Material excavated from beneath London for Crossrail's new cross-capital rail link is to be used to create a huge wildlife reserve in Essex.
Clay, chalk, sand and gravel taken from the construction of Crossrail will be transferred by ship to Wallasea Island, which the RSPB will transform into 1,500 acres - nearly 2.5 square miles - of tidal wildlife habitat.
The agreement links Europe's largest construction project with the continent's biggest wetland creation scheme.
The project, to help replace wildlife sites damaged by climate change, was announced a year ago but depended on raising at least £12 million. Plans have altered since and costs have risen.
Graham Wynne, Chief Executive of the RSPB, said: "This is an astonishing agreement that one year ago, we could never have imagined.
"Wallasea will be the RSPB's most ambitious and innovative habitat recreation scheme. It will create a huge new area for birds and other wildlife whose existing habitats are being damaged and lost because of climate change.
"This is a ground-breaking deal between one of the UK's leading companies and an environmental charity. It is absolutely wonderful news for wildlife."
The Crossrail proposal was given Royal Assent in July. The 73-mile rail link from Maidenhead and Heathrow in the west, to Shenfield and Abbey Wood in the east, will be Europe's largest civil engineering project. Crossrail will include works on the existing railway network together with a central underground section from Paddington to Woolwich and Stratford.
The RSPB will next week submit a planning application to Essex County Council to transform Wallasea Island with Crossrail material.
Public consultation will start in December and Essex County Council is expected to reach a decision in the spring.
Crossrail material will be used to raise land on Wallasea, creating hillocks and dips into which seawater will ebb and flow. Calorie-rich saltmarsh, mudflats and other coastal habitats should attract rare and exotic birds such as spoonbills and black-winged stilts.
Kentish plovers could also make a return, after disappearing from Britain more than 50 years ago. Otters, saltwater fish including herring and flounder, and saltwater plants such as sea lavender and samphire are expected to thrive.
Crossrail main works should start in 2010 and bored tunnelling in 2011. The RSPB's work on Wallasea is expected to take between five and 10 years.
Simon Phillips, Crossrail Construction Liaison Manager, said: "We have been looking for a good way to reuse the excavated material from Crossrail for some time and we believe that we could not have found a better home for it than the RSPB scheme at Wallasea Island. Crossrail is the largest civil engineering project in Europe and we believe that by contributing towards Europe's largest new coastal wetland we will leave an appropriate and fitting legacy."
Dr Andre Farrar, the RSPB's Protected Areas Manager, said the Wallasea Project Manager, said: "From the outset, we recognised that working on Wallasea Island would be technically challenging and would need innovative solutions. With most of the land well below high tide level, just letting the sea in would have brought in too much seawater causing problems with navigation and erosion elsewhere in the Crouch and Roach estuaries. The use of high quality material is the best way of achieving habitat restoration on these low lying coasts."
Cath Harris, Media Officer, RSPB: 01767 693554 / 07739 921464
Crossrail Press Office: 020 3229 9552
Notes to editors
Wallasea Island is eight miles north of Southend-on-Sea. Its new saltmarshes will become natural sea defences, absorbing the power of the tides.
The island is only ten miles from the Thames Gateway and, once the transformation is complete, Wallasea could become a popular day trip for thousands of people living in Essex, the Gateway area and beyond.
Work on Crossrail will begin early in 2009 with tunnelling starting in 2011. The service is due to open in 2017, increasing London's public transport by 10 per cent. Eight new stations will be built.
The RSPB's Wallasea Island Wild Coast Project will create (148 hectares) of mudflats, acres (192 ha) of saltmarsh, acres (76 ha) of shallow saline lagoons and a second area of saltmarsh in anticipation of sea level rise. About eight miles of coastal walks and cycle routes will also be created as part of the project.
Saltmarsh is the zone between land and saltwater. Its range of species can rival the diversity of rainforests because daily tidal surges bring in nutrients and because of the mixture of creeks, exposed mud and specialist plants.
One cubic metre of mud contains enough worms and insects to match the calorie content of 16 Mars Bars. Mud and plants absorb pesticides and other pollutants.
Because of development and sea level rise, saltmarshes and mudflats are disappearing at a rate of 100 hectares each year. The government has set a combined target for the recreation of saltmarshes and mudflats, of 3,600 hectares (8,895 acres) by 2015.
The Essex estuaries are in the top five most important coastal wetlands in the country and are protected by national and European law.
Wallasea is currently farmed by Wallasea Farms Ltd and is being bought by agreement from a private trust that has owned the island for 50 years.
Wallasea was once five islands but is now one. The RSPB will restore these ancient divisions.
Wallasea is close to Ashingdon, where, in the Battle of Ashingdon in 1016, King Canute's Viking armies defeated the English king, Edmund Ironside. Remains of trenches in the nearby parish of Canewdon are thought to indicate the site of Canute's pre-battle camp.
The knot, Calidris canutus, a wading bird which will use Wallasea, has a Latin name after King Canute. Other returning species will include avocet, dunlin, redshank and lapwing. In winter, Wallasea will attract large flocks of brent geese, wigeon and curlew. Saltmarshes and other inter-tidal estuary land currently supports two million wildfowl and wading birds in the UK in winter.
Wetland restoration began on Wallasea in 2006 when Defra breached sea walls on the northern edge of the island, next to the proposed new nature reserve. That land is now managed by the RSPB.
Several RSPB reserves already allow seawater in to create habitats and improve sea defences and help birds affected by climate change.
Freiston shore on The Wash was opened in 2002 after sea walls were breached. It has a range of wetland habitats. The Wash is the most important site in the UK for wintering birds, with over a third of a million wildfowl and wading birds present during the winter.
Nigg Bay, on the Cromarty Firth is an area of mudflat, saltmarsh and grassland attracting large numbers of bar-tailed godwits, knots and other wading birds in winter. More wet grassland is being created for lapwings and redshanks.
Hesketh Out Marsh is a new RSPB reserve on the southern banks of the Ribble Estuary. Work there will help counter the effects of sea level rise. Existing sea defences will be strengthened and saltmarsh, saline lagoons and creeks created to help wading birds. The project, like Wallasea and Freiston Shore, will significantly contribute to the government's saltmarsh creation target.
Lakenheath Fen was a carrot field ten years ago but is now reedbeds, marshes and woodland. Bitterns, bearded tits and marsh harriers are amongst its scarcer species all of which need reedbeds. Reedbeds on the east coast are being lost because of sea level rise.
The Royal Society for the Protection of Birds
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