Stephenson Street flood scheme

Overview

 Update 10 July 2023

Over the last six months our contractor, Alun Griffiths, has been working hard on the construction of the flood scheme at Lliswerry. Here’s a summary of the work that has been completed so far:

Vegetation clearance

Vegetation clearance along the length of the flood scheme from the northern extent in Coronation Park to Liberty Steel in the south has now been completed. This clearance work has allowed our contractors to commence the sheet piling section of the flood defence.

Sheet piling work

Sheet piling work along the River Usk began in April and is scheduled to be finished by late August 2023.

Sheet piling is a type of deep foundation used in construction work. The sheet piles used are recycled and renewably produced steel sections that are driven to a set depth into the ground. They have interlocking edges and fit together to form a structurally sound wall or barrier. They do not result in damage to the surrounding ground, unlike bored or contiguous concrete piling.

The sheet piles have been inserted using a hydraulic Giken press which has helped to significantly reduce the vibrations and noise disruption to local wildlife and industry.

Creating a new route for local businesses around the Felnex Industrial Estate

Preparation work for the raised section of the highway off Eastbank Road is underway. The new highway is due to be completed in Spring 2024. This will provide an alternative route for road users in the area, should the floodgate on Corporation Road be operated for maintenance purposes or prior to anticipated peak tidal flows. 

Improvements to the Wales Coast Path

Work has begun on the Wales Coast Path to improve the public footpath; this will enhance the route visually and offer greater accessibility.  

This aerial drone footage show the progress that has been made on the new flood scheme so far: 

https://vimeo.com/849458461/cab0d2f7fa

What’s happening next?

Enabling works in the form of a sewer diversion in Coronation Park is due to start in July 2023 prior to commencing embankment improvements within the park.

The reinforced concrete wall base has commenced adjacent to Hansons’ off Eastbank Road. Work is progressing towards the Marshalls’ site boundary in the coming weeks.

Sheet piling installation using the Giken method is underway from the Hanson’s conveyor towards Coronation Park.

The alignment of the new road is progressing via ‘box cutting’. This operation removes the unsuitable soils & subsoils, allow for placement of granular material to provide a suitable foundation.

Material retrieved from box cutting is being used to surcharge an area termed ‘the carousel’. The carousel is to be a section of heightened road in the shape of a letter ‘C’ that allows the flood wall to transition beneath. This surcharge places additional weight to the area consolidating the low-grade clays below, therefore improving their bearing capacity to construct the road and flood defence upon, with reduced further ground improvement intervention.

The vegetation strip along the ‘railway wall’ area, adjacent to Sloblands Lagoon, Liberty Steel is complete and ground preparation is underway to construct a flood wall and associated access track.

Update 09 January 2023  

Natural Resources Wales (NRW) has successfully appointed Alun Griffiths as the main contractor to carry out the construction for the new flood defence scheme for Liswerry Newport, with work set to get underway in the Spring. 

The scheme will reduce flood risk to over 2,000 properties and involves bolstering parts of the existing 1350m flood embankment along the eastern riverbank and constructing new flood walls, a section of highway and a flood gate.

Vegetation clearance along the length of the scheme from Coronation Park to Liberty Steel will begin in February. Enabling works for the raised section of highway is due to commence in March with highway cutting and sheet piling works programmed to start in April.

The work is expected to continue through to the end of summer 2024.

Flood risk in Liswerry, Newport

Map showing properties at risk of flooding with and without the proposed defences

Homes and businesses in Liswerry are vulnerable to flooding from the River Usk during periods of heavy rainfall and high tides. Leisure amenities and infrastructure such as the A48, Newport International Sports Village, Newport Stadium and Dragon Park are also at risk.

There is an existing flood bund along the River Usk between Stephenson Street and Corporation Road, but this is old and no longer fit for purpose.

Many of the businesses in the industrial estate which runs alongside the river already experience small scale flooding from low points along the river bank – most notably during Storm Dennis in February 2020.

Without intervention, we estimate that a flood could overtop the existing bund and cause significant damage to homes and businesses in the area in the future.

The industrial estate is a key contributor to Newport’s employment and economy. A large-scale flood in this area could have a disastrous impact on the local economy and community.

The cost of a significant flood affecting the area is estimated at £230m.
 

Proposals for new scheme

The existing flood bund stretches 1,350m along the eastern embankment of the River Usk.

The proposals recommend raising parts of the existing earth embankment. In other areas, new flood walls will be constructed to raise the defence to the required level.  

