24-hour traffic expected on Hwy 20 by this weekend
By Ann McCreary
After being closed for three months to repair damage from mudslides and erosion, Highway 20 over Loup Loup Pass partially opened on Monday (July 10), with one lane of traffic through the two most-damaged locations for a few hours in the morning and evening.
The partial opening allowed commuters between the Methow and Okanogan valleys to travel over the Loup between 6 – 9 a.m. and 4 – 8 p.m. By the weekend, the road was expected to be open 24 hours a day.
The one-lane, gravel sections opened Monday with pilot cars guiding traffic through. At milepost 211.85, about 3 miles west of the summit, paving of both lanes and guardrail installation was expected to be completed by Friday (July 14) to allow traffic to travel normally, said Dan Lewis, project engineer for the Washington State Department of Transportation (WSDOT).
Repairs at milepost 221.08, about 6 miles east of the summit, will take a few weeks longer, Lewis said. However, that stretch of roadway is anticipated to be open to 24-hour traffic by the end of the day Friday with one unpaved lane of traffic controlled by a temporary signal, Lewis said.
Crews were working to rebuild the slope below the road at that location, after having to construct a rock buttress at the bottom of the slope to prevent it from sliding away. Repairs were made more difficult because multiple springs of water were flowing from a hill above the work area, causing further erosion.
Work was underway to rebuild the road shoulder, with the goal of repaving the road there by the end of July, Lewis said.
The current contract for the repair work was scheduled to end July 20, but WSDOT retained the contractor, KRCI of Wenatchee, through the end of the month to complete the repairs, Lewis said. Repair costs for the Highway 20 damage are expected to total up to $5.5 million.
The problems on Highway 20 began with heavy rains during the first weekend in April, which caused flooding and mudslides that damaged nine sections of the highway and forced closure of a 16-mile stretch of the road.
Initially WSDOT predicted the road would reopen by May, but further damage caused by saturated soil and continued erosion meant that repairs took much longer than originally anticipated.
At milepost 211.85, massive quantities of saturated dirt — about 5,000 truckloads — had to be excavated and replaced with dry fill before the road could be reconstructed. New culverts were installed there, and at several other damaged locations.
The washouts and debris flows are largely a result of past wildfires, particularly the Carlton Complex Fire of 2014. Hillsides above the highway were burned during fires that destroyed vegetation and in some areas damaged soil so badly that it is unable to absorb moisture.
Several debris flows were caused by burned, dead trees that fell across drainages and created dams that collected debris and water. When the dams broke open, they released torrents of water that carried rocks, trees and mud and washed out the roadway below.
The rush of water and debris was more than culverts, designed to carry water under the roads, could handle, Lewis said. In some cases the culverts became blocked and water flowed over the highway and tore out fill below the highway.
Commuters who travel over the Loup Loup Pass to work have been forced to take a detour via Pateros since early April, roughly doubling the time and distance required for the trip.