Chris Hodson explains the latest twist in the long-running saga on SuDS implementation.
After long delays, on 12 September the government announced an alternative approach to implementing Sustainable Drainage Systems (SuDS) using the planning system, and taking effect in spring 2015.
It is well recognised that sustainable drainage systems and techniques such as concrete block permeable paving are needed to help fight flooding and pollution, particularly in the context of overloaded sewers, urbanisation and climate change. There is ample research to demonstrate the link between growing urbanisation and flooding, as notably shown in the Pitt Review into the summer 2007 floods. Here, more than two thirds of the 57,000 homes affected were flooded not by swollen rivers but by surface water runoff or surcharge from overloaded drainage systems.
The 2010 Flood and Water Management Act, which resulted from the Pitt Review, was set to make SuDS mandatory for any construction work that affects the ability of land to absorb rainwater. Under the Act, SuDS Approving Bodies (SABs) would have to be set up by local authorities to approve and, where appropriate, adopt SuDS schemes.
Further reading
Interpave’s recent discussion document SuDS + Permeable Paving Today, Edition 2
The government’s consultation proposal is available here
Yet these measures still cannot be directly applied until application of Schedule 3 of the Act and the long-awaited National Standards for SuDS and related guidance, both of which are still in draft.
In June, Defra announced that yet another proposed implementation date – October 2014 – would now be missed. The repeated delays have been largely attributed to housebuilders’ concerns about added costs, as well as local authorities’ lack of time and resources to set up SABs.
Now, in an about turn, a ministerial statement issued on 12 September reaffirmed the government’s determination to encourage SuDS for new developments and launched a consultation proposal that in effect by-passes the Flood and Water Management Act.
Instead, the planning system with national and local planning policies will form the basis for demanding SuDS on developments. Amended planning guidance, based on the latest draft National Standards for SuDS, will bolster existing National Planning Policy Framework encouragement for SuDS. The new guidance will therefore focus on adoption and long-term maintenance issues.
Water for the ‘soft’ landscaping at The Hazeley School in Milton Keynes is supplied from the concrete block permeable paving
Once implemented, planning conditions, Section 106 agreements and other measures are proposed to ensure that SuDS will be maintained for the lifetime of the development and this should not increase costs.
As the government proposal points out: “All the available evidence is that sustainable drainage systems are generally cheaper to build; and maintaining them will be cheaper (or need be no more expensive) than the same cost as is required to maintain conventional drainage at present.”
The government’s proposed planning policy changes should now come into force in spring 2015 and apply to new developments of 10 houses or more, or equivalent non-residential schemes.
SuDS technology is not new to the UK and is well established in other countries.
Conceptually, a SuDS scheme comprises a “management train” of interconnected features, each combining water storage, pollution removal and amenity benefits wherever possible.
SuDS replicate, as closely as possible, the natural drainage from a site before development. That is not to say that all SuDS features have to be vegetated – for example, concrete block permeable paving is a well-used SuDS technique – or that urban projects need to take on a rural character with lower housing densities. As the latest draft National Standards Guidance states, SuDS “should aim to manage surface water within sub-catchments, close to source and at or near surface as reasonably practicable”.
Recent guidance for both designers and regulators on how to go about implementing SuDS can be found in a Code of Practice, BS 8582:2013. It seeks to integrate SuDS with urban design in delivering amenity and community value as well as enhancing landscape and/or townscape character.
Chris Hodson RIBA is a consultant to Interpave, the trade association for precast concrete paving
