Variations in the acoustic field recorded during pile-driving construction of the Block Island Wind Farm

The Block Island Wind Farm, the first offshore wind farm in the United States, consists of five 6-MW turbines three miles southeast of Block Island, Rhode Island in water depths of approximately 30 m. The turbines include a jacket-type substructure with four piles driven at an angle of approximately 13 deg to the vertical to pin the structure to the seabed. The acoustic field was measured during pile driving of two turbines in September 2015 with an 8-element towed horizontal line array. Measurements began at a range of 1 km from the turbine on which piling was occurring and extended to a range of 8 km from the construction. The peak-to-peak received level, sound exposure level, and kurtosis from each pile strike were determined as a function of range from the pile. The ambient noise just prior to each signal was also measured to calculate signal-to-noise ratio values. Results provide insight into the transition from fast-rise-time impulsive signals at close range to slow-rise-time non-impulsive signals a...