Elizabeth line soil used to create bird haven at Wallasea Island

The soil was used to lift the ground and form wetlands designed to provide feeding, nesting and refuelling areas for birds

London sent more than three million tonnes of soil excavated during construction of the Elizabeth line to an Essex island, where it was used to raise the ground and create new coastal wetlands. Ten years after seawall sections were removed to allow the sea back onto Wallasea Island, the RSPB reserve has recorded nearly 40,000 birds wintering there, including thousands of Knot, Avocets, Grey Plovers and Bar-tailed Godwits. The site, known as Jubilee Marsh, is part of the RSPB’s Wallasea Island nature reserve in Essex. According to the Society, the land had been separated from the sea for hundreds of years before the RSPB began work to restore the island as a nature haven. The project later became linked to the construction of London’s Elizabeth line through a collaboration with Transport for London (TfL) as part of the Crossrail project. Instead of treating the soil removed during the railway’s construction as waste, more than three million tonnes of excavated material were transported from London to Wallasea Island. The soil was used to lift the ground and form wetlands designed to provide feeding, nesting and refuelling areas for birds. The work helped create the physical landscape that would later become Jubilee Marsh. The next major change came in July 2015, when sections of the seawall were removed. This allowed seawater to return to Wallasea Island for the first time in 400 years. As the sea moved across the newly created areas, it formed lagoons, saltmarshes and new islands. The RSPB said the rewetting of the island also provides natural flood defences because the wetlands can help absorb storm surges and rising water levels.

Nearly 40,000 birds recorded

A decade after the seawalls were breached, the difference in bird numbers is now clear. The reserve recorded a new wintering bird record of 39,000 birds last winter. The RSPB said the site, which once had only a handful of birds, now attracts nearly 800 Avocets and more than 10,000 Knot. It also recorded nearly 3,000 Grey Plovers and Bar-tailed Godwits. The increase has come as the restored landscape has developed into a place where birds can feed, shelter and use the wetlands during their seasonal movements. The new habitats created at Jubilee Marsh include lagoons and saltmarshes, along with the islands formed after seawater was allowed to return. The RSPB described Wallasea Island as an example of how a major infrastructure project can be connected with habitat restoration. The organisation said the soil from the Elizabeth line excavation was used to create wetlands rather than becoming a large amount of waste material.

Making of a nature reserve

Rachael Fancy, Wallasea Island Site Manager, said the area looked very different when she first started working there. “When I first started working at Wallasea Island it looked an awful lot like a construction site, because that’s what it was! But just ten years on there’s no evidence of the diggers or trucks. There’s just thousands and thousands of birds who now use it as a refuge, shelter, and nursery to their chicks. It’s an almost unbelievable transformation,” she said. Her description reflects the physical change at the site since the construction and restoration work began. The land that once held excavated material and construction activity has developed into a wetland used by large numbers of birds. Milo Sumner, RSPB England Coastal Programmes Manager, said the project showed what could be achieved when infrastructure work was carried out alongside nature restoration. “Wallasea shows what’s possible when business has an ethos of working with and alongside nature. The creation of the Elizabeth line was one of the most ambitious infrastructure projects in decades, and by collaborating we were able to create a win for nature and people from what would otherwise have been a huge pile of wasted soil,” he said.

Wetlands provide flood defence

The return of seawater was not only intended to create habitats for wildlife. The RSPB said rewetting Wallasea Island also provides a natural form of flood defence. The wetlands can help absorb storm surges and rising water levels. The new landscape includes saltmarshes, lagoons and islands, all created as part of the restoration work after the seawalls were breached. The project is also part of a wider area of wetland habitat along England’s east coast. The RSPB said these wetlands are important enough for wildlife to be included on the UK’s Tentative List for UNESCO World Heritage status. If selected, sites stretching from the Thames Estuary to Lincolnshire would be considered alongside internationally recognised locations such as the Galapagos Islands and the Great Barrier Reef.

TfL links railway project with wetlands

The project brought together the construction of a major railway line in London and the restoration of a coastal landscape in Essex. Isabel Coman, Director of Engineering and Asset Strategy at TfL, said the bird numbers showed the result of the collaboration. “It’s amazing that record numbers of birds are now thriving at RSPB Wallasea. Through the creation of the Elizabeth line, now the UK’s single busiest railway service, we’ve also been able to make a lasting, positive contribution to England’s east coast wetlands, which are a vital habitat for wildlife.” Coman said TfL viewed nature as an increasingly important part of its work and said the Wallasea project showed how the benefits of an infrastructure project could extend beyond London.