Geologic Considerations for Floating Offshore Wind, Gulf of Maine, USA

Abstract The Bureau of Ocean Energy Management (BOEM) has designated call areas within the Gulf of Maine outer continental shelf in water depths suitable for floating turbines (i.e., greater than 100 m). The objective of this study is to present an overview of the geologic and geophysical conditions and constraints within the Gulf of Maine where potential lease areas may be located. This work expands on the previous 2022 BOEM-funded desktop study supporting the US Department of the Interior, Bureau of Safety and Environmental Enforcement’s solicitation for areas of interest to the Bureau of Ocean Energy Management Technology Assessment Program on offshore wind technology (BAA No: 140M0121R0006) (Fugro 2022). The study utilized public domain geophysical and geotechnical data to evaluate the seafloor and near-seafloor geological and geotechnical conditions relevant to floating offshore wind. Data available from published scientific literature and offshore projects were integrated and evaluated using GIS and seismic interpretation software to identify and map geohazards, seabed and subsurface conditions, and key stratigraphic geotechnical units. These results are presented as maps illustrating seabed and subsurface conditions, including geohazards. Our evaluation of the study area indicates generally favorable conditions for offshore wind development, with site-specific considerations to be factored into engineering design. Key findings related to geological conditions include exposed bedrock, glacial deposits (including exposed glacial till and boulders), and very soft fine-grained sediments. Based on these conditions, the suitability of various foundation concepts is discussed. Other conditions include ocean usage, from fishing activities to vessel traffic. This paper will highlight potential geohazards and provide developers with an understanding of geological and geotechnical conditions in the call area. Understanding of geologic and geotechnical conditions will aid in feasibility assessment for floating wind developments within the Gulf of Maine call area.