Bubble curtain effectiveness during impact pile driving for monopile installation at the Coastal Virginia Offshore Wind project

The Coastal Virginia Offshore Wind (CVOW) pilot project consists of two 6-megawatt wind turbines located 27 miles off the coast of Virginia Beach, VA. Monopile foundations with a diameter of 7.8 m at the seafloor were installed via impact pile driving on two separate days during May 2020. A double bubble curtain was used during the installation of one of the monopiles and no sound mitigation system was used during the installation of the second. The resulting acoustic field was measured during the impact pile driving using a suite of stationary and towed sensors to characterize the effectiveness of the bubble curtain in attenuating the sound levels at various ranges and azimuths. Metrics including the peak sound pressure level, sound exposure level, and kurtosis of each pile strike were determined and analyzed as a function of distance from the foundation. The frequency and azimuthal dependence of the bubble curtain effectiveness was also investigated. [Work supported by Bureau of Ocean Energy Management (BOEM.)]