Work has begun on dredging waterways at the Olympic Park in east London to enable boats to carry construction material to the site.
A 60-tonne vessel has started dredging 1.4 miles (2.2km) of canal from Bow Locks on Bow Creek to the Waterworks River, beside the Aquatics Centre site.
It is expected to remove more than 7,000 tonnes (20,000 cubic metres) of gravel and rubble.
It will also get rid of tyres, shopping trolleys, timber and at least one car.
Olympic Development Agency (ODA) environment manager Richard Jackson said: "The Olympic Park is characterised by a series of waterways which act as green corridors running through the heart of the site.
"Currently, they are polluted, neglected and under-used, and have been treated as a dumping ground for everything from shopping trolleys to cars.
"This dredging programme is an important step in regenerating the waterways and will help improve water quality, creating better habitats for wildlife and plants."
Barges will be able to carry equipment in and waste and rubble out.
A wharf is being built on the Waterworks River near the Aquatic Centre and should be finished by June.
A new lock, Three Mills Lock, has been built at Prescott Channel. The £20m structure includes a tidal lock, a weir and a fish pass.
Richard Rutter, regeneration manager, British Waterways said: "Dredging the waterways of the silt and rubbish built up over the years in and around the Olympic Park is an essential part of the rejuvenation of East London's rivers.
"The dredged aggregates will be recycled and reused in construction works in the Olympic Park and these dredging works will help us to realise our dream of seeing both commercial freight barges and leisure boats taking to the water once again in east London."
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