Following the EA’s 2019 submission of the BTB Transport and Works Act to the Secretary of State the EA has responded directly to a comment made during the public consultation regarding ring fenced funding.
The background to the question is that if the BTB was located further downstream it can act in the same dual operation way as the Thames Barrier stopping tides coming in and creating a temporary reservoir to increase the conveyance of seaward fluvial flows. In 2014 the Thames Barrier closed 9x for tidal flooding and 41x for fluvial flooding clearly indicating the benefits of a dual function structure.
The EA /SDC BTB proposal does not use this dual operation solution; it has only a single Tidal function. Bridgwater is only getting half what the Thames Barrier does.
People have been given to believe that the funding for the BTB could only be used for Tidal defence rather than as a dual use structure where it could also provide some mitigation to a repeat of the 2014 flood as well as addressing rising sea levels. There was a risk Bridgwater would lose the funding if it asked for flexibility.
The
Submitted Comment (in blue)
2.
The BTB is not designed to improve fluvial conveyance in the River Parrett and
King Sedgemoor Drain. If it was located farther downstream it could operate in
both modes as the Thames barrier does. (it is not understood why the funding is
ring fenced for tidal defence only)
The EA
response below is of great importance with regard to the approval of this
scheme as it contradicts the common understanding that the HMG funds promised
in 2014 could not be used for a holistic flood defence solution in Somerset.
The design and the consultations clearly support only the BTB is a single
use design.
The
EA Response (in blue)
The Scheme is not designed to improve fluvial conveyance in the River Parrett and King Sedgemoor Drain. It is designed to provide a tidal barrier with improved downstream flood defences, to exclude extreme surge tides and prevent tidal flooding in Bridgwater. Funding is not ring-fenced as described, but is made available and allocated on the basis of benefits realised.
The EA response indicates a choice was made not to consider pluvial flooding and fluvial conveyance as a key consideration despite that was the 2014 flooding event event caused the BTB to be brought forward in the first place. Had it been a consideration the case for locating the Barrier further downstream would have had considerably more weighting and possibly changed the outcome of the site selection.
It should
also be noted that that the following non tidal benefits have not been
considered or influenced the work done to date.
The EA recently noted at the SRA board meeting on the 6th March that the 20 pumping stations on the Levels are coming to the end of their design life and there is no budget for their replacement.
The EA noted in the September 2016 public consultation that the location of the Barrier a small distance downstream of the KSD outfall to the River Parrett would provide benefits to the river flows.
The benefit of unlocking the KSD outfall providing increased value for money on the planned KSD enhancement have been ignored.
The benefit to the flooding of the Levels and to Somerset towns on the upstream tributaries of the Parrett that could have been taken benefit from this scheme have not been considered or taken into account.
The artificial separation Somerset’s of tidal and pluvial needs makes little economic, engineering or financial sense and this response indicates that it did not need to be considered. We could have had a barrier that protected the south Somerset Levels including Bridgwater from the sea and increased the fluvial capacity allowing more water to moved through the River Parrett and the King Sedgemoor Drain.
Extract from EA consulation boards Sept 2016
There is now a need to find out if this scheme was unnecessarily constrained. It needs to be established that the proposed BTB represents best values for money for the taxpayer and is part of a wider integrated flood defence solution for Somerset and if funding was not a constraint why do we have a single use solution?
Clearly an independent assessment and investigation is required to clarify the true situation and ensure that the scheme is doing what it should be doing and not what EA believes to be the case. Hopefully the Secretary of State will chose to place this project under the light of public scrutiny before making a final decision to ensure what is proposed is fit for purpose.
The relevant extract of the EA letter is reproduced below
All large infrastructure projects require an assessment of its impact on the environment. The Bridgwater Tidal Barrier is no different and as one of the UK’s first real climate change driven projects it is important that the long term impacts are understood not just the immediate aftermath of the construction process.
Screening and Scoping Opinions (Environmental Impact) Screening is the process of deciding which projects require an Environmental Impact Assessment (EIA). A scoping opinion only considers what information should be included in an EIA.
What we know
Infrastructure projects whether the BTB, the expansion of London’s railways in the 1800s or the construction of the UK’s motorways in the 70’s have well established long term impacts on our environment as society adapts to the change the project imposes on the area. In Bridgwater’s case the planned BTB removes 3 to 400Ha of potentially development land close to Bridgwater and its existing communication links (J23 of the M5). With the topographical constraints imposed by the M5, the railway and the River Parrett the other options for future development are few.
Bridgwater will in the 100 years of the BTB operation continue to expand and grow and a conservative assessment of the additional area of Bridgwater developed for housing and employment will be around 40% of Bridgwater’s current footprint. Bridgwater’s expansion has to go somewhere and it will impact on the environment beyond the immediate area of construction.
The water that will flood onto the the farmland with increasing frequency will be saline and will change the nature of the land destroying valuable freshwater habitat at Chilton Trinity and at Pawlett Ham’s and the ability to grow food.
A warming climate will see the arrival of new species in particular the Asian Tiger Mosquito to existing open water and bringing the inter tidal habitat up to Dunball as proposed by the Parrett Estuary Flood Management Strategy to the edge of Bridgwater’s habitable area threatening the health of people in North Bridgwater, Pawlett, Chilton Trinity and Puriton and the housing developments on King Drive. It is not unreasonable to consider that open water may well be considered in the same way as in other warm climates as being breeding grounds for mosquitoes and a source of the Zika virus and Denge Fever.
What the EIA opinion ignored.
