The U.S. Army Corps of Engineers will begin building a berm in the Oso mudslide debris Monday morning to help steer backed-up Stillaguamish River waters away from Highway 530.
The hope is that, if placed in the right spot, the temporary rock-and-gravel berm will help keep water out of saturated areas that crews haven’t been able to search yet, said Doug Weber, chief of emergency management for the Army Corps of Engineers Seattle district. It’s expected to be able to help divert water that has become part of a large pond on the east side of the slide.
Weber said the berm would also help prevent rising river water levels from flooding straight down the rest of Highway 530 toward Arlington, and where it could possibly damage more homes.
Without that being constructed, it’s highly probable flooding would occur further down Highway 530, according to Mike Asher operations section chief for the state incident-command team in charge of the mudslide response effort.
Weber said discussions with Washington state and Snohomish County officials about exactly where to build the berm and how big it should be will continue today.
The height of the berm will likely be low to start, then built higher as water levels rise. When the berm is no longer needed, Weber said, the material used to make it could be used to fill in the ground beneath a rebuilt stretch of Highway 530.
A contractor will be delivering the truckloads of berm materials on the Darrington side, where crews will begin constructing the berm and hopefully finish it in less than 10 days, Weber said.