SILVERTON — Four years after shoring up the Mountain Loop Highway at the Waldheim Slide, Snohomish County is finishing the $1.8 million repair project.
The main road repairs were done in 2011, after a landslide in December 2010 and flooding in January 2011 threatened to wash a stretch of the scenic byway into the South Fork Stillaguamish River. Crews stabilized the bank below the pavement, put boulders and wood debris at the bottom of the slope and rebuilt the road where it was cracking and collapsing.
Repairing the road wasn’t the end of the project, though. Federal regulations require the county to balance any impacts the emergency repairs had on the river by improving water quality and fish habitat nearby. It took years of working with engineers, environmentalists, local tribes and permit officials to finalize a mitigation plan.
“It’s just nice to complete the project as a whole,” said Max Phan, the county’s design engineering manager. “The biggest hurdle for this last piece was getting all the agencies together and finding a mitigation plan that works for everyone.”
Work is scheduled to start in August and should take about a month. After that, the Waldheim Slide repairs officially will be complete. No closures or delays on the Mountain Loop Highway are expected.
“This is the last piece,” Phan said. “We’re going to do the work when the water level’s lowest.”
Workers plan to put wood debris in the river downstream from the Waldheim Slide to improve habitat for fish. Areas disturbed while working on the emergency repairs are going to be replanted with native plants. Officials also have agreed to create a wetland near Beaver Creek to make up for any wetland habitats wiped out by the Waldheim Slide or destroyed during repairs.
The Snohomish County Council on July 8 awarded a $268,827 bid to Welwest Construction for “the improvement of the Mountain Loop Highway, (milepost) 20 at the Waldheim Slide.” The 2011 road repairs cost more than $1.5 million.
The Waldheim Slide, about a mile west of Silverton, has been a problem area for more than a decade. It’s at a spot where the road borders a bend in the flood-prone South Fork Stillaguamish River. County and forest service officials had been keeping an eye on the river and slope for years before the emergency repairs in 2011. At the time, they worried the section of road could give way entirely.
“The repair took care of it,” Phan said. “We really reinforced the downslope area, which was the big part of the problem. It’s been stable since.”
Herald writer Noah Haglund contributed to this report.
Kari Bray: 425-339-3439; kbray@heraldnet.com
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