Sustainable Drainage, SuDS and Planning – What do you need to know?

What are Sustainable Drainage Systems (SuDS)?

SuDS are basically drainage systems which aim to holistically manage water runoff onsite to reduce the quantity and increase the quality of surface water that drains into sewers from a development. They can take the form of ponds, permeable paving, green roofs, swales or wetlands for example. They are-  in effect – a collection of water management techniques or practices that aim to align modern drainage systems with a natural water process. SuDS help to make urban drainage systems more compatible with components of the natural water cycle such as storm surge overflows. They have become popular recently due to a better understanding of how urban developments can affect natural environments as well as concern for climate change and sustainability, have increased.

What planning applications require a SuDS report?

All new welsh developments (since 7 January 2019) of more than one dwelling house or where the construction is 100 sqm or more require SuDS for surface water.

Although efforts are underway to standardise the process across the 22 local authorities in Wales, there are still local variations.  For the basis of this article, I’ve researched Powys as the local authority.

What about SuDS in England?

In April 2015, national planning policy was strengthened and SuDS were made a requirement to be provided in all major new developments where appropriate.

England is not proceeding with the set-up of a Sustainable Drainage Systems Approval Body (SAB). However, it is estimated that changes in relation to SuDS may come into force in April 2020.

Are there any exemptions to the requirement?

Construction work which does not require planning permission is exempt. However, this does not apply if the construction covers 100sqm or more.

Construction of a single dwelling house or other types of construction which covers an area of land less than 100sqm is exempt.

What is SAB?

SAB means SuDS Approval Body, approval for the drainage scheme must be approved by SAB before construction can begin. The SAB is delivered by the local authority and is required to evaluate and approve drainage applications. The SAB has powers of inspection and enforcement. The SAB can offer non-statutory pre-application advice. You cannot start construction until both planning permission and SAB approval is granted.

How do you get SAB approval?

As previously stated, for this particular article I’ve chosen to research the Powys area. The SuDS scheme must meet the National Welsh Standards which includes requirements for:

  • hydraulic design
  • flood risk
  • water quality
  • biodiversity
  • amenity
  • construction and maintenance

It is likely that a significant amount of detailed design and infiltration testing must be done in advance of planning permission rather than as a later condition.

To ensure a valid application, as much initial supporting information as possible should be provided, this may include:

  • Details of ground investigation, confirmation of soil conditions including borehole or trial pit logs
  • Groundwater monitoring data (over a period of up to 12 months) and detailed infiltration testing data (including soil coefficients and standard percentage run-off calculations)
  • Detailed design of the proposals including construction specifications
  • Detailed maintenance and adoption plan

Is there a cost for SAB approval?

The SAB can make charges for the application fee plus site inspection. The fee for a full application is dependent on the size of the construction area. The construction area is defined by the area of land identified on a plan accompanying a planning application.

The fee is calculated to include:

  • £350 for each application plus an additional amount based on an area up to a maximum amount of £7,500.

The additional amount is calculated using the following:

  • £70 for each 0.1 hectare or fraction of hectare for the first 0.5 hectare
  • £50 for each 0.1 hectare or fraction of hectare from 0.5 hectare up to and including 1.0 hectare
  • £20 for each 0.1 hectare or fraction of 0.1 hectare from 1.0 hectare to 5.0 hectare
  • £10 for each additional 0.1 hectare or fraction of 0.1 hectare up in excess of 5.0 hectares.

SuDS application fee

What do I need to submit with my application?

  • Completed full application form, here is an example of Powys form for a full application
  • A plan specifying the construction area and the extent of the drainage system
  • Information on how the construction work will comply with the SuDS Standards
  • Information requested in the application form checklist
  • The appropriate application fee.

What is the process and how long will it take to get SAB approval?

Early discussions can take place with the SAB in advance of pre-application submission to confirm their broad agreement of the drainage strategy. Once the application and supporting documentation have been submitted to the SAB, it will be validated. If deemed to be a valid application, the submission will be technically assessed and a SAB officer will contact you to commence pre-application discussions. There is no statutory timescale relating to the Pre-Application process. All technical and non-technical discussions with SAB should be undertaken as part of the Pre-Application stage. Only in exceptional circumstances will the SAB contact you during its assessment of the full SuDS scheme application. Following feedback from SAB, any supplementary information will need to be submitted together with the second form. SAB will notify you of the outcome of its technical assessment and the full application may be approved subject to conditions. There is an appeals process should the decision not be favourable.

The SAB will have 7 weeks to determine applications, however, if the application requires an Environmental Impact Assessment the SAB has 12 weeks. Application forms and adjoining documentation will be available from your local SAB.

My Welsh planning application was submitted before 7th January 2019, do I need SAB approval?

SAB approval is required if the planning permission was granted subject to a condition as to a reserved matter and an application for approval of the reserved matter is not made before 7 January 2020.

SAB approval is not required for existing sites or development with planning permission granted or deemed to be granted (whether or not subject to any conditions as to a reserved matter) or for which a valid application has been received but not determined before 7th January 2019.

How do SuDS work?

SuDS work by making use of landscape and natural vegetation to control the flow of surface water thereby reducing the risk of flooding. These can be in the form of ponds, swales or permeable paving which slow down the release of surface water more than drainage which works through pipes.

What is the difference between SuDS and traditional drainage?

Generally speaking  SuDS mimic natural systems and differ from traditional drainage in that they aim to manage rain close to where it falls. This, in turn, helps to reduce the burden on sewerage systems and also help wildlife to thrive in urban and built-up areas.

What are the benefits of SuDS?

  • Better for the environment/encourages wildlife
  • Reduce pollution due to overwhelmed sewers discharging into rivers.
  • Long lasting and more resilient than conventional drainage systems
  • Better water quality
  • Reduce flood damage

Where can I get a SUDS report?

There are specialist environmental consultants who can assist with the application, in a similar way to how you would request an ecologist to provide a newt or bat survey.