Completion for ASEA Ecological Mitigation and Flood Defence Project

October 7, 2025 Agri-environment, Green Infastructure, Health and Wellbeing, Infrastructure, Strategic Advice, Urban Landscapes and Public Realm

The Avonmouth and Severnside Enterprise Area (ASEA) Ecology Mitigation and Flood Defence Project achieved completion in summer 2025, marking the end of the scheme’s construction. The award winning project is a joint partnership between The Environment Agency, South Gloucestershire Council and Bristol City Council. BAM Nuttall and Mott MacDonald joint venture (BMMJV) carried out the detailed design and construction, with construction commencing in 2020. We provided comprehensive landscape clerk of works services to help deliver this £120 million project.

NPA ASEA completion news birds flying over the Severn Estuary — Birds in flight over the Severn Estuary, which is internationally important for biodiversity.

Project completion is a significant milestone, with 17km of flood defences constructed along the Severn Estuary to help protect communities at risk of flooding from climate change factors including rising sea levels. The scheme reduces the risk of flooding for 2,500 homes and businesses, through a series of raised embankments, sheet piled walls, in situ concrete walls and precast reinforced concrete walls. £1.4 billion in economic benefits and 12,000 jobs are expected to result from the new flood defences unlocking the potential for investment within the Enterprise Area.

Importantly, the project also involved the creation of 80 hectares of new wetland habitats. This included the creation of species rich grassland, scrapes, ponds and copses at Northwick and Hallen Marsh. The new thriving wetland habitats support the Severn Estuary’s internationally important bird species and provide ecological mitigation for the Avonmouth and Severnside Enterprise Area.

NPA ASEA completion news Cake Pill site visit credit Environment Agency — Project team visiting Cake Pill as part of the lessons learnt workshop (Source: Environment Agency).

NPA ASEA completion news New Passage Road glazing panels — New Passage Road, Redwick, glass panels within the flood defence wall maintain views over the Severn Estuary.

The project has also improved the Public Rights of Way across the area, which are now open for the public’s enjoyment, including sections of the Severn Way and King Charles III Coast Path. At New Passage, a popular wildlife watching area, glass panels have been installed within the flood defence wall, which offer flood defence protection whilst retaining valued views over the Severn Estuary.

Nicholas Pearson Associates have been working alongside Binnies engineers, as part of the supervision team to monitor the preparation, construction and maintenance of the project. The role has involved regular site inspections and diligent reporting of the progress. The project completion was reached through developing robust working relationships between the contractor and specialist landscape sub-contractor, Environment Agency NEAS representatives, and in-depth collaboration with the wider site supervision team. Issues and challenges on site were solved proactively through regular communication and knowledge sharing, to promote successful establishment of the new landscape and habitats.

NPA ASEA completion news newly created wetland meadows in flower — Newly created wetland meadows in flower.

As part of the completion process, a lessons learnt workshop was held for the project, involving the delivery partners, client team, designers, contractor, project managers and site supervision team. Jamie Farnell (Director) and Rosie James (Senior Professional) represented the Landscape Clerk of Works team from NPA. This was a chance to reflect on what went well, and the key lessons learnt from the project. There was also an opportunity to visit the new realigned embankment and habitat creation areas at Cake Pill.