EVIDENCE suggests mud dumping from Hinkley Point C power station at Cardiff Grounds is sustainable, as sediment has been demonstrated to disperse over time, Natural Resources Wales (NRW) has said.

The environment watchdog was responding to comments by Barry and Vale Friends of the Earth, who say they “embarrassed” NRW with a recent freedom of information request.

A response to the request revealed that materials were detected on the seabed within the dump site off the Vale coast in April 2019 – six months after initial dumping.

“This clearly shows NRW was wrong in claiming the Hinkley excavated material would disperse in the currents,” said member of Friends of the Earth Max Wallis.

The information relates to results of a survey conducted by Titan Environmental Surveys Ltd in April 2019.

The 12 samples collected were analysed, and Friends of the Earth say compared with pre-dumping levels the samples showed both coarse gravel and clay remained from the dumped material, but NRW says that is misleading.

“Based on current evidence, we believe Cardiff Grounds disposal site is operating as a sustainable marine sediment disposal site as material has been demonstrated to disperse over time," an NRW spokesman said.

“We acknowledge that some of the material deposited on behalf of EDF in 2018 from the foreshore of the Hinkley Point construction site is different to the makeup of the marine sediment that others are licenced to dispose there.

“However, this is only a small percentage of what the site received during the monitoring period and would not be expected to change the nature or behaviour of Cardiff Grounds.

“Neither can you attribute the areas identified in the disposal site monitoring report to be from EDF’s disposal activity in 2018.”

Campaigners have called for the project to be looked at again by the Welsh Government, with a "thorough environmental impact assessment" to test the levels of plutonium in the sediment ahead of a second disposal in 2021.

A spokesman for EDF said: “Samples are now being taken for analysis ahead of a planned second phase. This work is expected to take around six weeks to complete, depending on the weather and tides.

"Further dredging is needed ahead of the drilling of six vertical shafts for the cooling water system, along with the installation of a fish recovery and return system and maintenance dredging at the jetty.

"The mud is no different to mud found elsewhere in the Bristol Channel. In order to further reassure the public, our sampling and monitoring plan will go above and beyond internationally recognised best practice, with more samples at greater depth and with a greater range of analysis - including tests for pure alpha emitting particles and tritium."