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Marine licence to dispose dredged material off the coast of south Wales

  • Contrary to some recent statements reported in the media, the dredged material is not radioactive waste. It is sediment from the Bristol Channel sea bed at the Hinkley Point C power station site
  • When assessing a marine licence, we consider the protection of human health, the environment and ensure activities do not interfere with legitimate uses of the sea
  • Before we issued the licence in 2014, sediment samples were tested in line with international guidance. Results showed the material was suitable for disposal at sea, having been independently assessed by Cefas[1] to ensure it did not contain any unacceptable levels of chemical or radiological contamination
  • Samples of the sediment have been tested again in 2017, to comply with conditions in the licence.  These samples were tested in the same way as the 2014 samples
  • We are confident that the results of the 2017 sample analysis again show the material is safe for disposal

What is the marine licence for?

The marine licence is to dispose dredged material from the sea bed at Bridgewater Bay in the Bristol Channel, into the Cardiff Grounds Disposal Site. This is an established disposal site for marine dredged materials off the coast of south Wales.

The source of the sediment is from the construction site of the Hinkley Point C power station off the Somerset coast in England.

Every element of the application was considered thoroughly. With the right Marine Licence conditions in place, we’re confident the proposed activity will not harm people or the environment.

We granted the licence in July 2014.

What environmental assessments were made before the licence was granted?

The applicant was required to undertake a chemical and radiological assessment of the dredge sites.

Chemical contaminants were assessed against Cefas Action Levels[2], UK guidelines to assess dredged material and its suitability for disposal to sea. The Radiological Assessment followed the conservative generic radiological assessment procedure developed by the International Atomic Energy Agency.

Cefas concluded that the material tested did not have unacceptable levels of chemicals or radiological materials and was suitable for disposal at sea.

We consulted with the Environment Agency (EA) as the lead regulator for Hinkley, and we both agreed it was a robust assessment of the radiological impacts and agreed with Cefas’s conclusion.

Why were deeper samples not tested?

NRW, the EA and Cefas were satisfied that data included with the application of deeper samples collected and tested in 2009 were still valid. As the material at depth would not have changed since this time, these results were considered in our determination, along with samples taken in 2013.

There is no scientific evidence of higher radioactivity in deeper sediments in the Hinkley Point area. Radiological monitoring of sediments at Hinkley Point is undertaken each year and results published annually in the Radioactive in Food and the Environment[3] report.

What are the conditions in the licence that ensure that people and the environment are protected?

Samples of dredged material are tested every three years to meet international guidelines. The licence required the licence holder to submit a new sampling plan for our agreement if they wished to deposit dredged material after March 2016, when the original sample data would be three years old. The licence prohibits any disposal after March 2016 without our written permission, to allow us to act should the new sample results raise any concerns.

We agreed a new sample plan with the licence holder in January 2017, following advice from Cefas. The new plan also required a chemical and radiological assessment of the samples.  This assessment has now been completed and we received the sample results in December 2017. We consulted with experts, including Public Health Wales, on the results of the latest analysis and are satisfied that the results show that the material is safe for disposal with no risk to people or the environment. 

The licence holder has an obligation as part of their licence to survey the disposal site before and after disposal to ensure the sediment they deposit has dispersed.  More details can be found in this survey plan.

What radionuclides were tested for?

All potential gamma emitting radionuclides (both naturally-occurring and artificial) in a sample, in the energy range (i.e. 60keV to 2MeV), are simultaneously scanned to identify and determine their concentrations. We have provided a list of potential gamma emitting radionuclides. Some radionuclides have multiple "line spectra" (column C) and this is why there are duplicate lines for individual radionuclides (column A).


If you would like further information on the licence, please email

Updated 06 June 2018 


[1] Centre for Environment, Fisheries and Aquaculture Science

[2] Cefas Action Levels. Marine Licensing: sediment analysis and sample plans. GOV.UK. 11 October 2016

[3] Radioactivity in Food and the Environment report 2015. GOV.UK. 27 October 2016.

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