The impact of pushing the economic development onto the Quantock Hills
The impact of building on the levels to the east of Bridgwater
The impact of seawater on the land.
Increasing the rate of salt ingress into the land due to retention of saline water in the borrow pits.
potential habitat creation for invasive species and the health threat they make to the local population.
The work done in in this document seems to irrationally imagine that
Bridgwater does not expand for the next 100 Years
Environmental changes will only be driven by sea level rise
The environmental impact is only in the immediate area of the scheme
There is a complete lack of appreciation of the what the BTB scheme entails and its impact on the environment. It studious ignores the wider impacts of this scheme and allows the development to move forward with little or no consideration of the impact. It offers no visibility to the public of what impacts may occur in the next 100 years. EIA are by nature speculative and in the case of the BTB scheme the applicants should provide a wider and more comprehensive assessment.
The EIA is simply inadequate and as a consequence make the work done incomplete and questionable in its efficacy. It is a continuation of the lack of vision and understanding of this project, a project that is key to the long term future of Sedgemoor and Bridgwater.
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.
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.
Reduce tidal flood risk to the highest number of properties and commercial businesses in Bridgwater and the surrounding are
Reduce tidal flood risk to critical infrastructure and utilities in Bridgwater and the surrounding area
Deliver a scheme that can be adapted for the future effects of climate change.
Align the project with the strategy set out in the PEFRMS (see also Section 2.2).
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).
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.
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.
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.
Minimise health, safety and welfare risks associated with the construction, and operation of the scheme.
Identify funding and partnership opportunities and outline any additional work to gain financial contributions.
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.
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.
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.
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.
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.
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
Denies the Bridgwater the economic benefit associated with developing land adjacent to a motorway junction (J23).
Denies Bridgwater the opportunity to build some 5000 houses and supporting employment centers
Forces future housing development to the south west of Bridgwater that will continue to increase the demand on on the A39.
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.
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.
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 pitOriginal SDC/EA drawing showing pits to be dug.SDC 2050 Transport Strategy map
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
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.
An old boss of mine says unintended consequences ismerely the failure to adequately consider the implications of the decision being made.
The location of the Bridgwater Tidal Barrier (BTB) is probably the most significant decision Sedgemoor District Council has made in many years. Rarely can such an important decision have been made with so little debate. If it’s in the wrong place we and the following generations live with the consequences for the next 200 years or so. No one is giving us another one if its wrong.
On the 26th July 2017 a full Sedgemoor District Council meeting agreed the location of the Bridgwater Tidal Barrier. This decision according to the minutes was apparently waived through without discussion. That the EA and SDC gave a superfical 3 page briefing document with so few key facts indicates just how confident EA and SDC officers felt able too simply ignore the longer term collateral environmental and economic impacts of this scheme. It is a clear indication of the low esteem our councilors are held in. Councillors lack of oversight of this scheme does indicate the officers probably wernt wrong. Silent oversight committees seems to have presided over continued and unsatisfactorily explained cost rises. The cost almost doubled in the the six months after the decision was made. Barely a word was said.
The Issue
Abandoning 1,400 acres of valuable land next to a motorway junction capable of supporting £1B of future investment (jobs) whilst unnecessarily forcing future housing onto the Quantocks foothills extending Bridgwater to absorb Cannington, Spaxton and North Petherton.
This decision will be seen as one of the most irresponsible and reproachable acts by councillors of any local authority at any time. SDC knowingly made a decision to convert the Parrett Estuary into an Intertidal Habitat and behind the the secondary flood defence create more areas of habitat suitable for freshwater mosquitios such as the Zika and Denge carrying Asian Tiger Mosquito to take up residence.
Limiting economic expansion, building on the Quantocks, poisoning the fresh water ecology of Chilton Trinity and Pawlett Hams and creating a future health hazard is hardly what we people voted councillors into office for.
If they did know why did they do it?
If they didnt know why not?
Why is this case?
The BTB design uses farmland downstream of the barrier to allow incoming saltwater to spill over riverbanks onto the farmland. It destroys the economic value of around 2.400 acres of land either to continue as low-grade farmland or 1,400 Acres of that total to the south of the Parrett providing land for nearly a £1B of economic development accessible from J23. Would any town throw such an economic legacy away with so little concern? Bridgwater has. The longtime environmental Impact of this scheme is equally as bad; the land being flooded will ultimately become saltmarsh and a large part of the local Quantock foothills unnecessarily developed
The December 2018 public consultation asked for feedback on three basic points
The details of the proposals for both the barrier and the downstream flood defences.
How you think the proposals may affect you, your land or your business.
What additional improvements you would like to see delivered as priorities, in addition to the barrier and the downstream flood defences, subject to funding.
Context
Large civil engineering projects influence long-term economic development as we have seen with development taking place around our motorway junctions; the proposed Bridgwater Tidal Barrier (BTB) will influence Bridgwater’s future development in a similar way for at least the next 200 years. The Bridgwater Vision published in 2015 and referred to in the presentation identified land for future development most of which is either now approved or starting to be built out under the local plan. Bridgwater is already reaching the limit of land that can be easily accessed from the town and the M5.
Assuming Bridgwater continues to develop economically at even half its present rate, during the design life of the BTB, an additional 25,000 houses will be built and together with land for employment and Bridgwater’s footprint will grow by around 40%.
