Costain has been awarded a £2million contract to demolish an offshore steel sheet pile barrier wall at the former Bradwell nuclear power station, in Essex. Bradwell, which ceased power production in 2002 after 40 years of operation is due to enter a 100-year ‘care and maintenance’ period in 2015.
The barrier wall stands approximately 400 m offshore and formed part of the Magnox power station’s cooling system. Cold ‘inlet’ water was drawn from the seaward side of the wall and the warmer ‘outlet’ water was pumped out on the landward side, the barrier wall preventing the cold and warm water from mixing.
The two steel barrier wing walls, each approximately 100 m long, are separated by a 30m-wide concrete central section. The sheet piles for the walls were driven 15 m into the river bed back in the 1950s.
A barge-mounted long reach excavator will open a diver access trench on either side of the piles. Divers will then use underwater Oxy-Arc cutting torches to cut the piles into 5m panels, commencing one metre below the existing riverbed level.
“The final cut to release each 14-tonne panel will be made above the water line, with the load being supported by a barge-mounted crane," said Hugh Nicholson, Costain seniour planner. The scrap steel will be loaded onto a barge and taken to a metal re-cycling facility in the Thames.
Works started in mid-October 2011 and are due to complete in February 2012. Environmental considerations have dictated that the works take place over the winter months in order to avoid any potential impact on the local oyster breeding season.
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