Designing concrete mixes for specific purposes often raises questions that you don’t know the answers to. Familiar products have fallen into disuse and new products are just new. A recent project in Shetland required a mix able to get into areas of heavily congested reinforcement that had previously failed the first time around.
Highly plasticised mixes look and behave differently from “ normal “ concrete and the current mix was a 100% Portland cement mix that appeared to have followed me over from Abu Dhabi with the same original contractor having developed a similar mix for two different projects. Shetland and Abu Dhabi having in common a lack of cement replacements particularly in the oil & gas industry. A situation further complicated as the current mix had a very high cement content was plasticised but not retarded making it very difficult to use in all but the simplest pours. It has very little time to be placed.
The rework had a number of challenges that followed from the earlier pour.
Hanging shutters that obstructed the passage of concrete.
A relatively small volume; less than 10m3
Over detailing of reinforcement; surplus reinforcement that had not been removed during original fixing.
Complicated shuttering and finishing that required considerable time to complete after the bulk of the concrete had been placed.
For the revised rework mix a new mix with the following requirements was developed.
A 10mm aggregate for congestion and cover issues.
Place using the chute from the back of the truck.
Delay the setting time to around 3 hours.
Retain the waterproof qualities of the existing mix.
Characteristic strength of 35N
Satisfy durability requirements for a Marine Environment.
TESTING & APPROVAL
Sika provided a S4 mix design based on the above requirement; to obtain client approval and to understand what we had and how it worked a simple test was done twice.
Batches of the revised concrete mix were mixed and held in a truck mixer replicating a long discharge time on site.
The truck mixer was progressively emptied over 3 hours.
Slump test were taken every 20 minutes and cubes at hourly intervals (1, 2 and 3 hours) for testing at 7 and 28 days.
Testing at EMN Plant’s Scatska Batching Plant in Shetland April 2017
RESULTS
they were very good
the mix stayed at or around the design slump only marginally dropping off in the last two results but still within limits.
cube results were consistent and all passed.
LESSON LEARNT
One important thing that was noted was that the consistency (slump) potentially drops for a short period below the specification ,about 1 hour after batching was completed, and then regains the required consistency. It occurred on both batches.
The lesson for Contractors, Consultants and QA /QC processes is that
The time from batching to the initial test is important and that there is the potential to reject concrete that is actually ok.
When doing trial mixes develop tests that explore what could happen when a concrete pour goes wrong and placing of concrete is delayed identifying any characteristics that might explain a rogue test result during placing operations.
On the 10th of July at Bridgwater Town Hall (2-7pm) the EA and SDC will reveal the final form of their scheme for the Bridgwater Tidal Barrier. Its construction will shape the town for the next two hundred years. It is planned to be commissioned in 2024 and designed to operate for 100 years. The operational date is a political one rather than climate driven and unlike most similar structures it will be located within the town rather than at the mouth of the river. Mitigation of a similar fluvial flood event to 2014 is not part of the barrier’s function.
People have been focused on the barrier yet the river banks are the important bit; what happens to them will decide how radically our existing landscape will change and have far greater impact than a set of gates. The downstream river banks are being maintained in accordance with the FCERM Strategy (the national flood and coastal erosion risk management strategy for England).Individual polices are detailed in the local 2010 Shoreline Management Plan covering the next 20, 50 and 100 years.
For the Parrett those policies say that within the operational life of the barrier “The long term vision is for a more naturally functioning estuary, through construction of set-back defences under a policy of managed realignment.” Land is being returned to the tidal zone.
EA maps produced in 2010 show how that will be achieved at Pawlett Hams and Chilton Trinity. The recently released BTB secondary flood defence plan and residual flood risk maps show the long term policies are being put in place. Only the river banks close to Combwich and Chilton Trinity housing will continue to be raised. Farmland will ultimately be flooded and lost as the majority of the river banks will cease to be raised to match climate change. Steart Peninsula’s habitat will in due course be extended to Dunball and Chilton Trinity.
