Policy information sourced from the Westminster City Plan

35. Flood risk

A: All developments should be safe for their lifetime from the risk of flooding, complying with the council’s Strategic Flood Risk Assessment (SFRA), Surface Water Management Plan (SWMP), Local Flood Risk Management Strategy (LFRMS) and the Mayor of London’s Regional Flood Risk Appraisal (RFRA).

B: A site-specific Flood Risk Assessment (FRA) must be submitted for:

  • developments of 1 hectare or greater;
  • all developments in Flood Zones 2 and 3; and
  • all developments within a Surface Water Flood Risk Hotspot.

VULNERABLE USES

C: Highly Vulnerable Uses will not be allowed within Flood Zone 3; in Flood Zone 2 they will be required to pass the Exception Test and should as far as possible be located outside of the Surface Water Flood Risk Hotspots.

D: Proposals for Essential Infrastructure and More Vulnerable Uses within Flood Zone 3 will be required to pass the Exception Test. Within the Rapid Inundation Zone, basement dwellings and basement extensions to existing dwellings will not be acceptable.

E: More Vulnerable Uses should, as far as possible, be directed away from Surface Water Flood Risk Hotspots.

F: A Flood Warning and Evacuation Plan will generally be required for More Vulnerable Uses within the areas at risk of tidal breach flooding, especially if the land use is within the Rapid Inundation Zone.

FLOOD MANAGEMENT INFRASTRUCTURE

G: All existing flood management infrastructure will be protected, including access for maintenance. Wherever possible, an undeveloped buffer zone of 16m should be maintained around flood defence structures, including buried elements of the flood defence.

H: Improvements to flood defences will be secured through planning conditions and / or legal agreements where the size, type and / or location of development impacts on flood risk. Development should not limit future raising of flood defences outlined in the Thames Estuary 2100 Plan.

I: Where appropriate, planning permission for developments which result in the need for off-site upgrades to the water or sewerage network, will be subject to conditions to ensure the occupation is aligned with the delivery of necessary infrastructure upgrades.

SUSTAINABLE DRAINAGE

J: New development must incorporate Sustainable Drainage Systems (SuDS) to alleviate and manage surface water flood risk. Development should aim to achieve greenfield run-off rates and demonstrate how all opportunities to minimise site run-off have been taken.

For more information please see the City Plan