Sustainable Flood Defence

The UK has a serious problem with leadership and sustainable construction where flood defence is concerned. There is a profound lack of critical thinking in the delivery of future UK flood defences and an unwillingness by agencies to get their  hands dirty at a local level. As a consequence government continues to fail regarding sustainability and value for money; taxpayer funded agencies seem unable or unwilling to work together.  It is a situation compounded by wildlife and environmental organisations who have seen an opportunity to gain control of and modify land in much the same way that monasteries such as Glastonbury once did.

Flood defence schemes are invariably seen in terms of a definable project that can be closed rather than the first step of a sustainable long term solution. The protected community needs to live with and manage these schemes  for 100’s of years after they are built. Our thinking on delivery is just too short and too expensive when it is a 300 year or so problem and especially when the initial solution only has a 100 year design life; it makes little sense. There is an obvious gap. That gap  means that today’s options should at least consider what happens next. Should we really  be adopting a solution today requiring the construction of a  replacement barrier tomorrow rather than a scheme today that has  provision or a plan for extending it already built in? Our current scheme takes planned obsolescence to a new level.

We should not be closing out future options for the generations that follow and we should follow our own rules for sustainable development

“Sustainable development is development that meets the needs of the present, without compromising the ability of future generations to meet their own needs.”

Delivery of the Bridgwater Tidal Barrier continues to be an exemplar of non-sustainable thinking. Part of the scheme requires the river banks between the tidal barrier and the village of Combwich to be maintained. The EA’s plan to do this work as part of the barrier construction contract. Material is to be dug from the adjacent protected fields  and where a future Northern Bridgwater Bypass might be routed.  Sedgemoor District Council (SDC) have protected in the Local Plan a potential crossing point on the River Parrett just south of the  A38 roundabout at Dunball.

Clearly excavating Chilton Trinity’s fields and creating a series of salt water pits that creates an ideal future breeding ground for salt marsh breeding mosquito’s is not what people have considered the consequence to be. It is far from impossible that in a generation Chilton Trinity and Combwich may ultimately become uninhabitable because of this excavation process rather than from the increased flood risk. Managing mosquito borne diseases may well become the larger challenge in low lying areas as our climate warms up. It is difficult to see how the EA could contemplate the creation of such a situation.

With whole life costs of the Bridgwater Tidal Barrier reaching £100M for a barrier, secondary banks and the raised river banks; banks that need continual raising means we need to consider modification of the delivery model to get the costs of this project under control.

That whole life cost  also ignores the 100 year economic impact,  both locally and nationally, of losing 1000’s  of acres of productive agricultural land  notwithstanding the questionable morality of a food importing country  choosing to export more of its food production offshore. 

If we are going to build the solution we have we need better and more economic delivery solutions than is currently proposed. We can then at least  ameliorate the present situation with a better delivery system.

Brexit allows the modification of the EU water and waste directives  that have now been written into UK law. We can now change the way in which we manage waste for the better.

Sustainable Construction

Every year Sedgemoor will build 5-600 houses and the excavation of foundations and drains for each of these houses will create around 15-20m3 of waste material (clay) suitable for re use as bank raising fill material. Sedgemoor’s  planned housing developments  will create around 9,000m3 per year that currently must be paid for to be disposed of. Housing developers could supply all the material needed to raise the banks. That is sustainable construction.

Over the 100 years life of the barrier there could be as much as 900,000 m3 of material we need to find a home for; material that could be used to build up the banks and preserve the land we have at Chilton Trinity for future generations. Even if the volume is  only 10% of the possible amount its probably enough to avoid digging up land at Chilton Trinity.

Under present EA proposals the EA is going to pay landowners for material that other organisations with similar material must pay to dispose of. We are meant to be reducing this sort of activity not making the situation worse.

We simply don’t need to get all the work in place in 2024; we need just enough to maintain the flood defence need and then use local resources to progressively deliver the longer-term solution with a local benefit to the economy. This work could be collectively done by local contractors under the supervision of either the EA or the Drainage Board. There is simply no engineering need for the EA to wantonly and unnecessarily destroy our landscape when cheaper and more sustainable alternatives are available.

