Cougar Mountain mines still a danger

The Industrial Revolution is colliding with the Information Age in the forests south of Bellevue.

Underground coal mines that operated from the 1860s through the 1950s are now abandoned – some burning and collapsing – and creating potential hazards for hikers who venture off the trails in Cougar Mountain Regional Wildland Park.

“It is more than just taking a bad fall,” said Ginger Kaldenbach, senior project manager for the U.S. Office of Surface Mining, the agency is responsible for monitoring and sealing abandoned mines. “Many of these mines emit toxic gases, and if someone fell into one that is burning, the temperatures are hot and they would be severely burned.”

Of particular concern to Kaldenbach are those involved in geocaching, a high-tech treasure hunt using a hand-held Global Positioning System monitor to track hidden capsules.

“They are looking at their GPS devices and may not see a collapsed mine and fall into it,” Kaldenbach said.

More than 13 million tons of coal were removed from beneath Cougar Mountain, leaving shafts and mines throughout the park. The collapsed mines look like steep ravines, but have the potential to collapse even further.

Park officials are concerned about hikers who leave the trails for any reason.

The King County Parks Department is erecting fences around steam vents near a recently mapped mine fire, and additional signs are going up describing the dangers throughout the park.

The mine fire in the park has been burning more than 50 years. Occasionally, steam can be seen rising from the ground when water reaches the fire. The Office of Surface Mining performed an aerial thermal imaging survey of the area in March and mapped the fire. It is about 100 feet by 200 feet, Kaldenbach said.

The number of abandoned mines in the Cougar Mountain area is unknown.

“The state has demanded maps from mining companies from the beginning, so there is a good map library,” Kaldenbach said. “But those maps were mainly a way for the state to collect royalties. That means that some shafts were not mapped.”

A later era of mining on the mountain is the source of many of the problems now being encountered.

“At the end of the coal era, unauthorized miners came in and pulled out the coal pillars supporting the shafts of existing mines. They also mined closer to the surface, destabilizing the area,” she said.

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