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Officials warned Boulder after 2005 wildfire that underground mine fire was 'imminent hazard,' long-term danger

A federal official warned that the potential existed for future fires and urged the City of Boulder to come up with a plan to maintain and monitor the area.

BOULDER COUNTY, Colo. — A 2005 wildfire – which flared in the area where last month’s devastating Marshall Fire is thought to have started – was sparked by an underground coal fire that was “an imminent hazard to humans” and a long-term danger, according to investigative reports and other documents obtained by 9Wants to Know.

In response to that fire, a federal official warned that the potential existed for future fires and urged the City of Boulder – which owns the land – to come up with a plan to maintain and monitor the area.

Sarah Huntley, a spokeswoman for the City of Boulder, said Tuesday that there had been "significant" work and monitoring of the area but needed to pull records before she could offer specifics.

Coal fires can burn for decades – or longer.

“They are very, very difficult – if not impossible – to put out,” Brenda Rice, a longtime fire investigator with the U.S. Forest Service who now is a private consultant, said of underground coal fires. “Once they ignite, they are burning very hot and generally just burning very slowly along that vein, along that coal seam.”

Rice led the investigation into the cause of the June 2002 Coal Seam Fire outside Glenwood Springs. It erupted from a long-burning underground fire, roared into the west side of town, and leveled 29 homes.

The fire south of Boulder on Dec. 20, 2005, broke out near the intersection of Marshall Road and Colorado Highway 93 – the same area where the first reports came in as last month’s devastating blaze erupted. Last week, 9Wants to Know reported that the investigators trying to pinpoint the cause of the Marshall Fire are considering whether the same smoldering underground coal fire could have been an ignition point.

“Coal seams are very much a very – what we refer to as a competent ignition source for wildland fuels,” Rice told 9Wants to Know.

Investigators trying to pinpoint the cause of the Marshall Fire are also looking at other possible sources – including downed electrical lines and a shed fire on property owned by a religious group.

There was no doubt the 2005 fire erupted from the underground coal fire in the area. Tests the next day showed ground temperatures of 200 degrees in one spot and 373 degrees in the area nearest a vent that apparently allowed the fire to escape and ignite brush. That same day, a state engineer called for an “emergency” response and noted the danger presented with “prevailing wind direction toward houses,” according to a report forwarded to the U.S. Department of the Interior’s Office of Surface Mining (OSM).

Work began within weeks to bring in 275 tons of gravel in an effort to cover over three “vents” emitting smoke and steam from the underground fire, according to a letter written by the chief of the federal agency’s Denver Field Division that was obtained by 9Wants to Know.

“The Office of Surface Mining … believes the three surface vents observed have the ability to cause future surface burning, therefore, we have declared this site an emergency,” James Fulton, then the agency’s top official in Denver, wrote in a letter to a construction manager for the City of Boulder.

The city obtained the land in the early 1970s for use as open space.

“The project will not eliminate the current underground mine fire, and will not eliminate the possibility for future surface burning in other areas,” Fulton wrote. “It would be prudent for the City of Boulder to remove any vegetation from surface cracks, as well as begin a long term maintenance and monitoring program in the area.

“Furthermore, OSM’s work at this site does not guarantee a safe environment for access by the public, city or county employees.”

The area was once dominated by the Marshall Mine and other coal mines. The Marshall Mine shut down in 1939, according to a state report. But some experts believe coal seams in the area around it have been burning underground since as far back as 1869.

It was just after 8 p.m. on Dec. 20, 2005, that someone called 911 from a home just across Marshall Road from the complex of long-abandoned mines known as Marshall 1 and 2 – part of which is also referred to as the Kitchen Slope Mine.

After firefighters arrived that evening, they doused the flames in 11 minutes – and were headed back to the station 35 minutes after the call for help, according to a report obtained from Mountain View Fire Rescue.

Now that same area is the focus of investigators trying to determine what caused the Marshall Fire, which raced across Boulder County on hurricane force winds, destroyed nearly 1,000 homes, and is believed to have taken two lives.

Contact 9Wants to Know investigator Kevin Vaughan with tips about this or any story: kevin.vaughan@9news.com or 303-871-1862.

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