Review of Cabling Techniques and Environmental Effects Applicable

Review of Cabling Techniques and Environmental Effects Applicable to the Offshore Wind
Farm Industry – Technical Report
Figure 3.25: Typical Detail for the Cable Crossing Arrangement using
Concrete Mattresses to Provide Separation and Cover
Rock dumping
Rock dumping is an established methodology for protecting subsea cables both
along their installed lengths and also at crossings with existing subsea cables
or pipelines.
Many of the major offshore rock dumping contractors such as Van Oord,
claim the technique is very resistant to both trawling and anchoring activities.
However, rock dumping is not generally favoured by fishermen who claim it sets
up a potential snagging point for their fishing gear. Furthermore, certain groups
see the introduction of substrates which are foreign to the locality as falling
into the category of undesirable. However, there is a counter review from other
groups who view the introduction of a new rock reef as a potential new habitat
for fish and other underwater species to colonise.
In shallower waters rock dumping is usually achieved either by the use of side
tipping vessels which deposit their cargo in a somewhat crude method that often
results in the need for larger volumes of rock to achieve the primary protection
method or by using a grab device which is illustrated in Figure 3.26.
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