Bridgwater Tidal Barrier Final Public Consultation

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.

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.

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.
All the Thames Barrier replacement options move the replacement barrier downstream perhaps as far as Tilbury. (July 2016 update)
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?

14/08/201813/09/2018

Build the Bridgwater Tidal Barrier at Combwich

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.

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.

05/03/201816/08/2018

Environment Agency – Landowner Information Pack

The Environment Agency (EA) like the many political parties with the word Democratic in their title seems ever farther away from what people imagine the organisation to be about. Protecting the Environment and the people seems not to be one of them if it gets in the way of its long term Parrett Estuary agenda at Chilton Trinity north of Bridgwater.

However any doubts that the EA doesn’t have a sense of humour or understands irony was firmly dispelled by its latest offering to the Chilton Trinity landowners. These are landowners whose land is impacted by downstream works resulting from planned construction of the £100M Bridgwater Tidal Barrier close to the town rather than is conventional practice at the mouth of the River Parrett.

In March 2018 each landowner was the recipient of a document called BRIDGWATER TIDAL BARRIER DOWNSTREAM FLOOD DEFENCES Landowner information Pack.

The EA’s apparent lack of understanding of the impact of salt water flooding onto farm land. is worrying. The expected floodwater is not like 2014 when the water that covered the Somerset Levels was predominantly fluvial run off (freshwater). This will be seawater coming up the River Parrett from the Seven Estuary that over tops the river banks.

This document also asks farmer’s to allow the Environment Agency to dig borrow pits in the land the EA are meant to be protecting. Borrow Pits are meant to be refilled with other less suitable soil so it does not lessen traffic as the EA claim but only if they are left as just open pits in which case they aren’t borrow pits. Do we really need to excavate the land we are meant to be protecting?

The alternative is a sustainable construction method that also seems to be a low priority of the EA. Construction of the bank improvements could be phased over a number of years using local contractors and material reclaimed from new developments.

The proposed pits will hold the seawater (saltwater) rather than see it quickly flushed away back to the river. Saltwater is poison to agricultural land and the habitat we currently have in Chilton Trinity. These pits will, according to the trial embankment test done for the Cannington Bends improvement scheme, need to be reopened or enlarged every 35 years of so to make up the levels as the made up river banks settle.

The EA promise going forward regarding maintaining bank levels quite rightly only talks about intent; the EA cannot provide a firm promise however they do know that once the land is poisoned the cost for further expenditure on bank raising will not be justified.

No one can say that the EA does not have a sense of humour especially when the Chilton Trinity farmers are encouraged by the EA to act as turkeys to vote for Christmas. The EA’s long term ambition of an inter tidal habitat remains our pantomime villain – he is behind us and we chose not to look around and see him. Whilst appearing to help the EA are actually creating a self fulfilling prophecy that will see the area become salt marsh.

This document

Only talks about 2024 and not 100 years in the future (2124) which is much more interesting for long term prosperity of everyone including our farmers handing land onto future generations. ( nobody says what happens when the banks can no longer be raised)
Confirms the level of protection they are planning to maintain to farm land is very low.
Omitted the future flood maps.
Omitted to mention that the flood water will be seawater .
Demonstrates on page 4 a complete lack of understanding of the impact of saltwater onto agricultural land. (Some Lincolnshire farmland has still not fully recovered from the 1953 flood when the North Sea over topped the sea defences)
Encourages the formation of borrow pits (actually just pits) that, when the banks of the River Parrett are overtopped, will trap seawater and ultimately destroy the value of the land its meant to protect. Destroying wildlife and fauna in the process that cannot handle saline conditions A case of the medicine killing the patient.
Creates through the use of borrow pits mores areas of stagnant water that in our warming climate will be a breeding ground for insects, one of the reasons given for not damming the River Parrett.
Fails to mention the pits will need to be used and extended at least 3x as according to the embankment trial the river banks will need raising every 35 years.
Does not mention the final height of the river banks in 100 years’ time, for every metre raised the bank get wider by 2 x 4.0m and the banks will need to be raised by around 0.80m. (2’6″) excluding the continued settlement of the river banks that always means 2 steps forward and always 1 step back.
Re-confirms that agricultural land will be preferentially flooded.
The EA commitment is qualified as only an “intent” . Will SDC ratepayers pay for the maintenance when they don’t get anything back? It’s a huge liability that SDC could end up with that has no benefit to the town. In a very short period of time, the cost of maintaining river banks to protect a small area of land and some ponds (flooded borrow pits) will not be considered worthwhile.

