Lesson learned from monitoring the environmental effects of construction of the first offshore wind farm in the US

James Miller1, Gopu R. Potty2, John W King3, Dennis R. Gallien4, Anwar A Khan5, Kathleen J. Vigness-Raposa6, Jennifer L. Giard6, Adam S. Frankel6, Tim Mason7, Arthur N. Popper8, Anthony D. Hawkins9 and Steven E. Crocker10, (1)University of Rhode Island, Ocean Engineering, Narragansett, RI, United States, (2)University of Rhode Island, Department of Ocean Engineering, Narragansett, RI, United States, (3)Univ Rhode Island, Narragansett, RI, United States, (4)HDR, Inc., 300 North Madison Street, Athens, AL, United States, (5)HDR, Inc., Athens, AL, United States, (6)Marine Acoustics, Inc., 2 Corporate Place, Suite 105, Middletown, RI, United States, (7)Subacoustech Environmental Ltd., Chase Mill, Winchester Road, Bishops Waltham, Hampshire, United Kingdom, (8)University of Maryland, Dept. of Biology, 2225 BPS, College Park, MD, United States, (9)Loughine Ltd., Kincraig, Aberdeen, United Kingdom, (10)Naval Undersea Warfare Center - Newport, 1176 Howell Street, Newport, RI, United States
Abstract:
Noise radiation from pile driving activities were monitored using multiple sensors during the construction of the USA’s first offshore wind farm located 3 nm off Block Island, RI. The 30-megawatt Block Island Wind Farm (BIWF) consists of five turbines in water depths of approximately 30 m and is scheduled to be online in 2016. The substructure for these turbines consists of jacket type construction with piles driven to pin the structure to the seabed. Pile driving operations generate intense sound, impulsive in nature at close range, which radiates into the surrounding air, water and sediment. The underwater acoustic measurement platforms consisted of a towed array consisting of eight hydrophones, two fixed moorings with four hydrophones each, a fixed sensor package for measuring particle velocity, and boat-deployed dipping hydrophones. The hydrophone array was towed from a position 1 km from the pile driving location to 15 km distance from the construction. The fixed moorings were deployed at 10 km and 15 km from the pile location. The fixed moorings consisted of four hydrophones each at depths of 10, 15, 20 and 25 m. Near field measurements of the underwater acoustic signals from the pile driving were collected with a tetrahedral array deployed at 500 m from the pile driving location about 1 m above the seabed. The boat-deployed dipping hydrophones sampled the acoustic field at locations from 0.5 km to 20 km from the pile driving locations. Based on these acoustic measurements and propagation modeling, the acoustic pressure field as a function of range and depth from the pile is estimated. The transition from fast-rise-time impulsive signals at close range to slow-rise-time non-impulsive signals at longer ranges will be addressed. This study will provide the required information to qualify the different zones of potential marine mammal effects (zones of injury, behavioral effects etc.) and to estimate exposure to fishes and other species. [Work supported by Bureau of Ocean Energy Management (BOEM)]
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