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

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

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

DOES THE BRIDGWATER TIDAL BARRIER MEET ITS OBJECTIVES?

Description

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

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

The BTB consists of two elements.

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

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

The EA / SDC / SRA Objectives

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

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

The Test

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

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

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

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

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

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

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

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

Specifically this proposal


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

In summary

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

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UK Construction; the coming change is not what people imagine

The UK Government initiatives through the Construction Industries Training Board (CITB) and the construction industry in general continues to think in terms of migrating people’s skills.

What has been apparent for a long time is that with the UK’s  an ageing population and the crutch of our cheap overseas labour being removed the time is right for the wholesale removal of people from the construction process.  Companies like Laing O’Rourke are making the investment, but the rest of the UK construction industry seems oblivious to the tsunami of change about to hit Europe.

China with its ageing workforce is already making huge strides with true OSM and it won’t be long before we see Chinese companies bringing that technology to the UK and the EU. With automated factories and sites running 24 hrs day they will slash delivery times and cost. Soon to be legalised automated driving systems means even the delivery trucks won’t need drivers or be constrained by driving hours.

If the Chinese dont drive OSM the cost of second hand manufacturing robots will. A used robot usually seen in a car factory can now be bought for £10-15k (1/3 of the annual employment cost of a semi-skilled operative) and with 60,000 hours time left in the machine that is less than 25P per hour plus operating cost. It won’t be long before the change in our process is driven from the bottom up.

A look at this advert tells you what you need to know

http://www.globalrobots.com/product.aspx?product=23064

In many ways UK construction stands on the edge of a new industrial revolution with the cost of automating construction dropping and entry levels cost being within reach of small companies and not just the largest the conditions to disrupt UK construction is well timed. It will soon be possible to create low cost production lines using second equipment manufacturing small construction elements for an investment of less than the cost of a UK house.

The CITB initiatives looks less like progress and more like King Canute. UK construction faces with the exception of maintenance being wiped out as an industry unless it changes rapidly.

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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.

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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Bridgwater Tidal Barrier Cost; an unacceptable defence

The January 2018  news that the estimated cost of the Bridgwater Tidal Barrier (BTB) had reached £100M caused the BBC last week to interview stakeholders at the EA, Sedgemoor and Bridgwater Town Council. Anyone who heard the interviews and knows anything of the history of this project will be as equally concerned as Bridgwater’s Town Council. The risk regarding withdrawal of funding is real; Government will not accept being led on and neither should the ratepayer which is becoming the real story of the Bridgwater Tidal Barrier.

EA and SDC interviews.

  1. The EA chose somewhat disingenuously to blame the hike in price on the Government making a perfectly normal and responsible demand regarding cost information. Information not previously provided to the SDC ratepayer. It was clear during the public consultations (the boards are still available on the SDC website) that the selection method (river width) was flawed in ignoring the cost of the downstream works and the associated maintenance costs that went with them. Cost confusion about this project has been a problem ever since work started on developing options and presenting the options to the public. Previous written responses raised this issue in March 2016 and nothing was done to clarify the situation in subsequent public consultations.
  2.  The well known poor ground conditions of the Parrett Estuary were again blamed. Ground conditions have become a convenient hook to hang cost increases on. If the costs associated with ground conditions are being continually underestimated at such a late date there is clearly a management issue that needs to be fixed. 
  3. SDC again conflated Cameron’s “never again “statement made in 2014 with the Bridgwater Tidal Barrier. People will continue to imagine that the Bridgwater Tidal Barrier will somehow mitigate a 2014 flood when that isn’t the case.

Readers can listen to the program on BBC iPlayer for a few weeks. Move the bar along to hear the EA at 40min and SDC is around 140min

The defence of the cost is indefensible.

The reality is that neither the EA’s technical management team, those responsible for providing senior project management/Governance (EA/SDC) or the councillors providing oversight have the necessary experience for a project like this. (£29M was beyond their reach and £100M is farther still and requires experienced management).  The BTB  was always going to get away from under them as it clearly has.

As a contributor to the EFRA Future Flood Prevention report in 2016 I highlighted the issues that are deeply embedded in this project. Entitled Managing local UK infrastructure; the Client Deficit.  it highlighted the lack of  an independent adviser to stakeholders as a continuing problem with UK locally managed infrastructure projects, it is a situation repeated elsewhere and in Somerset the SRA is a particularly good example of people being responsible for delivering projects that they are not experienced or qualified to do and not being provided with the support they need. The KSD  expansion project seems to be struggling in a similar way to the BTB. Googling ones mobile phone is not a valid substitute for experience nor is having laid a patio in earlier years.

