Abandoned mines pose danger

Open entries to abandoned mines are a dangerous legacy from more than a century of mineral exploration in the Inland Northwest.

Everyone who ventures onto public lands should be aware of them, federal land managers say.

“We know there are a lot of abandoned mine workings on the national forest and we have an active program to close them,” said Greg Graham, mining geologist for the Colville, Okanogan and Wenatchee national forests.

Closing entrances to mines became a priority in the Idaho Panhandle starting in 1995, when two young men died from exposure to toxic air minutes after entering the Blue Slide limestone mine along Lake Pend Oreille near Bayview.

Since then, the Forest Service has been inventorying abandoned mine sites in much of the Inland Northwest, where more than 1,500 abandoned mining operations lace the ore-rich mountains of North Idaho and Eastern Washington.

On the Panhandle National Forests alone, at least 380 openings have been documented, including portals to 347 horizontal “adits” and 33 vertical “shafts.”

Since then, 175 of the worst ones have been addressed, said Jeff Johnson, Panhandle National Forests engineer.

A similar inventory on the Colville National Forest initially found only 15 open and potentially dangerous mines.

That number has grown to about 30 sites, many of them with multiple openings rated as moderate to high hazard, Graham said.

“We’ve completed work at about 23 of those sites,” he said. “But this project is constantly evolving. With the help of workers and the public, we’re always finding more. It’s going to continue for a long time.”

Progress is limited by funding, he said.

In August and September, Forest Service workers closed 10 adits and one shaft on the Colville Forest ranging from the Chewelah area to Northport, he said.

An all-terrain vehicle rider was hurt two years ago at one of sites near Chewelah, where he fell into a 20-foot shaft as he walked into the dark end of a horizontal adit, Graham said.

To remove the hazards, shafts often are filled with an expanding polyurethane foam and dirt while adits are often closed with metal gates that allow bats to come and go.

Blasting is not used to closed mines, said Jeff Johnson, Panhandle National Forests engineer.

“We’ve learned that the land eventually caves in behind the blasting area and leaves another opening,” he said.

“Nowadays, miners are expected to close their entries in the final reclamation,” Graham said.

Meantime, because of the unpredictable potential for toxic gases and instability, “We discourage anybody from going underground in a mine opening,” Johnson said.