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Underwater Noise Mitigation during UXO detonation

We have been working together with Hydrotechnik- Lübeck for years now to offer our clients a noise mitigation system that can be used during the detonation of UXO. Our OSV Noortruck was the first Big Bubble Curtain ship (BBC-ship) to be used, which has been deployed until now, and operated over three hundred bubble curtains. Noortruck’s last BBC-operation took place during the hammering of windfarm foundations in 2016 at Windfarm Nordergrunde, Germany. Since 2017, we now offer the approved HY75 system of Hydrotechnik-Lübeck exclusively for noise mitigation during UXO detonation. Noise mitigation during hammering of foundations is directly offered by Hydrotechnik-Lübeck.

Big Bubble Curtain what’s in the name…

The Big Bubble Curtain (BBC), or in German ‘Großer Blasenschleier’ (GBS), is a compressed air system for sound absorption in water. It’s developed by Hydrotechnik-Lübeck, in line with respective conditions and with subsidies from the Federal Ministry for Environment, Nature Conservation, Building and Nuclear safety (BMUB). The system serves primarily to provide sound protection during offshore pile driving and offshore munitions blasting. The Big Bubble Curtain especially protects porpoises and seals which use ultrasound as orientation in water. The limit specified by the BMUB of 160 dB sound exposure level (SEL) applies in German waters of the North and Baltic Sea, measured at a distance of 750 m from the sound source.

 

History and development

The Big Bubble Curtain originates from the compressed air barrier technology which we have been using for more than 50 years to protect floating debris and oil. In 2006, after the initiative of the “NABU Schleswig-Holstein” (environmental association) and various environment protection associations, we initially tested whether the system of a compressed air barrier could also be used to minimize underwater noise. Munitions from the Second World War were to be blasted in the Kiel Fjord. A nature reserve for porpoises nearby was in acute danger.

The system was first used in 2008 in the offshore section of the Baltic Sea during pile driving to build the Research Platform FINO3. The BMUB made a considerable contribution to cover costs for scientific research and further development. The University of Hannover and the company, BioConsult, Itap GmbH were also involved in the project. The Big Bubble Curtain is now used in almost all construction works for offshore wind farms and blasting works in the North Sea and Baltic Sea.