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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4 Physical change<br />
4.1 Introduction<br />
The purpose <strong>of</strong> this section is to describe <strong>and</strong>, as far as is possible, quantify<br />
the fate <strong>of</strong> sediment disturbed when the cable burial techniques described in<br />
Section 3 are employed in a range <strong>of</strong> varying seabed conditions. It addresses the<br />
physical nature <strong>of</strong> the change but not the potential effect on parameters which<br />
is covered in Section 5.<br />
The key parameters that will affect the volume <strong>of</strong> seabed sediment disturbed,<br />
brought into suspension, dispersed in the surrounding sea area <strong>and</strong> finally<br />
re-deposited on the seabed during cable burial operations are:<br />
●<br />
●<br />
80<br />
The cable technique being used; <strong>and</strong><br />
The site conditions i.e. seabed type, tidal <strong>and</strong> wave conditions.<br />
This appreciation <strong>of</strong> the extent <strong>of</strong> the physical disturbance resulting from cable<br />
burial operations enables the environmental impacts discussed in Section 5 to<br />
be placed in context.<br />
The main parts <strong>of</strong> this section cover:<br />
● Section 4.2 outlines the site conditions that can influence the type <strong>of</strong><br />
equipment necessary for cable burial.<br />
● Section 4.3 discusses the level <strong>of</strong> sediment disturbance that is likely to occur<br />
when cable burial is undertaken with the range <strong>of</strong> techniques discussed in<br />
Section 3 <strong>and</strong> the ground conditions defined in Section 4.2.<br />
● Section 4.5 discusses the dispersal <strong>and</strong> re-deposition or settlement <strong>of</strong><br />
sediment brought into suspension. This section also covers methods available<br />
to quantify the dispersal <strong>and</strong> settlement <strong>and</strong> discusses recent experience<br />
from the UK <strong>of</strong>fshore wind farm industry.<br />
4.2 Site Conditions<br />
4.2.1 SEABED CONDITIONS<br />
The geology <strong>and</strong> geomorphological characteristics <strong>of</strong> the seabed will determine<br />
the type <strong>of</strong> sediment disturbed during the cable burial operations <strong>and</strong> will also<br />
have a significant influence on the type <strong>of</strong> equipment used for these operations. A<br />
good underst<strong>and</strong>ing <strong>of</strong> seabed conditions is, therefore, required for engineering<br />
planning <strong>and</strong> to assess the environmental impacts <strong>of</strong> the burial operations.<br />
The ground conditions that will be encountered during cable burial may<br />
comprise a range <strong>of</strong> material sizes from fine to coarse sediments <strong>and</strong> rock.<br />
To aid underst<strong>and</strong>ing <strong>and</strong> provide consistency, soil <strong>and</strong> rock types discussed