On January 6, 2020 Multnomah County Transportation closed NW Rock Creek Road between NW Skyline Blvd. and NW Elliot Road near 16305 NW Rock Creek Road due to a culvert failure. A collapsed culvert threatened to undermine and flood the road. The rural road in the west hills will remain closed at the culvert for several months while the county conducts a major repair to replace the culvert.
About 30 feet below the road surface, a two-foot diameter corrugated steel culvert carries a tributary to Rock Creek under the road. The bottom of the culvert rusted out, allowing the culvert to clog with dirt and rocks. After a heavy rain, the blocked culvert backed up stormwater on the uphill side of the culvert, creating a lake that put pressure on the road embankment and threatened adjacent property.
County Road Maintenance staff installed a pump to direct water over the top of the road. The pumping equipment remains in place and blocks the road to traffic. While property owners and visitors can still access properties on either side of the closure, through traffic needs to detour around the closure using NW Elliot Road and NW Skyline Blvd.
The County’s engineering staff investigated the culvert failure and are designing a permanent repair. The culvert is at such a great depth under the road that replacing it may require removal of hundreds or perhaps thousands of dump truck loads of material. Repairs are expected to begin in early February and will likely take several months to complete. A larger, more durable culvert will replace the one that failed. For safety, the public is asked to not enter the road closure by motor vehicle, bicycle or even on foot.
Multnomah County has jurisdiction for this section of NW Rock Creek Road and 274 miles of roads in unincorporated areas and in the east county cities of Fairview, Maywood Park, Troutdale and Wood Village. For project information, visit www.multco.us/rockcreek or follow us on Twitter @multcoroads.