energy during the minimum soft-start period does not exceed 2,300kJ and assuming the animal swims away from the sound source at the onset of piling (as per JNCC guidance (JNCC 2010)). The onset of auditory injury could also be considered unlikely for pile driving at the East Anglia THREE site using the higher hammer blow energies following the soft-start, as the animal would be expected to be beyond the predicted impact ranges from the pile, provided it flees the sound at the onset of piling as assumed by JNCC (2010). However, the effect of SEL dose may increase the risk over larger ranges;
Instantaneous injury (auditory and non-auditory) of fish is estimated to only be likely at ranges less than 250m from the pile, although the effect of SEL dose may increase this range. However, fish in very close proximity to the pile are likely tomove away from the pile during installation thus decreasing their SEL dose;
Pinnipeds may suffer instantaneous TTS and exhibit a fleeing response to the piling noise at ranges up to about 2.5km;
Low and mid-frequency cetaceans would not be expected to suffer instantaneous TTS or exhibit a fleeing response to the noise at ranges exceeding 500m from the pile;
Harbour porpoise may suffer instantaneous TTS and exhibit a fleeing response to the pile driving noise at ranges of up to about 8km from the pile;
Behavioural response/possible avoidance ranges, considered in this assessment as a more modest behavioural response compared to fleeing, are estimated out to about 37km to 70km from the sound source for harbour porpoise;
Mid-frequency cetaceans at the East Anglia THREE site could be considered to be likely to avoid ranges up to about 4km from the foundation and may possibly avoid the sound source at ranges up to about 12km, depending on the location of the foundation and the bearing away from the foundation;
Low-frequency cetaceans could be considered to be likely to avoid ranges up to about 20km to 35km from the foundation. Possible avoidance may be observed at a greater range around the foundation, of about 42km to 93km, depending on the activity of the animal, the location of the foundation within the site and the bearing away from the foundation, with the longer avoidance distance only occurring along limited transects from the source; and
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 9 Underwater Noise Page 10
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