What are the Sequential and Exception Tests?

Sequential Test

The Sequential Test and Exception Test are commonly referred to during the planning process, but what are they and what is involved?

What is a Sequential Test?

A sequential, risk-based approach should be followed to steer new development into areas with the lowest risk of flooding. This is achieved by reviewing reasonably available sites, to confirm there are no other potential locations for the proposed development which are at a lower risk of flooding. Development should not be allocated or permitted if there are reasonably available sites appropriate for the proposed development in areas with a lower risk of flooding. The strategic flood risk assessment will provide the basis for applying this test. The sequential approach should be used in areas known to be at risk now or in the future from any form of flooding.

When do you need a Sequential Test?

In England, flood risk is broadly classified into three Flood Zones. Flood Zone 1 (lowest risk), Flood Zone 2 (medium risk) and Flood Zone 3 (highest risk). If a proposed development is located within Flood Zone 2 or Flood Zone 3 and at risk to flooding, then as part of the planning application the applicant is required to apply the ‘Sequential Test’.

A Sequential Test is not needed where:
• The site has prior allocation for development and was subjected to the test at the plan making stage (provided that there is no change to the proposed use and no significant changes to known flood risk at the site, now or in the future which would have affect the outcome of the test).

• The proposed development is located within Flood Zone 1 (Unless there are flooding issues within the area of the proposed development. This can be identified contacting the Local Planning Authority or checking their Strategic Flood Risk Assessment).

• The application is for a development type that is exempt from the test, as specified in footnote 56 of the NPPF i.e. householder development, small non-residential extensions (with a footprint of less than 250m2) and changes of use; except for changes of use to a caravan, camping or chalet site, or to a mobile home or park home site.

How do you Conduct a Sequential Test?

There are 3 steps in the process which should be followed.

Step 1: Identify the Area.

Firstly, the scale of the area to search for land needs to be determined and agreed with the LPA. This needs to be proportionate to the scale of the proposed development.

Step 2: Identify Potential Site Locations.

Compile a list of all suitable and available site locations within the study area. The list should include sites with planning permission in place for similar developments, allocations in the Local Plan as well as any ‘windfall’ sites, such as sites on the brownfield land register.

Step 3. Suitability of Identified Sites.

Thirdly, once the potential site locations have been identified, each site will need to be assessed for:
• Any potential constraints (e.g., heritage or ecology)
• Capacity, estimated using local density policies; and
• The flood risk of the site.
The risk of flooding to the site will need to be compared against the other alternative site options identified using the above steps. Online resources to compare flood risk include:
• The EA Flood Map for Planning
• The Environment Agency’s Long Term Flood Risk Information. https://flood-warning-information.service.gov.uk/long-term-flood-risk/map
• Any Strategic Flood Risk Assessment reports developed by the lead Local Flood Authority.
Following the review, if no other suitable alternative sites are identified, then the Sequential Test is considered to be passed. All the information findings should then be submitted to the Local Planning Authority (LPA) with the planning application.

What if the Sequential Test Fails?

If it is not possible for the proposed development to be located in areas with a lower risk of flooding (taking into account wider sustainable development objectives), an Exception Test may have to be applied. The need for the Exception Test will depend on the potential vulnerability of the site and the nature of the proposed development.
The National Planning Policy Framework (NPPF) requires that, if following the application of the Sequential Test, if it is not possible for development to be located in lower risk zones, the Exception Test must be applied where the proposed development is more vulnerable to flooding.
The National Planning Policy Framework states ‘the application of the exception test should be informed by a strategic or site-specific flood risk assessment, depending on whether it is being applied during plan production or at the application stage.’

What is an Exception Test?

The Exception Test provides a method of how the planning applicant will manage the flood risk at the proposed development. The Exception Test is required when vulnerable development or infrastructure is proposed in areas of medium and high flood risk (Flood Zones 2 and 3), and where the Sequential Test alone is not sufficient.
However, before an Exception Test is required, a Sequential Test must initially be conducted.
A successful Exception Test must demonstrate the sustainability benefits of the development to the community outweigh the flood risk.
It must also be demonstrated that the development will be safe for its lifetime in the context of flood risk, taking into account the vulnerability of its users and that the development won’t increase flood risk elsewhere.
How to demonstrate the development will be safe for its lifetime?
As part of the exception test, it must be demonstrated how the proposals will ensure the development itself can safely mitigate against flooding and ensure it won’t increase the flood risk of others offsite. This can be done by the following:
• Assess and identify the characteristics of a possible flood event scenarios e.g., the source of flooding, potential depths, velocity of flowing water. (To assess these characteristics, a Flood Risk Assessment is usually required).

• Review the structural stability/safety of the proposed development. (This is usually confirmed with an Architect with additional PFR measures installed/suggested around the development).

• Evaluate the safety of people within and adjacent to the building. (Are residents capable of deploying PFR measures such as flood barriers? Are they able to Evacuate? Are sleeping areas raised or located on ground level?) These are all considerations which can affect the design proposals.

• Measure the impact of the development on neighbouring properties. If there is a chance that the flood risk may be increased elsewhere due to a development, mitigation measures will need to be implemented to reduce this risk, such as Compensatory storage, Permeable Paving or a surface water management strategy.

How can FPS Environmental help?

At FPS Environmental we have considerable experience in supporting clients through all stages of the planning process. Our services range from site walkovers to initially assess site settings, advising on sustainable drainage options (strategy and design), and undertaking complex Flood Risk Assessments across a diverse range of commercial and residential developments.
We offer a very friendly and professional service and are happy to advise and assist with any queries regarding planned development.
If you’re unsure and need advice about a proposed development, please contact our team of specialists who can advise at enquiries@fpsenvironmental.co.uk or call 020 8050 3194.

Get In Touch

If you’d like to raise an initial enquiry or ask us a question, please feel free to drop us an email via the form below.