation and handling of hot materials if we get frequent wind gusts above 15 miles per hour,” Tafi said. “So we’ve had some shutdowns this last week because of wind. All of those hot materials are covered and we no longer work on them.”
Crews are digging down about 30 feet, and then mixing the smoldering coal with water, sand and other materials to bring the temperatures down below 80 degrees. The material is then placed back into the earth, and the ground is covered up.
The excavation work is expected to last through February, at which point the trail systems in the area will be rebuilt back to previous condition.