No one can say we were not warned about this EA scheme and still no one asks what happens after the proposed scheme, the Bridgwater Tidal Barrier, can no longer counter rising sea levels?

One can only appreciate the irony and the humour of the situation along with the EA’s other recent bits of entertainment

The gathering up the local newt population at Steart and their subsequent disappearance
Diverting migrating elvers away from their normal route to our freshwater river system into the Steart Peninsula scheme.
Planning to build a tidal barrier as far inland and upstream as possible contrary to all normal accepted good practice.

to paraphrase Churchill

never has so much money been spent in such a small place to so little effect

This document is at best poorly put together and at worst a device designed to obscure the true impact of the plan from those most affected

As this slow-motion environmental, and for Bridgwater, and economic car crash occurs we should not forget that three prominent members of the Wessex Regional Flood and Coastal Committee live within a mile or so of where this unnecessary and increasingly misrepresented process is going on. No objection or question is heard regarding the impact of the EA Scheme; there is no visible oversight.

The Internal Drainage Boards are equally silent as is the Somerset Rivers Authority

Finally, you know its wrong when that well-known litmus test is applied; The scheme in its present form has the support Ian Liddell-Grainger

15/08/201702/11/2018

Peruvian Duckweed

Most of us, especially if you live on the Somerset Levels or the Norfolk Broads, often see our rhynes (ditches) and ponds covered in duckweed.

It is not the pest we think it is.

This week after nearly two years preparatory work and 40 years of passion by Texas based inventor of the system Paul Skilicorn. I am in Peru as part of Lyndon Water‘s management team led by CEO Ray Anderson working to deliver a truly unique water treatment project. Using duckweed as a key element in the treatment process we will clean urban wastewater on an industrial scale and then turn it into potable drinking water to WHO standards. Water to the same standard that in Europe we take for granted 24 hours a day.

If all goes to plan in a little under 18 months people in an area of northern Peru will be free of a 30 year stench from its failed sewage treatment plant and the region receiving additional potable water to increase availability of drinking water and reduce the strain on depleting aquifers.

October 2018 Update

Paul Skillicorn recently left Lyndon Water and has set up a competing business. with Ramiro Priale.

Why Duckweed?

Duckweed is just about the fastest growing plant in the world. As duckweed grows it removes nutrients and other contaminants converting suspended elements in wastewater into usable biomass. We separate and take the suspended solids for anaerobic digestion to generate power before the duckweed cleans the water.

Duckweed under the Lyndon Water process is harvested and converted into fish food, animal feed, high protein superfoods or for energy generation. Some of the feed we produce will then be used to support Lyndon Water‘ s food production at a new and nearby integral fish farm and Aquaponics facility that forms part of the Lyndon Water system. Nothing is wasted.

Glue 2’s Duckweed Harvester and lagoon system.

Glue2’s vision of what future water treatment might look like this.

The harvester design and the lagoon system design is by my engineering consultancy Glue2 Limited . We have also developed a process for concurrent transportation and processing of duckweed suitable for use in remote locations using minimal permanent infrastructure. All equipment and buildings are modularised and based on ISO containers and dimensions.

We take wastewater and make drinking water, the waste we turn into food and power. What’s not to like?

