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Sahalee Way NE Drainage Improvement Project
This 24-inch pipe is buried 20 feet under Sahalee Way NE and is cracked and at risk of failing. If not fixed soon, the pipe could collapse which could cause sinkholes or the road to slide.
Status update
May 2025
King County will close Sahalee Way NE between NE 50th Street and NE 37th Way to replace and repair two failing drainage pipe culverts under the road.
What to expect:
- The road will close on Saturday, June 28, 2025, at 6 a.m. and reopen on Wednesday, July 2, 2025 at 6:30 p.m.
- Both directions of Sahalee Way NE between NE 50th Street and NE 37th Way will be closed 24 hours a day to all traffic for up to five days, including emergency response vehicles.
- All travelers, bus routes and emergency response vehicles will use a signed detour. Please plan for up to 15 extra minutes of travel time.
Why we need to close the road:
- Sahalee Way NE is too narrow to fit the large excavator and keep traffic moving. Crews also need daylight to safely work around three underground gas lines.
- If the damaged pipes collapse, water could rush out and cause sinkholes– or completely wash out the road above.
- If that happens, the road could be closed for up to a year to fully rebuild it.
Thank you in advance for your patience. By acting now, we can avoid a much larger emergency closure later.
Project overview
King County will replace one pipe and rehabilitate another under Sahalee Way NE between NE 50th Street and NE 37th Way near the City of Sammamish. The joints in the metal culvert under the 4600 and 4800 block of Sahalee Way NE are failing and water is seeping into the ground making the soil soft. If these pipes are not replaced, the water entering the ground may reduce the stability of the slope and cause the area to slide.
We understand that closing Sahalee Way NE is a significant impact to the community. We are doing everything we can to keep the closure as short as possible, this includes working over the weekend. If we don’t do this work now, and a pipe collapses, the emergency repair could cause the road to be closed for up to a year.
This area has been subject to some large slides that closed the road for many days in the mid-1990s and earlier. Approximately 20,000 vehicles use this road every day.
- To replace the pipes, crews will close Sahalee Way NE between NE 50th Street and NE 37th Way for five days in from June 28th to July 2nd to prevent future slides.
- All vehicles, including emergency vehicles such as fire trucks, METRO buses, bicycles, and pedestrians must use the detour on 244th Ave NE during the closure.
What to expect during construction:
- Sahalee Way NE will be closed 24/7 from Saturday, June 28th at 6 a.m. to Wednesday, July 2nd at 6:30 p.m. for construction. The road is too busy, and the pipe is too deep to keep one lane open or to do the work at night.
- Crews must dig down and remove a section of road and it will not be safe for vehicles to be present with a deep construction pit in the road.
- All vehicles, including emergency vehicles such as fire trucks, METRO buses, bicycles, and pedestrians must use the detour during the closure.
How will King County keep residents and drivers informed during construction?
We are working with the City of Sammamish and City of Redmond to share information with travelers who use this road. Our crews will put up temporary signs to let travelers know construction dates and times. We will also send postcards to homes and businesses in the many communities along Sahalee Way NE to share information about construction dates and times.
If you would like us to reach out to your organization or homeowners association, please contact Amy Bresslour.
Frequently asked questions
In the 4800 block of Sahalee Way NE, crews will slip a new, stronger pipe inside the existing one. The new pipe will also be able to handle a 100-year flood.
There are two large drainage pipes that run under Sahalee Way NE between NE 50th Street and NE 37th Way. When working, these pipes drain water away from the hillside reducing the risk of a slide. Both of the pipes are damaged and must be replaced:
- Thirty-inch metal pipe that is rusting and cracked will be replaced by sliding a new heavy duty plastic pipe that is 18 or 24-inches wide into the current pipe and routing water to the new pipe.
- Twenty-four-inch metal pipe is old and rusting. It will be filled with concrete and retired. A new heavy-duty 24-inch plastic pipe will be installed nearby and will replace the current pipe.
Photos
The joints in this 24-inch pipe underneath 4600 Sahalee Way NE are failing at the top. With enough pressure, it is possible the pipe could cave in. If the pipe caves in, water will build up soaking the soil around the pipe and possibly causing the surrounding slope to slide. Additionally, as the cracks gets wider and soil is washed away, sink holes could develop and parts of the road could fall into this empty space. We will fill the existing the culvert and build a new culvert above it.
This is the culvert near the 4600 block of Sahalee Way NE. When the culvert sticks out like this, you can see that soil underneath has eroded and fallen away. Eventually, the pipe is no longer supported, and it fails completely.
This is a picture from 1996 in the same area. King County repaired a sunken and cracked Sahalee Way NE. The instability of the ground in this area is the reason we pay such close attention to these culverts. The culverts are an important way to manage water under the road.