SR 530 Reconstruction
Atkinson reconstructed SR 530, which was impacted by the catastrophic Oso landslide on March 22, 2014. The scope of work included raising the grade of the roadway as much as 20 feet, constructing drainage and stormwater treatment facilities, replacing six fish passage culverts, wetland mitigation, and roadside restoration and erosion control.
Atkinson and designer Jacobs Engineering, together with the team's earthwork subcontractor and design consultants, developed a design which secured the project win.
The proposed design allows Atkinson the opportunity to construct a significant amount of the new roadway outside the footprint of the existing road. This approach affords the much needed space to repave and open the existing SR 530 within 19 days to two-way traffic, and suspend the one-way piloted traffic operation.
In addition, Atkinson proposed the tie-in between the new and old roadways utilize crushed rock surfacing so traffic never drives on gravel borrow, which reduces the risk of third party damage. Atkinson's team also developed a design at the "knoll" (approximate center of the project) that allowed the increase of the slope to 2:1 by installing horizontal slope drains and reduce the amount of excavation on site by 50%. Finally, instead of paying over $2 million to buy wetland mitigation credits at an existing WSDOT wetland bank, the team proposed to buy a local property in the Oso area, permit, design, and install a wetland mitigation site.
All of these approaches and innovations led to Atikinson's commitment to complete the project on September 24, 2014—seven days ahead of WSDOT's October 1 deadline.