• Observing and modelling
• Marine Climate Change Centre (MC3)
• Ecosystems and biodiversity
• Assessing human impacts
  • Marine planning
  • Dredged marine sediments
    • Beneficial use
    • Managing contaminated sediments
  • Offshore renewable energy
  • Underwater noise
• Animal health and food safety
• Fisheries information

Dredged material being used to supplement habitat creation

Related links

• Our services: dredging and disposal
• Marine Management Organisation
• MMO: licensing dredged material disposal
• Marine and Coastal Access Act 2009

Dredged marine sediments

Dredging and the disposal of dredged material constitute some of the most important issues in coastal zone management.

By "dredged materials" we mean sediments or rocks with associated water, organic matter, etc removed from areas that are normally or regularly covered by water, using dredging or other excavation equipment.

In the UK, approximately 40 million tonnes of dredged material are annually disposed of to the marine environment at estuarine and offshore sites licensed by the Marine Management Organisation (MMO).

Dredging is essential:

• to maintain navigation in ports, harbours and marinas
• for the development of port facilities
• for flood mitigation
• for removal of sediments from structures, basins and water intakes.

Typically, about 80% of the material arises from maintenance dredging, to keep ports and harbours open and functioning.

Depositing dredged material

The greater proportion of dredged material is, by its nature, similar to undisturbed sediments in estuarine and coastal waters - that is, it is either uncontaminated or only slightly contaminated by human activity (at, or close to, background levels).

Under certain circumstances, the concept of the beneficial use of dredged material can result in solutions that satisfy the needs of industry, the regulator and society at large. It has been encouraged by the regulator for many years.

However, a smaller proportion of dredged material removed from estuarine and coastal waters may have been contaminated by human activity to such an extent that major environmental constraints need to be applied when considering the further use of such sediments or its disposal at sea. 

Appropriate management solutions for contaminated dredged marine sediments (CDMS) require a well-thought out strategy - covering legal, technical and socio-economic considerations.

The disposal at sea of dredged material may pose a threat to marine life if not properly controlled. In England and Wales it was first brought under statutory control in the Dumping at Sea Act 1974, with subsequent legislative updates over the years. The Marine and Coastal Access Act 2009 now enshrines the current legislative controls and requirements.

The rest of this section focuses on:

• case studies of beneficial-use schemes
• a study supporting strategy development for managing CDMS
• a specific GIS tool that provides information about levels of contaminants in marine sediments in UK waters.

For more information about our work in this area contact: regulatory_assessment@cefas.co.uk.