Projected cost of Bridgwater tidal barrier balloons to £220m

The EA and Somerset Council have been working to deliver the tidal barrier across the River Parrett between the Express Park in Bridgwater and the neighbouring village of Chilton Trinity – a barrier which will provide protection to more than 11,300 homes and more than 1,500 businesses.

The barrier is in the early stages of construction, with the final business case awaiting its sign-off from the Treasury.

But the cost of this significant infrastructure project has risen rapidly over the last six months in light of high inflation and supply chain issues within the construction industry.

The tidal barrier was one of the major projects identified within the Somerset 20-year flood action plan, which was created in early-2014 in response to the catastrophic floods which hit the Somerset Levels and Moors in the winter of 2013/14.

The barrier will be constructed across the River Parrett between the Express Park and the neighbouring village of Chilton Trinity – with a footbridge running over the top to enable pedestrian and cycling access to both sides of the river.

A proposed design for the Bridgwater Tidal Barrier project. (Image: Environment Agency, Somerset Council)

The barrier will have two ‘vertical lift’ gates which can be closed to prevent water from flowing upstream during very high tides – something which would put Bridgwater and the neighbouring villages at great risk.

New flood defences will also be created downstream of the barrier to prevent flooding and protect numerous species, including eels and fish.

At the time the 20-year flood action plan was approved, it was estimated to cost between £27m and £30m in staffing time alone.

By the time the Treasury approved the outline business case in September 2021, the predicted cost of the barrier (including staff time and materials) was £99m.

This increased further to £128m by the time the initial access road to the construction compound off Saltlands Avenue was completed in June 2023 – a process which had been delayed after asbestos was discovered near the site.

The EA admitted in June 2023 that the cost of the barrier was “bound to increase” – with the EA’s Wessex regional flood and coastal committee putting the cost at an eye-watering £249m only a short time after this admission, blaming “a significant increase in risk allowance, inflation, and design and construction costs.”

The construction site. (Image: Daniel Mumby)

Since the summer of 2023, the EA has been working to bring the costs of the project down to £220m – still more than twice the amount the Treasury had originally approved.

A spokesperson said: “From now we expect to spend £150m on constructing the whole scheme. 

“In addition, in accordance with government guidelines on future inflation allowances, and industry-standard risk strategies, we will allow £70m for risk and contingencies.

“The majority of the funding will be provided by central government mainly through flood defence grant in aid (FDGiA), with approximately ten per cent being provided by partners including Somerset Council (through CIL and the Bridgwater town deal), the Heart of the South West Local Enterprise Partnership (LEP), the Wessex regional flood and coastal committee, the Somerset Rivers Authority (SRA) and the Department for Education.”

The Bridgwater town deal is providing £23.2m for numerous regeneration projects, such as the regeneration of the Northgate Docks, the delivery of the ‘celebration mile’ and upgrades to the Dunball roundabout – with an unspecified amount being allocated to the tidal barrier.

Sedgemoor District Council confirmed in March 2021 that £1 in every £5 of community infrastructure levy (CIL) from new housing developments within the (now former) district would be allocated to the tidal barrier.

The EA’s current estimates assume that inflation in the construction industry will remain at seven per cent until 2029 – meaning the cost could continue to fluctuate depending on the cost of concrete, steel, energy and labour.

An aerial shot of the Bridgwater Tidal Barrier site in September. (Image: Somerset by Drone)

The Wessex regional flood and coastal committee – which most recently met in Weston-super-Mare on Wednesday morning (January 17) – estimates that £35m has already been spent on the barrier project.

It estimates that a further £156,245,638 will be spent on the project between now and April 2030 – though the majority of this is earmarked to be spent before April 2028.

The Treasury has yet to sign off on the final business case – but the EA said it was confident this would happen before the end of the year.

A spokesperson said: “Our programme allows for the final business case being approved by the autumn of 2024. We aim to have an operational barrier in early-2027.”

Rachel Burden, the EA’s Wessex area flood and coastal risk manager, provided a further update when the SRA board met in Bridgwater on Friday morning (January 19).

She said in her written report: “Construction of the access track to the barrier site and the site compound are now complete. Work to extend the haul road access to the local downstream defences is currently being constructed.

“A major milestone was reached in September 2023 with the driving of test piles, the data from which is being used to refine the scheme design and construction methodology.

“The project team are scoping further enabling works, with the focus being on critical path activities in the project programme. This will mean construction of the barrier and the downstream tidal bank improvements can make rapid progress after the Treasury approves the full business case, which was submitted in September 2023.

“Discussions are well underway at the highest level within the EA, Defra, and the Treasury to ensure any additional funding required is secured to deliver an operational barrier by early-2027.

“The protection to 12,800 properties that this flagship scheme will deliver, along with £2bn of benefits for the local area, mean it remains a hugely positive asset for the town, with the EA expecting to achieve £7.50 of benefits for every £1 spent.”

An artist's impression of the tidal barrier. (Image: Somerset Council)

Until the Treasury signs off on the final business case, the EA’s contractors will focus on the downstream infrastructure east of Straight Drove, clearing the necessary land within the Express Park and beginning to construct the temporary bypass channels (into which the river will flow while the barrier’s foundations are constructed).

A spokesman for the EA said: “To enable construction of the barrier itself we will construct the temporary bypass channel in 2024, starting with installing steel sheet piles in the spring.

“We also plan to drive steel sheet piles into the bed of the River Parrett to create a cofferdam within which the barrier will be constructed.

“Tubular steel piles will then be driven inside the cofferdam and these will support the concrete base slab of the barrier itself.”

For more information on the tidal barrier project, visit www.somerset.gov.uk/beaches-ports-and-flooding/bridgwater-tidal-barrier.