Trafford Design Code


Boundaries and Edges

Protecting Existing Landscape

Drainage and SUDs


Gardens and Small Spaces

Management and Maintenance

Layout, parking and public realm

Landscape and Nature

Drainage and SUDs


A large proportion of Trafford Borough is within a nationally recognised Critical Drainage Area. This means that significant areas are at a direct risk of flooding, whilst other areas have a vital role to play in preventing excess water run-off impacting those more critical areas. Each and every site has its role to play in addressing flood risk.


In an increasingly unpredictable and changing climate, it is imperative that sustainable urban drainage solutions are achieved, wherever possible.


The ultimate positive solution is where the landscape and nature combine to deliver sustainable drainage.


Sustainable Urban Drainage systems (SUDS) have the ability to:

  • Hold back water run-off
  • Prevent flooding
  • Remove or reduce contaminants / pollutants from water on site
  • Form an inherent part of an inspiring landscape or urban setting
  • Provide habitat as part of the system


Drainage and SUDs

It is no longer acceptable to simply “get water off site” in the most efficient engineered manner (pipe).


SUDS components work in a number of ways. They:

  • Infiltrate (soak) into the ground
  • Convey (flow) into a watercourse
  • Provide Storage on site and Attenuate (slow down) the flows of water.

SUDS schemes can use a combination of these processes. Every site has its part to play in mitigating flood risk. The landscape and nature elements of a site should contribute as positively as is possible to achieving this.


Larger sites with greater areas of open space have a significant role to play. For example, the open space system can successfully combine with a SUDs scheme.

The Airfields, Deeside


Sitting at a low level, with marginal falls, and alongside the river Dee, this former Airfield site was developed through a landscape-led approach that placed the landscape infrastructure, and drainage strategy at the heart of the development, with large swales running through the open space elements of the scheme and defining the layout of the subsequent commercial, residential and industrial land parcels. The swales and system of connected ditches slowed and effectively stored water run-off from the new development.

Combining planting with 'natural' drainage solutions

There can be an incredibly successful symbiosis between landscape, nature and sustainable drainage systems. Hence, it will be expected that landscape, nature and SUDs are the first design tools in achieving a successful drainage scheme.


These ‘natural’ drainage solutions can provide all of the identified SUDs benefits. Additional benefits that these can bring to wildlife as well as human-related benefits are also well documented. ‘Natural’ drainage solutions must be considered and incorporated wherever possible within sites. These may include:


  • Wetlands
  • Planted attenuation basins and ponds
  • Planted infiltration ponds
  • Planted strips, trenches and swales
  • Bioretention areas
  • Rain gardens

Examples of SUDs on streets

Other Sustainable Drainage Systems

There is a well-documented hierarchy of sustainable drainage solutions.


Wherever possible, ‘natural’ drainage solutions should be introduced into a site’s landscape design and network of connected spaces. Where this is not possible, justification is required and other sustainable drainage solutions can be utilised. These can include:


  • Rainwater harvesting
  • Green roofs (on buildings or structures)
  • Permeable surfaces
  • Channels or rills
  • Engineered soakaways, trenches or basins
  • Geo-cellular storage systems
  • Inlet, outlet and control systems

Supporting background information

At the outset of the design process, the ground condition, water table and capacity for the entire site to drain in a sustainable manner should be confirmed through an appropriate technical assessment and report.

This preliminary baseline assessment and report must identify:


  • How the existing site is drained
  • The existing soil type and water infiltration opportunity across the site
  • How sustainable drainage solutions can be incorporated within the site
  • What sustainable opportunities exist on site to deal with water run-off in a sustainable manner (the “How” and the “Where”).

This baseline report must be submitted with the application and evidence should be presented at the submission stage to demonstrate how this information has fed in to the design.

Examples of SUDs on residential sites

SUDs layout plan

A proposed SuDs layout plan and accompanying statement must be prepared with any planning application submitted. Applications must also be accompanied by a North West SuDS pro-forma, Flood Risk Assessment and Drainage Strategy / Statement as appropriate.


This information will include details of:

How a sequential approach to sustainable drainage on site will be implemented, as follows:

    1. ‘Natural’ drainage solutions (most preferred)
    2. Other sustainable drainage solutions (good)
    3. All other drainage solutions (last resort)

This information should be proportionate to the nature, scale and type of application. It must demonstrate that the proposed SUDs scheme can be achieved, including:


  • Indicative levels information
  • Requisite drainage capacity
  • Storage capacity of SuDs
  • Outfall capacity

Drainage and SUDs case studies


Derwenthorpe by Studio Partington for Joseph Rowntree Foundation Derwenthorpe was one of the first large-scale low carbon communities in northern England. Its ‘green’ heating and

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Airfields, Deeside

The Airfields, Deeside Sitting at a low level, with marginal falls, and alongside the river Dee, this former Airfield site was developed through a landscape-led

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Mayfield Park

Mayfield Park by Gillespies and Studio Egret West for Mayfield Partnership Mayfield Park brings nature and green open spaces right into the heart of the

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Permeable paving options