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Dutch-style flood defence unveiled in Somerset

In a UK-first, a Van Oord-led consortium has installed a energy absorbing flood defence system made of precast concrete blocks for Stolford on the Somerset coast.  

The Hillblock system uses champagne cork shaped high-density concrete blocks to absorb the energy of storm waves.

The blocks are anchored onto steel piles and concrete kerbs.

Despite their weight, when struck by powerful waves, the blocks are able to move which dissipates the energy of the wave and reduces the distance the wave travels.  

By taking power out of waves it means height of other sea defences can be lowered with the add on effect of reducing material usage and cost for defences.  

The system has been used extensively for costal defence in the Netherlands, where the system was first developed. A consrotium led by Dutch maritime works contractor Van Oord including Keir, Royal HaskoningDHV, and Mackley installed the system for the Environment Agency. 

The agency’s executive director for flood and coastal risk management John Curtin said: “This is an exciting engineering first for UK – the new technology installed at Stolford can reduce wave energy by up to 30% compared to the shore protection traditionally used. It will provide valuable protection to this Somerset community and the surrounding agricultural land.”  

“It is also great example of our joint work with the Dutch government, with whom we have a long history of mutual sharing of knowledge and best practice in the management of floods and climate change.” 

Royal HaskoningDHV flood resilience manager Jaap Flikweert added: “Block revetments are the default solution for protecting Dutch sea defences against storms. 

“A €1bn (£860M) improvement programme over the last 20 years has driven a lot of innovation: sharper design rules, better blocks, streamlined placement methods. We are opening up all this innovation to the UK, and Stolford is the first scheme to profit’.” 

Stolford has a history of coastal erosion and flooding, which the system aims to reduce.  

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Readers' comments (1)

  • Could it be clarified, what is the 'first'? I assume it is the 'Hillblock' PC system as opposed to pre-cast concrete revetment blocks? Armorflex PC concrete revetment blocks/mattresses were used on the Redcar FAS scheme for the EA back in 2013. The revetment system installed on 'The Stray' (southern extent of the project) were at the time, the first use of revetment mattress placed in a direct sea facing arrangement. Significant wave modelling of wave dynamics was undertaken along with incorporation of an innovative anchoring system. The energy absorbing layers below the blocks were actually recycled inert by-product material taken from the then Redcar steelworks.

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