Background

Need for a surface water FRA

There are two main flood risk considerations – the flood risk resulting from the change of use of greenfield land to developed land which will reduce the natural drainage permeability of that land leading to increased flood risk elsewhere.

The risk to occupiers and /or others of surface water flooding due to increased run-off. Even at outline stage the applicant needs to be able to demonstrate that surface water balancing can be achieved to a 1% (plus climate change) standard. All sites should aim to provide flood risk reduction/betterment.

The FRA should use available historic information, surveys and local knowledge to establish what the impact of flooding would have been based on previous events. This can then be used to establish any mitigation measures necessary to protect the development from future events.

Surface water may occur due to local sewer or other drainage constraints, groundwater and surface water run off problems in the area. These may be identified within the Strategic Flood Risk Assessment for the relevant local authority and from the updated flood map for surface water available on the Environment Agency website. The FRA will need to investigate the cause and effect of such local flooding as well as identifying appropriate mitigation / flood risk reduction.