New Seattle tunnel machine to solve stinky problem

Bertha may be sitting idle, but another boring machine in Seattle, Swizy, is ready to move.

“We are replacing the (Fremont) pipeline that has been in use for about 100 years,” said Annie Kolb-Nelson with King County’s wastewater treatment division. “It’s showing its age and is in need of replacement.”

Related: Seattle’s stinky problem that dumps into Lake Union when it rains

The pipeline being replaced, called the Fremont siphon, is a bit different than most running underneath Seattle. It’s located beneath the canal between Fremont and Queen Anne.

While one Seattle tunnel project has caused high-profile headaches, the area continues to experience a flurry of underground work as the county and city race to replace an aging infrastructure &#8212 the sewage and wastewater system in particular.

As it stands, Seattle’s wastewater system is outdated. When stormwater overwhelms the pipes, as it often does, the overflow, which includes waste, pours into area waterways such as the canal, Lake Union, Lake Washington and Puget Sound.

“During storms, this particular pipe carries up to 220 million gallons of wastewater a day,” Kolb-Nelson said. “It is one of the most heavily used pipes in our regional sewer system.”

That’s why the replacement projects are important.

“It will stop it from going into the canal,” said Marty Noble, King County’s project representative for the Fremont siphon.

“What we have now is a 138-inch line,” he added, noting it intercepts multiple lines from Seattle’s north end. “It takes all the UW flows, Fremont flows, Wallingford and all the other communities. That comes down Canal Street right now. It crosses the canal. That tunnel was put in in 1910.”

And Swizy won’t be the first sub-canal tunnel replaced in recent time. Another tunnel running underneath the canal at Ballard was recently replaced, using a slightly larger boring machine – one that could accommodate a crew. And the pipeline it replaced was made of wood.

Ultimately, all tunnels lead to Discovery Park where a wastewater treatment facility is located. But tunnels like Fremont’s are showing their age. Should the Fremont siphon fail, it could cause a major problem for north Seattle, and potentially the waterways.

Two new tunnels

Like Seattle’s famous Bertha boring machine, Swizy is brand new. But that is about all the two machines have in common. Bertha is the world’s largest boring machine while Swizy, named after the wife of one of the tunneling contractors, is the smallest in town. It bears the title of a “micro-tunneling machine” and is smaller than the machines digging tunnels for Seattle’s light rail, and smaller than the machine slated to bore from Ballard to Wallingford. It’s so small that a crew cannot fit inside. It’s controlled remotely.

And unlike the attitudes many Seattleites hold toward Bertha, Swizy has seemingly won over the hearts and minds of the Fremont community. Its christening on Tuesday drew a large crowd of neighbors, school-age, students and tourists who signed the machine. A German TV crew was on site to film the event &#8212 Swizy was engineered and built in Germany.

The Fremont siphon replacement project is the latest in a series of infrastructure updates throughout the region to be completed over 30 years. A tunnel slated to be bored underneath communities from Ballard to Wallingford will act as a reservoir to hold wastewater until it can be pumped into the system.

Swizy will be lowered to the bottom of a 90-foot-deep pit this week. It will then bore forward about 20 feet below the floor of the canal and emerge in a pit located in Queen Anne. It’ll repeat the journey and in the end, there will be two new tunnels fit for 60-inch pipes.

The project is expected to be completed in 2017.