Under the present BTB scheme low quality farmland directly beside Junction 23 that could have provided space for at least £1B of economic development, housing and jobs will be lost to the town. Alternative land over the next 100 years will need to be found and that will invariably mean development moving on to high quality agricultural to the south and west of Bridgwater. We will build on the land that feeds us whilst living ever farther from planned and established centres of employment to the north and north east of Bridgwater (Horsey). Building at Horsey will require a new bridge over the King Sedgemoor Drain; money that could be used to cross the Parrett and bring forward a much needed northern bypass.
Location
The reader should take cognisance that the two options studies done for this scheme, the first included highly improbable options such as the Bridgwater Bay power lagoon and outside the influence of the authors. The second option study looked at the same solution at a limited number of locations and would always arrive at the narrowest part of the riveras the prefered solution. It was a superficial study and lacking rigour and at the time of this note the final information used by an SDC sub group remains unpublished despite an FoI request to Sedgemoor District Council remaining outstanding.
Other options and locations to protect Bridgwater and the downstream villages were available but not considered.
Description
The Bridgwater Tidal Barrier is a 7mile long inland tidal surge flood defence scheme with a 100 year design life based on sea level rising around 800mm during this period. Similar to the current Thames Barrier it consists of two elements.
Riverbanks profiled to preferentially spill seawater, during extreme tidal surge conditions, onto farmland at Chilton Trinity and Pawlett Hams.
A small double vertical floodgate barrier located in the industrial and employment Express Park area of Bridgwater and approximately 1 mile from the town centre.
The replacement Thames Barrier will be sited more conventionally at the mouth of the Thames; Combwich is Bridgwater’s equivalent location.
Key features
The riverbanks are expected settle
and need reconstructing every 35 years
The height to which the riverbanks
can be raised is limited by the poor ground conditions.
Although needed no provision of any
kind for a replacement is considered.
Contaminates around 2400 acres of
farmland with salt water
Constrains economic development to
the northwest of the town.
Significant loss of existing freshwater
habitat in line with managed realignment policy 7d39 of the Shoreline
Management Plan to create an intertidal habitat.
EA DIAGRAM SHOWING SALTWATER FLOWING ONTO FARM LAND
Operation
The closure of the barrier at low tide creates a
separation of the two types of water that use the River Parrett. Upstream
freshwater from the Parrett and its tributaries such as the Tone; Yeo and Cam
will be impounded behind the closed gates. Downstream the freshwater will finish
emptying into the Severn and the then the empty river filled with seawater on
the incoming tide.
All flooding shown downstream of the Bridgwater Tidal
Barrier will therefore deposit salt water onto the land. This is saltwater and the impact should not be confused with the 2014
event.
The land in question at Chilton Trinity has not been
flooded with salt water in this way within living memory. Pawlett
Hams was briefly flooded in the early 80’s and flooded Pawlett from the north
where no flood defences are planned.
Summary
What is clear is that considerable ambiguity remains
in the proposal. Many issues are simply ignored or the messages contradictory. The
following summary and notes provides some comments that should be addressed.
It is disappointing that such an important scheme
appears to have been given so little strategic thought whilst the barrier
appearance and immediate landscaping seems to have received considerable if
unsuccessful attention.
Clearly the priorities of the design and client team are
not those of the ratepayers who do not need a solution where the medicine kills
the patient which is what we appear to have.
River
Banks
One consistent underlying theme is that once the
barrier is built the land to the north and south, Chilton Trinity and Pawlett
Hams, will ultimately become intertidal habitat in line with existing published
policies.
The key supporting facts are
The cost estimate that does not include for future riverbank reconstruction
Planned flooding of agricultural land with saltwater.
The claim made “Bridgwater
and the surrounding area will be better protected against a severe flood by
building the barrier and improving the downstream flood defences. These works
will also maintain the current standard of defence to agricultural land”.is
misleading to landowners indicating that farming will simply carry on as
normal. With the frequency of saltwater flooding increasing the land will not support
the type of grass needed for agricultural. Areas of Norfolk are still
recovering from single sea water incursion 65 years ago.
Borrow Pits
No location for the pits was given, which side of the secondary flood defence. It would not be unreasonable to assume between the river bank and the secondary flood defence. A rough estimate would indicate that the scheme will need around 100,000m3 to 150,000m3 of clay creating a large open area (7-8Ha) of stagnant water that will through our now warmer summers become more saline as they will operate as a large evaporation pond. That mechanism does not allow the wildlife enhancement described to occur.
Locations were shown to stakeholders but not the public
Environment
A number of claims are made regarding the lack of environmental
impact that this scheme has on the ecology however changing the habitat from
freshwater to saline will fundamentally change the area in line with the
published strategy of changing the land to an intertidal habitat.
2,400 acres of fresh water habitat is destroyed
through repeated seawater flooding.
Cost or Intention
An estimate of £94M is given in the EA presentation. Through a FoI request (03 April 2018) The EA provided an estimated whole life cost closer to £160M. That estimate assumed £12.4M Net Present Value or £55M cash cost over 100 years including for maintaining and rebuilding the riverbanks that is around 4x the value of the land. Economically this statement on maintenance costs makes funding the future bank rising impossible. If the circa £100m estimate is correct this would cover the gate maintenance and not the riverbanks.
The expected need to rebuild the riverbanks twice in the 100-year design life is not mentioned in the presentation and the assumption must be that the intention will not become reality and would conflict with clauses 1.10.1 and 1.10.2 of SDC’s Parrett Estuary Flood Risk Management Strategy
The whole life cost of the scheme is either
£100M with one set of the riverbank improvements at the time the barrier is constructed.
£160M with three sets of the riverbank improvements including the time the barrier is constructed and subsequently at 35-year intervals after that. That must be the budget.
Did nobody ask why?
