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The drainage question: are SuDS working for us?
- Thursday February 23, 2023
By Richard Harman IHE member, IEng FIHE, partner and head of engineering at Berrys
It’s now been over four years since the Welsh Government implemented Schedule 3 of the Flood and Water Management Act 2010 and the corresponding Statutory Standards, and nearly three years since Water UK published the long-awaited Appendix C Design and Construction Guidance (DCG) for sewers. Both were dubbed as being the solution to the provision of sustainable drainage (SuDS) for new development in Wales and England respectively. So are we surrounded by well-designed development sites that incorporate SuDS infrastructure as an integral feature of the development? If only life were that simple.
Let’s deal with England first. Following the 2008 Pitt Review and the subsequent implementation of the Flood and Water Management Act in 2010, the newly formed Lead Local Flood Authorities (LLFAs) were all gearing up for Schedule 3 of the Act, and therefore the formation of SuDS Approval Bodies. A date of October 2012 was agreed, but the implementation never came – the Government folded due to industry pressure. At the time, it all felt like it might be a step too far too soon… Plan B was therefore actioned and an approach of updating the Water UK Sewers for Adoption manual, along with changing the legal definition of a sewer, was agreed. This would allow the water companies in England to adopt and maintain SuDS. Fast forward to spring 2020, following much consultation, and the DCG has finally launched and replaced the former Sewers for Adoption guidance.
Overall, the DCG was not hugely different from Sewers for Adoption 7, but it includes many updates and additions to deal with the adoption process for SuDS, along with the parent adoption procedures. However, the key issue is that the standards for surface water SuDS were still to be set by the LLFAs and the scheme designs and parameters would still be approved through the planning process.
The SuDS guidance issued by LLFAs across England varies dramatically, as do the experiences of the staff reviewing and approving proposals. This means that often the industry doesn’t know where it stands when reviewing development sites in areas it’s not used to. Plus, the process often doesn’t seem to have teeth for providing SuDS proper, as per the industry standard Ciria C753 SuDS Manual.
Often conflicting policy objectives result in, if you’ll pardon the pun, SuDS being watered down. For example, on a medium-sized housing development site, a proposal for high quality infiltration basin located in a well-positioned area of open space was shunned. Why? The basin area would be excluded from the open space area and the developer would have to mitigate this by providing more open space, therefore losing plots. The answer? Buried soakaway crates below the open space – and a huge opportunity for biodiversity and landscape enhancements was missed. Unfortunately, we’re seeing this type of conflict time and time again. Possibly Biodiversity Net Gain will help to focus minds on this, or will it become yet another disjointed policy? Time will tell.
Moving over the border to Wales and after roughly three years of adjustment, it feels like the development industry is getting used to the SuDS approval bodies (SABs) and the statutory standards. The industry is starting to come to terms with the fact that site drainage needs to be an integral part of the site masterplan phase. With the Welsh Government having published a very robust set of rules within the Statutory Standards, generally we all know where we stand.
On the SAB side, the situation also seems to be improving; initially responses to applications were very slow and lacking in detail. It is understood that no funding was provided up front for the formation of the SABs and the fee scales are set by the assembly, so local authorities have had to work their way through this and build momentum in their resources. It’s helpful to the overall process if the SAB pre-app service is used, as this allows an early meaningful conversation on sites and provides a little extra funding to the SAB for them to do a good job. Overall, after a shaky start, the process now seems to be working well.
DEFRA has now published their review of Schedule 3, following a period of engagement with stakeholders. The review document makes for some sensible reading, with an acceptance that changes are needed for the successful and mandatory delivery of good quality SuDS in England. The headline recommendation is that ‘…the government must act and implement Schedule 3 to the Flood and Water Management Act 2010 as written’. A firm commitment has therefore been laid out to bring SABs back to the fore in England, with a target to implement Schedule 3 by 2024, following a period of public consultation this year.
The review has also considered how the SAB model will work in England, with many references to the lessons learned from the Schedule 3 journey in Wales. The key recommendations are: the SAB role and adoption is best sat within the existing LLFAs; SAB approval will be required for most developments of 100 square metres or more; SuDS standards for England will be published; and finally that the funding model for the operation and maintenance of SuDS is up for review, following some concern raised over the Wales commuted sum approach. The review document can be viewed at www.gov.uk/government/publications/sustainable-drainagesystems-review.
Overall, it appears that the future for SuDS in England is looking positive. The implementation of Schedule 3 is likely to provide the consistency and certainty that the development industry needs, which ultimately will result in better planned developments. There will likely be a knock-on effect to highway improvement schemes, which could create some headaches to resolve due to additional burdens on land, space, and maintenance.
Given our experience of 2012 when Schedule 3 was last considered, the 2024 implementation date does seem a little ambitious. But the concept of SABs is less daunting than it felt back then. If the industry rallies together, this engineer believes the target could be reached.