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Subsea Dredging for Cable and Scouring Area Burial/Reburial

Subsea cable burial beneath the seabed tends to become the standard practice for offshore wind farms. Fishing vessel trawls and ship anchors are one of the main causes of damage to unburied subsea cables, particularly in Europe where wind farms are located on or near major maritime routes and fishing areas.

Initial cable burial is typically done using subsea trenchers or ploughs deployed from cable installation vessels. Trenchers (and ploughs) are very large, heavy and expensive pieces of equipment which uses various techniques (depending mainly on the nature of the seabed) to dig a trench which is typically 1 to 3m deep. They are usually mobilized in one single, intensive campaign to limit the costs.

Dredging Tools for Trench Completion:

The size and deployment mode of trenchers and ploughs may not allow them to trench over the last tenths or hundreds of meters around a wind turbine or substation. Lighter, more flexible and less expensive techniques are then needed to complete the job. We design, manufacture and deploy for that purpose ROV and diver-operated dredging and jetting tools. They can be deployed from light vessels, barges or even the wind turbine platforms themselves within reasonable timeframe and costs.

Dredging Tools for Reburial/Deburial of Cables and Foundations at Scouring Areas:

Scour is the displacement of soil, silt and sand on the seabed due to currents, tides and storms. It has a major impact on wind farm subsea facilities as it tends to create holes near objects laid on the seabed due to the acceleration of currents around them, resulting in the deburial of cables and fragilization of foundation base. Our dredging tools are particularly suited for the local reburial of cables and foundations subject to scouring.