According to the National Planning Policy Framework (NPPF) and Environment Agency (EA) guidance, if your development falls into one of the following categories a Flood Risk Assessment will be required to accompany your planning application:
located within Flood Zones 2 or 3 inclusive of minor development and change of use
more than 1 hectare (ha) in size and is located in flood zone 1
less than 1 ha in flood zone 1 and includes a change of use in development type to a more vulnerable class (for example from commercial to residential) where the development could be affected by sources of flooding other than rivers and the sea
Located within flood zone 1 however, has been identified to have critical drainage problems by the Environment Agency
A flood risk report will also generally be required if your development is proposed within 20 metres of an EA main river or EA flood defence.
How do I check to see if my development is located in a Flood Zone?
You can check to see if your development is located within a Flood Zone via the Environment Agency’s Flood Map for Planning service. To find out whether your development is located within a Flood Zone you just need to enter either the site's postcode, National Grid Reference or Easting and Northing.
When don’t I need a Flood Risk Assessment?
Leading on from when a Flood Risk Assessment is required it is also important to understand situations where developments do not require a FRA.
Under NPPF Guidance, a Flood Risk Assessment will not be required to accompany your planning application if the proposed development will occupy less than 1 hectare and the site is located entirely within Flood Zone 1 (check the EA's flood risk map to find out).
Why have I been asked for a Flood Risk Assessment when my development is in Flood Zone 1 and is less than 1 ha?
The only exception to the Flood Zone 1, less than 1 hectare rule is if your development site has been identified at risk of flooding from a source other than a river or the sea such as from surface water.
Sites at risk of only surface water flooding
can be found throughout the UK and are particularly common within built up, urbanised areas. Large parts of London for instance are at risk of surface water flooding including Harrow, Croydon and Brent which all have designated Critical Drainage Areas (CDAs), as notified to the Local Planning Authority by the Environment Agency. A Critical Drainage Area is an area where the drainage infrastructure has been identified to be at a critical risk of failure, which could give rise to surface water flooding within the catchment during a storm event.
In these locations your development may also require an accompanying Surface Water Drainage Strategy to detail how post development storm water runoff will be managed.
What do I do next?
GeoSon have extensive experience of undertaking Flood Risk Assessments throughout England compliant with both National and Local Policy requirements. Over the years our experienced consultants have helped hundreds of developments obtain planning permission ranging in size from residential extensions and change of use applications to large scale 100+ unit residential schemes and commercial/industrial parks.
For more information on how we can help with your development give us a call.