South West Water has started work on a £2.2 million flood defence scheme to protect Exeter's water supply.

A 600-metre long steel sheet piled wall, ranging from 1.5 metres to 2.4 metres high, will be built around Pynes Water Treatment Works at Upton Pyne, near Exeter, to protect the site in the event of severe flooding from thenearby River Exe.

Around 1,000 cubic metres of earth will be moved during the work as the steel wall is driven into the mudstone five to six metres below ground. Some of this will be used to create refuge areas for livestock.

In the floods of summer 2007, Mythe Water Treatment Works in Tewkesbury, Gloucestershire, was flooded. Around 140,000 properties lost their water supply. The clean-up operation, replacement of damaged equipment and supplying clean water to customers cost Severn Trent Water in the region of £25 to £35 million.

Following the floods, the Department for Environment, Food and Rural Affairs instructed all water companies to review their sites and take appropriate measures to protect those at risk from flooding.

The scheme at Pynes has been designed to guard the works against a future one in 100-year flood event, plus an additional allowance for climate change. It has been reviewed and agreed by the Environment Agency.

Project Manager Mike Court said:

"Pynes Water Treatment Works is at risk of flooding as it is built on the River Exe flood plain.

"A significant flood, like those seen in Gloucestershire in 2007, could significantly damage the works and adversely affect the water supply to Exeter and the surrounding area.

"This crucial scheme will protect our customers' water supplies for years to come."

The scheme has been designed by AECOM Limited and will be built by Dean & Dyball Civil Engineering Limited. It is due to be completed by December 2010. The construction work will not affect the water treatment process.