FLOOD RISK ASSESSMENT

Government data shows that more than 5 million UK properties are at significant risk of flooding. With the changing climate, flooding is an increasing threat. It’s not just about a development’s proximity to rivers and coasts. Flood risks also arise from surface water sewers and blocked drains or culverts, for example.
However, informed and strategic development planning – in which flood risk assessments are often a vital element – can minimise the impact on homes and on the continuity of businesses, services and infrastructure.

When is a Flood Risk Assessment necessary?

A flood risk assessment (FRA) is now a standard requirement for any planning application over one hectare and for any development near a main river. FRAs alert developers to potential flood issues and the relevant government recommendations. Furthermore, they offer recommendations for reducing risks and impacts, ensuring the best long-term outcomes for commercial, industrial and residential projects alike.

Different types of FRAs are needed depending on the size and stage of the development and the level of risk. Operating throughout England, Scotland and Wales, we carry out the right type of FRA for your build and deliver the report and paperwork you need to support your planning application.

Flood risk assessment level 1 – Screening Study

  • The Level 1 Study will indicate whether there is potential for flooding, and identify any surface water issues.

The study typically includes:

  • Assessment of readily available existing flood risk information
  • Comment upon the feasibility of developing the site and appropriateness of the development with respect to PPS25

This may include:

  • Review of existing drainage information
  • Recommendations for further work/investigations such as Exception / Sequential Tests

Flood Risk assessment level 2 – Scoping Study

The Level 2 study will further investigate the risk of flooding to the site and the impacts and constraints upon site development that would then arise. The study will consist of:

  • Liaison with the Environment Agency, Local Planning Authority and Sewerage Regulator to obtain advice on flood risk and drainage issues / constraints at the site
  • Utilise provided topographical surveys to compare predicted flood levels and existing ground levels
  • Assessment of climate change on the development and flood levels
  • Recommend finished floor levels
  • Emergency egress routes in times of flood
  • Give preliminary advice on flood warning and evacuation procedures
  • Mitigation measures e.g. flood resilient construction techniques
  • Assessment of the existing and Outline design for proposed surface water drainage arrangements and the use of SUDS / attenuation systems
  • Make further recommendation for a Level 3 Detailed report if required

FLOOD Risk assessment level 3 – Detailed Study

The Level 3 study is required when detailed flood level information is not available and the Environment Agency require further quantitative analysis such as Flood Modelling to be undertaken. In addition to the Level 1 and 2 study components, the Level 3 study will consist of:

  • Hydraulic calculations and modelling to quantify the flood risk on and off site
  • Undertaking full drainage strategy using infiltration testing etc. to prepare detailed designs for approval by regulators.

Typically, for most projects AVIE would produce a Level 2 study due to time constraints. Our early involvement in development will save time and money by identifying constraints and engineering solutions for achievable and affordable results. As part of a coherent and concise approach, Phase 1 Desk Top Studies and Viability Appraisals are also available and could be necessary indicators of potential development constraints.