18Sep 2018

susdrain – Why do we support it and why are we Partners?


Written by Phil Gelder BSc DMS CEng MICE – Richard Allitt Associates Ltd


SuDS are designed to replicate as closely as possible the natural drainage from a site before development. It is accepted that SuDS reduce the potential impact of flooding and offer many more benefits: including impact upon water quality, amenity value and biodiversity. As well as new development sites there are also many excellent examples where SuDS have been retro-fitted.


SuDS have been a long time coming and indeed my involvement goes back many years, can anyone remember BMPs? I can.


I still have vivid memories of trying to convince stakeholders from a myriad of organisations that SuDS was the way forward and that we could all benefit if we would only ‘bite the bullet’ and go for it. I sat on the Working Group that produced the Interim Code of Practice for Sustainable Drainage Systems way back in July 2004. This document wasn’t ideal but it was a start.


Since that time there have been an untold number of excellent publications and guidance documents by organisations, particularly CIRIA, which has moved our understanding and knowledge forward considerably –  so why does there still seem to be so much resistance to SuDS?


Prior to the Ministerial Statement in December 2014, LLFAs were gearing up to implement Schedule 3 of the Flood and Water Management Act (2010) and were establishing SuDS Approval Bodies (SABs). All this was swept away to be replaced with LPAs delivering SuDS through the NPPF. The provision of SuDS is therefore controlled through appropriate conditions being applied through the planning process.


The Statement specifically refers to major developments i.e. that contain 10 dwellings or more, or, the equivalent non-residential or mixed development. By implication developments smaller than this are not considered, this is surely a missed trick?


The long awaited SuDS standards which have now been in place for over 3 years are non-statutory  – so in effect have no status in law and simply offer guidance and do not have to be complied with.


We now know that in Wales Schedule 3 and the appropriate standards will be implemented in 2019, well done to the Welsh Assembly!


It is still commonly believed that developments that incorporate SuDS features are more expensive to develop than those drained by traditional methods, but is this really the case? Cost is always an issue but it must be balanced against other wider benefits. In RAA Ltd we have been involved with several schemes modelling the impact of both traditional and SuDS led alternatives to show the benefits. One example of this is by properly considering groundwater conditions at design stage to prevent flooding issues post implementation.


A major challenge is the adoption of SuDS and their ongoing operation and maintenance. It is vital that there is effective engagement between Developers, Local Authorities and if appropriate Water and Sewerage Companies (WaSCs) to ensure that suitable arrangements are put in place for the lifetime of the development.


Over the years there has been much debate about the WaSCs and their apparent stance on SuDS. This stance is slowly changing and the imminent publication of Sewers for Adoption – 8th edition by the water industry may go some way towards addressing this.


RAA Ltd has been involved with susdrain from its inception and we are proud to be a full partner of the community and will be continuing this relationship for the next period.  Being a partner of susdrain enables us to proceed with the confidence and knowledge that we are part of a much larger, well respected community that has national recognition.


We have a young team of modellers at RAA and we are committed to developing SuDS modelling with the next generation of innovative thinkers.  Currently we have two graduate modellers who have begun specialist research projects in SuDS modelling.  They are looking in depth at the different types of SuDS, how they work and how to model them including what information is needed and what tools are available.  The resources available on the susdrain website have been key to their research and that is why we had no hesitation in continuing our support for the susdrain platform.


It is only by working together that we can deliver the benefits we all know SuDS can deliver.

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