A new flood gate is also proposed for Corporation Road, along with a new stretch of highway to improve access to the industrial estate when the flood gate is closed.

Outline of scheme proposals. View the PDF file for full details.

Improvements to riverbank defences

• A 240m stretch of the existing bund through Coronation Park will be raised.
• A 590m stretch of the existing bund to the south of Coronation Park will be raised and upgraded with a new sheet pile wall.
• A 640m stretch of new concrete wall through the Felnex industrial estate.
• Minor localised ground raising of the Stephenson Street highway to maintain the required defence level, as well we two other areas of localised raising of the top of the river bank further to the north.

Installation of new flood gate

• A new flood gate will be installed across Corporation Road where it passes beneath the railway bridge to be closed ahead of any forecasted major flood events. 
• A new 700m long stretch of highway will connect the current dead-end of Corporation Road to the Felnex Industrial Estate allowing traffic to exit Corporation Road when the flood gate is closed.
• Two new short lengths of concrete flood wall in private industrial land in the south of the scheme.

Standard of flood protection and climate change

The proposals would increase flood protection to a one in 200-year flood event standard (this refers to a significant event which has a 0.5% chance of occurring in one year or a 63.3% chance of occuring in 200 years). This is in line with the Severn Estuary Flood Risk Management Strategy.

The proposals have been developed with climate change in mind, accounting for sea level rise and the predicted increased in rainfall over the next 50 years. We estimate that over 1,100 homes and 1,000 businesses would benefit from reduced flood risk as a result of the scheme, taking into account future climate change predictions.

Landscaping and public space enhancements

Visualisation showing proposed Wales Coast Path footpath upgrade. 

The existing flood bund is a public footpath and also forms path of the iconic Wales Coast Path. NRW is responsible for managing and promoting the Wales Coast Path and understands the value it brings.

The proposals will require a very minor realignment of the Wales Coast Path in some areas to allow for the raising of the existing bund and the installation of a new sheet pile flood wall.

Our plans include upgrading the affected section of the Wales Coast Path, as well as improvements to the green space at Coronation Park.

A new path will be created within Coronation Park to provide better connection between  the riverside  and the sports pitches, creating a circular walking route. Viewing platforms will be integrated into the embankment to allow for resting areas and provide a connection with the riverside habitats.

Tree and wildflower planting will be provided within the park to increase local biodiversity, in addition to three urban forests providing around 1,600 new, young trees.

Additional bins will be installed to reduce litter and dog waste and new interpretation boards providing information on the project, biodiversity and heritage of the area.

Visualisation showing proposal for sheet pile wall and Wales Coast Path footpath upgrade.

Environmental considerations

The River Usk at this location is a Special Area of Conservation (SAC) and Site of Special Scientific Interest (SSSI) and extends from the river to the crest of the embankment. Parts of the embankment are also Sites of Importance to Nature Conservation (SINC) for their habitats.

Shad, a species of fish, are a feature of the SAC and are sensitive to vibration.

Historical records also show a number of protected species in the area – including Schedule one birds, otters, bats and barn owls. Surveys have also identified potential habitats for water vole, dormouse, badger and great-crested newt.

Extensive species-specific surveys within a study area have confirmed that these are not likely to be found or breeding within the affected works area. Trees near the scheme were further investigated for bat roosting potential in May 2021 and work adjacent to one tree shall be undertaken under an agreed Precautionary Method of working to reduce the potential for disturbance.

Construction of the scheme has been planned to minimise the impact on any sensitive species and habitats to ensure there is no permanent loss to protected habitats. Techniques such as ‘silent’ hydraulic machinery will be used during construction in sensitive areas to minimise noise and vibrations. The location of the proposed defences is far enough away from the river (>40m) to avoid the potential for any vibration effects on fish during their migration season.

Despite sensitive design, we’ve identified approximately 650 trees and shrubs that will need to be removed during construction. An assessment of these has identified the majority to be low value, self-seeded and stunted trees and shrubs. To mitigate e for this, we plan to replant approximately 1,600 new, young trees creating three ‘urban forests’ primarily at Coronation Park.

Outline of landscaping proposals. View the PDF file for full details.

More information about how we have considered the impact on the environment can be found in our planning application documents (scroll down for attachments).

More information

If you’d like more information about the scheme please get in touch by emailing stephensonstreet@naturalresources.wales 

What happens next

The contract tendering exercise has now been completed. Work is estimated to begin on site early 2023.