Lane starts digging massive tunnel in Seattle to store untreated stormwater

  • door

Lane Construction, a US subsidiary of Italy’s Webuild, has begun excavating a 4.2-km-long tunnel in Seattle, Washington state, that will collect and store untreated stormwater and sewage to prevent it from flowing into the city’s surrounding water.

In parts of Seattle, sewage and stormwater share pipes, and heavy rain causes around 276 million litres of untreated overflow enter the Lake Washington Ship Canal, Salmon Bay and Lake Union every year, harming wildlife.

The 5.5m-diameter tunnel running from Ballard in the west to Wallingford will be able to hold some 110 million litres until the water treatment plant is ready to process it, Webuild said.

Overflow will enter the tunnel through five vertical shafts at Ballard, East Ballard, Fremont, Queen Anne and Wallingford (Graphic courtesy of Seattle Public Utilities)

Overflow will enter the tunnel through five vertical shafts at Ballard, East Ballard, Fremont, Queen Anne and Wallingford. Since Queen Anne is on the other side of the ship canal, a smaller tunnel will be dug under the canal to convey its overflow to the main storage tunnel.

For the main tunnel, Lane will use a 5.5-metre-long tunnel boring machine that was named “MudHoney”, after one of Seattle’s famous grunge bands, in a public vote.

Among Lane’s other projects, there is a Caloosahatchee basin storage reservoir to reduce harmful discharges into an estuary in Florida, and the Three Rivers Protection & Overflow Reduction Tunnel (3RPORT) in Ft. Wayne, Indiana.

Top image: Lane will use a 5.5-metre-long tunnel boring machine that was named “MudHoney”, after one of Seattle’s famous grunge bands, in a public vote (Courtesy of Lane Construction)