Thursday, April 28, 2011

Recycling bridges the gap between cost and environment

By guest blogger Noel Brady

You recycle those paper cups, bottles and old documents to keep them out of the landfill. Curious to find out how much landfill space a 300-foot-long, four-lane bridge would take?

Neither was our I-405 project team. That’s why we recycled 100 percent of the NE 12th Street bridge in downtown Bellevue after crews demolished it in March to make way for a longer, wider bridge to connect new ramps to I-405 and SR 520.

After bringing down the bridge, crews hauled away nearly 4,000 tons of concrete, 225 tons of rebar and truck loads of wood to recyclers. In addition to cutting carbon emissions from production, recycling construction materials saves money.

Crunching the NE 12th St. Bridge over I-405

“In the old days it would’ve been taken to a landfill”, said Seema Javeri, WSDOT Project engineer. “Now we’re recycling road and bridge materials and even going back and restoring DOT property that was used for dumping 25 years ago.”

The state does not require recycling in bridge demolition, but it is becoming the norm as the market for recycled materials grows. Today we routinely write construction specifications that make it easier to recycle materials. Plans often require concrete be laid in panels for efficient removal and recycling, and they allow a higher percentage of recycled materials in cement than was the standard in the past.

“It’s one thing to recycle material,” said Steve Mader, an environmental manager for I-405 Corridor Design-Builders, “but it’s better to upcycle” or preserve materials during demolition to keep them in good condition for reuse. His firm routinely crumbles concrete on site for use as base rock. And his crews take care not to twist and mangle used rebar, which can increase its market value as much as five times.

Starting back in the 2002 with its Record of Decision, the I-405 program has followed a guiding principle to leave the environment better then it was found, Javeri said. That means building better drainage and filtration systems, planting more vegetation and recycling more materials.

Visit the Sustainable Transportation Web page to learn how we support the environment, economy and communities in our mission to keep Washington moving.

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