In addition to any requirement for a Flood Risk Assessment (FRA), the following information with regard to surface water drainage must be submitted:
Outline Planning Application
Any outline application for a development falling within the definition of ‘major’ shall be accompanied by a drainage strategy. Information to include:
- indicative sustainable drainage principles for the development
- topographical survey showing how water naturally flows on the site together with
- groundwater and land drainage flows
- proposed destination for surface water post-development
- ground investigation results for infiltration (if appropriate)
- existing and/or proposed watercourses
- existing and/or proposed surface water sewers and/or pumping stations
- surface water flows onto the site, flows from the site and flood risk to and from the site
- offsite works which may be required to provide surface water drainage or mitigate
- against flood risk
- sensitive receptors
- general maintenance principles
Full Planning Applications
In addition to details required for an Outline application (listed above) the following shall be provided:
- details of compliance with Defra non-statutory technical standards
- off-site works
- consents required
- flow paths through the development
- surface water storage volumes and locations
- sub-catchment areas
- treatment train components
- proposed landscaping and/or vegetative systems
- design calculations for:
-greenfield run-off
-brownfield run-off if appropriate (including reductions)
-peak flow rates
-surface water volumes
-storage requirements
-drain down times
-multi-use areas
-exceedance routes
-temporary drainage during construction
-climate change allowances
-future development allowances
-details of how the sustainable drainage system is to be maintained, and by whom, for the lifetime of the development