8.5 Exceedance and flood risk

The layout should consider flood flow paths in the event of a failure of any part of the system.

While systems will be designed to a high level of performance, typically 1 in 100 years plus a climate change allowance, there is still a risk that capacity will be exceeded or that there will be a failure such as a blockage.

SuDS systems and site layouts should be designed to be resilient against flooding by ensuring that flood flow paths are directed away from buildings and vulnerable infrastructure.

Designers should refer to the Environment agency's risk of flooding from Surface Water mapping, and Surrey County Council flood maps, to establish the existing flood paths and areas of surface water flood risk (reference 32). The Environment Agency's Digital Terrain model (DTM), based on LiDAR surveys, is also a useful tool in establishing existing flow paths and minor watercourses. [Reference 33]

References

• Reference 33: https://data.gov.uk/dataset/f0db0249-f17b-4036-9e65-309148c97ce4/national-lidar-programm (Return to content for reference 33).