Design process

The South Gloucestershire local plan required the final phases of development to incorporate a SUDS. The council’s guide to SUDS for developers helped the designers understand the policy and the engineer met the local authority to ensure that their plans met the policy requirements.

Maximising development space while minimising run-off

The design for the final phases needed to minimise and manage water run-off and potential flooding, while accommodating the developer’s desire to maximise the developable land to ensure a good commercial return.

During the early design stages it looked as though these two factors were in conflict. The original proposal was to create a large wet detention pond with a controlled outlet to restrict run-off. However, this meant that significant areas of the site would be given over to drainage ponds, using up valuable development land.

Creative solutions

The engineer came up with the concept of using a permeable paving system and a small detention pond, which would maximise the amount of land that  could be developed. The developer was keen to include attractive landscaped ponds, but the topography of the site meant that the only suitable location for detention ponds was the south-east corner of the site. The solution was to create a small detention pond in this corner, along with an attractive but non-functional pond at the centre of the development.

The designer used hydraulic models to estimate the future rain and flow rate output for the scheme.