North-Central Mercer Island Residential Streets
Construction will last about eight months on each street - sign up for updates to receive the start date when it's available.
This StoryMap focuses on the North-Central Mercer Island residential streets. These include SE 22nd St, SE 22nd PL, 78th Ave SE, SE 24th St, and 81st Ave SE.
To learn more about the Mercer Enatai Sewer Upgrade project as a whole, visit the project website .
The blue line on the map shows the new sewer pipeline. King County is also upgrading the North Mercer Pump Station and the City of Mercer Island's Lift Station 11.
What are we building?
King County is installing approximately four miles of new sewer pipe across north Mercer Island and Southwest Bellevue. Some of the new pipe will be installed underneath residential streets. Work will have an impact on everyone who lives or travels on the affected streets.
This image shows the new pipeline in purple with the approximate location of the pipe on each street.
What to expect
Construction is disruptive.
Everyone who lives or travels on streets under construction will be impacted by the work.
We will send out alerts so you can plan ahead if you live near the active work area.
Crews will use a construction technique called “open-cut” trenching to bury the pipe where it needs to go. During open-cut construction, crews will:
- Dig a trench,
- Lay the pipe in the trench,
- Attach the new pipe to existing pipe,
- Fill in the trench, and finally,
- Restore the surface.
Open cut construction video shows you what to expect
This image shows a trench box holding back soil so workers can install pipes. On residential streets, the trench is approximately 8 feet wide.
Like any construction project, there will be noise, dust, traffic impacts and other inconveniences.
- Permitted weekday work hours are 7 a.m. to 7 p.m. We will provide advance notification of any weekend or after hours work.
- We will detour regular through traffic around these streets. Residents will have access to their homes.
- Residential streets will be reduced to one lane.
- Flaggers will direct traffic.
- Emergency vehicles will always be able to access streets under construction.
School bus stops may move temporarily. King County is working with the Mercer Island School District. They will communicate changes to you in advance of any moved bus stops.
Services such as garbage, recycling, package delivery and mail will continue uninterrupted. Residents may need to move garbage bins across the street during active construction. King County will provide advance notification of any changes to bin locations.
Some of the work we are doing will take place in the public right-of-way. This may include green spaces on the side of the road, often called parking strips. We know that many residents have improved these areas with landscaping.
In areas where we need to dig up the public right-of-way, we will give neighbors advance notice so they can remove any landscaping improvements they have made for use in other places. Crews will survey the right-of-way limits, and you may see flags or stakes indicating the property boundary.
To meet City of Mercer Island code requirements, if your plantings do extend into the public right-of-way we will not replace them after the project.
If you are concerned about construction impacts to vegetation or other items in the right-of-way, please contact the Community Relations Team at 425-305-3578. We can help you plan ahead for potential impacts.
Schedule and duration
Construction on the overall sewer upgrade is underway and will last into 2025.
Each street will experience about eight months of construction. We will provide advance notification of construction activities on our website, in door hangers and through our email list.
Please sign up to receive updates about this section of the project to stay up to date on the work and schedules.
Detour routes
We will provide local access to residents on affected streets. Scroll through the maps below to see where vehicles, pedestrians and bicycles that are traveling through the area will be detoured. Note that the detour routes change depending on where the work is occurring.
Detour route for SE 22nd St, SE 22nd PL, 78th Ave SE and SE 24th
Detour route for cars, pedestrians and bicycles
The detour route for vehicles is different from the detour for bicycles and pedestrians on 81st Ave SE
What you'll see when the work is done
King County will restore areas based on permit conditions.
When construction is complete, we will restore areas based on permit conditions agreed upon with the City of Mercer Island and other regulatory agencies.
Some restoration work, such as paving streets and planting vegetation, is best done during certain seasons. This could mean a gap in time between the end of construction and when restoration occurs.
How to reach us
We are committed to working with you during construction.
Here is what you can expect:
- Flyers on your door with advance notice of construction activity.
- Regular web updates.
- Email and/or text announcements.
- Quick resolution of problems and concerns.
- Call or email us . We will get back to you within one business if it is not an emergency. If it is a project-related emergency, we will get back to you right away.
Talk to us!
For more information or to schedule a virtual meeting, contact the Community Relations Team:
- 425-305-3578
- NMEsewer@kingcounty.gov
Learn more
Visit the project webpage to learn more and sign up for email and/or text alerts: www.kingcounty.gov/MercerEnataiSewer
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