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Introducing EDC's
SuDS Selector
Sustainable Drainage Systems (SuDS) manage rainfall in a way that works with nature. Rather than moving water quickly through pipes, SuDS slow, store, filter and re-use rainwater close to where it falls.
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Introduction to SuDS
Why SuDS Matter
Well-designed SuDS deliver benefits beyond drainage and flood management. They can:
Reduce flood risk and improve climate resilience.
Improve water quality by filtering pollutants.
Support biodiversity and create wildlife habitats.
Enhance public spaces and contribute to wellbeing.
Increase urban greening, shade and cooling.
Create attractive, distinctive and multifunctional places.
Integrating SuDS from the outset can help create an efficient drainage strategy while supporting long-term landscape quality and resilience.
Benefits for house builders and developers
Considering SuDS early can help developers create a more efficient and coordinated drainage strategy. Using surface-based features may reduce reliance on extensive underground pipework and large end-of-system attenuation, while avoiding the cost and duplicated effort that can arise when SuDS are added late in the design process.
When designed as part of the landscape, SuDS can also support attractive streets and open spaces, strengthen placemaking and contribute to the long-term value and marketability of a development. Early coordination between drainage, landscape, ecology and design teams helps identify the right measures for each part of a site and supports a clearer route through planning, construction and handover.
The Four Pillars of Sustainable Drainage
SuDS should be designed to deliver four connected outcomes:
Water quantity - Manage surface water runoff to reduce flood risk and erosion by slowing, storing, re-using and infiltrating rainwater.
Water quality - Filter pollutants before water returns to the environment.
Amenity - Create attractive, multifunctional spaces for residents and visitors.
Biodiversity - Provide habitats and strengthen ecological resilience across a development.
Four pillars of sustainable drainage
The four pillars show how SuDS manage water while supporting water quality, amenity and biodiversity.
A SuDS-first approach
Ebbsfleet promotes a SuDS-first, pipes-last approach. Sustainable drainage should be integrated into masterplanning, landscape design and engineering from the earliest stages of a project, rather than added after a conventional drainage system has been designed.
The most successful schemes use a series of linked features throughout the site. Managing rainfall close to where it falls reduces pressure on downstream infrastructure and makes better use of opportunities within buildings, plots, streets and open spaces.
The SuDS train
The Do’s and Dont’s of SuDS Design
Use these principles to integrate SuDS into the development design and avoid approaches that reduce their effectiveness or lead to avoidable redesign.
Do
Start with SuDS: Integrate SuDS from the earliest stages of masterplanning and consider surface-based measures before relying on conventional below-ground drainage.
Use the right team: Coordinate drainage, landscape, ecology, highways, buildings and utilities throughout the design process.
Create a connected SuDS train: Combine building, plot and street-scale measures so that rainfall is managed progressively across the development.
Choose the right feature for the right place: Select measures that suit the location, development type and their role within the wider system.
Coordinate above and below ground: Show relevant below-ground landscape elements, including soil cells for SuDS-enabled tree pits, on coordinated drawings.
Protect soil: Design and manage SuDS areas to avoid compaction and contamination.
Plan for maintenance: Consider access, planting establishment and long-term maintenance when selecting and locating SuDS features.
Don’t
Rely on a single end-of-pipe feature: Using a connected range of upstream measures can reduce reliance on large attenuation features at the end of the system.
Add SuDS after the layout is fixed: Late changes can limit opportunities, duplicate design effort and result in poorly integrated features.
Select features only to gain points: The assessment score should reflect measures that are suitable, deliverable and connected to the wider SuDS train.
Ignore soil and levels: Compacted soil, unsuitable falls or poorly coordinated connections can prevent features from working as intended.
Treat SuDS as isolated engineering features: SuDS should contribute to landscape, biodiversity, amenity and placemaking as well as surface-water management.
Soil and Ground Conditions
Healthy, uncompacted soil is essential to the long-term performance of many SuDS features. Compaction caused by construction activity reduces the soil’s ability to absorb, store and filter water and can also restrict healthy planting.
Soils should therefore be specified, protected and managed throughout design and construction. Where compaction cannot be avoided, suitable remediation may be needed so that SuDS can perform as intended.
Uncompacted and compacted soil
Why soil matters
Soil helps SuDS features to store and filter rainfall, support planting and slow the movement of surface water. When soil becomes compacted, pore spaces are reduced and water cannot move through the soil as intended. This can increase surface runoff, contribute to standing water and prevent planting from establishing successfully.
