Gravel pit operation at "toe" of major landslide halted by state

Federal and state regulators have ordered a halt to all operations at a Naches-area gravel pit at the toe of the landslide that buried a portion of Highway 410 last month.

An emergency order from the Washington Department of Natural Resources says any excavation at the Simmons and Son gravel pit could set off another landslide and poses "an immediate danger to the public health, safety or welfare or the environment."

The gravel mine was partially buried by the slide, one of the biggest to ever hit a state roadway. The cause of the slide remains unknown, but some experts say the mine's operations could have been a factor in destabilizing the slope.

The federal Mine, Safety & Health Administration also issued a similar order, prohibiting anyone from entering the mine site.

According to the DNR order, the owners of the site had started clearing away debris from the toe of the landslide in preparation to begin mining again.

Removing material from the toe of an active landslide is a "truly terrible idea," said University of Washington geologist and landslide expert David Montgomery. "In the grocery store, you don't pull the oranges off the bottom of the pile."

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com