The present scheme means that the opportunity to increase the conveyance capacity of the Parrett capacity by moving a future replacement barrier downstream is lost. Taunton Deane and South Somerset may have to build fluvial storage on their land in the future. Opportunities for a cost effective bypass will be lost to the detriment of Bridgwater and West Somerset. As a naturally occurring event Somerset land owners will not receive compensation. Bridgwater will pay around £20m in lost land values towards the present scheme. A major economic impact on Somerset as a whole is just being ignored.
It is simply not true or credible that the BTB can somehow be divorced from the EA’s longer plan for the Parrett Estuary; a plan prepared in 2010 predating the 2014 flooding of the Somerset Levels.
The Bridgwater Tidal barrier in its present form passed its sell by date in 2014 when fluvial flooding moved from management on the Levels to flooding within our homes. Even today people still imagine that the Bridgwater Tidal Barrier is somehow part of the scheme to mitigate the 2014 flood, it could be but it isn’t. The Levels’ will still flood as they did in 2014 if we get similar weather conditions.
With little information in the public domain including the option studies that supported the original 7 location and the shorter list of 4 it is not unreasonable that this scheme has many questions of transparency. it is unacceptable that important and relevant information is not available to the public ahead of the final consultation on the 10th of July. That flood maps produced in September 2016 have only just been published giving people little time to understand the implications of what is planned.
If the FCERM Strategy and Parrett Estuary Flood Management Strategy are executed in their present form 1000’s of acres of agricultural land will be lost to food production. Is it morally right that the UK which cannot feed itself should export even more of its food production overseas and possibly deny food to others? This lack of responsibility on our part will no doubt be further compounded when our overseas aid budget has to be used to relieve a famine we as a nation knowingly or perhaps worse unknowingly contributed to.
To reach this situation there is a clear lack of leadership, vision, scrutiny and oversight by those organisations and people charged with delivering the plan and the infrastructure for Somerset. Neither SDC nor the SRA has any engineering or qualified staff able to lead on flooding and has chosen not to bring in people that could. There is also a clear engineering deficit in the delivery of Somerset’s flood defences.
People should go along to the consultation and ask
Is turning the River Parrett back 500 to 1000 years and extending the Steart Peninsula wildlife habitat to Dunball whilst constraining economic development really what Bridgwater and wider Somerset need?
Why wasn’t a barrier considered at Combwich and extending to Pawlett Hill that would protect the whole area. Arguments that we might impinge on the edge of the SSI is not an argument for not even looking at the possibility.
Why does the barrier only do TIDAL and not FLUVIAL (2014 rainfall) with equal importance?
What is the extra cost of building a barrier with a bridge on it?
Bridgwater will shortly be given its final opportunity to be consulted on the planned Bridgwater Tidal Barrier at its chosen location near Express Park. Did anyone really wonder why Bridgwater’s barrier, probably uniquely in the UK, is situated not at or close to the mouth of the River Parrett?
The reason is that in 100 years or so time it probably will be.
The start of the River Parrett will have moved to be at or just upstream of Dunball where the secondary flood defences meet the raised raised river bank.
The EA’s well concealed Shoreline Management Plan (SMP) intends over the next 100 years to return the Parrett Estuary to its original form. They intend to allow the sea to over-top the river banks spilling out over the existing farm land to ultimately form an inter tidal habitat stretching from the Steart to Dunball.
People have been told by EA that “river banks will be maintained” and imagine the EA intends to continue raising the river banks. That is not true; what it actually means is that the banks will stay at the preset level whilst sea levels continue to rise. Ultimately the sea will come over the top of the banks naturally generating the planned realignment of the Parrett and avoiding paying landowners compensation. Banks will only be raised locally and the impact can be seen on the recently released flood maps. This was known about before the September 2016 consultation but never presented. The EA’s repeated statement on protection is duplicitous at best and misleading at worse.
