Defence Online

Refurbishment of one of Somerset’s most critical tidal defences will extend its design life by a further 25 years to ensure ongoing protection for Bridgwater and the Somerset Levels.The Environment Agency leading work on the £4.2M investment to upgrade the Dunball Sluice, which has been controlling flood flows on King’s Sedgemoor Drain and the River Parrett Flood Relief Channel for 51 years.The Department for Environment, Food and Rural Affairs is funding the work with £650,000 partnership funding provided by Somerset Rivers Authority.The structure, which has four gated culverts, is located where King’s Sedgemoor Drain meets tidal flows on the River Parrett. As well as preventing flooding, the gates also prevent the tide from bringing saltwater into King’s Sedgemoor Drain and impacting on nationally and internationally designated freshwater habitats.The refurbishment of the mechanical and electrical components of the sluice will be combined with environmental improvements to encourage the migration of eels and improve access for otters between the King’s Sedgemoor Drain and the River Parrett. Health and safety improvements for Environment Agency staff and contractors who operate and maintain the sluice will also be completed as part of the scheme.The current phase of work follows on from a £1.5M investment in the sluice completed in 2015 to speed up flow out of King’s Sedgemoor Drain at periods of high tide. This was a permanent solution to the temporary structure built in the winter of 2013/2014 when the Somerset Levels were affected by severe flooding. The flooding that winter led past ICE president Jean Venables to call for dredging in the Rivers Parrett and Tone to reduce risk of future flooding.Speaking about the latest investment at Dunball Sluice, Environment Agency flood and coastal risk manager Rachel Burden said: “The project will extend the life of Dunball Sluice. Reducing the potential for failure and mitigate the risk of flooding to properties and internationally and nationally important freshwater habitats.”The two year upgrade project has been planned in order to minimise impact on the continuing operation of the sluice. If there is a need to move water out of the system into the Parrett but the tidal gates can’t be used due to the state of the tide, then temporary pumps can be set up at the sluice to pump water over the structure and into the river. This was last done in 2014 and upgrades have been made since to better accommodate temporary pumps deployed from the nearby Bradney depot.Commenting on the upgrade Somerset Rivers Authority chair Mike Stanton said: “Dunball Sluice is a crucial facility. Refurbishing it boosts the SRA’s own major scheme to increase the floodwater-carrying capacity of the River Parrett and King’s Sedgemoor Drain.”Like what you’ve read?