Flooding – Page 3 – Steve Trowbridge

20/04/201727/05/2017

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.

18/04/201729/09/2019

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.

25/03/201728/05/2017

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

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.

22/03/201708/08/2017

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.

19/03/201722/01/2018

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

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.

13/03/201718/09/2017

Bridgwater Tidal Barrier Location

Today the Environment Agency and Sedgemoor District Council confirmed the recommendation to build the Bridgwater Tidal Barrier within the town.

If this is built at this location everyday millions of cubic metres of saltwater will unnecessarily be brought up the river into the town and particularly North East Bridgwater. Ultimately we will get the very flood this is meant to prevent.