We all now understand that the Bridgwater Tidal Barrier solution (location) was driven solely by the promoted idea that “river width”  somehow equated directly to project cost;  getting the barrier as far upstream (narrowest point) was the cheapest option for the EA. it was always a flawed strategy and the cost we are now seeing is the result of that approach. It is the result of not doing work that should have been done during the options study.  The initial cost of the downstream raising of the river banks and the cost associated with the intent to continue to do so does not appear to have been fully considered in the original location decision.

Unfortunately, valuable and costly time was spent on what sort of gate we should have had rather than looking at the overall solution and there was no challenge to the 2009 B&V spread of locations. Long term costs and the EA’s rather ambiguous position regarding the long term raising of the river banks were conveniently ignored in the 2016 public consultations.  Consultations that completely ignored the principles set out in  Government guidelines on public consultations.

This situation was compounded by the obvious client project inexperience shown in the rush to engineering studies before an outline plan was agreed that always results in the cost escalation we are seeing. The sudden arrival of the secondary flood defences is something that should have been highlighted in the option studies, it may not have been needed at sites farther downstream and was not shown in the early public consultations. After 30 years of managing the design process on much larger projects than the BTB starting a project without a real plan is always a trap waiting for the unwary. Sadly, as a result of the BTB execution strategy what we now have is less normal project delivery and more an episode of Grand Designs.  At least the consultants should avoid any blame.

What was striking in last week’s radio interview was the lack of any new arguments after all the work that has apparently been done to support the scheme in its present form. What is equally impressive is that both the EA and SDC imagine that Bridgwater will not want to grow beyond the line of the barrier over the next 100 years or that a critical piece of infrastructure should be located so close to the town. Shouldn’t someone have asked how big will Bridgwater be in 100 years? The whole BTB project appears to have now deteriorated to the justification of an original poor decision. It is most disappointing.

The information the ratepayer has seen to date raises questions of transparency or competency neither of which seems to have been achieved or available to any degree. 

Ratepayers should not be paying for all the people involved in the BTB project and the broader Somerset Flooding issues to be learning on the job which seems to be the case.

Its well past the time that the Bridgwater Tidal Barrier including its location is independently reviewed before it is presented to the ratepayer one last time.  Its time we considered moving the Bridgwater Tidal Barrier downstream to Combwich.

The questions of

  • transparency with regard to cost and economic impact.
  • management team  competency
  • oversight competency and relevant experience 
  • the approved barrier location
  • what happens at the end of the 100 year design life; Bridgwater Tidal Barrier 2?

clearly needs to be looked at as the information previously provided to the public and one assumes our councillors did not reach the standards we should expect and was wrong.

Projects do not suddenly almost double in price in 15 months without good reason. The defence of the cost increase presented in the interviews was as unacceptable as the scheme itself has now become.

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Bridgwater Tidal Barrier cost reaches £100M

Sedgemoor District Council  and the Environment Agency  recently reported at the Somerset Rivers Authority (SRA) meeting  in January a 50% increase in the cost of the Bridgwater Tidal Barrier. The reported cost appears to have increased from  £70M in October 2017 to £100M in January  2018  (five months) and yet it went through without comment .

The cost escalation of a scheme that does nothing to address the 2014 fluvial flood is eye watering and yet, according to the minutes, no action is taken to explain why this escalation had occurred and what action was being done to mitigate it. The mere acceptance by our elected members is not acceptable if the delivery of our infrastructure is to be managed locally rather than through central government.

Bridgwater Tidal Barrier Cost History

  1. March 2014 the cost of  barrier was reported at £26M
  2. September  2016 The EA  gave the public figures during a public consultation  various options with costs;  site 5 the selected site was costed at £45M – £60M.
  3. October 2017 the BBC reported on the cost of the scheme to be  in the order of £70M  “Bridgwater tidal barrier costs ‘could go up by £10m”
  4. January 2018  indicates the cost is now around £100M as noted below from the published SRA draft minutes.

In a period of around 15 months from September 2016 to January 2018 the cost of the Bridgwater Tidal Barrier scheme rose by around £50M or 100% and not one word of concern is  expressed or recorded in the public domain. This cost is now  nearly 4x  the original cost estimate in 2014.

Bridgwater Tidal Barrier is now a £100M scheme where

  • the financial investment makes no contribution to mitigating a repeating 2014 fluvial flood,
  • repeated saltwater flooding onto farm land from the River Parrett is seen as being an acceptable regime despite poisoning farmland and wildlife. 
  • there is no plan in place beyond the barriers  100 year design life
  • brings saltwater  onto our agricultural land

Looking at the numbers the only thing that can be concluded is that the cost estimates presented to the public and to councils for the purpose of decision making were widely inaccurate or inconsistent either of which is unacceptable for investment decisions; especially decisions that affect the long term future of Bridgwater and Somerset Levels beyond.

