UKWIR has published a useful new report: Improved understanding of retrofit SuDS whole life cost, carbon and delivery to enable deployment

It shows that the costs, carbon and wider delivery complexities of retrofitting SuDS are generally poorly understood and very sensitive to assumptions and the local context. This is a risk for companies when committing to and delivering investment programmes. Companies need to have both confidence in understanding the performance of proposed SuDS solutions and robust estimating methods to establish and present a sound evidence base of costs, carbon and benefits.

This project, led by Stantec with HR Wallingford, ICS and Gardiner & Theobald, aims to improve the water industry’s understanding of retrofit SuDS to enable deployment and delivery. Key project outputs are:

• A cost and carbon estimating tool accommodating 11 different types of SuDS
• A desktop review of the impact of urban diffuse pollution on waterbodies
• A review of Ofwat data tables, methodology and cost models to evaluate how these might impact on SuDS delivery
• A summary of practitioner learning and approaches to successfully retrofit SuDS through a series of roundtables, interviews and site visits
• An evaluation of SuDS modelling approaches, including model testing on performance of overflows and how they are affected by intercepting surface water
• An industry review of the challenges to implementing SuDS, with key policy and regulatory recommendations