Final filling of Seattle’s Battery Street Tunnel begins

SEATTLE — The final filling of Seattle’s Battery Street Tunnel has begun.

According to the Washington State Department of Transportation, crews are pouring a special type of concrete into the tunnel through ventilation grate and holes in the tunnel’s roof.

The pouring is starting at the north end of the tunnel at Denny Way.

Officials said the low-density cellular concrete is mixed on-site. Mobile equipment is staged adjacent to Borealis Avenue and will stay there for several weeks before moving to the south end of the tunnel, adjacent to First Avenue.

For the next few months, crews will pump the concrete from the south end of the tunnel using a series of hoses placed throughout, officials said.

Officials said the final filling of the tunnel will use about 40,000 cubic yards of the concrete to fill the roughly nine vertical feet left inside.

“This is a lot of material. By comparison, CenturyLink Field reported using about 10,000 cubic yards of concrete in its construction,” a spokesperson for WSDOT said.

Click here to learn more about low-density cellular concrete.

WSDOT officials said people in the area should expect single-lane closures on Battery Street and cross streets between First and Sixth Avenues and along Borealis Avenue between Sixth Avenue and Denny Way during construction.

The machinery will also create an increase in noise.

Once the concrete is poured, officials said crews will then work to improve the surface of Battery Street.

“This work has already begun on some blocks, and includes patching over the tunnel’s ventilation grates, building new sidewalk and ADA-compliant ramps, and installing new street lighting,” WSDOT said. “The tunnel’s south portal has been the construction staging yard for the job and will be turned into a slope and then handed over to the City of Seattle.”

The project is expected to be completed in 2021.

Cox Media Group