When you next see duckweed covering a pond or rhyne it’s not a pest but it’s cleaning up our water. It’s not all of the story of the process but it is the key.

Lyndon Water led by Ray Anderson off to see the Peruvian Government in Lima

Director Paul Bryant, CEO Ray Anderson, Lyndon Water in Country Manager Ramiro Priale & Chairman Lewis Jeffery

Letter of community support for our project just received 15th August 2017

05/06/201726/09/2018

Chilton Trinity and Pawlett Hams

The EA’s 2011 document Managing flood risk on the Severn Estuary provided the EA’s vision for Steart Peninsula including what subsequently became the Steart Marshes salt marsh scheme.

Pawlett Hams no longer protected after 2030

Under present plans six years after the completion of the proposed Bridgwater Tidal Barrier Pawlett Hams will cease to be defended. That means that the river banks will no longer be maintained and the process of handing more farmland back to the sea will start again. The estuary will in time return to the state it was in more than 500 years ago before the levels were drained. According to the EA this will see 387 Ha or just under 1000 acres of farmland lost to food production and the local economy although only 47Ha is actually required to make up for coastline squeeze.

The Parrett Estuary Flood Risk Management Strategy (PEFRMS) is a document remarkable for its narrow vision that is more interested in extending the habitat for birds whilst completely failing to understand or chooses to stay silent on the impact of saltwater on agricultural land. The only economic impact considered seems to be tourism.

Parrett Flood Management Recommended Strategy

Section 2.1.6 (b) notes that

North Devon and Somerset Shoreline Management Plan (Hartland Point to Anchor Head), Halcrow, due 2010. We are concurring with their emerging policies.

As such much of the real detail is provided in the EA’s Shoreline Management Plan rather than the overarching Parrett Estuary Flood Management Strategy which is a long term plan to let down the flood defences along the River Parrett allowing the sea up to the edge of Chilton Trinity and trading off land in Sedgemoor for economic development elsewhere around the Severn Estuary. It is a step back in time with individual communities afforded long term term flood protection rather than comprehensive flood defence. The high level strategy for the PEFRMS is provided below following on is information from the shoreline management plan and recently available information for the preferential flooding of farmland as part of the Bridgwater Tidal Barrier Scheme.

Pawlett Hams Realignment is the complete loss of Pawlett Hams as can be seen from the key plan in the Parrett Estuary Flood Management Strategy and noted in item c above.

Applicable Shoreline Management Plan delivery of the Strategy that includes the loss of 387 Hectares (1000 Acres of land) at Pawlett Hams is reproduced below.

Parrett Estuary (Combwich to River Brue) Policies 7d38 to 7d42

Individual policies for various sections of the River Parrett and adjacent land are listed below. 7d39 is worth noting as it has the next major realignment of the flood defences after Pawlett Hams allowing the River Parrett to come up within 1000m of the village of Chilton Trinity.

Full copies of the EA policies can be found at

Steart Peninsula (Stolford to Combwich) 7d34 to 7d37

Parrett Estuary (Combwich to River Brue) 7d38 to 7d42

Timescales

all documents refer to timescales and these are

Short Term (to 2025)
Medium Term (to 2055)
Long Term (to 2105)

Chilton Trinity

South of the Parrett the EA ultimately proposed to let the marshes return to the very edge of Bridgwater whilst Sedgemoor District Council and the EA’s Bridgwater Barrier team have left a space at site 4 for a bridge that is on the way to a planned inter tidal area and represents the expansion of the Steart Peninsula scheme up to Bridgwater.

EA presentation Severn Estuary Forum 2017

Managed Realignment

the planned retreat of the existing flood defences

Policy 7d42 Flood defences from Dunball To the River Brue

Policy 7d39 Combwich to Bridgwater (Parrett west) managed realignment.

Those two policies when implemented will along with Steart Marshes and the Bristol Ports land transform the Parrett Estuary. There will be no new link possible between West and East Somerset.

