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Environmental report complete on SR 520 floating bridge pontoon project


December 10, 2010

SEATTLE – The final environmental impact statement (EIS) for the Pontoon Construction Project was published today and evaluates the effects of building a casting basin and 33 concrete pontoons in Grays Harbor for a replacement SR 520 floating bridge. The pontoons will be available for emergency replacement of the vulnerable floating bridge across Lake Washington or stored for a proposed new six-lane bridge scheduled to open to traffic in 2014.

Issuing the report means the Washington State Department of Transportation (WSDOT) now is one step closer to final design and construction on the pontoon project.

“We plan to begin construction next spring and look forward to putting hundreds of people to work in Grays Harbor,” said state Transportation Secretary Paula Hammond. “These pontoons will be available to form the backbone of the floating bridge and keep this vital transportation link open.”

The final EIS published today evaluates the effects of building a pontoon casting basin that is smaller than the original eight-pontoon concept analyzed in the draft EIS. WSDOT worked jointly on casting basin designs with Kiewit-General Joint Venture (K-G), which was awarded the $367 million contract for the project in January.

The document evaluates two possible project sites. WSDOT named the Aberdeen Log Yard as the preferred site for the project in August 2009 – pending environmental review – and recently purchased the property from Weyerhaeuser for $4.8 million. The Aberdeen Log Yard continues to have lower estimated development costs and fewer risks associated with building the project, according to the final EIS.

The report updates analysis on several topics – including transportation, economics, and energy and climate change – and responds to public and agency comments and questions from the draft EIS.

With the final EIS complete, the Federal Highway Administration can select the final project site and sign the record of decision. WSDOT and K-G can then obtain construction permits and begin construction in spring 2011.

Design-build is a type of contract that combines project design and construction into a single contract. A designer and contractor combine forces to submit a detailed design and construction proposal with a fixed price.

The floating bridge and pontoon construction projects are funded in part by toll revenue scheduled to be collected on the floating bridge starting in spring 2011. The Legislature set the SR 520 program budget at $4.65 billion for improvements from I-5 in Seattle to SR 202 in Redmond. Toll revenue and state and federal funds provide about $2.37 billion in funding for the SR 520 improvements. WSDOT will continue working with the state Legislature to identify additional funding for other improvements in the corridor.

More information about the SR 520 Program is available at


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