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Structure Scour Mitigation

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Subsea structures placed on sandy soils are prone to a type of erosion called scour. Especially at sites with strong currents, accelerated erosion around a structure can occur due to the interference of the foundation on the local flow pattern and velocities.

The main issues associated with scour damage are:

  • Reduction of foundation stability
  • Settlement induced overstress on connectors and end terminations;
  • Pipeline free spanning
  • Fatigue associated with Vortex Induced Vibrations (VIV)

We have a long track record of successful scour mitigation projects that you can rely on.  Our range of engineered solutions to prevent scour are well tested and proven. Our engineers draw on these case studies to optimise a solution for every application, considering design life, budget, soil type and marine spread capacities.

Our technology tool kit includes: 

  • Articulated Concrete Block Mattresses (ACBM) to stabilise coarse aggregates and revetment walls.
  • Fronded mats which deliver active stabilisation, remediating and protecting against scour in transient seabed scenarios;
  • Coastmat – consisting of concrete mats backed by a specifically engineered geotextile, actively consolidating fine, silty soils beneath while preventing any sediment migration paths. 
  • GroutMatt – Grouted scour skirts providing a fast to install, in-situ grouted mitigation method that can integrate into the mud-mad of a structure.
  • ReefMatt – an ecologically enhanced block mattress which incorporates habitat features to boost marine life growing on the mattress.


The main method to prevent scour is to stabilize a filter layer by covering it with rocks or concrete weights in the form of articulation mattresses.

Subcon’s coastmats consist of a woven polypropylene base layer with the concrete blocks casted directly onto it.

Articulating mattresses take a large deck space on a vessel for installation and need a relatively large crane capacity to be installed.

Scour skirt take minimal deck space on the installation vessel and can be easily moved in position by ROV or diver.

The buoyant fronds in frond mats dissipate the wave and current energy close to the seabed.

The lower velocities have a lower transport capacity as a result, therefore collecting sediment from its surroundings. As such, these can be used to remediate existing areas of scour.

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