SCOUR FEATURE
FIG 1
FIG 2
MAINTENANCE ACCESS AND MAT REMOVAL
At some point during the life of the wind farm it may be necessary to remove the mats to access the cable (and they will certainly have to be removed when decommissioning the site).
The mats have been
designed with this in mind. Briefly, the mats are laid down in sections, and their positions recorded onto ‘As built’ charts. The mats are also fitted with polypropylene rope. If access to the cable is required, the mat or mats covering it are identified and located.
Whilst the forces acting on the mat would make it very difficult to lift (part of the reason for its stability), by fitting a spreader bar to the loops of rope at one end, the mat can be peeled (like a plaster) from the seabed, spilling the trapped sediment and reducing the mass and forces as it goes: thus making it much easier to complete the operation.
After the required O&M work is completed the removed mats can be replaced, all without disturbing the other mats or significantly increasing the risk of scour in the short term. Additionally, decommissioning will be more complete with the SPS mats because of this.
COMPARISONS
By comparison any rocks dumped will have been washed away, and a report published by IMCA October 2011 highlighted that the removal of concrete mattresses is proving problematical as they tend to decay overtime, making them difficult to lift effectively.
REDUCING COST, DECREASING RISK This novel approach to scour has the ability to significantly reduce costs of scour remediation and protection. The solution can improve overall protection for cables, reducing maintenance cycles, and has the longer term potential to reduce related insurance premiums through better control of the cable’s immediate environment.
Scour Prevention Systems Ltd
www.scourprevention.com
www.windenergynetwork.co.uk
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