To compound the EA’s lack of transparency it seems to have lost its moral compass with regard to those less fortunate. Locally with nearly 2000 acres at Steart already lost to food production the EA’s SMP will see another 3000 acres lost to UK food production at time of growing food insecurity . As a country that cannot feed its self that lost acreage along with all the rest of land lost through Managed Realignment will have to be replaced overseas taking away food that could be used for famine relief and the less well off. It is the worst type of modern colonialism. It is a situation made all the worse by the fact that the UK’s aid fund may be trying to alleviate problems we are causing. Not much in the way of joined up government.
Serious questions need to be asked of the those County and District Councillors who seem to be on all the committees but do little to bring the EA to account and are prepared to promote the exploitation of other people’s land to avoid looking after our own.
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.
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 BruePolicy 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.
2025 1:200 Flood Return
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
A year or so ago when Sedgemoor District Council (SDC) and the Environment Agency started work on the Bridgwater Tidal Barrier (BTB) scheme they jointly decided not to spend money on an economic impact assessment.
As a result of that decision there is now no way for councillors, ratepayers and business to measure and benchmark the wider commercial and economic impacts of BTB project. The project is now simply valued and measured by government rules. This is especially important for those ratepayers and the HoW LEP who will directly pay for a proportion of this scheme. For Somerset’s councillors there is no visibility of the potential direct local (Somerset wide) benefit. With a preferred location agreed and the full details still yet to be seen or shown to the public it is difficult to see how the Bridgwater Tidal Barrier can be proceeding as it is.
There is a need to scrutinise the EA’s proposed Bridgwater Tidal Barrier and its management of the delivery of the scheme. There urgently needs to be some form of independent peer review to support the decisions of councillors and EA employees who do not have suitable engineering qualifications and experience. No private company would do this.
The River Parrett catchment and its capacity affects much of South and Central Somerset; almost every town is on one of its tributaries. The wider opportunity that Somerset’s flood defence expenditure presents has to date been largely ignored and is in danger of being squandered. Sensible promises made in 2014 have been quietly allowed to disappear.
If you live within the Parrett Catchment or in West Somerset this article will be worth reading for economic reasons alone.
River Parrett Catchment Area
By 2024 nearly £100M will have been spent on flood related work within Somerset and the majority of the money focused to the north and north west of Bridgwater. The EA’s managed realignment at Steart Peninsula and the adjacent Bristol Ports property deal for it proposed container port that is of no economic benefit to Somerset sees nearly 3000 acres of farmland removed from the the local economy.
However
The Levels will still flood and as they did in 2014; they will simply drain more quickly.
A flood defence system will have been built that only works for sea water (tidal) and that will probably have to be replaced because it will not be viable to extend its design life because of the ground conditions along the river banks.
The expansion of Bridgwater over the next 100 years ignored.
The rather novel concept of putting a tidal flood barrier 5 miles upstream of the mouth of the River Parrett and into the town implemented.
An additional 2,000 acres of productive agricultural land will be in the process of being lost to agricultural bringing the total of land lost to the local economy to 5,000 acres including Steart Peninsular and the Bristol Ports land deal.
There will be no bridge over the Parrett although the myth that you cannot easily have both on one structure will have been discredited albeit too late.
No beneficial integration with a future Bridgwater bypass considered or provided.
An important relationships between the capacity of the KSD/Sowy expansion and the impact of the location of the BTB never mentioned or costed.
The planned loss of Pawlett Hams to the sea lying hidden in the Parrett Estuary Flood Risk Management Strategy.
Perhaps the most unfortunate decision to date was naming the barrier/barrage the Bridgwater Tidal Barrier and sending mixed messages as to its purpose. That single act has reduced interest and scrutiny both in Sedgemoor and further afield to almost nothing. Only 180 people came to a public consultation in September 2016.
The introduction on the SDC barrier website reproduced below implies on the last line that it “could play a critical role in reducing flood risk” (tidal) and not the fluvial flow it started talking abut; they are not the same thing but did meet once in 2014. Two different things have been conflated into one message.
The barrier is not designed to mitigate a another 2014 flood
with regard to fluvial (rainfall) flooding
Would it now have had an impact on another 2014 flood? NO
Could it be made to have an impact on another 2014 Flood YES.
