Benson Lock has two five tonne lock gates installed

Two five tonne steel gates have been lifted into place at an Oxfordshire lock as part of its refurbishment.

The new structures have replaced the 30-year-old timber gates on the Benson Lock on the River Thames and are expected to last 60 years.

The new lock gates are part of a £3m Environment Agency programme of capital works on the River Thames running from August 2011 to March 2012.

To carry out the structural repairs the lock had to be completely drained.

Environment Agency waterways engineer Paul Power said: "This is a highly unusual opportunity to see a lock out of operation and drained to the bottom. A lock without water is a rare sight."

Electro-fishing tools

Work on the site began in early November when more than 450 fish were caught at the lock and returned to the river using electro-fishing tools.

The Environment Agency said this involved passing an electric current through the water, attracting and momentarily stunning the fish, enabling them to be easily removed.

In 2011 more than 8,000 vessels passed through the lock.

The existing Benson Lock chamber was built in the 1890s and is the only lock on the River Thames to have a cast iron base and lower walls.

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