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Bridgwater Tidal Barrier; EA submits Planning Application via Transport and Works Act

The Environment Agency has recently submitted its application to build the Bridgwater Tidal Barrier through the Transport and Works Act (TWA). Its rather like a planning application to Sedgemoor District Council but in this case its to the Secretary of State.

The EA TWA submission repeatedly sets out 10 objectives for this scheme and this article examines whether the Barrier we are being sold does what the EA and SDC say is on the tin.

DOES THE BRIDGWATER TIDAL BARRIER MEET ITS OBJECTIVES?

Description

The scheme consists of two elements designed to keep the sea out of Bridgwater town centre for the next 100 years. Dunball and Bristol Road have to take their chances if there is a breach where as Chilton Trinity gets a second level of protection.

Ultimately the EA plan is to hand over the existing downstream fresh water habitat to the sea creating an inter-tidal habitat. The effect will be to bring the coast from the Steart Peninsula up to Dunball converting the existing farmland to mudflats and salt marsh.

The BTB consists of two elements.

  1. 7 miles of improved river banks that will be maintained for 20 years after the construction of the BTB after which that maintenance will cease and the frequency of the saltwater inundation on the land will be allowed with increasing frequency and the freshwater habitat poisoned.

2. A large reinforced concrete structure with two lift gates located in unconventionally inland and exposed to salt water with a large tidal range that causes one of the most corrosive mechanisms for this type of structure.

The EA / SDC / SRA Objectives

These objectives are presented with no basis as to how they were arrived, what the pass fail criteria is and the implications of not meeting the objectives.

  1. Reduce tidal flood risk to the highest number of properties and commercial businesses in Bridgwater and the surrounding are
  2. Reduce tidal flood risk to critical infrastructure and utilities in Bridgwater and the surrounding area
  3. Deliver a scheme that can be adapted for the future effects of climate change.
  4. Align the project with the strategy set out in the PEFRMS (see also Section 2.2).
  5. Align the project with the recommendations set out in the ‘Protecting Bridgwater and the Somerset Levels & Moors from Tidal Flooding, Flood Risk Management Review’ (Black & Veatch, 2014) (see also Section 2.2).
  6. Ensure the design and operation of the scheme aligns with Local Plan policy for development and does not restrict the future development of Bridgwater and the surrounding area.
  7. Ensure the design and operation of the scheme aligns with Local Plan policy for development and does not restrict the future development of Bridgwater and the surrounding area.
  8. Minimise the impact on environmental receptors during the construction and operation of the scheme. Deliver mitigation as required to protect those receptors that may be affected, whilst maximising positive environmental outcomes.
  9. Minimise health, safety and welfare risks associated with the construction, and operation of the scheme.
  10. Identify funding and partnership opportunities and outline any additional work to gain financial contributions.
  11. Develop a sustainable scheme that minimises future operation and maintenance.

The Test

Objective No 3; Deliver a scheme that can be adapted for the future effects of climate change

It is not stated what those effects of climate change are believed to be, the reader is therefore wrongly invited to presume that the only effect will be rising sea level whilst ignoring other potential changes to the environment and what provisions for adaption have been included in the design as the statement implies.

To illustrate that the EA has not met its own objective I have the following observations.

  1. In order to support this statement, there would need to be a set of assumptions and the concept as to how it might be achieved.in order to judge whether the statement was correct, and the objective met . No such statement exists in the submission.
  2. The stated position of the EA/ SDC/ SRA is no pre-investment for a future scheme; there is no plan B or provision in terms of reserving space for the construction of a new barrier behind or in front of the proposed one.
  3. The TWA submission implies that the structure would  be useful beyond its design life of 100 years and quotes a 1:1,000 return period as being available for flood defense. The BTB is a reinforced concrete structure and in the saline (seawater) environment of the River Parrett such structures do not do well and it  is likely that structure would need to be replaced rather than adapted.
  4. The indicated clearance between the barrier gates when lifted  and the underside of the access bridge shows no provision for taller gates needed to accommodate rising sea level beyond the design basis.
  5. The planned abandonment of the downstream River Parrett riverbanks some 20 years after the barrier structure is completed means that  the  secondary flood defenses ultimately become the primary flood defence and the future shoreline close to Bridgwater. Much of these banks particularly  adjacent to the A38 are founded on the near liquid clay that underlay the Somerset Levels. Nearby Cannington Bends with similar ground conditions continues to settle and the submission notes the need for it to be made up every 30 years or so. It is worth noting that the trial embankment test results do not form part of the supporting documentation. Higher banks will increase the risk of settlement or a breach occurring and triggering an event that the scheme is meant to stop.

