Policy information sourced from the Hertsmere Site Allocations and Development Management Policies Plan

SADM14 - Flood Risk

The risk of flooding will be avoided and reduced by:

  • locating development within areas of lower flood risk through the application of the sequential test and then applying an exception test in line with the National Planning Policy Framework (NPPF); and
  • ensuring that development proposals in flood risk areas actively manage and reduce flood risk by applying the sequential approach at site level.

Where new development is proposed in a flood risk area, a site specific Flood Risk Assessment will be required. This must take into account the risk associated with all types of flooding.

Development must satisfy the following principles:

  • It must not increase the risk of flooding elsewhere.
  • Within sites at risk of flooding, the most vulnerable parts of the proposed development should be located in areas of lowest flood risk, unless there are overriding reasons to prefer different locations.
  • Floor levels of development in Flood Zones 2 and 3 should be situated above the 1% (1 in 100 years) plus climate change predicted maximum water level, plus a minimum watertight depth of 300mm above the normal water level.
  • Development at risk from any form of flooding should be flood resilient and resistant, with safe access and escape routes: it should also be demonstrated that residual risks can be safely managed.
  • Development should incorporate appropriate flood resilient features and flood mitigation measures.
  • Where possible the footprint of existing buildings should be reduced.
  • Any necessary flood protection or mitigation measure should not have an undue impact on nature conservation, landscape character, recreation or other important matter.
  • There should be no net loss in flood storage on site.
  • Flood flow routes should be preserved.
  • Where possible, flood storage should be maximised through the use of green infrastructure and sustainable drainage systems.
  • The risk from all types of flooding should be reduced as a consequence of development, wherever possible.

Where necessary, planning permission will be conditional upon flood protection and/or runoff control measures being operative before other site works.

For more information please see the Hertsmere Policies Plan