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SR 530 Emergency Roadway Reconstruction

SR 530 Emergency Roadway Reconstruction

Repairing SR 530 after the Oso landslide
Arlington, Washington
Washington State Department of Transportation
Jacobs Engineering
Contract Value
$20.5 Million
Completion Date
Market Sector
Roadways & Bridges
Self Performance

Atkinson reconstructed 1.6 miles of SR 530 from MP 36.78 to MP 38.24 in Snohomish County. The catastrophic Oso landslide on March 22, 2014, damaged the roadway, wiped out a neighborhood, and took 43 lives. Work included raising the grade of the roadway up to 20 feet to account for the revised flood plain, constructing drainage and stormwater treatment facilities, replacing six fish passage culverts, mitigating wetland impacts, restoring roadside, and erosion control.

The Atkinson/Jacob's design and project approach won the job. First, our solution allowed us to build a significant amount of the new roadway offline—outside the footprint of the existing road. This gave us the room to repair and open the existing SR 530 roadway within 19 days (on June 23) to two-way traffic on paved road. This was a significant improvement to residents as the existing solution was a one-way piloted traffic operation on a gravel road. Second, when constructing the tie-in between the new and old roadways, Atkinson committed to placing crushed rock surfacing so that traffic never drove on gravel borrow—reducing the risk of third-party damage. Third, we developed a design at the "knoll" (approximate center of the project) that allowed us to increase the slope to 2:1 by installing horizontal slope drains and reduce the amount of excavation on site by 50 percent. Finally, instead of paying over $2 million to buy wetland mitigation bank credits, Atkinson purchased a local property adjacent to SR 530 to permit, design, and install a wetland mitigation site. When complete, Atkinson donated the property to the Snohomish County Parks Department as a set-aside land trust. This created open space, species habitat, and room for more wetland mitigation development.

Atkinson completed the project on September 24, 2014—seven days ahead of WSDOT's October 1 completion date and six months after the landslide.

Atkinson participated in establishing a community memorial where area residents and families came together to plant 43 trees—one for each of the 43 lives lost in the landslide.

I want to thank you and your staff for all the cooperation and coordination in assisting us in our endeavor.
Robert Morrison, PE, Construction Supervisor, Snohomish County Public Works