There is nothing within the TWA submission to support the statement that the objective has been considered, addressed or met.

Objective 7; Ensure the design and operation of the scheme aligns with Local Plan policy for development and does not restrict the future development of Bridgwater and the surrounding area.

Bridgwater if it maintains its present level of growth in housing and employment will need to increase its footprint by 40% during the design life of the BTB. Much of the allocated land in the present Local Plan approved in 2019 is already under development with only the new Gravity Development at Puriton providing substantial employment land. The only other low quality land available for housing and employment , around 1400 acres strategically close to Junction 23 will be used by the BTB as an operational flood plain to take seawater when barrier is in operation.

There is no statement explaining what Objective 7 actually means or how the objective is achieved.

Specifically this proposal


  1. Denies the Bridgwater the economic benefit associated with developing land adjacent to a motorway junction (J23).
  2. Denies Bridgwater the opportunity to build some 5000 houses and supporting employment centers
  3. Forces future housing development to the south west of Bridgwater that will continue to increase the demand on on the A39.
  4. Increases the separation between residential and employment centres with housing moving to the south and employment to the north ans as consequence increasing the amount of commuting and demand on the road system that ultimately restricts economic development.
  5. the SDC 2050 transport strategy shows the Northern Bridgwater Bypass crossing the operational flood plain created by this scheme. Roads creates economic development and the Transport Strategy and BTB appear to have conflicting objective for the land to north of Chilton Trinity.

In summary

The location of the Tidal Barrier ignores the expansion of Bridgwater over the next 100 years showing no consideration for the planned expansion of the town. There is nothing in the BTB submission to indicate what considerations have made. The EA/SDC decision not to commission an Economic Impact Assessment means that statement cannot be substantiated and explains the lack of a coherent position on objective 7. The Objective is clearly not met.

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EA blocks early Bridgwater Bypass Route

In October 2019 the EA produced a plan to block off the only remaining early route for a Bridgwater Bypass. Despite being close to the A38 and having no village (Chilton Trinity) to consider material the EA has decided to dig another borrow pit rather than use locally excavated clays, material that is always available as part of local construction works primarily house building. That pit located in the only remaining place is where an early Bridgwater Bypass can go and the river is at its narrowest.

What this borrow pit means is that nothing can happen until EDF finish with the Park and Ride at Dunball.  This pit will see the taxpayer pay for a longer more expensive bridge and wait longer for traffic relief.

Bearing in mind that this borrow pit could be anywhere and is not actually needed as alternative supplies of suitable fill are always available the only logical reason for this location appears to be to ensure that SDC’s flagship Gravity development does not have any immediate competition. If that is not the case SDC councilors need to be explaining why economic opportunities are being blocked on their watch, why we are not building sustainably and not building in the most economical way.

Despite Sedgemoor District Council declaring a climate change emergency (Bill Revans instigation) the Bridgwater Tidal Barrier scheme continues to ignore any attempt to make this scheme sustainable and reduce cost.

Where is the scrutiny of this scheme by councilors?

Where is the sustainability?

What could be a better plan than to dig a very big hole where you might need to build a road?

annotated extract of SDC drawing showing bypass route and borrow pit
Original SDC/EA drawing showing pits to be dug.
SDC 2050 Transport Strategy map
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Somerset Flooding- A silver lining lost

A year or so ago  when Sedgemoor District Council (SDC) and the Environment Agency started work on  the Bridgwater Tidal Barrier  (BTB) scheme they jointly decided not to spend money on an economic impact assessment.

As  a result of that decision there is now no way for councillors, ratepayers and business to measure and benchmark the wider commercial and economic impacts of BTB project.  The project  is now simply valued and measured by government rules. This is especially important for those ratepayers and the HoW LEP who will directly pay for a proportion of this scheme.  For Somerset’s councillors there is no visibility of  the potential direct local (Somerset wide) benefit. With a preferred location agreed and the full details still yet to be seen or shown to the public it is difficult to see  how the Bridgwater Tidal Barrier  can be proceeding as it is.

There is a need to scrutinise the  EA’s proposed Bridgwater Tidal Barrier and its management of the delivery of the scheme. There urgently needs to be some form of independent peer review to support the decisions of councillors and EA employees who do not have suitable engineering qualifications and experience. No private company would do this.

