What are the SuDS related amendments to the policy framework?
Previously, paragraph 165 of the NPPF stated that:-
" Major developments should incorporate sustainable drainage systems unless there is clear evidence that this would be inappropriate. The systems used should... where possible, provide multifunctional benefits".
The equivalent paragraph is now 182, providing more explicit guidelines around SuDS:-
"Applications which could affect drainage on or around the site should incorporate sustainable drainage systems to control flow rates and reduce volumes of runoff, and which are proportionate to the nature and scale of the proposal. These should provide multifunctional benefits wherever possible, through facilitating improvements in water quality and biodiversity, as well as benefits for amenity."
What does this change means for SuDS on developments?
This is a change which sees the requirement for SuDS being applicable to all developments, not just Major ones, which is a welcome change - even small development sites have significant roles to play in surface water management.
Let's look again at that last sentence: "These should provide multifunctional benefits wherever possible, through facilitating improvements in water quality and biodiversity, as well as benefits for amenity."
...wherever possible... When are multifunctional benefits (water quality, biodiversity and amenity) possible? Every time, everywhere, provided they are considered early enough in the design process.
Image: York University buildings with integrated green SuDS providing an attractive sense of place
What we don't need to see is the following kind of nonsense 'SuDS Feasibility Assessments' in Flood Risk / Drainage reports (extract from a recent small housing development application):-
Green Roofs x Not suitable for scale of project & dwellings with pitched roofs.
Basins and Ponds x Not suitable due to unavailability of space as per the proposed site plan.
Filter Strips, Swales and Bio-Retention x Not suitable due to unavailability of space as per the proposed site plan.
Tanked Systems ✓ Could be used as surface water attenuation
In other words, design decisions were made about both the character of the buildings and the layout of the site which deliberately precluded the incorporation of green SuDS features in favour of a tank-based system. It was however, perfectly possible (and sustainable, and cost-effective) to have incorporated those multifunctional benefits: water quality, biodiversity, amenity - the other 3 'pillars of SuDS' as described by the CIRIA SuDS manual.
Will the 2024 NPPF herald a new era of multifunctional SuDS on all developments?
We would love to think so - and the NPPF certainly strengthens the case for it. But, as long as developers and drainage engineers carry on ignoring the climate and biodiversity crises and designing like it's '1960 with a bit more rain', multifunctional SuDS will continue to be the exception rather than the rule. "Wherever possible" provides an excuse to those who would use it, despite the 2015 CIRIA SuDS manual stating, up-front: "Provided that drainage is considered early enough in the outline design of a new development then there is no reason why SuDS should not become the norm everywhere.... Where SuDs are designed to make efficient use of the space available, they can often cost less to implement than underground piped systems ".
Image: Swale provides an incidental play landscape in Upton, Northamptonshire
Equate the term "Wherever possible" with "Everywhere!"
Whilst we all continue to await Schedule 3 of the Flood and Water Management Act ( see 2B Blog post 2016: "The implementation of a broader, more effective set of solutions is urgently required and long overdue") many local authorities now have now adopted local plans/SPDs that specifically mention SuDS. For example, Calderdale's 'Flood Risk and Drainage' SPD, "includes the importance of using Sustainable Drainage Systems".
The changes to the NPPF around SuDS helps to strengthen the planners' position at the local level, as well as national. We, as an industry, need to encourage and support our planning colleagues, who would also benefit greatly from the direction and capacity that could be provided top-down, through implementation of Schedule 3, and resources to support it. In the light of the weight placed on sustainable drainage by the new NPPF, Planning Officers and Lead Local Flood Authorities (LLFAs) need to question the too-often poor surface water designs that come before them, and have the knowledge and confidence to equate the term "Wherever possible" with "Everywhere!"
By Bill Blackledge CMLI