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State preparing to mitigate underground fire that has burned in Boulder County for decades

Lewis Site in Boulder County
Posted at 8:36 PM, Aug 28, 2023

BOULDER, Colo — Boulder County held a virtual community meeting Monday to discuss the latest with an underground coal mine fire that has burned for decades, as it prepares to begin mitigation efforts this fall. The Lewis Coal Mine fire has been burning for more than fifty years, but recent observations by the Colorado Division of Reclamation, Mining and Safety (DRMS) have increased pressure to mitigate the fire and debris.

The Lewis site is very close to the suspected starting site of the Marshall Fire in 2021. In findings released from its investigation into the Marshall Fire’s origins earlier this year, the Boulder County Sheriff’s Office announced that it was likely caused by a downed Xcel power line and embers from an earlier fire on private property, and not related to the underground mine. Even still, the DRMS has observed more surface fracturing and cracking, and increased venting, leading to a concern for future fire risk above ground.

“I think our concern with the site is we’ve seen activity increasing,” explained Jeff Graves, the director of the Inactive Mine Reclamation Program. “As the coal is consumed, we end up with a much higher risk for wildfire ignition.”

State preparing to mitigate underground fire that has burned in Boulder County for decades

Crews will be digging about thirty feet underground, just below the coal mind, and removing any burning or smoldering coal, the county announced in a statement. The coal will then be blended with rock or soil and monitored until it is less than 100 degrees Fahrenheit. The state will be monitoring the site during the process to make sure the surrounding area stays safe, and will not dig on days with high wind.

“We are planning on having, at all times, a 21,000-gallon storage tanker of water on site,” said Senior Project Manager Tara Tafi. “So, if something were to flare up, we could quickly knock it down.”

The Lewis Coal Mine site sits underneath two private properties, but in a statement, Boulder County said both property owners are supportive of the state’s mitigation plan. The project is slated to start in October 2023 and be completed by spring to avoid water filling the Davidson Ditch, which sits above part of the mine.

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