The  River Parrett catchment  and its capacity affects much of South and Central Somerset; almost every town is on one of its tributaries. The wider opportunity that Somerset’s flood defence expenditure presents has to date been largely ignored and is in danger of being squandered. Sensible promises made in 2014 have been quietly allowed to disappear.

If you live within the Parrett Catchment or  in West Somerset this article will be worth reading for economic reasons alone.

River Parrett Catchment Area

By 2024 nearly £100M will have been spent on flood related work within Somerset and the majority of the money focused to the north and north west of Bridgwater. The EA’s  managed realignment at Steart Peninsula and the adjacent Bristol Ports property deal for it proposed container port that is of no economic benefit to Somerset sees nearly 3000 acres of farmland removed from the the local economy.

However

  • The Levels will still flood and as they did in 2014; they will simply drain more quickly.
  • A flood defence system will have been built that only works for sea water (tidal) and that will probably have to be replaced because it will not be viable to extend its design  life because of the ground conditions along the river banks.
  • The expansion of Bridgwater over the next 100 years ignored.
  • The rather novel concept of putting a tidal flood barrier 5 miles upstream of the mouth of  the River Parrett and into the town implemented.
  • An additional 2,000 acres of productive agricultural land will be in the process of being lost  to agricultural bringing the total of land lost to the local economy to 5,000 acres including Steart Peninsular and the Bristol Ports land deal.
  • There will be no bridge over the Parrett although the myth that you cannot easily have both on one structure will have been discredited albeit too late.
  • No beneficial integration with a future Bridgwater bypass considered or provided.
  • An important relationships  between the capacity of the KSD/Sowy expansion and the impact of the location of the BTB never mentioned or costed.
  • The planned loss of Pawlett Hams to the sea lying hidden in the Parrett Estuary Flood Risk Management Strategy.

Perhaps the most unfortunate decision to date  was naming  the barrier/barrage the Bridgwater Tidal Barrier and sending mixed messages as to its purpose. That single act has reduced interest and scrutiny both in Sedgemoor and further afield to almost nothing. Only 180 people came to a public consultation in September 2016.

The  introduction on the SDC barrier website reproduced below implies on the last line that it “could play a critical role in reducing flood risk” (tidal) and not the fluvial flow it started talking abut; they are not the same thing but did meet once in 2014. Two different things have been conflated  into one message.

The barrier is not designed to mitigate a another 2014 flood

with regard to fluvial (rainfall) flooding

  • Would it now have had an impact on another 2014 flood?          NO
  • Could it be made to have an impact on another 2014 Flood       YES.

Somerset’s councils seem to have no interest in this scheme yet they should because

Somerset County Council (SCC)

Despite having the SRA under its wing and councillors jointly at County and District level there is little in the way of a long term vision that can be see being developed.

A shorter more strategic tidal scheme closing off the South Somerset Levels from the sea  by closing the short gap between the hills from Combwich to Pawlett Hill has not been considered.

Such a scheme would

  • Secure the south Somerset Levels from the sea.
  • Improve the fluvial capacity of the River  Parrett to the benefit of Taunton Deane and South Somerset as well as Sedgemoor.
  • Provide a bypass and improved  road link to West Somerset using EDF’s extended Cannington Bypass.

 

West Somerset

West Somerset’s economic development is constrained by two roads (A39 & A358) and the need to navigate across either Bridgwater (A39) and Taunton (A358)  road systems to get to the M5. With little or no options and no Government money available as part of its road budget it is an area of Somerset where the wealth and opportunity of its population is always constrained and likely to continue. No doubt why it loses industry and income.

It is difficult to understand why West Somerset isn’t trying to improve its economic link to the M5 motorway and via the A39  to Frome, Wells, Shepton Mallet, Street, Glastonbury and Yeovil.

Constructing the Bridgwater Tidal Barrier at Combwich with a road bridge taking advantage of the recently constructed EDF extension to the Cannington Bypass would provide a significant economic benefit to West Somerset.

Taunton Deane & South Somerset

Both local authorities rely on their respective tributaries Rivers Isle, Cary and Tone to convey surface water to the River Parrett and onwards to the sea. No amount of SUDs, storage on the Levels or slow the flow is going to change the fact that you can only get so much fluvial flood water out through the River Parrett. That constraint will ultimately have to be faced by limiting economic development  The opportunity has not been taken to leverage  the long term benefits for the two districts by moving the  barrier downstream.

