New policy on sustainable drainage systems (SuDS) is challenging planners, architects and developers to rethink how we can develop and live alongside increasing environmental risks such as flooding. Michael Piotrowski, Report Manager and Project Consultant from GeoSmart Information, examines the changes in local and national guidance and the move towards more sustainable ways to build properties.

Introducing impermeable surfaces such as roads, pavements and roofs in a new development increases the amount of surface water flowing into drains and sewers. This adds to the risk and severity of flooding.

Much of the existing sewer network is unable to cope with an increase in surface water runoff due to its condition and capacity. Many sewers are susceptible to blockages, flooding homes and businesses with huge financial implications.

In recognition of these risks, new SuDS policy requirements were published in April 2015. These requirements have built upon the Floods and Water Management Act 2010, requiring developers and landowners to consider the suitability of the site for more natural drainage solutions such as SuDS.

The National Planning Policy Framework has been updated, requiring new developments in areas at risk of flooding to give priority to the use of SuDS and demonstrate the proposed development would not increase flood risk to third parties.

Building regulations have also been revised, so that developers are required to consider infiltration to ground or to a surface water feature where conditions permit, in preference to discharging to sewers. Planners are now favouring developments that include SuDS which reduce the volume and slow the rate of surface water runoff.

Important new guidance has just been published this month for property professionals, including property and planning lawyers and their developer clients. The author, John H Bates, Drainage Barrister at Old Square Chambers, explicitly advises:

“There is a presumption in favour of SuDS for new developments. SuDS are the preferred approach to managing surface water runoff. Lawyers should commission a pre-application SuDS report to ascertain whether SuDS are appropriate or not, because this has important legal repercussions for your client.”

There is now a requirement for SuDS to be implemented, where appropriate, either through a relevant planning condition or within the design from an early stage. While it may have an impact on the feasibility of some sites, SuDS shouldn’t be seen as a restriction to development and can prove attractive to buyers through improved community amenity.

SuDS are designed to replicate the natural drainage from a site (pre-development) to mitigate flood risk both on and off site. They provide areas for water storage and drainage as close as possible to where the rain fell, providing a valuable water resource as well as reducing flood risk. As a result, far less surface water is discharged into traditional sewers, taking pressure off of existing drains and river systems.

SuDS can also make communities more resilient to flood risk, significantly improve the quality of water leaving a site and enhance the biodiversity of a local area.

Understanding the site drainage conditions and options for SuDS are therefore essential for developers and landowners ahead of submitting a planning application at the pre-planning stage or to address a planning condition prior to permission being granted.

GeoSmart provide a range of SuDSmart reports on site infiltration drainage conditions. They can be used to provide evidence on suitability or otherwise and answer specific questions required by the Local Planning Authorities and Lead Local Flood Authorities.

For a copy of the SuDS Guidance for Property Professionals and to enquire about SuDS Suitability Reports for your site, visit www.geosmartinfo.co.uk, email info@geosmartinfo.co.uk or call us on 01743 276 150.

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