By Pat Jenkins
State Route 7 in the Alder area will likely remain closed into October while efforts continue to keep a hillside from crumbling onto the highway.
A permanent solution to the problem isn’t expected to be in place until then, according to the state Department of Transportation (DOT).
The highway has been closed between Alder Cutoff Road and the State Route 161 junction since June 7. That’s when DOT workers discovered rocks and debris had tumbled down the hillside and that trees high on the slope were leaning, which indicated that more slippage of the hillside could be imminent, officials said.
Some of the sliding material reached the highway, but no motorists or highway workers were injured. There have been no injuries since, either, but DOT has kept the closure in force for the public’s safety and to make it easier for crews and geotechnicians to work in the area.
Tests of the soil on the hillside and observations by geotechnicians indicate the hillside remains unstable, though not as unsteady when the weather is dry, officials said.
DOT has decided to stabilize the hillside by installing a soil nail wall – virtually a blanket material that will be fixed permanently with soil nails, said Lisa Copeland, a spokeswoman for the department.
A contractor from California will be hired to do the work, but won’t be able to start until August. The project will probably take until October to complete, Copeland said. She added that the timeline is typical for such projects.
She said the technique that will be used is common in many places in Washington, but will be used for the first time at the trouble spot in Alder.
A landslide at the same location in April forced a closure of the highway. In May, DOT crews removed trees and other material from the hillside in an attempt to help stabilize it. The sliding continued in June, however.