Underwater Noise from Drilling Activities During Offshore Wind Farm Construction

Installation of bottom-fixed offshore wind turbines requires large specialized vessels, such as dynamic positioning or jack-up vessels. Acoustic signatures of two drilling vessels were recorded using drifting and moored acoustic buoys during the construction phase of Saint Brieuc offshore wind farm in 2020 and 2021. The acoustic data revealed that noise from onboard activities, such as hydraulic systems, cannot be dissociated from drilling noise when investigating the increase in ambient noise during drilling activities. Median root-mean-square received levels at a 400m range were 130 dB re <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\mu \text{Pa}$</tex> during drilling and up to 143 dB re <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\mu \text{Pa}$</tex> during arrival and jacking-up of vessels.