The selection decision of the current site (Site 5) was chosen purely on the basis of the width of the river and must now be called into question.  It would appear that the cost of the other downstream elements of the scheme must be causing this cost escalation. A cost and concern that were dismissed at the time of the consultation. 

Bridgwater Tidal Barrier is now a £100M scheme where

  • the financial investment makes no contribution to mitigating a repeating 2014 fluvial flood,
  • there is no plan in place beyond the barriers  100 year design life
  • repeated saltwater flooding onto farm land from the River Parrett is seen as being an acceptable regime despite poisoning farmland and wildlife. 
  • the EA wants to dig up the very land its meant to be protecting to win the soil  for flood defences.

No project should be seeing this amount of budgetary increase  without  challenge.  Cost escalation on this scale is unacceptable and unnecessary. There is clearly a continuing problem regarding a  lack of oversight both technically and financially in this project.

What should be done?

The extra £50M buys a much better scheme than the one Bridgwater is getting. £100M would allow

  1. the barrier to be located as is normal practice as close to the mouth of the river as possible which in this case  is Combwich. Combwich was never looked on the basis of cost, clearly that is an argument that can no longer be supported.
  2. elimination of most of the downstream river works that the EA’s tests indicate will need to happen every 35 years or so.
  3. increased fluvial capacity in the River Parrett and the King Sedgmoor Drain potentially benefiting communities beyond Sedgemoor
  4. a solution that can be economically extended beyond the 100 year design life currently offered.

£100M is £1M a year for next 100 years on scheme that will be rendered redundant once the river banks can no longer be raised to combat sea level rise; the scheme in present form is throwing money away 

The public expect that those on scrutiny committees to use there position to bring transparency  and accountability to the process of public expenditure. Such bringing to account appears to be sadly lacking together with visibility of any independent engineering review that a project of £100M warrants. The project is growing in value and the oversight is not growing with it.

Unfortunately what we see happening is the management of infrastructure projects by people, primarily councillors  and  officers who are unqualified to do so. The SRA is a prime example of an organisation primarily engaged in  the commissioning of engineering activities with no engineers in lead roles.  The Bridgwater Tidal Barrier has become a Grand Designs episode of Civil Engineering

Way forward

A  Public Inquiry  into the management  of the Bridgwater Tidal Barrier scheme should be convened that should look at

  1. Cost
  2. Management
  3. Consultation process
  4. Location  (including the examination of Combwich)
  5. Competency and experience  of councillors  and officials  to manage civil engineering works such as the Bridgwater Tidal Barrier and other SRA projects.,

 

 

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Retention of Concrete Consistency

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.

  1. A 10mm aggregate for  congestion and cover issues.
  2. Place using the chute from the back of the truck.
  3. Delay the setting time to around 3 hours.
  4. Retain the waterproof qualities of the existing mix.
  5. Characteristic strength of 35N
  6. 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.
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A Tidal Surge Barrier, A Bridge & Dunball Wharf

One of the problems with building the Bridgwater Tidal Barrier downstream of Dunball Wharf is the marine traffic to Dunball Wharf. Sedgemoor District Councils current draft local plan states “The Council will support the continued operation and potential development of Bridgwater Port including Dunball Wharf and Combwich Wharf (Policy D16 applies). It will also support the re-establishment of active commercial wharf’s at suitable locations elsewhere on the River Parrett. In all cases the construction or operation of new wharf’s should not adversely impact upon the Severn Estuary internationally designated site.”

The reality is that  the Dunball Wharf’s with their tidal drying berths, dependency on  high tides and difficult navigation is never going to be a commercial success but the 200m wide river at Combwich might. Construction of  the tidal surge barrier could enable the relocation of Dunball Wharf to a better location.

Much hangs on what is considered to be adverse.

Concepts of what the river structures might look like have not been forthcoming since 2009. Apart from the tower  and turning vertical gate Bridgwater’s gate structure will be considerably shorter than the Hull Barrier structure we have  been repeatedly shown.

What would a barrier with a road bridge  options look like?

Another wharf at Combwich, EDF have  one there already, would not require an opening bridge or clearance much more than Drove Bridge on the NDR. A tidal surge barrier with a 40m fixed navigation span and a road deck might look like

Keeping Dunball Wharf  would require a one larger gate and an opening bridge. Dunball currently sees 40 or so vessel movements a year so its operation would not affect the bypass traffic.

The engineering is relatively simple and with a purpose built wharf everything could be shipped in during construction.