Collateral Impact
This scheme is presented at completion in 2024 and
looks only at immediate local impacts. Construction
will have immediate and long term wider negative consequences for Bridgwater
none of which have been raised or addressed despite written assurances that
that would not be the case.
Economic Impacts
Loss of 1400 acres of key land suitable for £1B of economic investment for housing and industry that is directly accessible to Junction 23.
Creation of a working flood plain over which a potential bypass might need to be constructed.
Increasing separation of housing from employment by forcing development elsewhere.
Loss of economic food production on prime agricultural land
The loss of in existing land values of around £12m and potential bankruptcies where the land is used to secure business loans.
Environment
Impacts
Destroys 2400 acres of fresh water habitat through deliberate seawater flooding initially during extreme tidal events but ultimately becoming within the normal tidal range.
Forces development to take place on high quality agricultural land to the south and west of Bridgwater.
Forces apart residential and employment areas with a consequent long term cost to the economy and the environment.
Places increased demand on the A38, A39 and Kings Drive as industrial development is forced east to Horsey and to the approved BAE industrial site.
Barrier Superstructure
The barrier superstructure is 2 to 2.5 times higher than it needs to be and lacks any shape that reflects its functionality. It achieves the rare combination of being both pretentious and mediocre. With a structural volume that must be four times what could be reasonably required to support its function it is bloated, unnecessarily expensive and will be difficult and expensive to maintain. Overhanging shapes require specialist access equipment for maintenance. Everything on the structure seems designed to cost more than is necessary. Its appearance seems to owe more to Mr Blobby and the Teletubbies than the Falkirk Wheel, it doesnt do anything like the Falkirk Wheel so hardly a tourist attraction.
The very large ovoid bridge structure will be
particular difficult to maintain, it will be almost impossible for safe
inspection of the lower quadrants to be made or worked upon. The form of the
structure indicates little attention appears to have been taken with regard to
the Construction, Design and Management 2015 regulations with regard to the
safe operation and maintenance
The poor design of this structure extends to the
gates, rather than protect the gates from the salt loaded wind driven rain, the
site is classed as a marine environment, rain will be spilled from the ovoid
bridge onto the gates increasing maintenance and reducing the life of the
gates.
As a piece of architecture and a piece of engineering this structure almost certainly fails on cost, function, operator safety and buildability.
Storage Buildings are provided when the EA has a depot nearby at Bradney.
Did no one ask why we need additional buildings at the barrier site?
Presumably they would also attract rates?
Sustainability
The lack of sustainability in this project is very
concerning;
The decision to excavate burrow pits to reduce
construction traffic seems highly questionable. “Where possible, we will excavate material locally from ‘borrow pits’.
This will minimise the need to bring in material to build the new downstream
flood banks and reduce construction traffic.”
The EA was more than happy to bring excavated material from its Cannington flood project to Chilton Trinity yet the more sustainable option of building the banks over a longer period using spoil from building sites is not considered. It’s not as if the defences need to be at their final levels until the last planned rebuilding of the banks 35 years before then end of the design life. This work could be done on an opportunistic basis over the next 50 years or so in a sustainable cost effective method by local contractors.
The continuing reference to 2055 that is key date in the shoreline management plan indicates thatany future raising of the river banks is unlikely to occure.
This process would also assist in maintaining accesses
and local resources able to respond to urgent requirements such as a breach in
the river bank.
Finally just to prove the point the EA/SDC presented on page 7 of the stakeholder presentation three images of unrelated events to support its postition.
West Quay collapse, an old wall collapsed when it got too much water behind it; we see thse failures alongside our roads all the time but we dont try and link them to climate change or a tidal barrier.
The 2014 flood was a pluvial (rain) event and the Bridgwater Tidal Barrier is not designed to mitigate a repeating event. There is clue in the word Tidal. Unfortunately many people in Bridgwater and the surrounding area believe that it is part of a pluvial flood defence scheme.
one was applicable
WEST QUAY & 2014 ARE NOT TIDAL EVENTS
Perhaps an SDC, Town or county councillor reading this might decide to ask some serious questions about this project, one can only hope.
The impact of wildlife organisations on locally managed flood projects is a concern. They seem to be free to make unsubstantiated statements whilst pursuing their objectives with little public visibility, criticism or professional oversight and it is a growing problem. It is a situation becoming increasingly familiar and yet another example of our growing democratic deficit where minorities impose their ambitions on the majority. The Somerset Levels, the Parrett Estuary and Bridgwater’s need for a flood defence from the sea has brought many of these parties with their own agenda to one location each focusing on what they consider to be important. Bridgwater seems to be well down the list of importance despite the planned construction of the Bridgwater Tidal Barrier. The purpose of this article is to provide an explanation as to how this is happening.
Context
Bridgwater currently builds around 500 houses a year and if that rate continues at even half that rate for the next 100 years we could expect to see the number of houses in Bridgwater rise by 25,000 taking another 700Ha (1,700 acres) of land for housing and a further 300Ha needed for employment. This 1,000Ha’s will see Bridgwater’s existing footprint grow by at least 50%, The 25,000 houses and associated economic development will generate perhaps 300,000m3 of clays and soil waste.
With flat and level land needed for employment land at the old BAE site and at Horsey offer the only other viable employment options to Bridgwater and they are to the northwest. New housing will be forced onto good quality farmland south along the A38 swallowing up North Petherton and eventually meeting Taunton coming the other way and to the west developing the land between Bridgwater and Cannington. Bridgwater will consume its high value agricultural land on the hills as it, like the rest of the country, continues to build our outdated ideas of housing.