Future (long term) Inter tidal habitat – salt marsh and mud flats

Total agricultural land lost to agricultural will be around 5000 acres. There is a certain irony that the EA policies will in reducing UK agricultural land export food production abroad and potentially increase famine oversees.

In the short term the proposed secondary flood defences shown below are required because the EA will not keep raising the banks above the present levels. sea level rise will continue and the frequency of seawater flooding will increase. The route of the secondary flood defence is not dissimilar to the future managed realignment above.

Secondary Flood Banks based on Bridgwater Tidal Barrier at Site 5

The gap in the flood defences at Walpole still left open for floodwater to flood the area as it previously did in the 80’s

After the planned completion of the Bridgwater Tidal Barrier a 1:200 flood is expected by the designers to flood land to the north of Chilton Trinity with saltwater. The maps below represent some of the 50 maps prepared by the BTB designers to support the decision on location of the BTB barrier; the complete set of maps can be found on the SDC Strategic Flood Risk Assessment page.

The maps below show the impact of the river banks not being raised to match rising sea levels apart from the protected communities. The end result is the preferential flooding of farmland with saltwater during certain tide and storm conditions as presented during the Severn Estuary Forum 2017 held in Bridgwater.

None of this information was presented during the two EA/SDC public consultations in 2016.

The map below shows one of breach locations modelled. A breach can occur anywhere, the map does not say its saline (salt) flood waters escaping from the river. They are merely designed to provide an idea of the likely consequence of it happening. The full pack of maps shows a number of breach locations and these are yet to published by Sedgemoor District Council.

River Bank fails at Dunball at land to the north of Chilton Trinity flooded

One of the maps produced by the designer showing the safety risks associated with their present scheme.

BRIDGWATER TIDAL BARRIER ; SITE 5; FLOOD HAZARD 1 :1000 YEAR FLOOD EVENT

03/05/201707/08/2018

Bridgwater Tidal Barrier a Fatal Flaw

The existing Bridgwater Tidal Barrier scheme has a flaw.

Water can go around it.

Any system including a flood defence system is only as good as its weakest link. The banks of the River Parrett is the Achilles heal of the EA’s scheme.

The ground along the river is simply too weak to support the continued raising of the river banks and from the EA’s point of view too expensive to maintain. The Parrett’s highest tides hidden behind the raised banks are already at the top of the doors of Bridgwater’s houses along the A38.

Even before it’s been built and the complete scheme revealed to the public the EA is working on adding secondary flood banks (dashed red lines) on the premise of a bank failure or a future decision not to maintain the existing flood defences. The drawing below is a scheme the EA has to fix the flaw. The red arrow is the open back door at Walpol where a breach to the north could circumvent all the defences. When the Dutch build a dyke they don’t build another one a few hundred metres behind it; clearly the EA expects a failure to occur or the river to over top.

The line in green is an option never considered by the EA but one that would offer much better protection than what is being proposed.

EA Secondary Flood Barrier, Downstream Bank Modifications and Alternative Barrier Route

This is information never presented to the public in any of the consultations in 2016.

To my knowledge Bridgwater will have the UK’s only tidal surge barrier not located at the mouth of the river it’s meant to control. At Bridgwater’s present rate of expansion the proposed barrier will in 100 years time not be just near the centre of Bridgwater but within the centre of its developed area. Only in Somerset would anyone come up with the plan we have and think its acceptable to have a scheme that has such an obvious flaw. Let’s also not forget that the EA’s other wider site downstream is being reserved for a road bridge to land that the EA is not protecting in the same way as existing housing. What happens when that is to be developed? Start again?

The ratepayer should have had real options presented rather than the EA’s version of the Henry Ford motto “any colour you like as long as its black”, ie anywhere in the river as long as its at the narrowest part of the river we can persuade people to accept.

The letter below confirms that the barrier can be circumvented.

EA Letter to Chilton Trinity landowner