The Lamb Drove housing project at Cambourne in Cambridgeshire is one of the most important SuDS schemes in the UK as it demonstrates integrated SuDS design in housing together with detailed monitoring of the functionality, performance and amenity value of the system. Robert Bray Associates were appointed by Royal Haskoning to provide SuDS detail design expertise on the project.
The Flows Project was an EU initiative to demonstrate flood resilience in housing together with showing how housing can be protected from floods. The project sought to illustrate SuDS ‘best practice’ in housing.
The Lamb Drove site was selected for the project as it had planning permission and could be built within the project timeframe. In this sense it was a retrofit scheme although the site needed little modification for a SuDS design.
Our SuDS design integrates the flow, storage and treatment of surface water into landscape and amenity areas in a clearly legible way. Day-to-day flows are managed within discreet features running through the development, whilst the volumes of water generated by larger rainfall events are accommodated in wider greenspace areas. Many features are designed and managed to promote biodiversity with the system now providing a network of wildlife corridors into the heart of the development. The SuDS features have also become recreational play space.
The design identified two main flow routes and also two sub-catchments with the second flow route travelling outside the original site boundary in public open space. The use of this public resource delivered biodiversity and amenity interest at no added cost to the wider community.
The scheme was deigned to demonstrate a comprehensive suite of SuDS components: beginning with ‘source controls’ within a permeable paved road area and under-drained swales within the development; continuing the Management Train in normal swales, basins and wetlands; and a final pond as the site control.
There are a number of important elements to the Lamb Drove design. The low discharge rate increased storage volumes. The opportunity to use public open space ensured that expensive and unsustainable underground storage was unnecessary. The SuDS landscape created was more interesting than before, meeting social and biodiversity aspirations, and was paid for by the developer.
Despite reluctance to use permeable pavement by the County Council Highways Dept., this SuDS technique has continued to function as designed for over 10 years with no dedicated maintenance. It has eliminated the need for gully pots which are a hazard to wildlife and costly to maintain. Despite the lack of formal maintenance the pavement has continued to work well without loss of performance.
Location : Cambourne, Cambridgeshire
Return period: 1 in 100 year return period with a 30% allowance for climate change.
Techniques : Swales, basins, wetlands, ponds, permeable paving, under-drained swales.
Discharge destination: existing ditch and Cambourne ‘blue infrastructure’
Discharge flow rate: 3L/sec/hectare
Client : Royal Haskoning