Bridgwater will therefore become an even more difficult place to live and work as the gap between residential development and employment continue to grow. Every day a large part of Bridgwater’s population will get up and drive along the A38 and A39 to get to work. Bridgwater will not even start considering a bypass until 2040.
Apart from the normal lack of imagination by planners and developer’s Sedgemoor’s (Bridgwater) greatest problem now appears to be the wildlife and flood pressure groups that seem to take an extreme view in the pursuit of what they consider to be in their interest. They show little tolerance or understanding that people also live on the Levels and in Bridgwater and ignor the EU directives that accept people must come first. The true impact of their objectives is concealed and never addressed.
These organisations also seem immune from any need to consider facts in their statements whilst criticising property developers for the smallest omission. The irony that is they now ape those same commercial organisations in assembling land and changing its use without considering its long term impact on the wider local population and it should be lost on no one.
Some typical examples
Steart Peninsula
The local economic benefits alluded to as part of the original Steart Peninsula planning application remain unproven and therefore represent little tangible benefit to the local population yet quoted as fact by The Severn Vision statements.
This plan will expand the existing saltmarsh by 833% around the Severn Estuary and in Bridgwater’s case large areas of agricultural land removed from food production and converted from a freshwater environment to a saltwater one (intertidal habitat). To date two phases have been completed; The Steart Peninsula and the RSPB reserve (funnded by Bristol Ports) both of which remove economic activity and destroy an existing habitat to create another. A process little different from modern housing development. Whilst an argument might be made on the basis of geography for these two areas to be returned to the sea no such argument exists for the destruction of Pawlett Hams and Chilton Trinity including areas of the SSI.
This is a process promoted by the following organisations
Wildlife and Wetlands
The Wildlife Trusts
RSPB
National Trust
Campaign for Rural England (CPRE)
Severn Rivers Trust
With regard to Bridgwater it makes claims regarding carbon savings whilst ignoring the collateral effect of moving Bridgwater’s housing developments onto higher quality agricultural land and increasing commuting distances. Also ignored is the loss of food production on 5,000 acres of land and the transfer of that food production overseas. It is particularly misleading in its statements with regard to Bridgwater providing no supporting evidence as to the negative benefit that it has considered in any balanced and holistic way. It is completely one sided yet already two key elements have been delivered, Steart Peninsula and RSPB reserve. The Bridgwater Tidal Barrier will deliver the southern land at Chilton Trinity and Pawlett Hams .
Bridgwater Tidal Barrier
The Environment Agency and Sedgemoor District Council’s Dec 2018 public consultation made a claim with regard to the lack of any environmental impact of this scheme. The EA and SDC have not considered environmental impacts beyond the immediate area of the scheme despite this scheme imposing restrictions on economic development forcing residential development to the south and west of Bridgwater and employment to the northwest of the town.
It is worth noting that HPC looked at issues far beyond the immediate area of the power plant when it did its enviromental impact assessment.
Environmental Impact Statement
This statement above cannot be true as
Seawater is shown overtopping the river banks onto the existing farmland, the fact that it is seawater is misleading.
The farmland at Chilton Trinity and Pawlett Hams will be poisoned for agriculture through the introduction of saltwater
The existing wildlife that requires a freshwater environment will be destroyed.
The location of the borrow pits, which side of the secondary flood defence, was not shown. The plan to excavate 100,000m3 of material will create a lake of nearly 13 acres that will act as a reservoir for saltwater.
1,400 acres of high quality farmland suitable will be unnecessarily developed invariable towards North Petherton and Cannington as this scheme will convert 1,400 acres of low quality farmland that could have been used to saltmarsh.
100 years of lost food production on 2400 acres of farmland.
100,000m3 of clay will be unnecessarily excavated from the land being protected whilst during the same period 300,000m3 will be produced as waste through normal housing and industrial construction activities.(the secondary flood defences do not need to be completed to the full height during intial construction
Denying economic development in the north-west will increase commuting efforts in the local community generating avoidable C02; the scheme ensures the increased separation of employment areas from housing.
The claims regarding this scheme are questionable at best and the lack of information misleading at worse. The extract from the EA/SDC public display indicates a plan to create a stepping-stones for species that are not identified.
Campaign for Rural England (CPRE)
The CPRE’s support for The Severn Vision that results in the wholesale destruction of a large area of our existing productive landscape and the equivalent of 10 500 acre farms is not what we imagined their core mission to be that says
“We campaign for a beautiful and living countryside. We work to protect, promote and enhance our towns and countryside to make them better places to live, work and enjoy, and to ensure the countryside is protected for now and future generations.”
How allowing saltwater (seawater) onto productive farmland that has taken 500 years to remove the salt from seems a strange way of protecting our countryside.
Somerset’s Wild Trust (SWT)
Another supporter of The Severn Vision.
Somerset’s Wild Trust’s website says
Since the 2013-14 flooding events, the dominant narrative in the floodplains has focussed on hard engineering schemes and dredging to reduce flood risk, overlooking flood risk reduction techniques that work with nature and provide a range of benefits to society. A future is developing where more public money will be spent on fossil fuel intensive dredging and pumping, to further drain the peat soils of the Levels, thus releasing more carbon and exacerbating climate change. As peat is drained, it shrinks, lowering land height and making the area ever more vulnerable to extreme weather. Well-informed debate on the future of Somerset’s low-lying areas in the face of rising sea level is limited, so a further vital part of our work on the Levels is to communicate a more optimistic narrative which gives nature its proper value.
