Massive North Mercer Island/Enatai sewer upgrade underway

Crews are using part of boat launch parking area for construction.

By Andy Nystrom • May 12, 2022 4:30 pm
The new pipeline crossing the East Channel will be an “inverted siphon” – a U-shaped pipeline with high ends on the shorelines, and a low point in the middle along the lake bottom. Courtesy of King County
The new pipeline crossing the East Channel will be an “inverted siphon” – a U-shaped pipeline with high ends on the shorelines, and a low point in the middle along the lake bottom. Courtesy of King County

With the long-awaited North Mercer Island/Enatai sewer upgrade underway, King County crews are using a portion of the boat launch parking area for construction.

While the launch is still fully operational, parking spaces are at a minimum in the area and overflow parking will be available at City Hall.

In her city manager’s report at the May 3 council meeting, Jessi Bon said the crews required a big staging area for the project and the launch parking lot was selected. It’s an inconvenience, she said, but the city lacked alternative locations.

“We appreciate your patience as King County works on this vital improvement to the Island’s sewer infrastructure,” the city said in a notice to the community, adding that construction vehicles will be moving in and out of the area throughout the day.

Bon said the launch parking area utilized for staging sits on Washington State Department of Transportation property and is also marked as part of Aubrey Davis Park.

“I want to assure that when the construction project is over, that area will be restored according to the guidelines in the Aubrey Davis Park master plan,” she said.

The massive project — which is expected to reach the finish line by early 2025 — will feature an upgrade of four miles of sewer pipeline along with an upgrade of the county’s North Mercer Pump Station and the Island’s Lift Station 11 at Fruitland Landing, according to the King County Wastewater Treatment Division. The pipes to be replaced carry wastewater from the local pump station to Bellevue’s Sweyolocken Pump Station.

The pipes — which were installed in the 1970s and are aging and reaching capacity — serve the areas in north Mercer Island, the southwest portion of Bellevue near Enatai Beach and the Town of Beaux Arts Village.

According to a May 4 project update on the King County website, “Surveying and utility location will take place in neighborhoods, public parks, and along the I-90 trail. Most work will take place in the public right of way. King County will notify property owners ahead of any work on private property.”

For more information on the project, visit www.kingcounty.gov/mercerenataisewer.

Also on the Aubrey Davis Park front, the picnic shelter that was damaged in a fire on June 1, 2021, is nearing its replacement completion, according to Bon in her report.

The city contractor’s work on framing out the new roof structure is expected to be finished sometime in June and rentals could be available this summer. For rental information, visit www.mercerisland.gov/rentalinformation.

Mercer Island Fire Department (MIFD) crews extinguished a small trash can fire that reached the covered area roof of the picnic shelter, according to the MIFD in a previous Reporter story. The exposed wood framing members of the structure were severely damaged, and flames could be witnessed from Interstate 90. A MIFD press release noted that the fire may have been deliberately set since firefighters spotted another burned trash can in the area.