Washington County Land Use and Transportation has selected a repair method for the Timber Road landslide and expects to begin work in the summer of 2024, with a planned completion date at the end of 2024.
According to the county, the “Shear Key at Roadway and Embankment Reconstruction” method outlined in documents obtained earlier by the Banks Post was selected after the costs and benefits of a number of options were developed by Tigard-based Cornforth Consultants and reviewed by county staff.
With funds expected to be drawn from the county Road Fund, repairing the road will come in at an estimated $3 to $5 million.
“We will be excavating the soft earth under the road and in the downhill embankment down to stable ground and replacing it with a stronger rockfill to improve stability,” said Washington County Land Use and Transportation spokesperson Chris Lueneburg in an email.
The contractor listed a number of advantages and disadvantages for the concept; one challenge would be that the plan would likely require the county to acquire additional right-of-way from adjacent property owners.
There will be no temporary repair to reopen the road in the meantime; while the county had looked at options to open the roadway on a temporary basis, it will stay closed until the project is completed.
“An interim repair would use considerable resources and be destroyed during construction,” the county noted.
The county had examined the difficulties in reopening the road on an interim basis in internal discussions and documents, and in an email to the Banks Post, Lueneburg said it could be a difficult, even dangerous task to get a temporary fix in place.
“Basic pavement repair (like blade-patching) would not improve slope stability and could create serious risks for travelers,” he said. “Landslide movement is unpredictable, especially during the rainy season, and substantial pavement displacement can happen over short periods of time– as was evident in March when we decided to close the road,” he added.
More significant temporary fixes would come in around $1 million, wouldn’t address the slide issue on a long-term basis, and would end up being destroyed when a more permanent fix is in place.
Timber Road has been closed since March 6 following a landslide that saw the pavement begin to buckle. Cracks in the pavement, noticed by county staff in January, had suddenly worsened as snow melted in the Timber area.
“Timber Road is closed indefinitely between Strassel and Cochran roads, due to slow-moving landslide activity,” the county said in a press release at the time. The route between Gales Creek and Timber has yet to reopen.
For additional updates on the landslide repair project, visit the project website maintained by Washington County online at www.washingtoncountyor.gov/lut/projects/timber-road-landslide-repair.