This statement ignores that the Somerset Level’s is an artificial environment that needs regular maintenance and seems to conflate the need to dredge Somerset’s rivers and the need to get pluvial flows from the upper Parrett catchment areas to the sea bypassing the levels storage with an idea that somehow this process is designed to shrink the peat. “A future is developing where more public money will be spent on fossil fuel intensive dredging and pumping, to further drain the peat soils of the Levels, thus releasing more carbon and exacerbating climate change” is a particularly spurious and misleading statement. It sounds like people are secretly pumping water off the levels as some sort of conspiracy.
Anyone with any knowledge of the Levels would know that retaining water levels is just as important to the Levels as draining them. No one is going to drain the peat. Well informed debate requires informed knowledge and that is clearly not the case with this statement by the SWT.
FLAG Flooding on the Levels Action Group
FLAG reflects its single issue origins seemingly taking its position on Somerset’s farming industry geographically from the lands relationship to Moorland and what is best for Moorland.
A post (Nov 2018) supporting Somerset’ s farming industry on the Levels was made by FLAG making Brexit the largest threat to farmers in anticipation of a nonexistent trade deal with the US; no doubt the cause of the 2014 flood and global warming will in time also be subscribed to Brexit.
FLAG’s postion downstream of Moorland at Chilton Trinity and Pawlett Hams is quite different. Flag is altogther less compasionate regarding the farmers there having their land flooded with saltwater to alleviate upstream flooding. Concern is simply dismissed by a statement worthy of Marie Antoinette “let them raise salt beef or lamb”. It completely ignores that the Bridgwater Tidal Barrier has already destroyed land values for 2,400 acres of land and food production we might have gained. Reverse nimbyism seems to apply; as long the flooding is on someone else’s land FLAG appears to be happy whilst refuses even the smallest tacit support for or willingness to consider alternatives tht might have a better outcome for the wider community.
Conclusion
Whilst our wildlife organisations may have started with good intentions what is clear is that many people associated with these organisations simply don’t understand the mechanisms of the Somerset Levels, the impact of what they propose (The Severn Vision) and in most cases don’t care if it doesn’t suit their agenda. They fail to consider that ultimately the economy pays for everything and destroying local economies will ultimately call into question the viability of protecting our environment; the ratepayer maintains the roads used to get to our wildlife sites and will pay or make a significant financial contribution to the cost to the current planned defences and the their subsequent replacements. A case of shooting the goose that lays the Golden Egg of in this case chasing away industry and people.
It is clear that many organisations support the existing proposals to turn the Parrett Estuary into a saltmarsh. The decision by SDC and the EA not to commission an economic impact assessment has allowed those organisations and the Environment Agency to create the worst possible long term economic future as there is no assessment mechanism other than the government investment rules to measure the value of this scheme. Allowing the undermining Somerset’s agricultural industry, wasteful development and not working towards an integrated low energy society is not what we should be doing.
Ahead of the forthcoming last public consultation on the Bridgwater Tidal Barrier (BTB) the rate and tax payers might consider asking what becomes of Bridgwater after the BTB reaches the end of its design life?
The answer is simple.
if there is no barrier capable of keeping the rising sea out there will be no house insurance, no mortgages and Bridgwater the town will not be a viable place to live.
Our present proposed EA flood defence scheme is based on retreating as far back from the sea as we can, it deliberately puts our backs to the wall On one side of the barrier we will ultimately have the inter tidal habitat (the sea) and on the other our housing and industry.
No space is being provided behind the proposed barrier to create another bigger one. As a consequence there will be nowhere to go with a replacement that does not have a huge and unnecessary price tag. There is an irony that land at Chilton Trinity returned to the sea under the present scheme and the planned managed realignment in 2055 will be inadvertently reclaimed under a downstream replacement barrier albeit land now poisoned with salt.
With sea level rise continuing for hundreds of years past the design life of the BTB one would expect that as responsible people we would give some consideration to what happens next. Unfortunately, like so many things in need of fixing and investment we seem content to kick the problem into future refusing even to consider how we might make some provision to help those that follow us.
Many years an Arup engineer called Poul Beckmann wrote the opening sentence of a document with the line “Human nature is that we put off until tomorrow what we should do today”. Never has that been more true today than in Somerset. Somerset’s failure to develop a realistic, affordable and sustainable long-term strategy is unforgivable. It really is time for some of the promises made by our political leadership on this issue to be delivered and people stop making excuses why things cannot be done. Simply working our way through the Somerset 20 years plan and saying the future is not our business is irresponsible and unacceptable.
what was the question?
The SRA was asked “What is the SRA and its partners working assumption for the replacement of the existing scheme and barrier?
The written answer received from the SRA answer is in blue
From day one, the tidal barrier will be designed in such a way that it will still provide a 1 in 1,000-year standard of protection in 2125. The design includes an allowance for climate change up to 2125.
Climate change does not stop in 2125!!!!
1:1,000 sounds good but its just the margin on the starting point and degrades over time. The Dutch use 1;10,000 and maintain it as the level of protection.
The downstream defences will be designed in such a way that they will still provide a 1 in 200-year standard of protection in 2055, with allowance for further adaption for climate change over time.
2055 is important because this is the date from which managed realignment is implemented under Policy 7d39 of the Shoreline Management Plan.
EA explaining the scheme in 2017
It is to be expected that any piece of infrastructure would need updating after 100 years. We cannot decide now how future generations may wish to live or what their priorities for infrastructure will need to be. This is why, for example, there are plans for the Thames Barrier to be re-built in future decades but decisions on exactly where and what will be required are deliberately being left for later.
