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Site and design chosen for Bridgwater Tidal Barrier

A site on the River Parrett between Express Park and Chilton Trinity village has been selected as the optimum location for a Bridgwater Tidal Barrier.

An Environment Agency and Sedgemoor District Council project team has also decided that the best design for the Barrier would be a structure with two vertical lift gates.

The team’s choices follow public consultation last autumn, in which two potential sites for a Barrier were proposed. All responses have been considered and further technical assessments made.

The site selected is known as Site 5. Judged against Site 4 – which is about halfway between Express Park and Dunball Wharf – Site 5 was found to have seven factors in its favour, such as the greatest confidence that it could be successfully built and operated. (Text continues below image showing an exhibition board from the public consultation last autumn, directly comparing Sites 4 and 5).

Locations 4 and 5 side by side on Bridgwater Tidal Barrier exhibition board 9


A Bridgwater Tidal Barrier is a key part of Somerset’s 20 Year Flood Action Plan, which is overseen by Somerset Rivers Authority (SRA). The SRA is using Growth Deal money from the Heart of the South West Local Enterprise Partnership to support the initial development stages of the Barrier project. The aim is for a Barrier to be working by 2024. It will protect around 10,000 homes and 600 businesses.

The next steps now are to develop ideas for the appearance of the barrier and landscaping. These ideas will be put out to consultation, so that anyone interested can have their say, in late summer/early autumn this year.

What follows is a briefing prepared by the Environment Agency and Sedgemoor District Council.

Click to download a two-page briefing on the selection of the Bridgwater Tidal Barrier site and its preferred design.

Or keep reading for a version of that briefing, which has been slightly edited to work better as a web page, not a PDF.
   

Bridgwater Tidal Barrier – Update on choice of location and gate type

The construction of a tidal barrier for Bridgwater is a key component of the 20 year Flood Action Plan for Somerset. The Environment Agency and Sedgemoor District Council are working in partnership to deliver the barrier by 2024, subject to funding and approvals. Previous consultation documents can be viewed at: http://www.sedgemoor.gov.uk/bridgwaterbarrier

Site location

A consultation was held in September to consider two locations to site the new Bridgwater Tidal Barrier. These were:
  • Site 4 - approximately halfway between Dunball Wharf and Express Park
  • Site 5 - between Express Park and Chilton Trinity Village
During the consultation period, social media posts were viewed over 3,700 times and approximately 150 people attended the meetings and events held for the public, stakeholders and local businesses. A total of 78 responses to the consultation were received indicating there is continued support for a barrier. Over half of the 78 responses favoured Site 4 as the preferred location for the barrier.

Feedback in support of Site 4 included:  
  • Would provide more opportunities for development along Bristol Road and to the west of the river
  • Provides a better opportunity for a future road crossing to help traffic flows in Bridgwater
  • Provides the most storage capacity for river flows when the barrier is closed    
  • Might have more space available to build a visitor centre
  • Could be less disruptive during construction
Feedback in support of Site 5 included:
  • More affordable than Site 4
  • Less risk of silt build-up and impact on navigation around Dunball Wharf than Site 4
  • Less impact on the natural environment

Conclusion: Site location

Following technical assessments and consideration of all points raised, the Environment Agency and Sedgemoor District Council have jointly concluded that the best solution for Bridgwater is to locate the barrier at Site 5, which is between Express Park and Chilton Trinity village. The reasons for this are:
  • Greatest confidence of achieving permissions for construction at this location, and it is the least cost site
  • It leaves the narrowest point in the river available for any future road crossing and northern by-pass
  • Investigations have shown that the channel is less stable at Site 4, which makes it more difficult to predict the impact a barrier would have on the river and navigation
  • There are several access points available for construction, to help manage disruption
  • There is less risk of unpredictable siltation issues near Dunball Wharf, which would require costly maintenance dredging
  • The width of the river is narrower at Site 5, meaning the structure will be smaller requiring less maintenance costs
  • It fits with aspirations in Sedgemoor District Council’s Green Network Plan for a pedestrian bridge linking Chilton Trinity with Express Park. This aligns with the principles and aims of the Bridgwater Vision

Gate type

The consultation also introduced the two different types of gate that could be used to form the barrier: a vertical lift gate or a rising sector gate. Investigations show that the best design for the Bridgwater Tidal Barrier is a vertical lift gate, comprising two gates. Two gates give the best flexibility and reliability for operation generally and allows for continued navigation during maintenance.

A vertical lift gate offers:
  • Proven reliability in a very silty, tidal environment
  • Lower maintenance and operational costs
  • Similar technology to other Somerset sluices which means that there are no requirements for specialist staff
  • Ability to be used to pen water for potential future amenity uses
  • Potential to flush silt beneath the gate to assist maintenance
  • Potential to add pedestrian bridge and cycleway

Next steps

Selection of the optimum location and gate type allows the project board to progress the scheme design. Ideas will be developed for the appearance of the barrier and landscaping of the site over the next few months. At the same time, more detailed assessments will be made of the impacts the barrier may have during construction and in the longer term. Thoughts will be shared – and people’s views sought – during consultation in summer/early autumn, 2017.

If you would like to contact the project team, please email: bridgwater.barrier@environment-agency.gov.uk

If you would like to get in touch please contact us at sra@somerset.gov.uk or tel: 01823 355111
The Flood Action Plan is now overseen by the Somerset Rivers Authority and can be contacted on the above.