Welsh Standards Light the Way for Future SuDS Delivery

Written By: Regional Technical Manager, Hydro International UK Stormwater Divison

Having been born and bred in Wales, as well as currently living there, I can be forgiven for a little favouritism for the Welsh way of doing things. The new interim non-statutory SuDS standards for Wales are certainly different from their English and Scottish counterparts – and I believe they are worth studying, even for professionals working elsewhere in the UK, to help light the way to future best practice.

The Welsh Government published the new Recommended Standards for Sustainable Drainage Systems (SuDS) in January 2016. They follow a long period of development in which Natural Resources Wales (NRW) worked closely with professionals and undertook a public consultation.

The standards are non-statutory and voluntary but, it’s fair to say, they give detailed 64-page guidance to help designers, developers and local authorities prepare for successful planning applications that take into account the policy and preferences of the Welsh Government.

The non-statutory standards also present an opportunity to test the standards, while the NRW considers whether to proceed with full commencement of Schedule 3 of the Flood and Water Management Act (FMWA) 2010 – an approach that has now been rejected in England.

By comparison, the English non-statutory standards published last year, are just two pages long and the Welsh standards are generally much more true to the original FMWA intentions. Here are some key differences. The Welsh Standards:

  • apply to all developments of more than one property, whereas in England SuDS regulations apply to major developments of 10 properties or more (or their commercial equivalent).
  • require SuDS to protect water quality by treating surface water runoff to reduce pollutant loads to acceptable levels.
  • require SuDS to intercept runoff of the first 5mm of a rainfall event (so far as possible).
  • make specific reference of biodiversity and amenity.

There are six technical standards, and the first sets out a hierarchy for the destination of surface water runoff, beginning with collecting surface water for re-use through systems such as rainwater harvesting, followed by infiltration to the ground. Discharge to a combined sewer is advised only when all other options have been considered.

The final standard sets out requirements for construction, cost-effective operation and maintenance, and ensuring the structural integrity of SuDS components over the design life of the development.

The document also sets out eleven key principles for SuDS design and implementation beginning with managing water on or close to the surface, and as close to the source of runoff as possible, treating rainfall as a valuable natural resource, and ensuring pollution is prevented at source. They also advise that SuDS should be ‘affordable’, taking into account both construction and long-term maintenance, as well as the environmental and social benefits of the system.

We are now seeing a very mixed and varied approach to SuDS design and implementation across the UK, with a range of regulation and non-statutory standards. The publication of the updated CIRIA C753 The SuDS Manual, provides overarching guidance for professionals working across the UK.

However, alongside the national standards, local authorities are also developing design guidance appropriate to their own regional environmental conditions and topography. It will be fascinating to see if, and how, regional variations develop and the outcomes for the number and efficacy of SuDS schemes now being designed and built across the country.

Very much a case of ‘watch this space’.


Download: Recommended non-statutory standards for sustainable drainage (SuDS) in Wales – designing, constructing, operating and maintaining surface water drainage systems


SuDS Manual Webinars: sign up for free webinars on the The New SuDS Manual (C753).


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