Somerset’s councils seem to have no interest in this scheme yet they should because
Somerset County Council (SCC)
Despite having the SRA under its wing and councillors jointly at County and District level there is little in the way of a long term vision that can be see being developed.
A shorter more strategic tidal scheme closing off the South Somerset Levels from the sea by closing the short gap between the hills from Combwich to Pawlett Hill has not been considered.
Such a scheme would
Secure the south Somerset Levels from the sea.
Improve the fluvial capacity of the River Parrett to the benefit of Taunton Deane and South Somerset as well as Sedgemoor.
Provide a bypass and improved road link to West Somerset using EDF’s extended Cannington Bypass.
West Somerset
West Somerset’s economic development is constrained by two roads (A39 & A358) and the need to navigate across either Bridgwater (A39) and Taunton (A358) road systems to get to the M5. With little or no options and no Government money available as part of its road budget it is an area of Somerset where the wealth and opportunity of its population is always constrained and likely to continue. No doubt why it loses industry and income.
It is difficult to understand why West Somerset isn’t trying to improve its economic link to the M5 motorway and via the A39 to Frome, Wells, Shepton Mallet, Street, Glastonbury and Yeovil.
Constructing the Bridgwater Tidal Barrier at Combwich with a road bridge taking advantage of the recently constructed EDF extension to the Cannington Bypass would provide a significant economic benefit to West Somerset.
Taunton Deane & South Somerset
Both local authorities rely on their respective tributaries Rivers Isle, Cary and Tone to convey surface water to the River Parrett and onwards to the sea. No amount of SUDs, storage on the Levels or slow the flow is going to change the fact that you can only get so much fluvial flood water out through the River Parrett. That constraint will ultimately have to be faced by limiting economic development The opportunity has not been taken to leverage the long term benefits for the two districts by moving the barrier downstream.
The reason to relocate the selected Bridgwater Tidal Barrier site downstream is that its preferred location does almost nothing to improve the conveyance of surface water to the sea. Where it is now proposed above the King Sedgemoor Drain outfall means that the full benefit of the KSD/Sowy expansion cannot be achieved or the capacity of the River Parrett optimised. Capacity that would benefit largely Taunton Deane and South Somerset. That scheme is being paid for by everyone and is simply not as good value for money as it could be. Rising sea and tide levels will reduce the time the KSD sluices can discharge. That situation will invariably negatively impact both districts by limiting how much water can go in to the system at their end.
It is therefore surprising that neither council has been pushing the barrier downstream where it could be used to increase conveyance in the same way as the Thames Barrier does. Increasing the overall capacity of the system when the Levels again flood is the priority and an opportunity not to missed offers one less obstruction to those two districts economic development.
Sedgemoor District Council (SDC)
South Somerset Levels
Sedgemoor opted to support a 15Km long scheme that cannot be extended (raised) as sea levels rise. Somewhere a bigger one will be required. Its consultants never looked at what would be the best scheme for Somerset or indeed wider Bridgwater. It is just what would be the cheapest for the EA whilst the SRA and SDC looked on. A location for the barrier where a bridge cannot be added to it is hardly planning for the future but it does ensure the ratepayer does not get value for money.
North Somerset Levels
Defending the North Somerset Levels could be achieved by the construction a new barrier from the Polden Hills to end of the Mendips (Brean Down). Such an undertaking could be easily done providing undeveloped land is identified. We could create a second line of defence over the next 30 years letting Somerset contractors run recycling operations allowing trains to bring in recycled materials to form a continuous flood defence. Its time managed retreat was abandoned.
What is disappointing is that with the SDC Local Plan under development there is no land being reserved for future improvements to the flood defences. The organised surrender of Somerset’s hard won land is being orchestrated by the EA under its Managed Realignment process and no one is challenging it. Everyone in Somerset should be interested in what is being done along the coast for safety and economic reasons. There is simply no plan.
Heart of the South West LEP
The Heart of the West LEP with its support of the BTB a project will ultimately damage local businesses based in most districts (£16-20M of lost land values) whilst in a current study is looking at improving rural businesses . The LEP is an organisation facing both ways to the detriment of everyone.
