Underwater noise reduction


Christopher McKenzie Maxon

Christopher McKenzie Maxon

Senior Consultant, Acoustics and Noise
T: +45 5161 6417

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Ramboll has performed underwater noise level measurements and assessed the effectiveness of a proto-type ‘cofferdam’ noise reduction system for offshore monopile driving. 

According to legislation from the EU, underwater sound emissions from the installation of offshore wind turbines must be reduced to minimize the harm to marine mammals from the extremely high underwater noise levels produced during impact driving monopoles into the seabed. Until now, no underwater noise limits have been enforced to reduce the noise. 

The noise reduction technology is based on a cofferdam system, which give results that comply with the recommended requirements of maximum: 160 dB Sound Exposure Level (SEL) and 190 dB Peak Level for underwater pile driving noise levels. So far, Germany is the only country to have ratified the legislation, but the remaining EU countries are expected to follow Germany’s example.

Ramboll has extensive experience with the measurement and prediction of underwater noise.

The next phase of the project is to measure the underwater noise levels noise levels during pile driving with the cofferdam noise reduction system for specific wind farms in German waters. 

From 15 to 20 December 2011, the cofferdam was tested in the bay of Aarhus, Denmark with very positive results. The cofferdam is the only technology that lowers the noise level and meets the requirements of the EU legislation. The cofferdam test was performed together with the following companies: LO NOISE, Siemens, Grundfos, and Trelleborg.


First Floor, Emerald Building
Oud Metha Road
PO Box 116921, Dubai, UAE
Tel:+971 4 334 3616
Fax:+971 4 334 3617

Mail: info@ramboll.ae

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