Review of Cabling Techniques and Environmental Effects Applicable

Cable types and installation techniques
manner which allows the barge to tow the plough whilst hauling on the deployed
anchor array until such time as the slack is taken up on the anchor wires and the
anchors have to be repositioned. The frequency of change of anchor positions
will be dependent on a number of factors such as water depth, predicted tow
forces and the size of barge etc. However, as a typical guide on a number of wind
farm projects undertaken to date, a burial length of between 100m and 200m
has typically been achieved on a single set of anchor deployments before the
anchors have to be repositioned. The deployment of anchors must be carefully
monitored and controlled whilst in the vicinity of other cable or pipeline systems
as would typically occur at a pipeline or cable crossing location to avoid any
potential damage to such existing infrastructure.
3.9.2 CABLE CORRIDORS FOR EXPORT CABLES
It is standard practice for the export cables from an offshore wind farm to
be consented to be installed within a cable corridor. The cable corridor may
typically be 500m to 600m wide of the centreline of the planned cable route and
provides the wind farm developer and cable installation contractor a degree of
flexibility to cope with the following:
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Avoidance of any localised obstructions such as wrecks etc. which do not
appear on Admiralty Charts but are discovered in later surveys specific to the
project;
Localised areas of difficult ground conditions where burial may prove difficult.
For example small rock outcrops, boulder formations or glacial till outcrops;
and
Routing of cables within the corridor limits to follow the troughs of sandwaves
in areas where mobile seabeds are known to exist.
3.9.3 CABLE INSTALLATION ON OFFSHORE WIND FARMS TO DATE
This section of the report contains cable installation information for offshore
wind farms which have been installed to date. It should be noted that only
limited information was available for a number of sites listed in Table 3.16.
Supplementary information has been obtained from additional news items and
data published on websites and with reference to articles which have appeared
in the technical press. Therefore, the assembled data is a collection of market
information from a wide variety of sources.
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