Following the EA’s 2019 submission of the BTB Transport and Works Act to the Secretary of State the EA has responded directly to a comment made during the public consultation regarding ring fenced funding.
The background to the question is that if the BTB was located further downstream it can act in the same dual operation way as the Thames Barrier stopping tides coming in and creating a temporary reservoir to increase the conveyance of seaward fluvial flows. In 2014 the Thames Barrier closed 9x for tidal flooding and 41x for fluvial flooding clearly indicating the benefits of a dual function structure.
The EA /SDC BTB proposal does not use this dual operation solution; it has only a single Tidal function. Bridgwater is only getting half what the Thames Barrier does.
People have been given to believe that the funding for the BTB could only be used for Tidal defence rather than as a dual use structure where it could also provide some mitigation to a repeat of the 2014 flood as well as addressing rising sea levels. There was a risk Bridgwater would lose the funding if it asked for flexibility.
The Submitted Comment (in blue)
2. The BTB is not designed to improve fluvial conveyance in the River Parrett and King Sedgemoor Drain. If it was located farther downstream it could operate in both modes as the Thames barrier does. (it is not understood why the funding is ring fenced for tidal defence only)
The EA response below is of great importance with regard to the approval of this scheme as it contradicts the common understanding that the HMG funds promised in 2014 could not be used for a holistic flood defence solution in Somerset. The design and the consultations clearly support only the BTB is a single use design.
The EA Response (in blue)
The Scheme is not designed to improve fluvial conveyance in the River Parrett and King Sedgemoor Drain. It is designed to provide a tidal barrier with improved downstream flood defences, to exclude extreme surge tides and prevent tidal flooding in Bridgwater. Funding is not ring-fenced as described, but is made available and allocated on the basis of benefits realised.
The EA response indicates a choice was made not to consider pluvial flooding and fluvial conveyance as a key consideration despite that was the 2014 flooding event event caused the BTB to be brought forward in the first place. Had it been a consideration the case for locating the Barrier further downstream would have had considerably more weighting and possibly changed the outcome of the site selection.
It should also be noted that that the following non tidal benefits have not been considered or influenced the work done to date.
- The EA recently noted at the SRA board meeting on the 6th March that the 20 pumping stations on the Levels are coming to the end of their design life and there is no budget for their replacement.
- The EA noted in the September 2016 public consultation that the location of the Barrier a small distance downstream of the KSD outfall to the River Parrett would provide benefits to the river flows.
- The benefit of unlocking the KSD outfall providing increased value for money on the planned KSD enhancement have been ignored.
- The benefit to the flooding of the Levels and to Somerset towns on the upstream tributaries of the Parrett that could have been taken benefit from this scheme have not been considered or taken into account.
The artificial separation Somerset’s of tidal and pluvial needs makes little economic, engineering or financial sense and this response indicates that it did not need to be considered. We could have had a barrier that protected the south Somerset Levels including Bridgwater from the sea and increased the fluvial capacity allowing more water to moved through the River Parrett and the King Sedgemoor Drain.
There is now a need to find out if this scheme was unnecessarily constrained. It needs to be established that the proposed BTB represents best values for money for the taxpayer and is part of a wider integrated flood defence solution for Somerset and if funding was not a constraint why do we have a single use solution?
Clearly an independent assessment and investigation is required to clarify the true situation and ensure that the scheme is doing what it should be doing and not what EA believes to be the case. Hopefully the Secretary of State will chose to place this project under the light of public scrutiny before making a final decision to ensure what is proposed is fit for purpose.
The relevant extract of the EA letter is reproduced below