Flood Risk Assessment for Major Development

In England, a FRA is required when the development or site is located in Flood Zone 2 and 3 according to the Environment Agency flood map for planning. An FRA is also required if the Site is in Flood Zone 1 when it is equal to or greater than 1 hectare in size or if it’s located within a Critical Drainage Area, regardless of its size.

Even with this in mind, the National Planning Policy Framework requires an FRA to be used to assess all sources of flooding. Therefore, an FRA could be requested even if your site doesn’t fit these requirements. Especially if there is a history of flooding, such as from a sewer or reservoir.

If your site is within 20 meters of an Environment Agency (EA) Main River, it’s also highly likely you’ll be required to provide an FRA with a particular focus on the EA Guidance.

The aim of the sequential test is to steer new development to areas with the lowest 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.

The National Planning Policy Framework (NPPF) states that all plans and strategic policies informed by a Strategic Flood Risk Assessment should adopt a sequential, risk-based approach to the location of development. Inappropriate development in areas at risk of flooding should be avoided by directing development away from high-risk areas. This isn’t always possible, and when it isn’t, the development should be made safe for its lifetime, tailored to its specific use, and without increasing flood risk elsewhere.

The sequential risk-based approach to the location of development should also consider the current and future impacts of climate change. In circumstances where it is demonstrated that the site could be at risk of flooding or is currently in a flood zone, then it is necessary to apply the Exception Test, which is discussed below in greater detail.

In summary, the sequential test is required to be applied for strategic planning purposes, reviewing site allocations and the flood zones they are located within to support the Local Plan. The Sequential Test can also be applied for single planning applications. In both instances, it is encouraged that new development should be located in areas of lowest flood risk – Flood Zone 1.

If your site is located in Flood Zone 2 or 3 then it could be requested by the Local Planning Authority and Lead Local Flood Authority to produce a Sequential Test, which justifies why development of your site in a flood zone over another which is not, is preferred and should be considered.

It should be further noted that where planning applications come forward on sites allocated in the development plan through the sequential test, applicants need not apply the sequential test. This is because it has already been conducted by the Lead Local Flood Authority / Local Planning Authority.

To determine whether your development may require a sequential test, as well as a Flood Risk Assessment, please contact us. We can work with you to discuss your site, development aspirations, and how best to mitigate flood risk.

The Exception Test is necessary when a development is located in a flood zone.

The need for the exception test will depend on the potential vulnerability of the site and of the development proposed.This is in line with the Flood Risk Vulnerability Classification set out in National Planning Policy Guidance.

The Exception Test consists of two parts. Both elements should be satisfied for the development to be allocated (Development Plan) or permitted (planning application).

For the exception test to be passed, it should be demonstrated that:

The development would provide wider sustainability benefits to the community that outweigh the flood risk.

The development will be safe for its lifetime, taking account of the vulnerability of its users, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall.

A professionally written, researched and thought-out Flood Risk Assessment can add real value to your planning application. It can reduce the costs of the application process through redesign, time, and water management.

Our highly experienced team can review developments against the policy requirements and flood zones. We then utilise our industry experience and local region knowledge to ensure that we provide you with the correct answer. We do this all for a highly competitive price, with no “one size fits all” quotes.

There are a lot of different parameters that can influence the time it takes to complete an FRA. Each project is unique and has different flood risks, designs, environmental conditions, topography, historic uses, and are subject to different planning policies. All of these can affect the time it takes for a flood risk assessment to be completed. The industry standard for an FRA is around 4 to 6 weeks.

Our team, however, have experience in supporting over 4,100 projects and have developed methods and techniques to analyse data efficiently and effectively review every aspect in a timely manner. On average, our FRA reports take 5 to 10 working days once we have received the necessary data.

At the very least, a Flood Risk Assessment must contain:

• Clearly georeferenced plan at an appropriate scale, including geographical features and all watercourses/other water bodies
• Site specific photographs showing areas of interest and potential hydraulic constraints
• Topographical information showing (as a minimum) the existing site levels on site
• Other topographical data including site cross sections in relation to the watercourse
• Key structural information which may include conveyance capacity calculations
• Other site-specific information including a historical flood study, and details of any flood alleviation measures in the vicinity
• A clear assessment of flood risk from all sources including fluvial, pluvial, coastal, groundwater, sewer and artificial features.

If a more detailed FRA is required, this may include hydraulic modelling to determine the potential flood levels on site and if any further mitigation measures are required.