Flood Risk Assessments

Flood Risk Assessments (FRA) and/or Sustainable Drainage designs (SuDs) are now required for all sites of greater than 1ha, or in other sensitive locations such as Critical Drainage Areas.

You might need an FRA when your development:

  • Sits in Flood Zone 2 or 3, this includes minor developments and changes of use
  • Is more than 1 ha in Flood Zone 1
  • Is 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 use) where they could be affected by sources of flooding other than rivers and the sea (for example surface water, drains or reservoirs)
  • Is in an area within Flood Zone 1, which has a critical drainage problem as notified by the Environment Agency 

At Peak Associates, we’ll tailor a design to your sites’ individual needs. An FRA reviews the risk of flooding posed to the site from a specified list of flood risks such as flooding from the sea, rivers and streams, canals, reservoirs (if a dam gives way), surface water flooding and groundwater. Although a fairly comprehensive list, the guidance requires everything to be considered at least in passing, before moving to look at those sources most likely to impact the site.

The report then looks at whther the land, given its location, is suitable for the development proposed. This is called the ‘sequential test’ and again all FRA’s for planning have to include this test. If the nature of the flooding is marginal a case for making an exception (test) is then required.

An FRA also needs to cover how this risk will affect the proposed design levels and layout of the development and make recommendations as to how these risks can be mitigated within the proposed design. This is often the critical part of the assessment. The report assesses the risk based on data provided by the Environment Agency, which categorises flood risk into three separate zones (Flood Zones 1, 2 and 3) depending on the level of perceived risk.

An FRA is required for all planning applications for the following developments:

  • In Flood Zones 2 or 3 (areas at a 1:1,000 and 1:100 year risk of flooding)
  • In Flood Zone 1 if the site area is greater than 10,000 square metres (1ha)
  • You may also be required to submit an assessment if the site is located next to a local non-mains river watercourse or a Critical Drainage Area (CDA)
  • Or if the site is known to be at risk of foul sewer flooding

Peak Associates’ staff have a wide range of experience in the production of detailed, site-specific flood risk assessments for all types of developments in accordance with the requirements of the ‘Sustainable Development’ requirement of the ‘National Planning Policy Framework’.

All flood risk assessments completed by Peak Associates are fully tailored to the unique requirements of each site and can be completed for all sizes of developments from small-scale residential developments to commercial expansions or new large commercial properties. Peak Associates have completed these types of assessments for sites across the country, including Cheshire, Greater Manchester, Lancashire, and Cumbria.

Related services to Flood Risk Assessments

Related projects to Flood Risk Assessments

During Storm Christoph in January 2021, heavy rainfall caused significant flooding across various parts of the United Kingdom.

A client of ours acquired land adjacent to a river with the intention of building a warehouse. However, the company proceeded with the construction without obtaining the necessary planning permission from the local council.

In many ways this work was initially a simple Flood Risk Assessment with the rather unusual twist that the flood had already happened.

With only 21 days until the existing planning consent expired we had to design a conceptual scheme, consult with local landowners and the LPA and then submit a RIBA 3 developed design for approval. 

Related sectors to Flood Risk Assessments


Heritage and Leisure

Construction site

Development & Construction

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