State Route 99 Alaskan Way Viaduct demoliton: old bridge, new purpose

September 24, 2019 | Kieways 2019 Q3

Above: Kiewit used recycled viaduct material as an environmentally friendly solution to fill the decommissioned Battery Street tunnel. Photo credit: Washington Department of Transportation

With the Battery Street Tunnel now in the rearview mirror for Seattle commuters, it was Kiewit’s job to decommission it.

The project involved the usual tasks, like removing the 1950s-era utilities, piping, and ventilation, as well as some more unusual ones, like working with utilities companies and the City of Seattle to repair and install new utilities.

Filling it could have meant trucking in material from miles away — adding to the cost of the project and carbon emissions from
spent fuel.

But Kiewit proposed an environmentally friendly solution: Recycle the viaduct rubble into useable pieces to fill the structure.

The concrete traveled to Terminal 25, a yard set up a couple of miles from the jobsite.

There, it entered a crusher where it was separated from any remaining rebar and processed into three-inch-minus pieces —
think super-chunky gravel — and brought to the tunnel.

Crews then transported the fill back to Battery Street and dumped the rubble through old ventilation grates on the tunnel lid via surface streets.

The filled tunnel holds 52,000 cubic yards, or 7.8 million pounds of the former SR 99 Alaskan Way Viaduct.

And the best part: Recycling the bridge has saved 52,000 cubic yards of rubble waste from entering local landfills.

Even more critically, it reduced the 363 metric tons of greenhouse gas emissions, 7,100 truck trips and 246,000 miles of truck travel that would have been associated with bringing in new fill.

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