State tries to snuff South Canyon mine fire
December 15, 2006
Aspen, CO Colorado
SOUTH CANYON – A state official is cautiously optimistic about the results of a project this year to reduce underground burning that caused the destructive Coal Seam Fire of 2002.
Work ended Thanksgiving week on efforts to shut off some sources of air to the underground coal seams.
Project manager Steve Renner, with the Colorado Division of Reclamation, Mining and Safety, said this summer’s efforts on the east end of the canyon didn’t put out the fire but he hopes they slowed it down.
“I suspect that we will see a decline in temperature over time as the ambient heat is released from surrounding rock,” he said.
Colorado’s largest underground coal fire has been burning in South Canyon, west of Glenwood Springs, since 1910. Mines there were abandoned in 1953.
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On June 8, 2002, the fire ignited surface vegetation, starting a blaze that winds quickly blew toward Glenwood Springs, resulting in dozens of homes being burned.
The complexity of the underground fire and unstable, porous nature of the surface there makes it hard to choke off all the airflow and put out the fire altogether.
“There’s thousands and thousands of fractures that you can’t even see that are probably inhaling” air, Renner said.
Even as contractors worked to seal off some air sources this summer, another formed when the ground subsided beneath mine cavities.
“So we went ahead and sealed that, too,” he said.
He said the subsiding ground left a hole that was maybe two feet wide by three or four feet long on the surface, but 20 feet in diameter and 30 or 35 feet deep just below ground.
“It was just a huge hole,” he said.
Crews also sealed one mine entrance and closed off three other holes that sometimes inhaled and other times exhaled air, depending on the barometric pressure and fire characteristics. They injected a mix of cement, water and fine-grained dirt under high air pressure to plug the holes.
Renner said this year’s work probably cost about $160,000. After the Coal Seam Fire, crews first focused their efforts on drilling underground to get a better knowledge of the mines there and the areas where burning was occurring.
“I’m pretty happy with particularly the exploratory work, getting a handle on understanding what the subsurface picture was,” Renner said.
The South Canyon fire’s complexity arises in part from the fact that three coal seams were mined, two of them overlying the third. As with other coal seams throughout the Grand Hogback, a prominent geological feature of western Garfield County, these seams lie at steep angles. They were mined from the bottom up, creating finger-like chimneys that facilitated burning wherever fires began.
About a third of the nearly three-dozen underground mine fires in the state are located in Garfield County, and concentrated in the Grand Hogback.
Renner said the next big project in the region is at the Skull Creek mine fire in Rangely. There, crews plan to use fans or similar devices at vents where there is lower pressure, and use it to draw in firefighting foam that is injected elsewhere. The objective is to help direct the flow of foam. In the past, crews have injected foam into areas of underground fires in places such as the Grand Hogback without knowing where the foam is going.
If the new technique is successful, it may have some potential for local fires, Renner said.