Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
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Potential impacts <strong>and</strong> mitigration measures<br />
experts. Information can be found on the Marine Life Information Network<br />
(MarLIN) website (http://www.marlin.ac.uk) <strong>and</strong> the UK Marine SAC Programme<br />
website (http://www.ukmarinesac.org.uk/marine-communities.htm) that provide<br />
detailed information on the sensitivity/intolerance <strong>of</strong> many key features <strong>of</strong> the<br />
marine environment. However, it should be noted that the knowledge base for<br />
determining sensitivity <strong>of</strong> species is limited <strong>and</strong> research is needed to increase the<br />
confidence in such predictions. Many <strong>of</strong> the species in the marine environment<br />
are likely to have some degree <strong>of</strong> tolerance to increases in suspended sediment<br />
in order for them to adapt to natural perturbations <strong>and</strong> are therefore likely to<br />
survive localised short term effects.<br />
A prolonged increase in suspended sediment concentrations can affect the<br />
penetration <strong>of</strong> light through the water column affecting the photosynthetic<br />
activity <strong>of</strong> macroalgae, phytoplankton <strong>and</strong> eel grass. This is unlikely, however,<br />
during the installation <strong>of</strong> cables, as suspended sediment is only a very localised<br />
short term effect.<br />
As the material settles out <strong>of</strong> suspension, it can cause smothering to sensitive<br />
species <strong>and</strong> can change certain habitat characteristics. Studies outlined in Section<br />
4.5.2 show the potential for settlement in site specific situations <strong>and</strong> generally<br />
conclude that the extent <strong>of</strong> the settlement will depend on the factors outlined<br />
above but, in general, the effect is expected to be short term <strong>and</strong> localised with<br />
one example showing settlement ranging from 20m up to a maximum <strong>of</strong> 200m<br />
either side <strong>of</strong> the cable, dependent on the state <strong>of</strong> the tide (Norfolk Offshore<br />
Wind, 2002).<br />
5.2.3 OTHER EFFECTS<br />
Potential contamination due to sediment disturbance<br />
Consideration must also be given to the potential for contaminant remobilisation<br />
during cable installation activities due to disturbance <strong>of</strong> contaminated sediments.<br />
It is, however, less likely that high levels <strong>of</strong> contamination would be encountered<br />
away from the coast, unless the cable passes close to a historic or active disposal<br />
site. The screening/scoping process will identify if the cable route is likely to<br />
encounter potentially contaminated sites; in which case it would normally be a<br />
requirement to undertake sediment analysis prior to decision making relating to<br />
this aspect.<br />
Electro magnetic field generation<br />
Submarine power cables can generate electro magnetic fields (EMF) in the<br />
surrounding seabed <strong>and</strong> water. The potential impact <strong>of</strong> EMF on fisheries is<br />
discussed in Section 5.4.<br />
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