SuDS require a special way of thinking. They’re arguably more sophisticated than conventional drainage. SuDS ask engineers to learn to use a new range of design, installation and maintenance skills. A successful SuDS is designed to mimic and work with the natural behaviour of water on a site. They slow the flow and replicate processes that existed before development.
A SuDS system could comprise a series of small SuDS installed plot by plot, such as rainwater harvesting and green roofs. They could be applied across a site in the form of tree pits, planters or porous paving — depending on the outcome of the hydraulic model and other site considerations. And, of course, the medium- and larger-scale SuDS structures, including swales, dry ponds and wetlands, may be appropriate in certain circumstances.
The choice of which SuDS to use, their number, combination and where to site them, all form part of the new challenge for drainage engineers. At the design stage, a hydraulic model can demonstrate the effects that different SuDS might have on a given site, including at times of peak flow. Additional to understanding the hydraulics, a SuDS expert will want to know about the local authority mindset and will be keeping an eye to the future maintenance of the SuDS features. It’s definitely a new way of working and a different type of challenge for drainage engineers.
But there’s an upside for engineers who get good at SuDS. They’ll be able to demonstrate that their SuDS expertise adds value to a development project. SuDS save space and improve amenity, at the same time as providing drainage on a site. That’s a valuable combination of potential wins for a developer. And the versatility of SuDS make them well suited to retrofit and brownfield projects, as well as to greenfield developments.
With new Design and Construction Guidance coming from Water UK in 2020 and Wales having already set up a network of SuDS Approving Bodies, the momentum in support of SuDS is building. Questions remain about where it’s best for adoption and maintenance responsibility for SuDS to reside, but the multiple benefits that SuDS offer suggest that these queries will be resolved. The engineers that get out in front and develop their mindset to work effectively with SuDS will surely benefit from the competitive edge.
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