Somerset needs some joined up thinking and understand the very negative implications of some of Somerset’s flood defence scheme.Only when its built and its limits apparent will people say “if only”.
The Options looked at by the EA lacked any sort of imagination or offered a long term solution; were simply variations on a theme and ignored the nearby topography that offered other options for the Bridgwater Tidal Barrier
It is unacceptable that better engineering options were not identified and presented to councillors; ultimately it should be the ratepayers decision to go for a better solution if they want to. The EA should not presume as it has in this case.
On the 14th July starting at 10.00 am the first opportunity to do something takes place when the SRA scrutiny committee meets in open session at Somerset County Hall, TA1 4DY.
Some Questions to Ask
Why is the Bridgwater Tidal Barrier not also designed to help to mitigate the effects of a similar flood to 2014?
What is the replacement plan for the Bridgwater Tidal Barrier?
What is the cost of a scheme with a bridge ?
Should we only be spending our money on such a limited scheme?
Why wasn’t Combwich and the resulting shorter flood defence system that protects a larger area than the current scheme considered by the EA?
Does the extension of the Cannington bypass towards Combwich necessitate the reassessment of the present scheme?
Should Somerset County Council be looking at a more holistic scheme for Somerset?
Should SCC commission a county wide economic assessment of what an alternative barrier scheme might deliver?
Do we need the EA or should the SRA be expanded to become a delivery focused organisation and the EA limited to a statutory consultee ?
Is the role of environmental charities in developing and influencing flood policy beneficial and do they have a conflict of interest?
Why after 3 years since the flood and 8 years since the barrier identified as the preferred solution is there almost no information about the scheme on the http://www.sedgemoor.gov.uk/bridgwaterbarrier website?
The EA plan another consultation on the full scheme later in 2017. Councillors of all Somerset’s districts might like to look at the economic impact of this scheme (BTB) on their own areas and perhaps county might look at the bigger picture.
An unintended consequence is only the failure to adequately consider a decision before it was made.
Rivers that discharge into the Severn Estuary are very different from most UK rivers. With a tidal range in the estuary of around 11m MLWN -3. 0 and MLWS -5.7 AOD and the river bed level at around 0.00 AOD. These levels means that at low tide in the estuary the water level is always below the bed of the River Parrett and the river simply empties into the estuary. In the case of the Parrett its a process that goes as far upstream as Oath and the changing tide sees the river refilling from the sea.
What is seen looking over the Bridgwater’s bridges is just one half of the normal tidal cycle you would see at the coast; at low (ebb) tide its purely fresh water going out and that can be seen on the West Quay tidal gauge where the graph flattens. Equally the point at where incoming seawater (saltwater) takes over from the freshwater of the Parrett and becomes a relatively small component of the rivers water can also estimated.
At low tides the river empties so completely that during periods of low fluvial flow it can actually dry out so much so that upstream of Combwich there is an old iron age path where people simply walked across the river at low tide.
High tides can be nearly 2m above the surrounding land and at Bristol Road nearly as high as the head of the doors and over the next hundred years that will continue to grow .
Ecologically it is largely a dead river. Nature likes, however bad, a consistent environment and the Parrett offers the greatest of changes twice a day from empty to full and freshwater to saltwater. The large amounts of Seven Estuary silt that arrives with the tides exclude sunlight and there is nothing to generate oxygen. Fish(salmon) and Elvers just transit the river on their way to the fresh water of the River Parrett and its tributaries.
It is a true challenge for The EU Water Framework Directive as there is little negative actions that can be done to it. The lack of water does not deter unrealistic claims that fisheries exist in the river.
The images below show River Parrett tides ( courtesy of GaugeMap)
West Quay One days TidesWest Quay One weeks TidesHPC Tide Gauge
The Hinkley Point tide gauge above shows the full cycle of the tide in compoarison to the truncated cycle at West Quay which is caused by the river bed being higher than the sea bed in the Seven Estuary.
