Somerset County Council has teamed up with Somerset Rivers Authority to improve the flow of water and lessen dangerous turbulence through King’s Sedgemoor Drain at Dunball north of Bridgwater.
Benefits include protecting the two bridges which carry the A38 over King’s Sedgemoor Drain (KSD) at Dunball, and reducing the impact of any future local flooding.
Work is being funded by Somerset County Council’s highways department to tie in with Somerset Rivers Authority’s proposed multi-million pound programme of improvements to the full 20km of the River Sowy and the KSD, from Monk’s Leaze Clyse near Langport down to Dunball sluice.
Dunball sluice is the only outlet for the KSD into the River Parrett and thence – when tidal conditions allow or pumps are used – out to sea, so it is important for the Somerset Levels and Moors that water should be able to flow through Dunball as smoothly as possible.
Contractors Crestmoor Design & Construction (project managed by consultants WSP | Parsons Brinckerhoff) used divers for a survey beneath Dunball Old Bridge, then moved on to the complex destruction of the historic obstruction known locally as the “lump of concrete”. Text continues after photo
CONCRETE ACTION: Contractors removing the historic “lump of concrete” from under Dunball Old Bridge. Complicating factors include working by water in a confined space – and a sewage pipe on the underside of the bridge.
The "lump of concrete" was left behind in the 1950s when an arched bridge structure was replaced by a flat deck. The lump’s removal is now being funded by Somerset County Council, using part of a grant that was given to Somerset by the Department for Transport after the devastating floods of 2013/14.
John Osman, leader of Somerset County Council and chair of Somerset Rivers Authority (SRA), said: “Many people have been calling for a long time for work to improve the flow of water through this crucial final stretch of King’s Sedgemoor Drain at Dunball, so I’m delighted that Somerset County Council has been able to make it happen. It’s also great to see Somerset Rivers Authority working in partnership, co-ordinating schemes, and taking wide long-term views. This is a scheme that will help to reduce flooding and protect the A38, a vital part of our road network. Two key aims of Somerset’s 20-Year Flood Action Plan, which is overseen by the SRA, are to maintain access for business and communities and ensure strategic transport connectivity.”
The “lump of concrete” has long acted like a bottleneck beneath Dunball Old Bridge – which carries A38 traffic southbound – and, particularly at times of high flow, made the water in the KSD more turbulent. The damaging effects of this were felt during the floods of 2013/14 a short distance downstream, in the scouring out of the foundations and the potential weakening of the pillars under Dunball New Bridge – which carries A38 traffic northbound. To repair and avert possible future problems, work under Dunball Old Bridge is being followed up by a Somerset County Council scheme to repair and strengthen Dunball New Bridge.
The Environment Agency is also planning action – after lump work under the Old Bridge is finished in October – to further smooth the flow through Dunball as part of the SRA’s over-arching scheme for the Sowy and King’s Sedgemoor Drain.