Constantly shifting rocks and mud on a slide-prone hillside in Trinity County have forced Caltrans officials to delay reopening Highway 299 until Jan. 8.
Caltrans Project Manager Matt Gowan announced Friday that the hillside 28 miles west of Weaverville, which dumped 100,000 cubic yards of rock and debris onto the highway on Monday, is too unstable to begin immediate cleanup.
Instead, crews will construct a detour around the slide, he said. The alternative route will be approximately 350 feet long and adjacent to the existing roadway.
The detour construction will delay reopening the highway to controlled one-way traffic, stretching the complete closure to nearly a month.
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Caltrans inspectors and geologists believe there could still be about 200,000 cubic yards of additional material on the hill with the potential to slide, said Trisha Coder, a public information officer for the District 2 office of the California Department of Transportation. That makes it unsafe for crews to clear debris from the roadway and an adjacent catchment area designed to hold the falling debris.
Highway 299 is the major east-west route from the northern Sacramento Valley to California’s North Coast. The closest alternative route is Highway 36, which adds around 90 minutes to a one-way drive. Highway 20 to the south and Interstate 5 to the north through Grants Pass, Ore., are even longer alternatives, Coder said.
Gowan acknowledged the inconvenience for motorists, especially during the holiday season, but said the highest priority for Caltrans is “the safe transportation of the traveling public.”
Crews will work on removing additional slide material while they construct the detour, said Coder.
Caltrans has already spent $3 million on the Big French Creek slide and requested emergency construction funds. The agency expects to invest another $6 million before it comes up with a permanent solution, Coder said.