Building the barrier in the town as planned does not give those in the future choices but leaves them no choice to but to go downstream and use land we have previously given back to the sea and to abandon the £100M investment the present scheme will have cost.
The response attempts to conflate the need to replace the 1970’s Thames Barrier as a reason not to make provision today for a replacement in Somerset. if you know you have to replace something why would you not plan for the replacement? Its an excuse.
We should be learning the lessons of the past rather than making a virtue of repeating the failures that the SRA reply implies.
The Thames Barrier Myth
The continual portrayal Thames Barrier shown on TV as an iconic single barrier solution is misleading; the barrier is actually part of the Thames Estuary flood defence system comprising not one but eight individual tidal barriers that all shut together. Five of the eight barriers are closer to Bridgwater’s situation than the “Thames Barrier”. They are however where they should be at the mouth of the rivers they defend not 5 miles upstream as with Bridgwater’s Tidal Barrier.
Thames Estuary Flood Defence
Using the Thames Barrier as an excuse for not planning a replacement in Somerset is particularly disingenuous for a number of reasons.
Nearly 60 years ago when the Thames Barrier was designed climate change was not understood as it is now. There was little provision for sea level rise just the post Ice Age tilt of the south of England to consider.
The Thames Barrier is upstream of what were active docks that had navigation rights in the Thames Estuary.
In Somerset we have a topography in the form of the Polden Hills, Pawlett Hill and Stockland Bristol that we can link and use to our advantage. London does not have such a luxury.
The most frequent use of the Thames Barrier is now the management of fluvial flood water rather than tidal surge. Something Bridgwater is not designed to do.
Sedgemoor District Council is able to reserve space for a bridge over the Parrett south of Dunball should its not be doing the same for a replacement barrier?
The collective response is No ; there is no plan.
The SRA, EA and SDC were conformed as having contributed to the response
Bridgwater Tidal Barrier; the Questions the public need to Ask
Once the question “how will the proposed Bridgwater Tidal Barrier be replaced?” the present scheme simply looks out of date and poor value for money.
The Bridgwater Tidal Barrier is repeating the same mistake as was made with the Thames Barrier system setting it as far upstream as possible. Because of the selected location a replacement would like the Thames Barrier have to go downstream towards Combwich. Confused? We should be.
When you go to public consultation some questions worth asking;
How will the proposed Bridgwater Tidal Barrier be replaced?”
What becomes of Bridgwater after sea level rise exceeds the design basis of the Bridgwater Tidal Barrier?
Why is there no long-term plan or vision for what comes next?
Why is the ratepayer required to provide money to raise river banks money protecting land at Chilton Trinity when the planned sea water flooding will make it of no economic value?
Why is not improving fluvial flow in the river system part of the scheme?
Why did the cost of the scheme almost double after the location was decided on?
The UK has a serious problem with leadership and sustainable construction where flood defence is concerned. There is a profound lack of critical thinking in the delivery of future UK flood defences and an unwillingness by agencies to get their hands dirty at a local level. As a consequence government continues to fail regarding sustainability and value for money; taxpayer funded agencies seem unable or unwilling to work together. It is a situation compounded by wildlife and environmental organisations who have seen an opportunity to gain control of and modify land in much the same way that monasteries such as Glastonbury once did.
Flood defence schemes are invariably seen in terms of a definable project that can be closed rather than the first step of a sustainable long term solution. The protected community needs to live with and manage these schemes for 100’s of years after they are built. Our thinking on delivery is just too short and too expensive when it is a 300 year or so problem and especially when the initial solution only has a 100 year design life; it makes little sense. There is an obvious gap. That gap means that today’s options should at least consider what happens next. Should we really be adopting a solution today requiring the construction of a replacement barrier tomorrow rather than a scheme today that has provision or a plan for extending it already built in? Our current scheme takes planned obsolescence to a new level.
We should not be closing out future options for the generations that follow and we should follow our own rules for sustainable development
Delivery of the Bridgwater Tidal Barrier continues to be an exemplar of non-sustainable thinking. Part of the scheme requires the river banks between the tidal barrier and the village of Combwich to be maintained. The EA’s plan to do this work as part of the barrier construction contract. Material is to be dug from the adjacent protected fields and where a future Northern Bridgwater Bypass might be routed. Sedgemoor District Council (SDC) have protected in the Local Plan a potential crossing point on the River Parrett just south of the A38 roundabout at Dunball.
Clearly excavating Chilton Trinity’s fields and creating a series of salt water pits that creates an ideal future breeding ground for salt marsh breeding mosquito’s is not what people have considered the consequence to be. It is far from impossible that in a generation Chilton Trinity and Combwich may ultimately become uninhabitable because of this excavation process rather than from the increased flood risk. Managing mosquito borne diseases may well become the larger challenge in low lying areas as our climate warms up. It is difficult to see how the EA could contemplate the creation of such a situation.
With whole life costs of the Bridgwater Tidal Barrier reaching £100M for a barrier, secondary banks and the raised river banks; banks that need continual raising means we need to consider modification of the delivery model to get the costs of this project under control.
That whole life cost also ignores the 100 year economic impact, both locally and nationally, of losing 1000’s of acres of productive agricultural land notwithstanding the questionable morality of a food importing country choosing to export more of its food production offshore.
If we are going to build the solution we have we need better and more economic delivery solutions than is currently proposed. We can then at least ameliorate the present situation with a better delivery system.
Brexit allows the modification of the EU water and waste directives that have now been written into UK law. We can now change the way in which we manage waste for the better.
