Sustainable Drainage Systems (SUDS) – the challenges ahead for SABs

Written By: Engineering Manager, Aylesbury Vale District Council.

Aylesbury Vale Berryfields Site Picture

We have come a long way in the last 10 years in getting surface water drainage considered at masterplanning stage on larger developments.  Their outline planning applications are generally accompanied by a comprehensive flood risk assessment and drainage strategy.  There is still, however, a real difficulty in getting these outline proposals reflected in the detailed drainage designs.

Even on a major development in Aylesbury, which was designed from the outset around a  SUDS scheme, the individual house builders who submit the full planning applications were at first reluctant to incorporate the outline, agreed proposals in their detailed designs.  This may have been because of the more fragmented approach once the site had been parcelled up between house builders, but I think it more likely that they are still not committed ‘hearts and minds’ on SUDS.

The situation with the small developers is more worrying still.  Planning applications frequently indicate ‘to soakaway or existing system’ in response to the question on how surface water will be dealt with.  If we are lucky the planning approval is conditioned so that a detailed drainage design has to be approved before construction starts, but it is evident from the designs submitted that there is very little understanding of soakaway design, never mind a more comprehensive SUDS scheme.

Another concern is that even where the engineering requirements of capacity, flood routes etc are understood, there is no consideration of the water treatment or ecological benefits which could be incorporated.

So what does this mean?  I think we all have a major challenge ahead when the SUDS Approval Bodies (SABs) come into force under the Flood and Water Management Act 2010, probably sometime next year.  Issues that remain to be addressed are:

  • At what stage should SAB approval be given on major developments,
  • How much emphasis should be given to water treatment on SUDS, given a priority of flood prevention, and
  • Just how do we get the message through to all developers large and small?

Now read the Local Authority Shared Case Study from Aylesbury Vale:  SUDS from the Start

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