RammSanderson is experienced in undertaking site-specific Flood Risk Assessments (FRA) and Water Framework Directive Assessments to the National Planning Policy Framework (NPPF) and TAN15 standards suitable for planning.

Why Flood Risk Assessments?

According to the Environment Agency National Assessment of Flood Risk (2009), 2.4 million properties are at risk of flooding from rivers and the sea in England, while 3.8 million properties are susceptible to surface water flooding. Approximately 55% of these residents know they are at risk.

It is usual for the Environment Agency (EA) to object to a planning application for sites above one hectare in Flood Zone 1 or those located within Flood Zones 2 or 3 of the EA flood maps until the question of flood risk has been appropriately addressed.

Flood Risk Assessments

Flood Risk Assessments (FRA)

Flood Risk Assessments are individually prepared depending on the site’s proximity to watercourses, size, topography, and pre-/post-development land use. Per EA guidance, a thorough walkover of each site is conducted to assess any structure or watercourse likely to affect local hydraulics.

Through consultation with the Environment Agency, Internal Drainage Boards (IDB), local authorities, and utility companies, our detailed FRA reports offer recommendations to mitigate the effect of fluvial flooding.

They also include site-specific guidance for access and egress (which must be provided for flood frequencies over 1 in 100 years), flood warning and evacuation procedures, and sustainable drainage strategies.

Strategic Flood Risk Assessments

Surface Water Runoff Assessments

Surface Water Runoff Assessments for both Greenfield and Brownfield sites are carried out to identify the risk of flooding associated with nearby surface water runoff conditions and to consider the effects that a change of permeability might have on the site and local hydraulics.

The report provides relevant calculations with an allowance for climate change and advises how to improve the existing runoff conditions in line with best practice guidelines. This includes a detailed review of pre-/post-development surface water runoff conditions using the Wallingford Procedure (modified rationale method) and the Institute of Hydrology Report 124 Method.

Strategic Flood Risk Assessments (SFRA)

Strategic Flood Risk Assessments (SFRA) highlight the areas of the site most susceptible to flooding in relation to areas allocated for future development. A comparative assessment of preferable sites is conducted to consider whether the proposed development location is appropriate for its intended use.

Drainage Strategies

All our Flood Risk Assessments include an indicative drainage proposal tailored to the site to incorporate Sustainable Drainage Systems (SuDS) in compliance with document H3 of the Building Regulation 2000 (as amended), which details a hierarchy for surface water disposal.

Through natural processes such as permeable paving, SuDS aim to restore or reproduce the normal drainage conditions of a site. In cases where this is not possible, gullies and drains are recommended to direct runoff to watercourses or permeable land within the site. The discharge of surface water to a sewer network is only proposed as a last resort to prevent deterioration in performance.

Water Framework Directive Assessments

The Water Framework Directive (WFD) is an EU legislation created to improve the ecological and chemical status of all types of water bodies in Europe. The directive was transposed into UK law after withdrawal from the European Union. WFD compliance assessments are required for housing and land developments as part of the planning and statutory consenting process.

A WFD compliance assessment evaluates the physico-chemical, biological, and hydro-morphological quality of all ground and surface water bodies. The primary objective of WFD assessments is to ensure development schemes do not threaten the qualitative and quantitative health of the water body.

River Habitat Survey

River Habitat Surveys

A WFD River Habitat Survey is a standard methodology for assessing hydro-morphology in bodies of water across the UK, as well as the monitoring of river habitats and assessing the potential impacts of proposed developments on the body of water and wildlife.

Electrofishing Surveys

A WFD Electrofishing Survey is conducted to obtain population, species, and behaviour data of any fish inhabiting a body of water near a prospective development site. This allows important decisions to be made about preservation, relocation, and channel realignments to ensure the protection of the fish.

RammSanderson has a team of experienced consultants ready to carry out Flood Risk & Drainage Surveys. Get in touch today!