By Ann McCreary
Looking down into a chasm that was previously part of Highway 20 near milepost 212, it becomes clear that photos don’t do justice to the extent of the damage that resulted from flooding during heavy rains two months ago.
The roadbed on either side of the deep hole sits about 90 feet above the site where repair crews using heavy equipment completed installation last week of two new metal culverts designed to protect the highway from similar washouts in the future.
The chasm resulted after more than 30,000 cubic yards of dirt and rocks were hauled away from the site, which is about 5 miles east of Upper Beaver Creek Road.
Water carried debris down a draw above the highway during an early April storm, blocking a culvert that ran under the road. Water collected next to the roadway, forming a pool about 30 feet deep and saturating the earth under the roadbed.
All that wet, unstable soil had to be hauled away before repairs could begin. Once that was done and the new culverts were installed, transportation engineers faced the next big issue — how to fill the huge hole up again.
“We realized that we had 20,000 to 25,000 cubic yards that we’d have to haul in to complete this,” said Dan Lewis, project engineer for the Washington Department of Transportation (WSDOT). That’s about 2,000-2,500 truckloads of dirt, he said.
Finding a source for that much material is difficult, and hauling it to the site is expensive and time-consuming, he said.
This week, WSDOT came up with a solution.
“We were able to work with the U.S. Forest Service to get access to the adjacent hillside,” Lewis said. “The quickest and most economical way was to try to get it right at the site.”
Saving time and money
The plan calls for clearing trees and vegetation off about 2 acres of Forest Service land next to the construction site, and using earth from that hillside to fill the adjacent hole and construct the roadbed.
“That was able to save us close to a half-million dollars in trucking. It saves a lot of money as well as time,” Lewis said.
Crews are working six days a week to expedite repairs at that location, milepost 211.85, and seven other flood-damaged sites along Highway 20 east and west of Loup Loup summit.
Lewis said WSDOT is hoping to be able to reopen the highway to traffic by July 20, when the current contract for road repairs ends.
Obtaining permission to use dirt from the adjacent Forest Service land “is a huge help in meeting that date,” Lewis said. The contractor, KRCI Construction of Wenatchee, “was very concerned about being able to finish by the 20th” if fill material had to be trucked in, he said.
“This makes the 20th a reasonable date,” Lewis said.
Before permission was granted by the Forest Service, WSDOT was required to complete a survey of the area “to confirm there are no archeological impacts,” Lewis said. That survey, requested by the Confederated Tribes of the Colville Nation, was completed Monday (June 5) and found no impacts.
“That was the last hurdle to getting this approved,” Lewis said.
Because the road repairs are being conducted under an emergency declaration by the governor, permitting for the project is expedited, Lewis said.
“We can do the official … environmental paperwork and easement with the Forest Service after the fact,” he said.
About 4 acres of Forest Service land is involved in the project, but only about 2 acres will likely be impacted, Lewis said. He said the contractor would probably begin clearing trees and vegetation this week. He said the trees “would become the property of our contractor.”
The contractor will have to haul in some large and small rocks to stabilize the site, but the agreement with the Forest Service solves the dirt problem, Lewis said.
Removing hazardous trees
In addition to reducing costs and time involved in the road repair, the arrangement has a couple of other benefits, Lewis said.
“The majority of trees on the slope have been burned and are dead, and over time would become hazard trees and sometimes fall on the highway. We’re able to remove some of those potentially hazardous trees,” he said.
In addition, the damaged section of highway is on a curve, Lewis said. After material is removed from the hillside on the interior of the curve, the hillside will be flattened alongside the highway, and drivers will be able to see better around the curve, he said.
“When the hill is pushed back it will give better sight distance,” Lewis said. WSDOT will reseed the slope next to the road with native vegetation in the fall, he said.
In addition to the major repair work near milepost 212, KRCI crews are working to rebuild the foundation beneath a section of road that was washed away at milepost 221.08 on the east side of Loup Loup summit.
A culvert became blocked at that location and resulted in a landslide that carried away dirt beneath the road. Crews are building a rock buttress at the bottom of the slope, about 200 feet below the roadway surface, and rebuilding the slope from the bottom up.
“Thankfully it wasn’t a full [road] failure,” and resulted in the loss of pavement and the shoulder on the outside lane, Lewis said.
After the major damage is repaired and the highway can be reopened to traffic, he said, repairs will continue on less severely damaged areas, including road shoulders and ditches.