This 29 October 2018 video from England says about itself:
Creating Wallasea Island nature reserve
Wallasea Island nature reserve is the UK’s newest coastal wetland. With tidal saltmarsh and mudflats, brackish lagoons, grazing marsh and freshwater grassland, as well as arable bird cover, Wallasea is a wildlife haven more than double the size of the City of London. Created using 3 million tonnes of material from London’s Crossrail Project. Helping people connect with nature and coastal heritage, and providing natural coastal adaptation to climate change.