Offshore wind turbine pile driving

When offshore wind turbines are installed, the large piles are hammered deep into the seafloor, which generates a lot of noise. To reduce the chances of causing harm to marine fauna, wind farm operators work with scientists and government agencies to understand how the sound from pile driving propagates through the surrounding seawater. Specifically, they look at how far away the animals would need to be to avoid either being injured (e.g. experiencing hearing loss) or experiencing a behavioral disturbance (e.g., will they become disoriented or confused? Will that affect their ability to find food, communicate, find a mate, care for their young?).

Here's a glossary of some of the terms and concepts included in the dashboard.

Foundation: The pile being considered for installation. This may be a monopile (a single pile) or a jacketed foundation (usually 3 or 4 legs). Monopiles may be more than 10m (30 feet!) in diameter. The piles supporting a jacketed foundation are also called "pin piles". They are generally smaller than the monopiles and may be "only" 3-5m in diameter.

Attenuation: The reduction in sound level (measured in decibels, or dB) that you might expect from a noise attenuation system (NAS).

Criteria: In this example, we're refering to the regulatory criteria being considered. Different criteria are evaluated for different possible effects, like hearing loss or behavioral disturbance. These criteria can get quite complex but overall the distinction to be aware of in this case is between injury and behavior. You'll notice that the impact ranges/distances can vary quite a lot between the different criteria.

Vibratory and Impact pile driving: These refer to different methods of pile driving. Impact pile driving involves essentially using a very large hammer to drive the piles into the seafloor, with distinct hammer strikes. Sometimes a pile will be installed with a combination of vibratory and impact pile driving. These two installation methods result in different "types" of sound. Vibratory pile driving is considered "non-impulsive" or "continuous", while impact pile driving is "impulsive" or "intermittent". This distinction becomes very important in the evaluation of impact ranges using different criteria for injury and behavior.