For more than a century, an underground coal fire has burned beneath Boulder County’s Marshall Mesa.
This deep-seated blaze, a relic of the area’s coal mining past, has posed risks to nearby communities.
Now, Boulder County officials and Colorado’s Division of Reclamation, Mining, and Safety are joining forces to extinguish this persistent hazard.
Marshall Mesa Fire: A Historic Blaze Under Boulder
The Marshall Mesa coal fire has been smoldering underground for more than a century, a result of the coal mining operations that were once prosperous in the region.
These fires can turn into hotspots that could start new fires, especially during Colorado's dry seasons, if they are not put out.
For many years, this persistent fire has served as a reminder of Colorado's mining past and the difficulties it has left behind.
In 2022, authorities investigated whether this underground fire could have sparked the 2021 Marshall Fire, which devastated more than 1,000 homes nearby.
Though the investigation ruled out the coal seam fire as the cause, officials recognized the importance of finally extinguishing the fire, especially as it is relatively shallow and close to residential areas.
Recent Efforts to Mitigate the Marshall Mesa Fire
Boulder officials announced a four-month strategy to address the subterranean fire in October 2024. To facilitate the project, the Marshall Mesa Trailhead was temporarily closed.
Using a technique that has worked well in previous coal fires, this project seeks to cool the fire by excavating and combining the hot coal with cooler rock and soil.
The closure of the trailhead represents a substantial advancement in the mitigation of fire hazards in the vicinity of the communities.
Workers are excavating about 182,000 cubic yards of burned material as part of the mitigation operations.
With such a massive volume of dirt and coal to handle, the project provides a complex problem.
Nevertheless, Boulder officials are hopeful that this strategy will stop any flare-ups in the future and provide long-term safety advantages.
Mitigation Process and Fire Control Techniques
To get to the coal that is on fire and put it out, workers are digging 30 feet below the surface, revealing the coal seam.
They then combine it with cold rock and dirt to lower the temperature to a safe level, preferably below 80 degrees Fahrenheit.
This cooling process is crucial for mitigating the risk of reignition, as coal can continue to blaze even when it is buried.
Additionally, any unburned coal discovered in the project area is being dug out by workers.
Officials aim to reduce the likelihood of future fires in the area by thoroughly blending and chilling this material.
The purpose of this meticulously orchestrated procedure is to safeguard the infrastructure and residences in the vicinity from the potential dangers of the underground fire.
Future Plans for Marshall Mesa Trailhead and Community Safety
Officials intend to rehabilitate the trailhead and surrounding surroundings after the fire mitigation work is finished.
The project involves the restoration of native vegetation to stabilize the soil and the grading of the landscape to complement the natural terrain.
These efforts will help to restore the area to its natural state, retaining its appeal for local hikers and inhabitants.
Boulder County will install a 20,000-gallon cistern to increase the fire resilience of adjacent communities, thereby further enhancing safety.
Together with trailhead enhancements, these initiatives represent a significant step in maintaining Colorado's mining heritage and averting more subterranean fires.
