Lewis County, WA — Mountain Pass Culvert Reline Stops Erosion

WSDOT Relines CMP Culvert, Designs Solution to Chronic Erosion

On White Pass, Lewis County, WA, the Washington State Department of Transportation (WSDOT) designed a long term solution to a chronic erosion problem alongside US12. This field report presents an existing application where Snap-Tite was used to reline a culvert on a mountain pass characterized by dynamic weather conditions and steep slopes. Traditional repairs relied on continual maintenance to sustain a safe roadway.
Alongside US12 near the summit of White Pass an existing 36-inch corrugated metal pipe (CMP) culvert conveyed water under the traveled lanes from an upstream gully and ditch. The outlet of the culvert was originally designed at ground level with a conventional rock riprap energy dissipater, which over time was washed down to a creek at the toe of the slope. The steep slope limited certain designs due to constructability issues. Using Snap-Tite increased both the speed and ease of installation and provided a long-term solution to the problem.

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