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244th Avenue NE Slide Repair Project
Project completed in summer 2024
August 31, 2024 - 244th Ave NE is now ready for travelers with a fresh layer of pavement and temporary striping. Beyond the newly installed guardrail along the north side of the road, the replacement retaining wall provides stronger, improved support for the hillside.
Status update
October 2024
Both directions of 244th Ave NE re-opened to traffic at 8:30 a.m. Saturday, Aug. 31.
Crews will return to the project location on October 7th and October 18th from 9 a.m. to 3 p.m. each day. Travelers can expect delays while crews reduce traffic, and flaggers alternate two-way traffic. The team will be landscaping, implementing final erosion control measures, and installing curbing. Please check this website or MyCommute for more information. This work is weather dependent and can be rescheduled.
Overview
This project replaced a damaged 90-foot-long retainment wall located below the north side of 244th Avenue NE near Redmond Fall City Road (State Route 202). The previous support wall suffered slide damage in winter 2020 and could not reliably support the edge of the roadway.
In February 2020, King County Road Services temporarily placed a barrier next to the damaged section of wall and moved both travel lanes over. The barrier and lane shift were put in place as a safety precaution to help prevent the road from damage and to stop the wall from shifting further.
The County closed a section of 244th Avenue NE for eight (8) weeks to complete the repair. Crews dug a nine (9)-foot-deep pit across both lanes of traffic to remove and replace the damaged 90-foot-long retainment wall, then replace the soil under the roadway with more stable soil.
The County filled the pit with dense, compact soil and repave the road at the end of the project. This, along with the new retaining wall will help prevent the road from sliding again.
The roadway returned to the full width in late summer 2024.
Location map
The project is located on the west side (southbound) of 244th Avenue NE, adjacent to the city of Sammamish.
Larger view (277KB)
Frequently asked questions
The slide repair work required crews to dig a nine (9)-foot-deep pit across both lanes of traffic to remove and replace the badly damaged 90-foot-long retainment wall and replace the soil under the roadway with more stable soil that won’t slide in the future.
Initially, we believed we could replace the retaining wall without digging up the road. But analysis by County engineers show that the heavy construction equipment needed to repair the wall could make the road slide more. This is because the soil under the road wasn't packed tightly enough, and the hillside wasn't stable enough to handle the extra pressure and weight of the construction equipment.
The County filedl the pit with dense, compact soil and repave the road at the end of the project. This, along with the new retaining wall will help prevent the road from sliding again.
Photos
August 2024 – Crews use a drum roller compactor to compact a layer of subbase material. This is a critical step that will allow the road the support heavy volumes of traffic on the pavement above.
August 2024 – A dumper truck hauls the final load of backfilling material to the project site. This material was used to refill and provide support to the area that was excavated on 244th Ave NE.
July 2024 – Workers place a steel beam, known as a "soldier pile," deep into the ground. This beam helps keep the ground stable and stops the soil from moving around.
July 2024 – A large drill, called an auger, drills into the soil on 244th Ave NE to prepare for the new steel soldier piles.
July 2024 – Excavated unstable soil is removed below the road to prepare for solider pile installation.
July 2024 – The tractor scrapes away old unstable soil and compacts the base using rocks to build a better base for construction.
Looking north: King County Road Services temporarily placed a barrier next to the damaged section of wall and narrowed the travel lanes in February 2020. Photo taken in February 2024.
Looking south: This is the view heading southbound on 244th Avenue NE. The damaged gabion wall is located below the shoulder, to the right of the guardrail.
Road maintenance crews continuously monitor the road for damage and to make sure the support wall has not shifted further. For example, crews repaired a large, cracked section of 244th Avenue NE on January 19, 2022. The damaged asphalt was caused by significant ice followed by rain during the recent winter storm.