Document ID: chunk:federal_register_of_legislation:F2024L00930:reg:2:p27
Version: federal_register_of_legislation:F2024L00930
Segment Type: reg
Provision Reference: reg 2 (pt 27/48)
Character Range: 135751–138679

and gas platforms to transport personnel. Most of these infrastructure projects require pile-driving during construction, which involves driving piles (beams or posts) into the seafloor to support the foundations of the structure. This creates strong (e.g. dependent on hammer energy; 237 dB re: 1 μPa @ 1 m for 1000 kJ hammer) and predominately low frequency (< 1000 Hz) intermittent noise (Hildebrand 2009). Oil and gas developments also include other activities that contribute to anthropogenic noise, including trenching and pipe laying during construction, drilling, power generation and pumping during operation.
Associated with a greater understanding of the impacts of climate change on our environment, there is growing demand for sustainable, or green energy, to reduce our greenhouse gas emissions. Subsequently, there has been an increasing number of offshore wind farms and tidal turbines proposed, developed, and installed globally in recent years, predominantly in Europe. Australia is undergoing the development and installation of offshore energy infrastructure, regulated through the Offshore Electricity Infrastructure Act 2021. Most research of underwater noise impacts related to offshore wind energy has focussed on the construction phase rather than the operational phase, and particularly pile driving (Stöber & Thomsen 2021), which requires an assessment of impacts to southern right whales and appropriate management. Most of the energy of operational noise from offshore wind infrastructure is in the lower frequency range (i.e. below 1 kHz) and underwater noise levels from operational wind farms increase with the size of the wind turbines, expressed in terms of their nominal power output (Tougaard et al. 2020, Stöber & Thomsen 2021).

    3.4.2     Seismic surveys
Seismic systems use intense, impulsive sound to actively image geological structures below the seafloor and seismic surveys used for oil and gas exploration are a particularly intense source of noise when undertaken. Marine seismic surveys are a method of locating and describing marine oil and gas deposits. This is achieved by using air gun arrays towed behind ships to release air downward under pressure, producing powerful (up to 260 dB re: 1 μPa @ 1 m) and predominately low frequency (5 to 300 Hz) sound waves typically repeated in ~10 s intervals (Hildebrand 2009). Impulsive sounds such as these present a greater risk than most continuous sounds because of the high peak levels and frequent repetition. Note that while the level of the anthropogenic sound is usually reported at 1 m from the source as is standard, it is the level of the sound when received by the individual that is relevant for the whale (but this value is more difficult to determine). At lower received levels other responses may occur such as displacement and behavioural responses, such as increased social and feeding call rates as demonstrated in