SC080052 - Retrofitting Surface Water Management Measures

Theme:Sustainable Asset Management
Project status:Completed
Start date:16/01/2009
End date:30/07/2013


New guidance has been published by CIRIA on how to retrofit measures to manage surface water run-off in urban areas in as sustainable a manner as possible, maximising the benefits and helping tackle future challenges. The Environment Agency was one of the funders of this project and several Environment Agency experts served on the Project Steering Group.

The new guidance describes a way to manage surface water run-off. This approach involves integrating the principles of urban design with surface water management in a move away from the traditional approach of using a pipe-based below ground system to one that uses a wide range of above and below ground surface water management measures. It offers a host of benefits including improving amenity, increasing biodiversity and enhancing land value.

Under this new approach, no space is considered useless. There are many opportunities to retrofit measures if conventional thinking is challenged and an innovative approach is adopted in both public and private areas of towns and cities. For example, space can be maximised to have a dual function and measures that mimic natural drainage processes can be introduced. The new approach becomes easier if a range of professions work closely together to provide joint solutions and all interested parties are involved early on in the process.

Retrofitting surface water management measures will provide:
 - drainage systems that mimic natural drainage processes;
 - management of pollution alongside flood risk;
 - the ability to adapt to and manage extreme events;
 - extra benefits from better amenity, improved biodiversity and greater resilience to climate change;
 - integration with urban design to create better places to live.

A range of surface water management measures should be used to cope with both typical and extreme events. In addition, each community and setting is different. Example measures include:
 - fitting existing buildings with green roofs and rainwater harvesting systems;
 - planting rain gardens in road verges to collect and store run-off;
 - reshaping paths and spaces between buildings to carry surface water and, during extreme events, to act as ‘blue’ flood pathways when drainage capacity drainage is exceeded;
 - designing and designating open areas such as parkland and car parks to act as temporary flood storage while providing at the same time green infrastructure benefits such as places for recreation.

The guidance provides a framework to help more effective retrofitting of surface water management measures (SWMM). It focuses on how to retrofit SWMM into the urban environment either as part of a strategic programme of work to manage flood risk or control pollution, or by taking advantage of opportunities as they arise.

The guidance is intended primarily for use by those working with the existing urban environment and who wish to adopt sustainable drainage systems (SuDS). It is intended to complement other SuDS guidance, national legislation and local policies. It is relevant to a wide range of organisations and professionals including spatial planners, architects, urban designers, drainage engineers, highway engineers, land managers, landscape engineers, local authorities, sewerage undertakers, environmental regulators and developers across the UK.

Copies of the guidance are available from the CIRIA Bookshop ( either as a free PDF or a print version at a cost of £180.00.