On March 22, 2014, a catastrophic landslide near Oso, Washington flowed thousands of feet across the Stillaguamish River valley, obliterating dozens of homes and spreading 10 million cubic yards of mud, trees and debris over a half mile area. The slide buried approximately one mile of SR 530- a critical highway that connects a string of rural communities- with up to 20 feet of debris, closing it for four months. 


SDA collaborated with the Washington State Department of Transportation to develop a unique application of Best Management Practice that provided enhanced treatment within the constrained footprint available for treatment. This was a particular challenge as the roadway alignment was severely constrained by the right-of-way, restricting the project footprint and limiting the amount of space available to treat run-off. Under these conditions, traditional treatment options were not viable.