Mott MacDonald Bentley wins highly competitive award for pioneering nature-based project

The Mott MacDonald Bentley (MMB) project team responsible for delivering the UK's largest integrated constructed wetland (ICW) proudly took home the Centenary Award for projects valued over £5m, at the annual Institution of Civil Engineers (ICE) Yorkshire and Humber Awards.

On behalf of Yorkshire Water, and working in partnership with Stantec, the pioneering 'first-of-its-size' scheme at Dearne Reach, Yorkshire, is now a benchmark for delivering low-carbon, nature-based solutions to support stormwater management and deliver water quality improvements.

MMB designed and built thirteen adjacent wetland cells - housing over 350,000 plants of 52 different species - engineered to naturally treat effluent to improve 4km of the River Dearne. Using natural processes such as sedimentation, filtration and biological uptake, the ICW removes pollutants including ammonia, biological oxygen demand (BOD) and suspended solids. The solution is a sustainable alternative to traditional concrete infrastructure - which would have entailed 7,000 m³ of storm storage - and is creating many new thriving habitats.

As the largest ICW of its kind in the country, Dearne Reach showcases the capability of the UK construction industry to deliver low-carbon, climate-resilient infrastructure at scale. Lessons learned from both design and delivery are already being shared across the industry, helping to drive continuous improvement and innovation in sustainable water management. In doing so, the project not only improves river water quality and biodiversity today but also strengthens the evidence base and confidence needed to accelerate adoption of nature-based solutions nationwide.

Commenting on why the project deserved the award, the ICE judges said:

"The Dearne Reach scheme is an exemplar for using nature-based solutions to respond to water challenges while delivering enhanced biodiversity and catchment-wide water quality benefits.”

The judges were further impressed by the project’s use of digital tools and AI to optimise how the earthworks were managed, congratulating the team for their commitment to excellence every step of the way, from feasibility through to construction.

Aerial view of the integrated constructed wetland cells at Dearne Reach

Thanks to its innovative, industry-leading and sustainable approach, the project is now a triple award winner. In 2025 the team achieved National Gold at The Green Organisation International Green Apple Environment Awards, and also received the win for 'Going the extra mile' at the Civil Engineering Contractor's Association (CECA) Yorkshire and Humber Awards.