Monitoring the acoustic effects of pile driving for the first offshore wind farm in the United States

The Block Island Wind Farm, the first offshore wind farm in the United States, consists of five turbines in water depths of approximately 30 m. The turbines have a jacket type substructure with piles driven to the bottom to pin the structure to the seabed. A number of acoustic sensors were deployed to monitor the acoustic properties of the pile driving activity. The acoustic sensor systems consisted of an eight element towed hydrophone array, two fixed moorings with four hydrophones each, and a fixed sensor package for measuring particle velocity. The towed array was towed from 1 to 8 km from the pile driving location. The fixed moorings were deployed at 7.5 and 15 km from the pile location. The particle velocity sensor package was deployed at 500 m from the pile driving location. This sensor package consisted of a three-axis geophone on the seabed and a tetrahedral array of four low sensitivity hydrophones at 1 m from the bottom. Data collected on these sensor systems will be presented. Acoustic levels and particle velocity observations will be compared and their implications in the context of effects on marine life will be discussed. [Work supported by Bureau of Ocean Energy Management (BOEM).]