West Quay- One Months Tides
Looking along the river it could be shown
River Parrett at Low Tide
2014 Flood
In 2014 the Somerset Levels flooded, normally excess water is stored on the levels and then pumped back into the river when the weather improves and fluvial flows have reduced. The floods occurred because the flood storage capacity of the land was exceeded.
The response to the flood and still the current plan is pumps some more fixed ones and temporary platforms for hired pumps such as the permanent platform at Dunball made ready for the next time the levels flood and improvements made to how fast the flood water can be drained off the Levels.
One important question is whether its possible to increase the amount of water that flows down the river without pumps?
The answer is yes; the Thames Barrier is used in that way when there is flooding and the Thames and its tributaries are at capacity. The barrier gates are closed at low tide creating a shallow reservoir normally filled by the incoming tide and floodwater coming down the river fills it up. Previous references to the Thames Barrier and the River Parrett were in relation to the type of gate rather than how the system operates.
How might it work in the River Parrett?
There are two sources of fluvial floes into the Parrett. The Parrett and King SedgemoorDrain (KSD) /Sowy River. Water unable to get down the River Parrett is diverted around Bridgwater via the KSD/Sowy and re-enters the Parrett at Dunball.
Dunball Clyce (River Parrett side)
Both sources can discharge when the tide is out but become tide locked when the sea re-enters the river. Creating a large temporary empty length of river downstream of Dunball would allow both sources to continue flowing and when full and matched with the tide allowed to go to the sea.
River Parrett – Increasing the Flow
To do this a gate is needed downstream of Dunball and the best location would be Combwich or somewhere in between. The Bridgwater Tidal Barrier is a gate that could have been used to do this.
EA Downstream Scheme
The current plan is to build the Bridgwater Tidal Barrier upstream of Dunball Clyce and with sea and tide levels continuing to rise allowing the sea to reclaim the farmland at Chilton Trinity and Pawlett Hams. The existing system returning to an inter tidal saltmarsh/mudflat covering the existing farmland at Pawlett Hams and most of the land to the north of the village of Chilton Trinity. The drawing below shows how the regime will change over the years to come.
River Parrett at Chilton Trinity & Pawlett Hams showing planned next 100 years
Has anyone noticed there actually isn’t really a plan for managing flooding in Somerset be it Tidal or Fluvial. Lots of headlines and pictures of grandstanding councillors on river banks but little substance. Our particular collective flood Emperor has no clothes whilst the myth that somehow the Bridgwater Tidal Barrier (BTB) is part of the solution to the avoiding a repeat of the 2014 flood is allowed to persist. People imagine that things are being done and there is a big picture somewhere. There isnt.
The Somerset 20 Year Flood Action Plan is little more than a maintenance list that should have been done and wasn’t; it is a complete misnomer. In three years since the 2014 flood there is no big plan looking forward the next 200 years. There is no context that explains where the value of all the money being spent is.
There is no excuse for such short sighted behaviour by our officials and elected representatives. At least the Somerset Rivers Authority (SRA) carried out an economic impact assessment of the 2014 flood which is more than the EA and Sedgemoor District Council (SDC) have done for the Bridgwater Tidal Barrier.
The development of new ideas seems to be more akin to those seeking alternative medicinal remedies; they seem to be ones that will turn the Levels into some theme park rather than look at something that can be delivered over the decades and centuries ahead. The Managed Retreat (Realignment) of our coastline is not a panacea to rising sea levels; it has its place but needs to be challenged when there are viable options. Giving the EA the excuse and licence to do little or nothing is not acceptable. Those involved with W&WT and the RSPB as consistent beneficiaries of these EA policies and alongside Natural England makes an unholy alliance that is no friend of Somerset’s people.
Plenty of councillors are sat on committees and they should be ensuring rigorous debate and the publishing of useful information rather than the almost complete lack of detail in the public domain. The private sector would not be allowed to get away with this lack of transparency or vision.
Since 2014 when it was rushed together for political expediency little has been done or achieved whilst show case projects are not what they seem
Bridgwater Tidal Barrier
Despite knowing that the rise in sea level has no recognised end date Somerset has decided on a 100 year scheme. Our King Canute moment.
