Coastal flood defence scheme cost rises by almost £10m after delays

Mark Mansfield

The cost of a major coastal flood protection scheme has risen by almost £10m after delays and problems with ground conditions.

Cardiff’s Coastal Protection Scheme is now forecast to cost £45.5m, up from £35.9m, while its expected completion date has been pushed back by ten months from October 2026 to August 2027.

The project, which is now more than 70% complete, is designed to protect 1,116 homes, 72 businesses and the Rover Way Travellers Site from coastal flooding and erosion for the next 100 years.

Cardiff Council said delays in securing environmental approvals from Natural Resources Wales and the Welsh Government added around nine months to the construction programme.

Challenging ground conditions which required design changes and revised construction methods aimed at avoiding the complete closure of Lamby Way have also contributed to the increased cost.

Welsh Government funding remains fixed at £30.5m through support for borrowing over 25 years, while Cardiff Council approved an additional £10m capital allocation earlier this year.

The scheme is now entering its final major construction phase, with piling work alongside Lamby Way due to begin on October 5.

Temporary traffic signals will be installed between the Southern Way and Lamby Way roundabouts on the evening of September 20 and are expected to remain until late February.

The original construction plans would have required Lamby Way to close completely.

The work involves installing the final section of 12-metre-long sheet piles along the riverbank, which will form part of the barrier designed to hold back the River Rhymney during high tides and storms.

The single-lane closure will extend along Lamby Way, with temporary lights controlling traffic at the Lamby Way and Rover Way roundabout.

Traffic management staff will be stationed at key points from 7am to 7pm to monitor conditions and adjust the signal timings as demand changes during the day.

The project team intends to remove the temporary lights over Christmas, provided the work has reached a stage where it is safe to do so.

Following discussions with businesses and other stakeholders, the council investigated alternative methods of carrying out the work, including undertaking construction from the water.

That option was ruled out because of environmental restrictions, protected habitats and nearby nature reserves.

The council said it had instead sourced specialist piling equipment from Europe, with only one suitable machine available for the work.

Motorists are being advised to use alternative routes where possible because of expected congestion.

Site preparation will take place from September 21 to October 2 before piling begins on October 5 and continues until December 11.

Further work will continue into February, including installation of pile caps and handrails.

Major elements of the wider project have already been completed, including the installation of rock armour along the River Rhymney and work to raise and maintain sea defences on the western side of the river.

Work is also continuing to raise existing coastal defence embankments.

Strategic investment

Cllr Dan De’Ath, Cardiff Council’s cabinet member for climate change, strategic planning and transport, said: “The Coastal Protection Scheme is a major strategic investment that will help protect Cardiff’s coastline from flooding and erosion for generations to come.

“Flood risk can have a major impact on residents and businesses, including making properties more difficult and expensive to insure.”

The council said officers were continuing to look for savings, including potentially replacing a proposed riverbank stabilisation solution with a monitoring and intervention approach, subject to further technical assessment.

Cllr De’Ath added: “Council officers continue to explore opportunities to reduce costs while ensuring the scheme delivers its original objectives.

“We remain fully committed to delivering this scheme and ensuring it provides the long-term protection Cardiff needs, while achieving the best possible value for public money.”

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