Review of Cabling Techniques and Environmental Effects Applicable

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