A massive plan to strengthen slopes, improve drainage and replace washed-out sections of Highway 12 over White Pass could be complete before the first day of summer.
“That’s our goal,” said state Department of Transportation construction engineer Will Smith.
“Our plan — and we think we can do it — is to get this next contract out for bid in January, begin work in late February or March and have it done by early June.”
Traffic has been flowing steadily over the pass without much problem since single lanes through washed-out areas were opened Dec. 22, transportation officials said.
Engineers are assessing the integrity of soil where large sections of the eastbound lane slid off the mountainside when heavy rain and flooding tore away slopes above and below the road and even buried a section under rock and mud Dec. 9.
The problems shut down a 27-mile stretch of the highway from Highway 123 near Packwood to just west of the Rimrock Tunnel.
Earlier this week, crews conducted exploratory drilling in areas of the two severe washouts — one about 9 miles west of the summit and another about 3 miles east of the summit.
A third washout, also west of the summit, has been repaired.
Working with traffic, it’s going to be a challenge — that’s for certain. I believe we can keep it open to one lane, but there may be delays and there may be brief periods of time we need to close it.
Department of Transportation construction engineer Will Smith
The drilling will allow engineers to determine the depth of loose soil and rock relative to the solid bedrock deep beneath, Smith said. “So we'll have a real good picture of what we need to do.”
Retaining walls will be constructed on those slopes to prevent future washouts, Smith said. Engineers are still determining the best way to construct and secure the walls.
One method would be to drive large I-beams deep into the solid bedrock and attach a wall to them, he said.
“That gives us a place to build up from that and will not allow the slope to give away,” Smith said.
Once the wall is secure, the slope will be backfilled with rock and soil and compacted, he said. Then the road will be repaved on top. More drainage points and possibly larger culverts will be installed as well.
The total cost of the project is estimated at $5.6 million. The state has already paid roughly $1 million to crews working around the clock to clear the highway of debris and stabilize slopes enough to get one lane open through damaged areas.
“We want to do the right thing for the least amount of money,” Smith said. “We want it to be safe and last a long time.”
The pass is expected to remain mostly open while crews work this spring, although there will be delays, Smith said.
“Working with traffic, it’s going to be a challenge — that’s for certain,” he said. “I believe we can keep it open to one lane, but there may be delays and there may be brief periods of time we need to close it.”
When heavy rain began falling and causing flooding from melting snowpack on Dec. 8, a maintenance crew stationed near the summit of White Pass began moving equipment to other maintenance sheds near Packwood and Rimrock, said DOT maintenance supervisor Alex McAvan.
“We were able to get equipment out, front loaders, excavators, everything necessary to take care of the outside,” he said.
After the White Pass shed was evacuated it couldn’t be reached for a week.
Crews then worked to clear water from the highway, but flooding overwhelmed the drainage system, McAvan said.
“We had water come across the road in many, many spots so we were working to divert that water off the roadway,” he recalled. “There was just no way to keep up with that amount of water in that short of time. It just flooded us out.”
The event reminded him of a washout two years ago that occurred near the current one east of the summit.
“It was kind of similar — we kind of knew what we had to do,” he said. “It’s not unusual to have conditions that are on the extreme side up here.”
All the days kind of run together when you’re up there that long. We pull resources and equipment from where we can to get done what we can get done.
Granite Construction project manager Jason Halverson
For the next 14 days, maintenance crews kept snow off the road, alternating with construction crews who were helping clean culverts, backfilling washed-out areas and drilling long rods — some measuring 20 feet long and 2 inches in diameter — into the mountainside of the eastside washout in effort to stabilize the remaining single lane.
Maintenance crews would get a one-hour window to come through and clear snow for construction crews, McAvan said.
“When they’d get a break, they’d move the drilling rig out of the way and we’d assume our position,” he said.
Construction workers spent the first week cleaning culverts and drains to divert water away so work could be done, and the second week drilling rods called soil nails into the mountainside and backfilling crumbled slopes, said Granite Construction project manager Jason Halverson.
There were anywhere from 30 to 40 construction workers on site at any given time, he recalled.
“All the days kind of run together when you’re up there that long,” Halverson said. “We pull resources and equipment from where we can to get done what we can get done.”
Working on steep slopes during rain and snow in temperatures often below freezing proved tough at best, said DOT field engineer Jerry Wood.
He called the maintenance crew the lynchpin behind the operation to clear snow from the road so construction could continue.
“I feel mostly for those guys dumping trucks,” he said.
It was raining and snowing and they were soaked, he said.