Flood Risk Assessment to Support your Planning Application

A Flood Risk Assessment is required by regulators to support a planning application or remove objections if a new development (including extensions) or change-of-use proposal (to a more vulnerable use) is in an area that is at risk of flooding by rivers, the sea, surface water or groundwater (or a combination).

The Environment Agency provides detailed guidance on what they would expect to see in a Flood Risk Assessment for different development scenarios, depending on the size of the development, which Flood Zone the development is located in and the vulnerability. To see if your proposed development or property is in a flood risk area, you can simply visit the ‘Flood map for planning’ website and put in your post code.

In addition, the Lead Local Flood Authority (LLFA) are statutory consultees for any new major development consisting of 10 dwellings or more. The LLFA, which are county councils and unitary authorities, mange local flood risks issues such as risks of flooding from surface water, ground water and ordinary watercourses. The LLFA have a responsibility to ensure that SuDS schemes conform with the requirements of the NPPF.

As a minimum, the National Planning Policy Framework (NPPF) states that a Flood Risk Assessment must be submitted:

• With all applications for development of sites in Flood Zones 2 (medium probability) and 3 (high probability) (i.e. such as areas having between a 1 in 100 and 1 in 1000 (1% – 0.1%) or greater annual probability of flooding from rivers or (0.5% – 0.1%) or greater from the sea).
• With applications for development of sites measuring 1 hectare or more in area in Flood Zone 1 (land assessed as having a less than 1 in 1000 (<0.1%) annual probability of river or sea flooding;
• With applications for development of sites measuring less than 1 hectare in Flood Zone 1 but where there is a known risk or history of flooding from other sources or is situated in a critical drainage area or within a local flood risk zone.
• For all major planning applications (10 dwellings or more).

Lustre Consulting can provide a full range of flood risk and Sustainable Drainage Systems (SuDS) design services from property level to catchment scale investigations. We specialise in undertaking Flood Risk Assessments supporting planning applications for residential and commercial schemes at any scale.

We take pride in our environmental multi-disciplinary team, which provides additional added value to our clients. Our Flood Risk services can be complemented with our in-house ability to undertake infiltration testing to BRE365, ground water monitoring, geotechnical investigations and Contaminated Land Assessment.

This allows us to provide the very best advice, design and deliver schemes in accordance with local and national policy requirements.

Using the latest methodologies, techniques, and software we use our skill and experience to achieve results that satisfy our clients’ interests, the requirements of regulators and the aspirations of our clients.

Our flood risk assessment services include:

• Review of flood risk in order to determine site constraints and development potential
• Flood Risk Assessments for planning applications
• Basement Impact Assessments
• SuDS proof of concept and opportunity assessment
• Drainage strategies for planning applications (surface water and foul water)
• Master-planning and site development support
• 1D and 2D hydraulic modelling and assessments
• Flood zone challenges
• Development of flood mitigation options and compensation schemes
• Catchment hydrology assessments
• Detailed drainage design
• Soakage and permeability testing
• Environment Statements (to accompany an Environmental Impact Assessment)

These are some frequently asked questions when commissioning a Flood Risk Assessment, you should also be asking yourself:

Do I need a Flood Risk Assessment?
It is recommended to firstly check the location of your proposed development or property on the ‘Flood map for planning‘ website to give an indication of the Flood Zone the site is located.

What if my site is in a Flood Zone 1?
Any development which is over 1ha in plan area, in a critical drainage area or with a proposal of 10 dwellings or more will need a flood risk assessment in order to undertake a review of the surface water flood risk pre and post development.

How long does a Flood Risk Assessment take?
As part of the assessment we usually have to contact the Environment Agency and LLFA to source any data or information. Whilst we always strive to meet your deadlines, the Environment Agency have a 21 day statutory response time. This should be considered when programming your assessment. However, we may be able to undertake a proportion of the work without the need for regulatory consultation.

How can I be sure I need a Flood Risk Assessment?
If you are unsure as to whether you require a flood risk assessment, please give us a call, so together we can discuss your requirements. Alternatively, please send an email to info@lustreconsulting.com and provide us with the site location and description of the proposed development.