Cascade Ridge Emergency Slope Repair
Stabilization of a 400-foot slope failure below SR 7, including soil-nail wall, subsurface drainage, guardrail and repaving — with the road reduced to a single lane.
What made it hard.
The slope moved after a week of record rainfall, taking out a shoulder and leaving one lane open with flaggers. Movement continued for several days, and another storm was forecast within the week.
The failure sat above a creek used by salmon, so sediment control had to be in place before any soil was disturbed.
How we built it.
We mobilized within eighteen hours of the notice, installed monitoring points and a temporary shoring system, and placed erosion controls before excavation. Soil nails and a reinforced shotcrete facing were installed from the top down as the slope stabilized.
Work continued through two more storm events, with the road kept open under flagger control except for short drainage installation windows.
Where it landed.
The road reopened to two lanes in 74 days, and slope monitoring has shown no further movement. The permanent repair included subsurface drainage that addresses the water condition that caused the failure.
On site.
They had equipment moving before we finished the emergency declaration. By the time the second storm arrived, the slope was shored and the road was still open.
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