DOT to stabilize rock face

The rocky face south of Deception Pass on Highway 20 will soon receive a makeover of sorts courtesy of the Washington State Department of Transportation.

Beginning Tuesday, Jan. 17, crews will remove loose rock and trees, then insert bolts into the rock overhanging the highway. The goal of the half-million dollar project is to stabilize the hillside and prevent any possible rockfalls onto Highway 20.

DOT spokesman Dave Chesson said the planned four-week project will affect traffic flow on Highway 20 through the area.

One lane of traffic will be closed from 7 p.m. to 6 a.m. Sunday night through Friday morning. All lanes will remain open Friday and Saturday nights.

Crews will also close all lanes of traffic as they complete certain types of work.

“When they are actually removing a large quantity of rock, that’s when the road will be closed for up to 20 minutes,” Chesson said.”They want to be incredibly safe about it, not only for the people doing the work but for the traveling public.”

Chesson said all lanes will be closed for up to five minutes at a time between 7 and 10 p.m., and for up to 20 minutes at a time after 10 p.m.

Wilder Construction, the company contracted for the restabilization project, was responsible for clearing and stabilizing the hillside following the deadly rockslide on I-90 late last year.

“It takes a lot of skill to do this type of work, and special equipment,” Chesson said. “Wilder has done a lot of these jobs and they do a good job of it.”

Chesson said geologists have been studying the area since late 2003, completing slope mapping and rock-fall hazard studies.

“They’ve taken a lot of time,” he said of the studies. “The nice thing about doing it this way is that we have the advantage of having a detailed geological

assessment of the slope. They have a detailed plan of action. They know down to the last boulder and shrub what they’re doing.”

The first step for crews will be preparing the rock for the stabilizing bolts. Chesson said workers will hang off the slope in harnesses and use pry bars to remove loose rock and tree roots that are fracturing the rock face. Once that work is completed, crews will drill into the rock to install the stabilizing bolts.

The bolts firm up the rock by connecting the unstable rock with a more stable part. When geologists conducted their studies, one thing they measured was how far into the hillside crews would have to drill in order to find stable rock.

Once crews drill into the stable rock, they fill the hole with epoxy and insert the stabilizing bar, explained DOT project engineer Dave Crisman. As the epoxy hardens, crews will place a plate over the stabilizing bar on the rock face and tighten a nut down to hold the whole thing in place.

Crisman said the bolts can often permanently stabilize the rock — although he cautioned that earthquakes or natural water erosion can sometimes cause further instability, which then requires a new set of bolts.

And since the work is being done within the boundaries of Deception Pass State Park, the parks department has asked crews to make the stabilizing project aesthetic, as well as practical.

“Some of these rock bolts we’re putting in, the parks department has asked us to recess them,” Crisman said. “We’re supposed to grout over them with a similar color as the rock.”

Crisman said the color-matched grout will make the bolts less obvious to drivers on Highway 20.

Work is scheduled to take about 18 days, and should be completed by mid-February, barring any inclement weather.

Chesson said the job was originally slated to begin in the fall, but the deadly I-90 rockslide and Chuckanut boulder removal projects took precedence.

Chesson said geologists have deemed the rock face on the north side of Deception Pass bridge to be safe. He said bolts were inserted to stabilize the rock about 10 years ago.

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