Cambridgeshire County Council
July 2010
- UK
- Built environment
- Flooding
A Cambridge Housing Society built a small scale affordable housing development in Cambourne which included sustainable urban drainage systems.
Main messages
Opportunities exist for the installation of SUDS measures even in small developments. Need specialist advice depending upon the scale of the development/installations.
In detail
Motivation
Growing pressure for new housing in the UK. Cambridgeshire a key growth area under the government’s housing strategy, with up to 50,000 new houses planned to be built by 2016.
It is also a relatively low-lying county where flooding in river valleys and urban watercourses is a major concern. The area is susceptible to combination events – where pluvial, fluvial and tidal flooding can occur together. There is also a high water table and a layer of impermeable clay, both of which contribute to the flooding risk.
The Water Framework Directive has a target of good quality ground and surface water by 2015.
Main players & partners
- Cambridge Housing Society
- Cambridgeshire County Council
- South Cambridgeshire District Council
- Flagship
- Cambridgeshire Wildlife Trust
- Royal Haskoning
- Defra
- EA
- Cambridgeshire Horizons
- RSHydro
- Robert Bray Associates
Process
Identification of flooding risk – sources and routes of flooding. Installation of a variety of measures to manage rainwater and attenuate extreme rainfall. Examples include permeable paving, detention basins, swales, a green roof, and water butts. Two year monitoring project set up to evaluate performance of individual features. Results to be compared with a control site with traditional drainage.
The site was identified in January 2004, with two years to design and install SUDS features. Residents moved in during spring/early summer 2006.
Outcomes
Generally, SUDS can bring reduced risk of flooding, groundwater levels replenished, new habitats for wildlife, cost savings, reduced water consumption, improved water quality returning to cycle.
Analysis
Strengths
Comprehensive SUDS system installed, approval of residents, enhanced opportunities for wildlife, improved water quality leaving the site than would be under traditional regime, cost savings – for development and for householders (no storm water drainage charges).
Constraints
The use of public open spaces, including adjacent, off-site open spaces, provides a viable solution to the problem of accommodating softer landscaped SUDS within housing developments. This will become more of an issue due to the Government’s policy within PPS3 of higher density developments (from Lamb Drove case study on Ciria website).