Flood Risk Assessment, Doncaster, South Yorkshire
Nov 28, 2014

RAB has completed a Sequential Test and a Flood Risk Assessment in accordance with National Planning Policy Framework in support of a residential development in a rural village near Doncaster.

The sequential test for the site involved:

  • liaison with Doncaster Metropolitan Borough Council (MBC);

  • assessment of the Doncaster MBC unitary development plan;

  • and market research;

with the purpose of determining whether any other sites are available within the same residential policy area that are at lower risk of flooding than the proposed site. RAB Consultants report concluded that there are no other suitable sites available and the planning authority stated “the applicant has clearly demonstrated that the sequential test has been passed and this has been carried out in accordance with the requirements of the Development & Flood Risk SPD”.

Following this, RAB Consultants carried out both a site visit to assess the flood risk within the local area and a topographic survey to establish ground levels across the proposed site and along potential evacuation routes. Our assessment to meet the requirements of the National Planning Policy Framework also involved:

  • Data collection, including the Environment Agency’s most recently modelled flood data for the lower stretches of the river Don;

  • Liaison with the Environment Agency, Doncaster MBC and Yorkshire Water;

  • An assessment of the risk of flooding from all sources including fluvial, surface water, groundwater and drainage related; and

  • Analysis of the risk of flooding to the site in the event of a flood defence breach or overtopping event.

The Environment Agency’s Flood Map for Planning (Rivers and Sea) indicates that the site is located within Flood Zone 2 and analysis of modelled flood levels confirmed that the site is expected to experience inundation during the 1 in 100 year (plus climate change) return period event.

The flood risk from the complex network of drains and ditches in the area was considered; however, as these are maintained and monitored by the IDB to ensure effective flow and reduce localised flooding, the site was considered to be at a low flood risk from this source.

Two evacuation routes are proposed within the report to ensure that occupants can leave the site and access higher land in Flood Zone 1. Furthermore, a flood warning and evacuation plan is included in the assessment ensuring that the site occupants are aware of the flood risk and what to do in the event of a flood.

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