We are going to build a scheme that cannot be easily extended or modified knowing full well that something else will be needed in the future but we haven’t decided what. A scheme that unlike any conventional tidal surge barrier it is actually to be in the town rather than down stream and at the mouth of the river. Bridgwater in probably 10 rather than 100 years will have enveloped the proposed barrier site. A solution with built in obsolescence that can be bypassed on day one does not seem a great idea. Children born today may see the BTB torn down. Why would Bridgwater buy it?”
Options such as closing the gap between Stockland Bristol and Pawlett Hill less than 2 Km ( 1.3 miles) long compared to around 15 km (10 miles) both banks from Combwich to the selected site in Bridgwater or 7.5 Km if you allow Pawlett Hams to go the way of Steart Peninsula.
Two option studies paid for by the taxpayer and Combwich not even considered as an option in either and the backdoor flood route at Walpole still not acknowledged when the EA visits landowners. The credibility of the EA , its consultants and our oversight committees is very poor.
King Sedgemoor Drain Improvement
The King Sedgemoor Drain improvement is a Fluvial conveyance scheme that cannot reach its full potential because of the location of the tidal BTB upstream of Dunball Clyce. The EA in this matter described themselves in recent correspondence as the SRA’s sub contractor.
Silos
Flood schemes are kept in silos of fluvial and tidal rather than in developing a single holistic solution for Somerset. The EA and other organisations make it very difficult to see the full picture. There is a serious lack of transparency, accountability and independent review in the process.
By 2024 nearly £100m will have been spent and the Levels will still flood. The Bridgwater Tidal Barrier is seen and portrayed as a Bridgwater only scheme where as moving it downstream of the KSD outfall would increase conveyance under fluvial conditions benefiting the districts of Taunton Deane and South Somerset. The SRA is nowhere to be seen generating debate and bringing together people to achieve a wider benefit to Somerset with state and local ratepayers money which was its reason to be created. The SRA’s one big opportunity missed. This is notwithstanding the missed economic opportunity for West Somerset
Transparency
There is more information in the public domain about EDF’s Hinkley Point C power station then there is about these schemes especially the Bridgwater Tidal Barrier. It appears the EA did not want the Chilton Trinity and Pawlett Hams landowners to be aware of what would not be done to protect their land choosing to hide behind the rather opaque Parrett Estuary Flood Risk Management Strategy. Something noticeably low key to the point of invisibility in the EA’s 2016 consultations at the Bridgwater Art’s Centre.
No imagination and no vision for our children’s future
With a blank sheet of paper and little or no restrictions on what we might do to protect the South Somerset Levels including areas of Sedgemoor, Taunton Deane and South Somerset there is still a blank piece of paper. Rarely has such an opportunity been squandered.
There is nothing that explains what happens to the Tidal Surge Barrier when we cannot raise the banks any longer which in reality we cant now and Pawlett Hams and Chilton Trinity have become mudflats/ salt marsh and the cost of building downstream prohibitive.
Its interesting to note how many people sit on more than one of these committees. These committees have people with no engineering knowledge or experience apart from the EA & IDB and all EA’s donkey work is done by US and Canadian third party consultants with no attachment to the area. The EA’s contribution to Somerset is questionable now as they have been reduced to little more than a middle man.
we must also not forget the groups
SRA Management Group
SRA Technical Group
Bristol Channel Strategic Coastal Group
South West Coastal Group
Southern Coastal Group
It really is time that Somerset had a suitable organisation capable of bringing a long term vision to secure the future of Somerset. Whilst attendance at committees is so lucrative nothing is going to get done . The EA is not a delivery based organisation and needs to be changed or replaced. The SRA has no structure or suitable people able to develop and execute the vision and solution we need. The system we have is clearly not fit for purpose.
The situation for Somerset, the rest of the West Country and no doubt other regions of the UK is that they need their own independent Engineers with local knowledge. Engineers able to provide continuity in advice to the committees and oversee the EA and IDB and other agencies.
