Progress report: KM slide repair is a challenging project
January 30, 2020
SR 4, west of Cathlamet remains closed because of a landslide near the eastern foot of KM Mountain. Washington State Department of Transportation Regional Communications Director Tamara Greenwell announced this progress report Friday afternoon:
"While landslide cleanup work along State Route 4, about 9 miles west of Cathlamet, is underway, the highway will remain closed. Full cleanup and stabilization of the slide is likely to take months, but our primary goal is to open at least one lane of the highway, as soon as possible. However, it is still unknown when that will happen.
"Crews have removed hundreds of the trees from the hillside adjacent to the highway, but challenging conditions are delaying efforts to reopen the highway. The soil is loose and saturated, making the use of heavy equipment on the debris field impossible. Tree felling crews, equipped with drag chains and chainsaws, are currently working on foot through the soft soil slogging, through hip-deep mud as they clear slide debris. Crews are also using heavier equipment with long reach attachments from the roadway.
"Tree removal work will continue on Saturday, but with heavy rain forecasted to move into the area late Saturday, crews likely will not work on Sunday. Early Monday, we will reassess the stability of the slope and plan to continue cleanup efforts. Crews are hauling debris material to a disposal site on the top of KM Mountain. The close proximity of the site makes quick work of taking truckloads of debris out of the area.
"Early next week, our engineering geologists will begin drilling to collect rock core samples to further assess the slide and help develop a long-term fix. While contractor crews continue cleanup efforts, a temporary barrier will be installed to provide a safe workplace for crews, and a travel lane for traffic, once it's safe to return travel through the area.
"This is the largest slide on SR 4 since the KM Mountain slide in February, 1990. The 1990 KM Mountain slide was much larger and washed out the highway, taking months to repair. This football field size slide has buried the roadway in debris but has not damage the structure of the roadway.
"Residents have asked if we will provide a detour for the current slide as we did for the 1990 KM Mountain slide. We do not expect SR 4 to be closed as long as it was closed in the 1990's. During the previous closure, we spent time and resources paving area logging roads and added safety signage. These roads have not been kept up since then and are not safe for highway traffic.
"During the closure of SR 4, traffic can use US 30 in Oregon by crossing the Lewis and Clark Bridge (SR 433) in Longview or the Astoria-Megler Bridge (US 101). Local traffic can use the Wahkiakum County Ferry, which will run free of charge on a 24/7 schedule during the highway closure.
"We understand the slide has a real impact for local travelers. We are working to share information as quickly as possible, and keep you posted on when we can safely open the roadway.
"Thank you for your patience."