One Year Anniversary of Oso SR 530 Reopening

Senior Scientist Wayne Wright returned to Oso, Washington, Friday in advance of the Sept. 22 anniversary of the reopening of SR 530 following the catastrophic landslide last year. Wayne toured the site and was pleased with the conditions of the waterways.

“Overall it looked really great,” Wayne says. “There was no scour, erosion or downcutting in the new stream channels. There’s a reason WSDOT [Washington State Department of Transportation] is so proud of that project.”

The March, 2015 landslide  spread more than 10 million cubic yards of mud and debris across a half-mile impact zone, obliterating the highway and blocking the Stillaguamish River. GeoEngineers was an important part of the Atkinson Construction design-build team, along with Jacobs Engineering and SDA, which completed the clean-up and rebuild of the road only six months after the landslide.

GeoEngineers provided the team with geotechnical engineering and hydraulic analysis. The geotechnical group designed a drain system in the slide area to control soil settling and provide a stable bed for SR 530. Landslide material completely cut off the Stillaguamish River and buried tributaries over a square mile. GeoEngineers’ river specialists helped design culverts and channels to restore that important salmon habitat and provide fish-friendly passage along six buried tributaries. The project received a national honor award at last year’s American Council of Engineering Companies (ACEC) Engineering Excellence Awards.

In the 18 months since the disaster, many have called for updated building regulations for construction on or near steep slopes. Local and state lawmakers have put a temporary ban on some building projects, while attempting to balance the needs for safety and continued development.

“It’s a crucial, and complicated issue,” Wayne says. “We all need to be proactive about taking steps to reduce future risk, avoid future disasters if possible, and be ready to react if necessary.”

GeoEngineers is an ongoing part of this crucial conversation around land use. Wayne is making several presentations on lessons learned from the Oso disaster and clean up. He’s presented this case study to the national American Water Resources Association (AWRA) and will provide a follow-up to that discussion at the national AWRA annual conference in Denver, Colorado, Nov. 16-19.

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