Review of Cabling Techniques and Environmental Effects Applicable

Review of Cabling Techniques and Environmental Effects Applicable to the Offshore Wind
Farm Industry – Technical Report
such, would be unlikely to venture close enough to the cable burial vessel to
become entangled. A review of relevant published literature and discussions
with installation contractors has not identified any reports of marine mammals
of any kind becoming entangled during cable burial operations.
5.6.2 MITIGATION MEASURES
Visual and other construction related disturbance, in relation to hauled out seals,
can be effectively mitigated by avoiding cable installation operations in the
vicinity of known haul out sites during sensitive periods, such as the breeding
season (late June to early July for common seal and late July to early December
for grey seals (although this varies with position around the UK). Wherever
possible, seal haul out sites should be avoided during the planning of the cable
route in order to completely remove the potential for disturbance to occur.
Further study is required to assess the noise levels produced by the range
of available cable burial devices and tools in the types of seabed sediments
encountered in UK waters. This can be achieved through real time monitoring
of cable installation, such as at North Hoyle, or through specific experimentation
and computer modelling. Only once sufficient, reliable data is available can
the disturbance caused by cable installation be understood and effectively
mitigated. As a precautionary measure, given the conservation significance of
the species involved, it may be necessary, as a minimum, to employ Marine
Mammal Observers on the installation vessel and to have a protocol in place
to delay installation activities from occurring if marine mammals are detected
within a predetermined distance from the installation vessel. Such a need would
be identified through consultation with the relevant nature conservation body
and the JNCC (JNCC, 2004).
5.7 Ornithology
Concerns and issues relating to birds, in the context of offshore wind farms are
primarily concentrated on the wind turbine array. The installation of both the
export and inter-array cabling is of significantly lower concern.
Potentially significant effects of cable installation on birds are limited. The main
area of concern would be:
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Disturbance of normal behaviour in the intertidal; and
Disturbance of normal behaviour at sea.
Other effects on birds would be limited to:
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Prey availability.