By Ann McCreary
Motorists should expect detours and delays to continue for several weeks on state highways 20 and 153, which were extensively damaged in recent floods and mudslides.
Sections of both highways — two of the three highways that access the Methow Valley — were washed out during torrential rains on Aug. 21 that brought down mud and debris from hillsides burned bare of vegetation during the July fires.
A dozen homes and properties were damaged by mudslides that plugged culverts, scoured out gullies and undercut roadways.
“We’re making progress on designing our fixes,” said Kevin Waligorski, project engineer for the Washington Department of Transportation (WSDOT).
“Some of these areas continue to change, with creeks cutting deeper into the channel or … running over banks,” he said.
Waligorski said repairing the roads will take another four to six weeks because of the extent of the damage, and because the work requires the cooperation of many private property owners and approval by state and federal agencies. The project is expected to cost $800,000 to $1 million.
About four miles of Highway 20, heading toward Loup Loup Pass, were damaged when Frazer Creek — normally a small stream — overflowed its banks and became a 60-foot-wide torrent that gouged huge crevasses next to the roadway.
A four-mile stretch of road on Highway 153 south of Benson Creek was also damaged when mud and debris surged down drainages above the highway and crossed the road. A section of the eastbound lane was undercut and eroded away near milepost 26.
“These areas are impacting not only the highways, but adjacent property owners,” Waligorski said. He said right-of-way agreements must be made with some property owners because the needed repairs will affect or take place on their properties.
“We understand that the property owners up here have been through a lot of issues. It’s been a traumatic time with fires, power outages and floods. We’re trying to work with property owners who have some concerns,” Waligorski said.
“We want to make sure they’re being dealt with fairly. We need to work with property owners to make sure we’re not going to do something that’s going to negatively impact them.”
Waligorski said affected property owners have been contacted and agreements are being negotiated.
Work on Highway 153 includes replacing a private culvert near Canyon Creek with a 42-inch culvert that will be maintained by WSDOT. A 48-inch culvert will be installed under the roadway near Leecher Creek.
Near Benson Creek, where a lane was lost when the road was undercut by flooding, WSDOT is proposing to install an 8-foot diameter culvert and is in discussions with an adjacent landowner about the plans. A 3-foot diameter culvert was in place before the flooding.
Plans also call for “armoring the slope of the roadway on the downhill side so if water overtops the roadway it won’t scour the road out,” Waligorski said.
The slope would be reinforced with a geotextile fabric and rocks, and large riprap would be placed in a creek bed below the roadway that was deeply gouged out by the slides.
The design was based on a hydrologic analysis that planned for a 100-year storm event, Waligorski said.
“Until the area is revegetated, we’ve got the potential for more heavy debris flow if there are heavy rains, or heavy rain-on-snow events,” he said.
On Highway 20 crews must contend with Frazer Creek, which created a new channel when it jumped its banks. It now runs right next to the highway along some stretches, as much as 100 feet away from its original course.
“It used to run out in the trees. We’re looking at putting the creek back into the original channel,” which will require digging out silt and debris deposited in the streambed during the flood, Waligorski said.
WSDOT also plans to move the highway about one lane width to the north in a couple areas at the upper end of the damaged sections where large washouts occurred. WSDOT is working on plans to adjust the roadbed with the state Department of Fish and Wildlife, which owns the land along those sections.
Single-lane traffic with a pilot car will continue along Highway 20 while repairs are underway, and the Highway 153 detour to the Twisp-Carlton Road will also remain in place until the roadway is restored.
An emergency contract for the construction project was awarded last week to Rains Construction of Malott.
