The double-wall pile is a new technology that could help the marine construction industry complete projects faster and at a lower cost. Strict industry regulations have historically made projects expensive and challenging. But this new tech could improve bridge, dock, pier, ferry terminals, and other marine structure projects.
What’s that racket?!
Pile driving is loud, and anything built in the water is usually supported by piles. The sound that’s created by pile driving comes from the hammered pile, which then expands and transmits sound waves, both above ground and under water, into the water and seabed.
Costing creatures & construction companies
The noise created by pile driving is harmful to aquatic life, including endangered fish, marine mammals, and birds. When a pile is hit, the sound becomes a shockwave which can drown out noises that fish and aquatic mammals depend upon to survive, causing injury and sometimes death. As a result, construction has to proceed slowly due to the potential hazards to wildlife. These hazards increase the cost of monitoring and mitigation.
Along comes the double
The double-wall pile, a viable solution to these problems, is a tube within a tube that decreases the volume of pile driving by about 20 decibels. The design is made up of an inner tube which is hit by a hammer and an outer tube that blocks the sound waves. There is an air gap between the two tubes which are connected at the bottom using flexible coupling. During pile driving, only the inside pile is struck. The outside pile does not produce any noise; as a result, pile driving noise decreases.
Researchers at the University of Washington (UW), including Per Reinhall, UW Mechanical Engineering Chair, and Peter Dahl, UW Professor of Mechanical Engineering, won a 2008 contest conducted by Washington State Department of Transportation (WSDOT) for “Experimental Design for Noise Attenuation for Pile Driving.” They wrote the proposal introducing the technology and leading to the start-up business, Marine Construction Technologies, which sells the new technology,
The double-wall pile technology is so promising that it has already piqued the interest of multiple agencies, including the National Oceanic and Atmospheric Administration (NOAA). This summer, the technology will be tested at the Port of Tacoma at Commencement Bay in Washington state.