The reason to relocate the  selected  Bridgwater Tidal Barrier site downstream is that its preferred location does almost nothing to improve the conveyance of surface water to the sea. Where it is now proposed above the King Sedgemoor Drain outfall means that the full benefit of the KSD/Sowy expansion cannot be achieved or the capacity of the River Parrett optimised. Capacity that would benefit largely Taunton Deane and South Somerset. That scheme is being paid for by everyone and is simply not as good value for money as it could be. Rising sea and tide levels will reduce the time the KSD sluices can discharge. That situation will invariably negatively impact both districts by limiting how much water can go in to the system at their end.

It is therefore surprising that neither council has been pushing the barrier downstream where it could be used to increase conveyance in the same way as the Thames Barrier does. Increasing the overall capacity of the system when the Levels again flood is the priority and an opportunity not to missed offers one less obstruction to those two districts economic development.

Sedgemoor District Council (SDC)

South Somerset Levels

Sedgemoor opted to support a 15Km long scheme that cannot be extended (raised) as sea levels rise. Somewhere a bigger one will be required. Its consultants never looked at what would be the best scheme for Somerset or indeed wider Bridgwater. It is just what would be the cheapest for the EA whilst the SRA and SDC looked on. A location for the barrier where a bridge cannot be added to it is hardly planning for the future but it does ensure the ratepayer does not get value for money.

North Somerset Levels

Defending the North Somerset Levels could be achieved by the construction a new barrier from the Polden Hills to end of the Mendips (Brean Down). Such an undertaking could be easily done providing undeveloped land is identified. We could create a second line of defence over the next 30 years letting Somerset contractors run recycling operations allowing trains to bring in recycled materials to form a continuous flood defence. Its time managed retreat was abandoned.

What is disappointing is that with the SDC Local Plan under development there is no land being reserved for future improvements to the flood defences. The organised surrender of Somerset’s hard won land is being orchestrated by the EA under its Managed Realignment process and no one is challenging it. Everyone in Somerset should be interested in what is being done along the coast for safety and economic reasons. There is simply no plan.

Heart of the South West LEP

The Heart of the West LEP with its support of the BTB a project will ultimately damage local businesses based in most districts (£16-20M of lost land values) whilst in a current study is looking at improving rural businesses . The LEP is an organisation facing both ways to the detriment of everyone.

Somerset needs some joined up thinking and understand the very negative implications of some of Somerset’s flood defence scheme.Only when its built and its limits apparent will people say “if only”. 

The Options looked at by the EA lacked any sort of imagination or offered a long term solution; were simply variations on a theme and ignored the nearby topography that offered other options for the Bridgwater Tidal Barrier

It is unacceptable that better engineering options were not  identified and presented to councillors; ultimately it should be the ratepayers decision to go for a better solution if they want to. The EA should not presume as it has in this case.

On the 14th July  starting at 10.00 am  the first opportunity to do something takes place when the SRA scrutiny committee meets in open session at Somerset County Hall, TA1 4DY. 

Some Questions to Ask

  • Why is the Bridgwater Tidal Barrier not also designed to help to mitigate the effects of a similar flood to 2014?
  • What is the replacement plan for the Bridgwater Tidal Barrier?
  • What is the cost of a scheme with a bridge ?
  • Should we only be spending our money on such a limited scheme?
  • Why wasn’t Combwich and the resulting shorter flood defence system that protects a larger area than the current scheme considered by the EA?
  • Does the extension of the Cannington bypass towards Combwich necessitate the reassessment of the present scheme?
  • Should Somerset County Council be looking at a more holistic scheme for Somerset?
  • Should SCC commission a county wide economic assessment of what an alternative barrier scheme might deliver?
  • Do we need the EA or should the SRA be expanded to become a delivery focused organisation and the EA limited to a statutory consultee ?
  • Is the role of environmental charities in developing and influencing flood policy beneficial and do they have a conflict of interest?
  • Why after 3 years since the flood and 8 years since the barrier identified as the preferred solution is there almost no information about the scheme on the http://www.sedgemoor.gov.uk/bridgwaterbarrier website?

The EA plan another consultation on the full scheme later in 2017. Councillors of all Somerset’s districts  might like to look at the economic impact of this scheme (BTB) on their own areas and perhaps county might look at the bigger picture.

An unintended consequence is only the failure to adequately consider a decision before it was made.