Enhancing biodiversity and reducing the use of carbon heavy materials with the UKs largest nature-based solution for stormwater discharges

Clayton West Integrated Constructed Wetland

Looking to improve water quality with a nature-based solution, Yorkshire Water set out to establish the Clayton West Integrated Constructed Wetland (ICW). The 43,000-square-metre (462,848-square-foot) free surface water wetland, which resides within a site double the size, is the largest ICW in the UK to treat stormwater overflow discharges. Yorkshire Water reached out to our team to help.

Our sustainable approach to stormwater management addresses the environmental challenges posed by storm overflows exacerbated by climate change. Unlike traditional grey engineering solutions, the ICW system can handle the variability and unpredictability of stormwater discharges through advanced hydraulic controls, simulated using computational fluid dynamics. By incorporating over 300,000 plants, Clayton West aims to deliver an over 30 percent positive biodiversity net change (PBNC) across the site.

Serving a population of 26,000, the scheme enhances biodiversity and reduces the use of carbon heavy materials like concrete. Alternatively, a grey infrastructure solution would have involved a 4.5-kilometre (2.8-mile) diversion of the wastewater treatment works final effluent discharge to a lower river reach and a 7,000-cubic-metre (247,203-cubic-foot) storage attenuation facility.

With this a nature-based approach to stormwater management, Yorkshire Water avoided impacting local amenities like the Yorkshire Sculpture Park, three wildlife sites, Breton Hall, and Bretton Country Park Local Nature Reserve. A community-focused plan resulted in a public right of way around the perimeter of the scheme, providing social value and supporting health and wellbeing. The scheme also resulted in water quality improvements in the River Dearne, a 60 percent reduction in embodied carbon, and a 40 percent reduction in operational carbon compared to a traditional grey engineering solution.