Brett Landscaping recently partnered with Severn Trent Water to collaborate on the UK’s largest SuDS project. The £76 million sustainable drainage project aimed to mitigate flood risk in Mansfield.

This case study explores the journey of transforming flood resilience in Mansfield and showcases the creative solutions employed to create a greener and more sustainable environment.

The Client

Severn Trent Water initiated the project in partnership with Mansfield District Council & Nottinghamshire County Council, after obtaining generous grant funding from OfWat.

The project aimed to establish a sustainable surface water drainage system with the capability to hold an impressive 50 million litres of water (equivalent to about 20 Olympic sized swimming pools).

The Challenge

The town of Mansfield faced significant flood risks due to inadequate combined drainage systems. The challenge was to develop a comprehensive solution that could effectively manage excess water during heavy rainfall, reducing the volume which is entering the combined sewer therefore mitigating the risk of flooding.

To combat the flood risk, we needed to utilise a series of SuDS measures designed to revolutionise the existing drainage infrastructure. These measures included the installation of swales, attenuation basins, rain gardens, and 50,000 square meters of concrete block permeable paving.

The Solution

Brett Landscaping was able to provide the perfect solution, supplying the Omega Flow permeable paving.

Our team of experts provided vital technical support and advice to the design team, which included key stakeholders from Severn Trent, AECOM, and Galliford Try to ensure that the SuDS systems were constructed and maintained to adhere to the British Standard (BS 7533-13: 2009). We also conducted CPDs and toolbox talks to increase understanding and knowledge sharing.

Part of the project involved retrofitting permeable paving with an infiltrating sub-base. A geotextile was used at the base of the pavement to allow for infiltration back into the subgrade. The sides of the pavements were lined with waterproof membranes to stop any surface water leaking into the existing road construction. Another feature of the pavements was the use of positioned preformed structural dams in residential parking areas on sloping sites, compartmentalising the surface water and stopping overflows at the lower end of the pavements.

This approach perfectly manages surface water runoff, preventing overloads of the drainage system and combined sewer overflows into water courses.

The Result

The implementation of SuDS resulted in substantial positive outcomes for the community of Mansfield.

By naturally reducing storm overflow activation, the system successfully mitigated the risk of flooding during heavy rainfalls, safeguarding the environment and the local population whilst providing valuable parking areas for the local residents.

The newly established drainage infrastructure also contributed to the preservation of Severn Trent’s waste network, rendering it less susceptible to being overwhelmed by storm events.

The integration of these solutions not only facilitated water management but also fostered a greener environment that supported biodiversity, benefiting local wildlife and communities.

The Omega Flow block paving demonstrated its value by offering durability and longevity, ultimately reducing the need for future maintenance. This feature proved advantageous to local authorities, who were reassured that the unique structural and hydraulic properties of the Omega Flow interlock will ensure a sustainable solution that would stand the test of time.

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