Colorado Agency Studies Land Around Old Front Range Mines
BOULDER COUNTY, Colo. (CBS4) - Homes across parts of the Front Range are facing an underground threat from old coal mines.
There's a potential of sinkholes forming because of the abandoned shafts across a four-county area -- Boulder, Jefferson, Broomfield, and southern Weld counties. A new study is now under way to try to protect people and their property from the danger.
Deep cracks and holes point to hidden hazards from digging underground.
"Coal mining; we have abandoned coal mining workings in this area," Karen Beery with Colorado Geological Survey said.
The first work was done by hand, using candlelight helmets. Later, special machines were invented to do the job. For more than a century coal was mined along the Front Range.
Much of the historic mining activity occurred in underground tunnels and caverns. Now 50, even 100 years later, the dangerously unstable ground can quickly collapse. It happened in a Weld County cornfield to the surprise of developers planning to build homes. Experts call it "subsidence."
"It happens in areas that are already developed with commercial structures, with schools with homes," Beery said.
Beery said a new study is being launched to better understand the hazards of historic mining.
Existing maps aren't always complete, according to survey director Vince Matthews.
"There are places up there that have subsided in the last decade that continually open up in places that surprise us when they do," Matthews said.
"In some areas we're not quite sure what the depth of the mine workings are; how far they extended," Beery said.
One mining area is now Boulder County open space and off limits to development.
The new study will focus on three towns in southern Weld County -- Firestone, Frederick and Dacono. The survey officials are hoping to get help in identifying hazards from longtime residents there and former mine workers.
The study is supported by a $250,000 grant from state and federal sources.
