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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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Sedgemoor 2050 Transport Investment Strategy- what climate emergency?

On the 20th February 2019 Somerset County Council declared a climate emergency  followed by Bridgwater Town Council on the 15th March and by Sedgemoor District Council few days later on the 20th March 2019. Clearly there isn’t any emergency according to the recently approved study Sedgemoor 2050 Transport Investment Strategy; the two key drivers of Sedgemoor’s  future, climate change through rising sea levels that threatens Sedgemoor’s low-lying land and the impact of an aging population higher than the national average, barely got a mention. Its quite clear that Sedgemoor just does not get it.

Transport infrastructure drives how our society develops, it brings development and investment and it is difficult to see how the adopted strategy delivers on any of those fronts apart from facilitating housing developers at Sanford Corner. What we do know is Sedgemoor’s reliance on the motorcar is particularly unsustainable not only for health  but the geography of  the area split into 3  by the M5, railway and River Parrett creates bottle necks everywhere. We don’t have enough crossing points and could not afford to build the bridges we need. Indeed, the published evidence says if we built all the improvements by 2032 it’s still not good whilst SDC won’t start looking at a bypass until 2030 and that will take at least 10 years to select the route, acquire the land and gain approval and be built 2040 would seem to be a fair delivery date for a bypass by which time our local population is predicted to be well on the way to 150,000 people. The same evidence also noted the bypqss from junction 24 offered greater benefits than from junction 23.

the map below is extracted from the report

Fig
Figure 3.2: Sedgemoor 2050 Transport Investment Strategy schemes for Bridgwater


Bearing in mind that with the studies supporting Hinkley Point Planning and  the work done for the Bridgwater Tidal Barrier and other post 2014 flood related studies the same team responsible for this report can have no excuse for a lack of knowledge however:

Gravity

Redevelopment of the old Royal Ordnance Factory at Puriton is trumpeted as some wunderkind  scheme yet the proposed access road on Puriton Hill will see all vehicles coming and going from the site having to climb  a hill in both directions. None but the most fanatical  cyclist from Bridgwater is going to do that hill twice a day and certainly not aging cyclists. It appears in London where the authors reside the Polden Hills don’t exist or even the rising Severn Estuary.

The irony of building an Energy Park with perhaps the least carbon friendly access route should be lost on no one.

Bridgwater Northern Bypass

The bypass will be built downstream of Bridgwater’s Tidal Barrier. The new road will cross the area (flood plain) designated to take water over topping  the River Parrett to save Bridgwater and will invariably make much of the planned secondary flood defences  redundant. It will also require raising the River Parrett banks at Cannington Bends that is always settling due to the poor  ground conditions. How far down stream would that go? The argument for the present configuration of the tidal barrier is that the 100-year design life, 800mm sea level rise is ok for now, sea level will rise 2 to 3m. The reason there is no provision for replacement or expansion made today we should not impose a solution on the generations that follow. Building the bypass downstream of the Bridgwater Tidal Barrier is exactly what SDC/SDC is doing, it is placing future generations in an invidious position with the need for a bigger tidal barrier downstream of the bypass. That we wont be able to develop land off the bypass because of the flood risk makes the bypass and barrier configuration all the more unrealistic or improbable or the Bridgwater Tidal Barrier needs to be revisited.

Bridgwater Tidal Barrier Flood Plain

The original route of the Bridgwater Northern bypass connecting  to the existing Cannington bypass  has been abandoned and a new route identified  between Sanford Corner (A39) crossing the overspill area of the Bridgwater Tidal Barrier and crossing the River Parrett somewhere around the site of the old BP jetty. It seems to adopt a developer’s route from 2017 that incorporated both a barrier and a bridge. Being downstream of Dunball Wharf it must be intended to finally shut the wharf and bring to end the Port of Bridgwater. It is important to understand that the importation of sand at Dunball Wharf is a significant part of Somerset’s present sustainability strategy keeping trucks off the road.

River Parret Bridge and Tidal Barrier at old BP Jetty.

Population context

The supporting evidence produced in 2017 by Steer Davies Cleave provides three interesting pieces of information for the people of  Sedgemoor.

  • Sedgemoor has a significantly higher proportion of the population over the age of 60 years compared to the national average (28% over 60 compared to 22% in England and Wales at the 2011 UK Census) and this proportion is growing. This will not only affect Sedgemoor residents’ mobility requirements, but also travel patterns, modal preferences, and influences the propensity for adoption of new digital and ‘disruptive technologies.
  • the population of the district could be between 150,000 and 160,000 by 2050. Sedgemoor’s transport networks will need to accommodate the increase in trips resulting from a larger and growing population.
  • The southern bypass option from junction 24 provides a better traffic benefit than the normally assumed  northern bypass from Junction 23.

Comment

Once again Sedgemoor and Somerset County Council have created a situation that flies in the face of common sense notwithstanding the recommendations of the DEFRA oversight committee that in the wake of the 2014 floods that infrastructure should be integrated  for both flood and transport to provide the tax payer with the most value for money. Nothing within the present SDC  transport and flood defence proposals could be farther away from those objectives. The rate and taxpayer is going to end up paying for two structures rather than one and the bypass will be viable for how long before its becomes impossible to manage Cannington Bends settlements and the sea engulfs the bypass. Surely we should be integrating our plans. Should we not be building the secondary flood banks along the route of the bypass?

Bypass with secondary flood defence.

Aging Populations need to move into the centre of towns where walking is a viable active mode of transport, people should not be marooned on housing estates and at the mercy of a bus service. Our town centre densities need to go and that means we need to build up and not out. Anyone reading the notice on the Monmouth Street development will not have missed the irony of proudly reducing densities and consequently displacing people to outskirts of Bridgwater and increasing the need for car trips and reducing support to the businesses in the town centre. As an example, people might consider why new housing being built is permitted to open directly onto Monmouth Street, is it right that those living in affordable housing will be subject to pollution from HGVs driving through the town.

Monmouth Street Affordable Housing

There is nothing remotely sustainable about this development when it uses one of the few sites in the town where a tall apartment building could have been built with the new hotel to the south and rest home to the north. It is a wasteful use of a key site. It also reflects the lack of ability and ambition of housing association SHAL, Sedgemoor District Council and developer alike. Houses have the most concrete, the greatest ratio of external walls that lose heat etc etc. This is the least sustainable form of housing.

As you can see below the doors of the new houses open directly onto Monmouth Street letting in every particulate and dust from passing HGV’s.

SHAL’s new affordable Monmouth Street housing – early Saturday morning 28th September 2019.

Our transport strategy should not only be about new roads but about reducing demand and increasing efficiencies of what we have not expanding a network that costs money to maintain. It is particularly unfortunate that despite our councils declaring Climate Change Emergencies they do absolutely nothing locally to mitigate the situation we have when it is within their power to do so. Its better to avoid the need for a road than to build a new one. Transport policy needs to address our housing and flooding policies. joined up planning ?

Cycle Routes got minimal consideration. Even with climate  change and the opportunity to something different not the smallest amount of blue-sky thinking happens. The old Somerset and Dorset Railway permanent way offers a cycle route from Bridgwater to Cossington and beyond. A safe routes with low gradients suitable for people of all ages, not even a thought was given whilst in other parts of the UK old rail routes are being exploited as new technologies give them new life. With a new cycle bridge over the King Sedgemoor Drain it would remove much of the A39 from cycling into Bridgwater.

Clearly,  we need  something better than the same people on the same committees who deliver no vision that the community can understand and work towards.  Yet again Somerset been let down by the leaders of our district and county councils who seem unable to develop a joined up vision people can support and work towards that the generations that follow can build upon.