NB there is only an intent to continue to raise the river banks 

To put this into perspective that recycled material would

  • build a bank 5m high bank from the Bridgwater Tidal Barrier to Combwich.
  • raise the banks and build the secondary flood defences up to match climate change.
  • raise the banks, build the secondary flood defence and start building new defences north from Pawlett Hill towards Highbridge.
5m high and nearly 5 miles long, 100 years of digging house foundations

Sea Level Rise

Sea level rise is not expected to slow for at least 300 years making both the barrier redundant as the river banks can only be raised perhaps another metre before they overload the poor ground conditions of the Parrett Estuary. Ultimately the long term plan for Chilton Trinity and Pawlett Hams’s will be realised.

The continued conditioning of the population by the EA to passively accept surrender to the sea as the first option for non-London areas of the UK is disingenuous and defeatist and never mind its land we need to grow food on.

Way Forward

At £100M the present solution for the  Bridgwater Tidal barrier is clearly neither sustainable or affordable. A situation that needs to be laid at the door of the Government, Somerset Rivers Authority and specifically the EA and Sedgemoor District Council (SDC) who provide joint project oversight.  We need

  1. Sustainability in what we do is placed at the centre  of our plans
  2. An independent inquiry into how flood defence is being delivered in Somerset.
  3. A peer review of the BTB project  into how it has arrived where it has.

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.

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 an 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 round 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.

 

 

Why things go wrong.

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.

Houses on Flood Plains

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 balconies
really useful balcony
Big Garages
a look through the future

West Quay Collapse

In November 2011 a section of Bridgwater’s West Quay collapsed. It was an old quay wall, possibly medieval in parts and close to or at the location where the demolished Bridgwater Castle  would gain access to the River Parrett. Whilst there is no official report explaining the failure it was probably the usual one;  a build up of water behind the wall that exceeded the ability of the wall to  resist it. It had rained very heavily beforehand. This is why holes are provided at the base of retaining walls to let the water escape and reduce the water pressure behind. Old walls often fall over and some relatively new ones fall over as well.

However since collapse the EA and Sedgemoor District Council  appears to have developed their own interpretation on the collapse implying that West Quay is a flood defence  which it isn’t. It was part of the old port of Bridgwater and the legacy of that commercial activity.

The EA’s public 1016 consultation boards on the Bridgwater Tidal Barrier imply that the West Quay collapse would not have happened if the Tidal Surge Barrier and its associated defences had been in place which  is implausible to say the least. It also makes a statement that the wall was in poor condition, who knows what condition it was in and a wall can be in perfect condition and still fall over if its capacity is exceeded.

EA Barrier Location Consultation March 2016
EA Barrier Consultation September 2016
Sedgemoor Draft Local Plan 2017

Sedgemoor ratepayer’s have been asked for comments on the location of the the Bridgwater Tidal Barrier in 2016 and the Draft Local Plan in 2017. They rely on the efficacy of the information provided by our statutory authorities and in the case of West Quay  the information and the story presented seems questionable.

 

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.

 

 

The Great Bridgwater Gate Debate

Bridgwater’s has had a long running debate over the type of gate for the proposed tidal barrier. Bridgwater Town Council and the Inland Waterways were led to believe that only a rising sector gate, similar to the Thames Barrier, could deliver the penned solution which they want in order to maintain the water level in the river and that would be delivered. As an an attendee to the September consultation the message of a rising sector was firmly reinforced to the public when a video of a rising sector gate was continuously shown at the now selected site and various supporting images included on the static displays.

The rising sector gate aka Thames Barrier was always a red herring and never going to be built. Only a barrier downstream of Dunball where the Hanson dredgers transit to Dunball might  have supported an argument for it.

Regardless of the merits of Penning the River Parrett the point made by the EA that penning could be incorporated at a later date is well made. To illustrate how that might be achieved can be seen below

Typical proposed Vertical Gate
Modified Barrier with Penning weir added, gates omitted for clarity.

Once the planned barrier has been built it would not be difficult to do  this if it was wanted.

What is more concerning is that after 2  years of presentations  people deeply involved in reviewing  the scheme  still do not understand  it. That they feel they were led to believe  a rising sector gate would be provided is completely understandable. It is also something that despite the issue  being closed in  November 2014 the EA have chose to keep open until now.   References to The Thames Barrier, Boston and Ipswich  were at best inappropriate. The Thames Barrier actually consists of a number of  other vertical gate  such as  Barking Barrier, Dartford Barrier as well as the more famous one.

Does  the gate type actually matter? No.

It is a  lesson to those presenting options to the public and our representatives.