WOODLAND — Repairs to the hillside that slipped and closed Interstate 5 north of Woodland early December should be complete by the end of the month, clearing the way to reopen the road’s remaining closed lane, according to the Washington State Department of Transportation.
Days of heavy rain led to the slide, which displaced trees, soil and boulders the size of cars during the afternoon on Dec. 9. The slide closed the freeway less than a mile north of the exit for Dike Access Road north for more than 24 hours — and choked off virtually all northbound traffic in the region after another slide closed Highway 30 in Oregon.
Since getting the all-clear that the hillside wasn’t going to keep sliding, WSDOT opened two of the three northbound lanes, and crews have built a dirt and gravel ramp up the hill for heavy equipment.
Jeffrey Katzer, a designer and inspector with the agency, said Friday that workers were drilling 12 50-foot-deep holes into the hillside and driving metal poles though them to help anchor the slope. Between every few of those, they’ll also drill 60-foot-deep holes to hold drain pipes to help improve water flow out from the hillside.
After the drilling is complete and the deck and ramp are removed, workers will lay down a seed and mulch combination.
“That basically seeds the slope so we don’t have erosion issues,” he said.
Even with a few delays for weather, Katzer said, the work is on or ahead of schedule.
He said he expected drilling work to wrap up, and work to pull down the extra rock and dirt to start, next week.
“When all is said and done, we’ll have it back to its normal slope, maybe flatter,” he said.
Department spokesman Bart Treece said work crews were out the night of the slide laying asphalt through the median, Treece said, in case planners determined crossing traffic into one of the southbound lanes would be the best option.
Before engineers determined it’d be safe to partially open the highway, Treece said crews had gathered hundreds of reflective barrels from around the state, and the detour into the interstate’s southbound lanes would have been 5 miles long.
“Not the most ideal solution,” he said. “But we would have had traffic going through.”
Treece said the estimated cost of the project is $700,000, but the exact price tag isn’t yet available. The money is coming from federal highway funds.
WSDOT keeps a list of possible slide areas near roadways, he said. The hillside that gave Dec. 9 was not on that list.
Katzer said engineers have yet to make any kind of determination of the slope’s overall stability or risk of giving way again, which will factor into the agency’s future plans.