We cannot afford
that each agency (EA, Highways, Rail) continues to builds its own thing, we need to combine flood defence with other infrastructure works.
that strategic flood decisions can be left to seconded senior local authority officers with little or no knowledge of the subject.
the lack of an independent peer review process.
The lack of transparency – there is nothing published on the BTB website that tells you why. There is little value value in an undated progress report that can be found there that does not measure progress.
all these organisations whose main purpose seems to be to invite people from other groups to attend their meetings at our expense.
WE NEED A PLAN and we need to end the Flooding Golden Goose.
on the 14th of July 2017 a meeting of the Scrutiny Committee will take place in Taunton . It is open to the public.
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.
I am currently in Shetland overseeing the rebuilding of some badly built concrete and reporting on the causes. One of the primary reasons for the situation is the multiplicity of organisations in the delivery process where people in those organisations chose to assume the “other people” whoever they were had looked at it and checked it.
The result was that a completely avoidable problem occurred. The details of the incident do not matter what does matter is the lack of knowledge and responsibility in the delivery chain. People assumed and did not have the experience to put their hand up or were overruled on issues that were clearly obvious if people followed normal practice.
The UK is seeing increasing local control of significant long term infrastructure development passing into the hands of local councillors who have no access to independent advice. The low level of scrutiny and lack of third party review now being applied to tax payers expenditure is of great concern. LEP funding organisations seem equally poorly equipped accepting what the EA, Highways and other statutory bodies choose to tell them.
In 2016 I provided written evidence to the House of Commons
Environment, Food and Rural Affairs Committee Second Report of Session 2016–17. The concern being that important infrastructure projects being locally run did not have adequate over sight. Once local authorities had the District Engineer whilst central Government oversight is at such a high level and based in London that it is largely irrelevant to the population. We have no competent independent oversight on the many state funded projects taking place regionally.
Recent correspondence with The Somerset Rivers Authority indicates that organisation has all the indicators of an organisation with inadequate resources and a scrutiny committees that appears to have no terms of reference and no access to third party advice. No large commercial organisation would operate in this fashion. It is noteworthy that the EA in response to recent questions describe themselves as a subcontractor to the SRA.
There is little doubt that there is some huge embarrassing and expensive mistake on the way. It is time the regions had independent Engineers who can advise our councillors and has the power to bring statutory organisations to the table. Someone who lives in the region who can drive solutions to the tax payers benefit rather than the continuing creation of separate infrastructure rather than integrated solutions.
As usual we have too many people in positions of influence who don’t know what they are talking about and consultants more concerned with fee income than doing the right thing. Bridges on Tidal Barriers for instance.
If the regions want independence they will need the tools to do the work. Our infrastructure delivery needs to better managed and supervised.
Building on flood plains is not seen as a good idea but that is only the case when you want to build the same style of house that we build everywhere and is already unsuited to our changing climate and increased recurrence of flooding. Governments have become quite irrational basis for restricting development on floodplains especially when fluvial flooding is considered in the same way as one caused by a failure of our tidal flood defences.
Somerset and similar low lying areas are not flood plains in the normal way, there is a enough room to accommodate the odd flood providing our houses are designed for that environment. There is nothing to stop development on land such as the Somerset Levels , the Fens and other low lying areas. We just need the right sort of housing.
Existing Government legislation uses a very blunt definition to restrict development but it really depends on the flood plain and what your living in which brings to the word vernacular. A misused word used by developers to continue building a product that suits their cashflow, that planners use because its safe and objectors use because apart from the great crested newt they have reasons to object and would rather put up with more of the same. We have a self fulfilling prophecy.
We cannot continue building wholly inappropriate housing just because it’s what we have become used to, our housing needs to adapt to our weather will be more extreme and flooding a regular occurrence. Flooding that in coastal areas is likely to be largely salt water rather than the largely benign floods caused by precipitation.
Its not good to have ground floors we need to put our apartments and gardens above the garages to be safe. This also means that the miserable balconies that have been provided to date need to increased to a size that is equivalent to the equally miserable gardens now considered acceptable. The difference between the two is no longer significant.
Big balconiesreally useful balconyBig Garagesa look through the future
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