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Sahalee Way NE Drainage Improvement Project
Status update
June 3, 2026
Last June, King County Road Services crews replaced and repaired two failing drainage pipe culverts under the Sahalee Way NE. A few remaining improvements still need to be completed in June 2026, including drainage improvements and slope restoration work.
From Monday, June 8 to Saturday, June 20, 2026, crews will reduce Sahalee Way NE between NE 50th Street and NE 37th Way to one lane each weekday from 8:30 am to 3 pm while they work in the shoulder to finish the drainage repairs. There will be no full road closure, and all vehicles will be allowed through the work zone. Please drive carefully and expect delays.
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Project overview
In 2025, King County replaced one pipe and rehabilitated 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 were failing and water was seeping into the ground making the soil soft. If these pipes had not been replaced, the water entering the ground may have reduced the stability of the slope and caused the area to slide.
A few remaining improvements still need to be completed this June. Crews will place a smaller 6 inch pipe inside the existing 24 inch metal pipe and fill the space around it with concrete to strengthen the pipe and keep water flowing properly. They will also replace the current manhole lid with a new one that has a shorter debris cage, to improve access to the pipe for maintenance.
Project location map
The drainage improvement project is located on Sahalee Way NE between NE 50th Street and NE 37th Way.
Budget and funding sources
The budget for this project is $1 Million, and funding is from local sources.
Project timeline
- Construction begins: June 28, 2025
- Construction ends: late-June 2026
Frequently asked questions
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 were damaged and needed to be replaced:
- Thirty-inch metal pipe that was rusting and cracked was replaced by sliding a new heavy duty plastic pipe that is 18 to 24-inches wide into the current pipe and routing water to the new pipe.
- Twenty-four-inch metal pipe is old and rusting. It was filled with concrete and retired. A new heavy-duty 24-inch plastic pipe was installed nearby and replaced the current pipe.
Photos
Crews gather to review the remaining work after completion of this portion of the Sahalee Way NE Drainage Improvement Project. The asphalt is freshly paved and needed to cure before it is driven on.
A much sturdier pipe now runs under Sahalee Way NE. This pipe can handle water from a 100-year flood.
Crews needed to dig out a section of the road, resembling a channel, to remove the pipe from below the road and add a sturdier one in its place.
Crews guided a large concrete cylinder into position below the road. The upgraded pipe was guided through the concrete piece and held in place.
Old, worn-out pipes were removed from underneath 4600 and 4900 Sahalee Way NE.
The joints in this 24-inch pipe underneath 4600 Sahalee Way NE were failing at the top. With enough pressure, it is possible the pipe could have caved in. If the pipe had caved in, water would have built 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 filled this pipe and built a new culvert above it.
This was 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.