2002, Hayes-McKenzie Partnership, Gunfleet Sands Offshore Wind Farm, Noise Impact Assessment

Description

Hayes-McKenzie Partnership have conducted a comprehensive noise impact assessment in 2002 for the offshore wind farm at Gunfleet Sands, including in-air and in-water assessments. 
It is anticipated that sound pressure levels underwater during the development stage may be sufficient as to disturb the marine environment.  Once the wind farm is operational, as the turbine blades rotate, it is anticipated that vibrations could arise and these would be transmitted down the wind tower and in to the underwater environment.  Once again, subsequent noise levels could be sufficient to disturb marine life.
The extensive nature of this kind of activity requires that an assessment of the potential impact on the environment be determined.  
The first stage in determining the scale of any potential impact on the environment is to determine sound pressure levels underwater during the construction and post-commission phases.  This project reports on the findings from a number of computer model simulations using frequencies appropriate to both piledriving and wind turbine operations and for this, the underwater acoustic propagation computer program SAFARI has been used.
The modelling results show that the sound pressure levels during the piledriving phase are likely to remain above background noise levels over a range of 20km; sound pressure levels during the post-commission stage for most of the frequencies considered in the range 20-2000 Hz are likely to fall below background noise levels at ranges between 200m and 1000m.  The exceptions to this are the 400 Hz and 500 Hz components where the SPL is likely to remain above the background noise level at ranges up to 2.5km.  Although risks remain numerous and varied, they are generally considered manageable.