Brett Landscaping and Severn Trent Water have been working on the UK’s largest sustainable drainage systems (SuDS) scheme. The £76m project, to reduce flood risk in Mansfield, will create a surface water drainage system that can hold 58 million litres of water.

Client: Severn Trent Water
Product: Omega Flow Permeable Paving

With funding approved under the OfWat Green recovery programme, Severn Trent and local authorities are working on retrofitting a series of SuDS measures across the Nottinghamshire town including bioswales, detention basins, raingardens, and approximately 50,000m2 of permeable paving.

As well as supplying the Omega Flow permeable paving, Brett Landscaping’s experts are providing technical support and advice to the design team – which includes Severn Trent, ARUP, AECOM and Galliford Try – to assist with the design, construction and maintenance of these systems so that they perform as is expected to the British Standard (BS 7533-13: 2009). They also carried out CPDs, toolbox talks and a site visit to previously installed permeable paving sites.

Part of the sustainable flooding resilience project involves retrofitting permeable paving, within highway land such as residential parking areas to tackle the runoff of surface water The permeable paving has been designed as either infiltrating with a geotextile base or non-infiltrating with a impermeable liner with a return to the sewer system. Where on steeper slopes the paving includes checkdams.

Omega Flow Permeable Paving

Omega Flow Permeable Paving

These SuDS systems will naturally reduce storm overflow activation by attenuating surface water and delaying or preventing it entering the combined sewer network. This will mitigate future overloads of the drainage system and reduce storm overflow activations into water courses.

Severn Trent’s waste network will be much less likely to be overwhelmed by storm events – while creating biodiversity, and a greener environment that benefits wildlife and communities.

The Omega Flow block paving will also give local authorities the added benefit of a longer lasting material that will reduce the need for any future maintenance.

Jamie Gledhill, Technical Engineering Manager for Brett Landscaping, said: “This scheme could be the first of many across the country as local authorities and water companies investigate the possibility of retrofitting SuDS.

“Sustainable drainage is due to be mandatory in all new housing schemes, but existing communities shouldn’t be forgotten when it comes to mitigating flood risk and preserving water.”

Adam Boucher, Operations Lead for Severn Trent on the Mansfield Green Recovery, said: “This is a big change in the way that flood risk is managed and we’re thrilled to be bringing SuDS to Mansfield. Working with Brett and our other partners, Mansfield is the first of its kind in the UK.

“This scale of wide surface water management project of its type and size hasn’t been tried before so we’re really leading the industry with this trial and its findings. Our project has the potential to deliver the blueprint on how we manage flooding risk in the future as well as reduce storm overflow activations and help us rewind the clock following the paving over of permeable surfaces and verges in our towns and cities over previous decades”.

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