Extensive seabed levelling and dredging experience

To place a structure on the seabed securely, the seabed should be as flat and regular as possible. If the seabed is irregular or undulating, the structure, for instance, a pipeline, cable or offshore structure, will suffer the risk of spanning and overstressing.

The Seabed Solutions team has first-hand experience from dozens of seabed levelling and dredging projects over more than a decade world wide.

Seabed Levelling and Rock Dump

Seabed Solutions has executed several environmental clean-up, seabed levelling, dredging and trenching projects in Norway and globally.

Are uneven seabeds common?

Uneven seabeds occure rather frequently. Often caused by soft seabed materials, sensitive to underwater currents. Undulting seabeds can also be caused by hard seabed like rocks, boulders and gravel. Conditions like this can result in unexpected transitions where steep slopes appear resulting in sections of unsupported pipelines or cable called free spans.

The problem on free spans

Free spans are frequently caused by the turbulence or scouring action of water and sands. The result is ections of the pipeline that are not touching the seabed.

The result is pipeline or cable fatigue caused by increased vibrations and currents. Larger free spans can also cause misalignment between connectors and solutions must be found to compensate for the unevenness.

Seabed levelling and pre-trenching

Seabed levelling,pre-trenching or constructioning of rock bed and berms can be made to reduce  the stress on the free span areas.

Appropriate seabed levelling equipment

Our Seabed Excavator is  a remotely operated, compact, flexible and powerful 380kW subsea multipurpose tool carrier and have proved to be a highly efficient main tool in seabed levelling and rock dump operations.

The 14” ejector system is powered by 2x 135kW water pumps and  with the dedicated suction nozzle enable a production rate in sand, rock dump and other loose sediments.

The large ejector system copes with most debris possible to enter the suction hose and is equipped with a flush back unit for handeling blockage issues that may occur during  work.

The suction nozzle for the ejector is equipped with both gripper, ripper teeth and water jets for handeling challenges as debris and dissolving clay.

An array of water jets are fitted to the suction nozzle to achieve the water velocity required to disolve stiff clay. Combined with ripper teeth this method has a proved very effective to dissolve very hard soil.

 

Seabed Levelling