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Flood and Ecology

Avonmouth Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project


This project is a partnership between South Gloucestershire Council, Bristol City Council and the Environment Agency and focuses on helping to support the growth of the Avonmouth Severnside Enterprise Area and protecting the existing communities from flooding. The project will help towards unlocking the economic potential of the Enterprise Area and benefit the local community by:

  • Managing the risk of flooding to keep pace with climate change and rising sea levels.
  • Ensuring that sufficient wetland habitat for birds is created to protect the internationally important habitats and species of the Severn Estuary site.

ASEA Project Partnership Team

Creation of New Pond

Current status of the project

Temporary road and lane closures

Map illustrating closure of part of Passage Road during flood defence scheme

Map illustrating closure of part of Passage Road during the construction of the flood ramps and associated structures on Passage Road 

As part of the works to construct the flood ramps and associated structures on Passage Road unfortunately part of Passage Road will remain closed until autumn/winter 2021.

The road closure is between the southern junction of Passage Road with the A403 and just beyond BMMjv’s site compound entrance, south of the junction with Aust Wharf Road. A diversion route is currently in place for both vehicles and cyclists, and an alternative footpath diversion route is sign posted. We apologise for the inconvenience whilst we undertake these works safely.

In addition, temporary traffic signals have been installed on the A403. These will be part time vehicle activated signals, that will only be used when we transport material across the A403.



We are reviewing all site operations and, where necessary, ceasing operations where we are unable to adhere to the guidelines. For example, we have suspended ground investigation works on site, where we considered that we were unable to comply with the social distancing guidelines. We are currently reviewing our procedures and methods for ground investigation to determine if with the correct Respiratory Protective Equipment (RPE) and Personal Protective Equipment (PPE) operations could recommence.

Bristol City Council and South Gloucestershire Council have both granted planning permission for 17km of improved sea defences and around 85 hectares of wetland areas for ecological mitigation:

  • You can access the planning application documents submitted to South Gloucestershire Council here. Should you need to search for it, the planning application number is: PT18/2505/R3F.
  • You can access the planning application documents submitted to Bristol City Council here. The planning application number is: 18/02847/FB.

BMM JV have been appointed by Bristol City Council, South Gloucestershire Council and the Environment Agency to undertake the detailed design of the flood defences and construction of the flood defences and wetland areas. BMM JV have been undertaking site investigation, survey and ecological mitigation works across the area since October 2019, with the main construction work scheduled to start in Summer 2020 on a phased basis until 2024. Please read our latest e-newsletter for the latest information


Figure 1 – ASEA scheme proposals

The proposed flood defence upgrade involves raising existing earth embankments and walls as well as innovative techniques using glass panels to ensure views out to the Severn Estuary are retained. Figure 1 provides an overview. For full details, please refer to the drawings contained within our full planning application. The new flood defences will allow for sea level rise caused by anticipated climate change to ensure flood risk is reduced for at least 60 years.

The new wetland habitat being created at Northwick and Hallen Marsh is to help protect the internationally important bird species that live on the Severn Estuary. The new wetland must be delivered to replace and expand any that is lost or disturbed by the development in the Avonmouth Severnside Enterprise Area.

The planning applications gives consent to raise the height of the flood defences between Aust and Avonmouth. The method we propose to use to do this varies from place to place (as shown on Figure 1) and includes:

  • Raising the height of existing flood banks
  • Building new, higher concrete flood walls
  • Building new, higher flood defences from steel sheet piles

Watch our short videos that explains the project, Click here.

Please refer to our Frequently Asked Questions page if you have any queries.

Avonmouth and Severnside Enterprise Area Ecology Mitigation and Flood Defence Project short video


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