Sustainable Drainage Systems (SuDS)

Sustainable Drainage Systems (SuDS) provide an alternative method for managing surface water by imitating natural drainage and helping urban areas to cope with severe rainfall. SuDS generally replace conventional underground piped systems which results in systems being easier to maintain and problems to be identified more rapidly. By capturing rainfall, this allows water to evaporate, soak into the ground or be released into a nearby watercourse at slower rates and volumes than traditional piped drainage.

Sustainable Drainage Systems (SuDS) are designed to manage rainwater in a way that mimics natural processes. Here are some benefits of SuDS:

Reduces Flooding: SuDS help to slow down and control the flow of rainwater, reducing the risk of flooding in urban areas.
Improves Water Quality: By filtering rainwater through natural materials like soil and plants, SuDS remove pollutants and improve the quality of water that eventually reaches rivers and streams.
Enhances Biodiversity: SuDS often include features like ponds, wetlands, and green roofs, which provide habitats for wildlife and support biodiversity.
Recharges Groundwater: Instead of letting rainwater run off into drains, SuDS allow it to soak into the ground, replenishing groundwater supplies.
Creates Green Spaces: SuDS can be designed as attractive green spaces, such as parks and gardens, which enhance the beauty of urban areas and provide recreational opportunities for people.
Cost-Effective: Over time, SuDS can be more cost-effective than traditional drainage systems because they reduce the need for expensive infrastructure and maintenance.

SuDS and developments

On 18th December 2014, the Department of Communities & Local Government (DCLG) released a Ministerial Statement on the implementation of SuDS. The statement made changes to the National Planning Policy Framework, requiring local planning policies and decisions on planning applications for major developments to ensure SuDS are used for the management of run-off, unless demonstrated to be inappropriate.

Consequently, it is essential that developers provide clear and appropriate information on SuDS when applying for planning permission for major developments.

Major developments are defined as any of the following:

Winning and working of minerals or the use of land for mineral-working deposits
Waste development
10 or more dwellings / 0.5 Ha or more
Building/s where the floor space to be created by the development is 1,000 square metres or more
Development carried out on a site having an area of 1 hectare or more

Sefton Council, in its role as Lead Local Flood Authority (LLFA), is a statutory consultee and, therefore, provides technical advice on major planning applications. Sefton’s Local Plan was adopted in 2017 and includes the policy EQ8 ‘Flood Risk and Surface Water’. An additional information document, the ‘Sustainable Drainage (SuDS) and Flood Risk Information Note’ (plus appendices) has been produced by Sefton Council to offer clear guidance to developers and others in relation to policy EQ8. These documents are linked below:

SuDs & Flood Risk -

Information Note

(Text & Appendices)

Provides guidance in relation to policy EQ8 ‘

Flood Risk and Surface Water’ of Sefton’s

Local Plan.

Appendix 1

Critical Drainage Areas

Appendix 1 contains maps of Sefton Critical

Drainage Areas.

Appendix 2 Other

Consent Regimes

Appendix 2 provides an overview of other

potentially applicable consent regimes.

Appendix 3 Help

Managing Surface Water

Appendix 3 highlights simple steps to reduce

surface water run-off & flood risk which would

benefit residents, businesses & local community.

Appendix 4 SuDS

Type & Benefits

Appendix 4 highlights common components of

SuDS and their green infrastructure benefits.

Additional background information on flood risk, historical flooding and surface water management can be found in Sefton Council’s Strategic Flood Risk Assessment (SFRA) and Surface Water Management Plan (SWMP). These documents are linked below:

Strategic Flood Risk

Assessment

The SFRA provides information on the

probability & consequences of flooding

in Sefton.

Surface Water

Management Plan

The SWMP provides detail on the extent,

mechanisms & consequences of surface

water flooding. It helps planners with

policy & other departments with emergency

response plans or climate

change adaptation measures.

Sefton Council, as the LLFA, have prepared a number of documents which set out the flood risk and surface water drainage information required to be submitted as part of major planning applications. These documents form part of the Council’s ‘Planning Validation Checklist.’ Planning applications for major development and for sites of 0.5 hectares in Critical Drainage Areas that are not submitted with the above information will not be regarded as a ‘valid’ application. These documents may also be beneficial to other (non-major) developments and are linked below: