Why does Cardiff need an improved sea defence?

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Cardiff's need for enhanced sea defence is driven by the growing threat of flooding due to rising sea levels and severe weather patterns. The Rhymney River, a key watercourse and a designated Site of Importance for Nature Conservation, poses a severe flood risk. Without a new and improved flood management system, local communities and businesses face increased danger. Erosion has compromised existing defences, and a new scheme will provide protection for the next 100 years, safeguarding 2,326 properties and 204 commercial sites, including critical transport and utility infrastructure.​

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Who says that parts of Cardiff may flood? Where's the evidence?

Forecasts of future climate conditions in the UK highlight increasing flood risks due to climate change, particularly in coastal areas. Cardiff, located by the River Rhymney and the Severn Estuary, is vulnerable. Historical erosion of defences, visible in different site areas, underscores the urgency for robust new sea defences to protect the city from flooding.

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Does the previous flood defence really have to be improved?

Most definitely! The rock armour revetments, sheet-pile walls, earth embankments, and block stone defences originally placed are no longer capable of preventing flooding. Parts have completely eroded, and what is left is significantly damaged and could not provide protection from the higher sea levels.

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What's at risk exactly? 

Local homes, businesses, critical infrastructure, and the travellers' site are all at reduced risk of flooding. The flood defences will protect 2,326 properties and 204 commercial sites from severe storms and tidal surges.

 

What precise area are we talking about for the work? 

The proposed flood defences will cover the coastline adjacent to Rover Way and the tidal reaches of the west bank of the River Rhymney to just beyond the Lamby Way roundabout.

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What benefits will we see as a result of the work?

Improved coastal defence systems will effectively manage flood risk and infrastructure erosion. The project aims to protect 2,326 residences and 204 commercial properties, maintain wildlife habitats, and apply varied materials and methods for optimal site protection. This initiative ensures Cardiff's resilience against rising sea levels and upholds the safety of local businesses and homes.

 

Who is involved with the project?

The project is managed by Cardiff Council, with oversight from the Welsh Government. Knights Brown, a company specialising in coastal protection work, will execute the construction of the defences.

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What improvements are being made as part of the work?

In the past, flood defences along the Severn Estuary and the River Rhymney included rock and earth

structures. These defences are eroded, no longer providing effective flood protection and are highly vulnerable to failure, especially as sea levels rise. The project will enhance and expand these defences along the coastline from Cardiff East Waste Water Treatment Works to the Lamby Way landfill site, aiming to prevent breaches, reduce erosion, and protect critical infrastructure.

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This scheme will improve and extend the coastal and fluvial defences along the coastline from the

 

Dwr Cymru Welsh Water (DCWW) Cardiff East Waste Water Treatment Works (WWTW) and upstream along

 

the west banks of the River Rhymney. It is anticipated that the project will:

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- prevent breaches of the existing defences

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- reduce erosion and flooding of critical transport, waste management, and energy infrastructure located

 

  immediately landward of the scheme.

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- Protect large residential and commercial areas located further inland, away from the coast and riverbanks

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Who will carry out the maintenance?

Once completed, Cardiff Council will be responsible for any maintenance requirement, including occasional repairs, vegetation management, and necessary inspections over the 100-year design life.

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How will the natural habitats for wildlife in the area be affected by this project?

The project will affect intertidal habitats, salt marsh areas, and the River Rhymney mudflats. Though some disruptions will occur, mitigation efforts include habitat compensation and bio-engineering for erosion control. The project strives to blend the defences with the natural environment over time, reducing visual and environmental impacts. All work will be undertaken in line with approved environmental management plans.

 

How will the Coastal Path and Public Rights of Way be affected?

During the construction phase there will be some disruption while parts of the riverbank are excavated. Information on any diversions to the coast path can be found here: Wales Coast Path / Temporary Path Diversions

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Impact on Residents and Businesses:

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How will construction affect businesses on the west end of the site?

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The majority of the construction work will be concentrated near the beach, creating a significant buffer area between the construction activities and public spaces. While there are businesses nearby, the impact on them is expected to be minimal due to this buffer.

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What construction effects can residents in the Ffordd Pengam area and Eastern Tremorfa anticipate?

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In these areas, construction will involve the installation of 19-meter sheet piles and earthworks, which may result in noise and vibrations. A thorough noise and vibration study will be conducted throughout the project to ensure compliance with current guidelines.

 

Impact on Traffic:

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How will traffic be affected on Rover Way and Lamby Way?

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Construction will require temporary lane and road closures on Rover Way and Lamby Way to accommodate heavy machinery. While efforts will be made to minimize disruption, some traffic management will be necessary to safely complete the flood protection works. We will provide advance notice of any road closures or traffic changes throughout the project.

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Community Engagement and Communication:

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How will stakeholders and the community be kept informed about the construction progress and its impact?

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We are committed to maintaining open communication with all stakeholders and the community. Regular updates will be shared through various channels, including newsletters, social media and our dedicated web page, to provide timely information on construction progress and associated impacts.

 

Feedback from the community is vital, and we encourage residents and businesses to share their concerns and suggestions to help us mitigate impacts collaboratively. You can email the project team at cardiffcds@knightsbrown.co.uk.