Thursday, January 29, 2015

New pile driving design about to make waves

By Ann Briggs

Field testing of the new double-wall
pile design. (Photo courtesy of the
 University of Washington)
New construction research is poised to make big waves both here and far abroad. We've been working in partnership with the University of Washington (UW) to find ways to reduce the noise created by underwater pile driving that will not only benefit and protect marine wildlife in the Puget Sound, but may also change marine construction practices around the globe.

Piles are long poles or tubes driven into the seabed to provide the foundation support for ferry terminals, docks, bridges and other structures. The noise created by hammering the piles into the seabed floor is easily carried underwater and can harm, and even kill, sensitive marine wildlife. As a result of those impacts, strict regulations on marine construction projects make them expensive and challenging to complete.

Our team of researchers, and environmental, construction and ferry engineers has worked with scientists to study the detrimental effects of underwater pile driving on marine environments for years. In 2008, the team invited both the construction industry and the academic fields to come up with a quieter pile design solution.

UW's Mechanical Engineering department submitted a winning proposal for a new pile design technology. With our research-funding support, UW engineers and graduate students studied the mechanics of why pile driving is so loud, how the sound is transmitted underwater and how to reduce that sound. With this knowledge, they created a double-wall pile design that confines the installation noise within the pile itself.

Mechanical Engineering PhD Candidate Tim Dardis reviews
the fabricated double-wall pile for field testing at
Commencement Bay in October.  (Photo courtesy of the
University of Washington)
With ongoing development of this innovative project, interest has spread and multiple agencies have now joined us, including the National Oceanic and Atmospheric Administration, with monitoring assistance from the National Marine Fisheries Service. This summer, full-scale field testing of this new design will be conducted in coordination with the Port of Tacoma at Commencement Bay. 
We anxiously await the test results, which have the potential to reduce marine construction costs and protect the environment, not just in Washington state, but in waterways around the world.

For more information on this project and other research benefits, contact WSDOT Research Director Rhonda Brooks.

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