Sustainable Urban Drainage Systems (SuDS)

With ever-increasing urbanisation, the ability for precipitation to penetrate the hard paved surfaces to the groundwater below is inhibited. This results in increased flood risk, overstressed sewer infrastructure, and reduced ability to replenish aquifers. Sustainable Drainage Systems (SuDS) mitigates these issues by replicating natural processes to manage rainfall.

There are many benefits to using SuDS to manage surface water runoff. Primarily, SuDS filter and attenuate surface water, reduce pressure on infrastructure, and where geological conditions permit, replenish groundwater supplies through infiltration. For SuDS which incorporate vegetation, however, there are ancillary benefits, which contribute in other ways to the community. These include:

  • sequestered carbon in plants and trees as they grow
  • improved thermal comfort resulting from evapotranspiration
  • increased biodiversity through ecological enhancement
  • opportunities for recreation and relaxation, particularly in larger green spaces
  • increased property values
  • improved air quality

Incorporating SuDS in developments, however, should also be viewed as opportunity to realise many of the benefits listed above, and are an easy way to obtain the support of the local community and local authority.

With effect from 6 April 2015 all major planning applications (developments of 10 or more dwellings or equivalent non-residential or mixed development) are expected to have sustainable drainage systems for the management of surface water run-off, unless demonstrated to be inappropriate. All development must give priority to SuDS as per paragraph 103 of the National Planning Policy Framework. When determining what is reasonable practicable and the minimum standards required information needs to be submitted that addresses the Non-Statutory Technical Standards for SuDS, this information is set out in the validation list and the Surface Water Drainage Statement.

The Council has amended the local requirements for validation of a planning application to include the submission of a validation checklist (Full or Reserved Matters applications or Outline applications) to support surface water drainage. We also require a Surface Water Drainage Statement, completed and signed (by a competent drainage engineer recognised by the Engineering Council, the Institution of Civil Engineers or equivalent), to be submitted with the technical evidence as part of the planning application.

Further information is available in the SuDS advice note.

Adoption of SuDS

In Woking Borough the developer has a choice to have proposed SuDS devices that either adopted by Woking Borough Council or retained by the development.

SuDS can be adopted by Woking Borough Council that:

  • are within public open space,
  • Serve more than one property; and
  • have been designed in accordance with Ciria guidance.

Adoption will be following a Section 106 agreement and all SuDS devices will attract commuted sums.

SuDS can be retained by the development in perpetuity and looked after by an accountable management company with a maintenance plan that must be accepted by the Local Planning Authority.