Sustainable Construction
Every year Sedgemoor will build 5-600 houses and the excavation of foundations and drains for each of these houses will create around 15-20m3 of waste material (clay) suitable for re use as bank raising fill material. Sedgemoor’s planned housing developments will create around 9,000m3 per year that currently must be paid for to be disposed of. Housing developers could supply all the material needed to raise the banks. That is sustainable construction.
Over the 100 years life of the barrier there could be as much as 900,000 m3 of material we need to find a home for; material that could be used to build up the banks and preserve the land we have at Chilton Trinity for future generations. Even if the volume is only 10% of the possible amount its probably enough to avoid digging up land at Chilton Trinity.
Under present EA proposals the EA is going to pay landowners for material that other organisations with similar material must pay to dispose of. We are meant to be reducing this sort of activity not making the situation worse.
We simply don’t need to get all the work in place in 2024; we need just enough to maintain the flood defence need and then use local resources to progressively deliver the longer-term solution with a local benefit to the economy. This work could be collectively done by local contractors under the supervision of either the EA or the Drainage Board. There is simply no engineering need for the EA to wantonly and unnecessarily destroy our landscape when cheaper and more sustainable alternatives are available.
NB there is only an intent to continue to raise the river banks
To put this into perspective that recycled material would
build a bank 5m high bank from the Bridgwater Tidal Barrier to Combwich.
raise the banks and build the secondary flood defences up to match climate change.
raise the banks, build the secondary flood defence and start building new defences north from Pawlett Hill towards Highbridge.
5m high and nearly 5 miles long, 100 years of digging house foundations
Sea Level Rise
Sea level rise is not expected to slow for at least 300 years making both the barrier redundant as the river banks can only be raised perhaps another metre before they overload the poor ground conditions of the Parrett Estuary. Ultimately the long term plan for Chilton Trinity and Pawlett Hams’s will be realised.
The continued conditioning of the population by the EA to passively accept surrender to the sea as the first option for non-London areas of the UK is disingenuous and defeatist and never mind its land we need to grow food on.
Way Forward
At £100M the present solution for the Bridgwater Tidal barrier is clearly neither sustainable or affordable. A situation that needs to be laid at the door of the Government, Somerset Rivers Authority and specifically the EA and Sedgemoor District Council (SDC) who provide joint project oversight. We need
Sustainability in what we do is placed at the centre of our plans
An independent inquiry into how flood defence is being delivered in Somerset.
A peer review of the BTB project into how it has arrived where it has.
The option of building the Bridgwater Tidal Barrier at Combwich was always affordable and as we now see the full whole life cost of the present scheme being made public its clear the best location was never considered.
Why Combwich?
Combwich would be a conventional location for a tidal barrier as its near the mouth of the River Parrett. Combwich is a unique site that would offer Somerset a long term solution to protecting the southern Levels as a barrier and associated embankment would close the narrow gap between Stockland Bristol and the Polden Hills via Pawlett Hill. The location also offers an appreciable increase in the fluvial conveyance capacity of the existing River Parrett catchment river system.
COMBWICH & BRIDGWATER TIDAL BARRIER LOCATIONS
Original image is courtesy of the British Geological Society.
The yellow colour in the above image is the soft clay deposited around 11,000 years ago. The existing river banks will see the new flood defences from Combwich up to the site of the proposed Bridgwater Tidal Barrier built on this soft material that is up to 20m deep. Defences that due to settlement will need to be built back up every 30-35 years defending land that will have been flooded with saltwater.
The argument is that it’s the cheapest solution where it is in Bridgwater.
People continue to believe the width of the river and the length of the barrier structure is the only driving cost of the scheme. Whilst size does matter it is not all that matters. Like most schemes that start without a clear direction the final cost proves to be significantly more expensive than expected and the Bridgwater Tidal Barrier is no exception. The EA project team didn’t understand its costs just its objective. They are not the same and nor are they aligned with securing Somerset’s long term future.
Most people are aware that present scheme originated from a 2009 scheme that was little more than a knee jerk reaction to climate change and the long-standing need for a control system in the river. What we have seen is that inexperience in project delivery saw the early focus on one element of the scheme rather than the scheme as a whole. Effort was exclusively focused on the barrier, the type of gate and location within a short length of the River Parrett and it clouded objective thinking about an holistic scheme. It was so bad that the EA team doing the barrier were unaware of the test bank being done by the EA and Team Van Oord; there was simply no joined up thinking.
Nobody at that time or since has been willing to stand back and take a cold hard look at what was needed when the Cameron Government’s political promise of post 2014 flood money removed critical thinking from the delivery process.
The simple fact is that every activity has a cost and the choice the client and the designer has is where you spend the money today and tomorrow. A simple comparison of where our money will be spent is produced below. You can spend money on lawyers and land agreements for secondary flood defences or spend the money on a better barrier. Paper does not keep the sea out.
Combwich offers a number of advantages that offset the barriers extra length and the constraints of the present location in Bridgwater. These advantages include the use of precast concrete construction, the availability of space for construction, no need for an expensive diversion channel and the long periods when the river is empty make considerable cost savings.
The key savings are given below.
Where the barrier money goes
a barrier structure could also support a future bypass.
Barrier and replacement Dunball Wharf at Combwich
The good thing about the River Parrett and there are very few is that its possible to work on the river bed without the need for a coffer dam. If you have the space and you’re in the infrequently used navigation channel of the Parrett you move and do things in the water during high tide and then drive down the bank onto a prepared river bed. and work during low tide.
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