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BOULDER COUNTY, Colo. (KDVR) — The Boulder County Sheriff’s office said Friday they aren’t ruling out any causes for the Marshall Fire, including underground coal mines.

“We are investigating any and all potential causes of the fire including coal mines in the area, power lines, human activity, etc. We are working diligently with our investigation partners to ensure the outcome of the investigation is thorough and accurate. We know our community members want to know what happened and we are doing everything we can to make that happen,” Carrie Haverfield, public information specialist for Boulder County Sheriff’s Office, said.

There are approximately 1,736 known abandoned coal mines in the State of Colorado, according to the Colorado Underground Coal Mine Fires 2018 Inventory Report.

“There are some known coal mines or seams in the area,” Seth Mckinney, fire management officer with the Boulder County Sheriff’s Office, said.

There are two known coal mine fires in Boulder County. One is the Lewis Mine, which is one mile south of Boulder on the northeast corner of the intersection of Marshall Road and Cherryvale Road.

The other is the Marshall Mine is located at the southeast corner of the intersection of Highway 93 and Marshall Road. The mine fire is located on City of Boulder Open Space. In October 2003, it was reported that the fire was moderately active with ground temperatures ranging from 118-130 degrees Fahrenheit. The smell of coal combustion was noted near the venting fractures.

According to the report, in February 2005, a recently constructed building was inspected for damage by subsidence believed to be related to the Marshall Coal Mine. Vents and subsidence features were identified under and around the building.

Also on in the report, on Dec. 20, 2005, a brush fire was started by a hot vent from the Marshall Coal Mine fire. The fire was quickly contained and extinguished. The origin of the fire was traced back to a 373-degree vent.

“We’re trying to be as transparent as possible with everything with the Marshall Fire,” McKinney said.

The Marshall Mine is located about a quarter mile southeast of where FOX31 and Channel 2 obtained video of what appears to be the start of the fire.

Pinpoint Meteorologist Jessica Lebel described how the winds were that day to see if it would make sense for the fire from the mines to blow up to the origin spot of the video.

“It’s probably pretty rare that we see anything spread north at the start of this fire. Usually, when they start it’s all one wind direction in the beginning until that fire grows big enough for things to become more erratic and unpredictable,” Lebel said.  

The cause of fire is still under investigation.