Crews working for WSDOT closed all lanes of traffic on State Route 161 during the weekend of July 22 - 25 to replace a culvert and reroute a sewer line.
Why did WSDOT close SR 161?
This is part of a larger project to widen SR 161 between Milton and Federal Way. In this specific piece of the project, crews replaced two 18-inch-wide pipes under the highway with a 12-by-6 foot-wide box culvert. The new culvert will reduce flooding and improve fish passage and habitat along Hylebos Creek.
Why was a full weekend closure necessary?
Crews needed to break through the pavement and dig a trench to remove the existing smaller pipes and install the larger culvert. A sewer line also ran alongside the old culvert. Crews disconnected the sewer line and rerouted it. Once the new 80-foot-long culvert was in place, crews reinstalled the sewer line. Next, crews filled in the trench then graded and repaved the roadway. To see what it all looked like, see these photos of the culvert replacement.
How will the new culvert help people and fish?
- Reduced Flooding The old culverts that were too small. As a result, the properties on the upstream side of the culverts often flooded during storms. WSDOT designed the new culvert to handle the flows of a 100-year storm.
- Improved Fish Passage and Habitat The old culverts were a dead end for fish swimming upstream. A wider and deeper culvert will make it possible for salmon, trout and other fish to reach an additional two and a half miles of potential habitat. The box culvert will also reduce erosion by using a gravel base that will slow high flows.