Protect soil from compaction
Applicants should identify areas intended for vegetated SuDS early and explain how these areas will be protected during construction. Good site practice includes:
keeping heavy machinery and repeated traffic away from future SuDS and planting areas
using designated access and haul routes where practicable
storing and handling soil appropriately to avoid compaction or contamination
protecting prepared soil profiles and installed SuDS layers
using an appropriate remediation method where compaction has occurred
SuDS soil
Rain gardens and SuDS-enabled tree pits rely on appropriately specified soil to support both drainage and healthy planting. The soil specification should be suitable for the intended feature and consistent with the approved landscape and drainage design.
Rain gardens
Rain gardens receive, temporarily store and filter runoff from roofs and paved areas. They can be incorporated within plots, streets and communal landscapes, providing drainage, biodiversity and placemaking benefits within the same space.
Rain gardens should have an uncompacted soil profile, suitable planting and a clear connection to the wider SuDS train. Their location and design should be coordinated with levels, utilities, landscape proposals and the source of incoming runoff.
SuDS-enabled tree pits
SuDS-enabled tree pits capture and manage surface water within the tree rooting area. They require sufficient uncompacted soil, an appropriate soil specification and careful coordination with utilities and other below-ground infrastructure.
Tree pits should be integrated into the street and landscape design rather than treated as isolated drainage components.
Key principle
Treat soil as part of the SuDS design. Protecting soil structure is essential to delivering the drainage, planting and placemaking benefits shown in the approved proposals.
Uncompacted soil contains pore spaces that allow water, air and roots to move through it; compaction restricts these pathways.
Protecting SuDS During Construction
Good design can be undermined if soil, planting, drainage layers or connections are damaged during construction. This page provides practical design guidance to help protect the SuDS features shown in the approved proposals. It does not replace approved construction details, planning conditions or evidence required by the Lead Local Flood Authority.
Protecting SuDS
During Construction
Before construction
Identify SuDS and planting areas that need protection on site plans and construction information.
Coordinate landscape, drainage, highways and utilities drawings, including below-ground elements.
Plan access, haul routes, phasing and material storage to reduce the risk of compaction and damage.
Confirm how soil and planted SuDS areas will be protected during the works.
During construction
Keep heavy machinery and repeated traffic away from protected SuDS areas where practicable.
Protect stored soil and prepared soil profiles from compaction and contamination.
Keep SuDS inlets and connections clear of construction materials.
Use the soil, planting and construction build-ups shown in the approved design.
Maintain planting, including irrigation where required, until handover or adoption.
Before handover
Remove construction materials and clear any blockages affecting SuDS features.
Check that planting is established and that the visible features accord with the approved design.
Confirm the arrangements for ongoing management and maintenance.
Technical requirements:
Applicants must also comply with relevant planning conditions and the Lead Local Flood Authority’s requirements for technical drainage design, construction evidence and verification.
How EDC will use this guidance
This guidance forms part of the wider Design for Ebbsfleet framework and supports the delivery of high-quality SuDS across Ebbsfleet Garden City.
The SuDS Selector supports EDC’s Sustainability Assessment System and provides a consistent methodology for applicants and planning officers when considering site-level SuDS provision. EDC will use it to inform pre-application discussions and assist with the assessment and scoring of SuDS within planning applications.
The SuDS Selector is non-statutory design guidance. It should be read alongside the Development Plan, relevant planning permissions and conditions, approved design codes and drainage strategies, and Lead Local Flood Authority requirements. It does not replace planning policy or statutory drainage requirements.
Applicants submitting Outline, Full or Reserved Matters applications should use this guidance to help identify appropriate SuDS features, develop a SuDS-first approach and demonstrate how surface water management has been integrated into the design of the development. Detailed specifications and technical information may be confirmed through planning conditions where appropriate.
Where proposals are brought forward under an existing outline permission, approved masterplan or design code, this guidance should be used as supporting guidance to help refine and enhance drainage proposals where appropriate. Existing approved principles will continue to apply unless superseded through a formal planning process.
Applicants are expected to comply with relevant planning policy and LLFA requirements and should engage with the LLFA at an early stage to agree the drainage approach, supporting information and verification requirements. This guidance complements those requirements and provides practical design advice on how SuDS can be successfully integrated at building, plot, street and neighbourhood scale.
A connected SuDS train manages rainfall in stages, from source control through conveyance and storage to controlled discharge.