If you are applying for planning permission for a new work site, you might need to undertake a flood assessment as part of this.

This depends on your local planning authority and their guidance. Large-scale developments will require a professional flood risk specialist to carry out the assessment.

Speedy has all you need to know below.


Flood Risk Assessments

A Flood Risk Assessment (FRA) is a report which details the main flood risks to a development site. Your local planning authority can refuse planning permission if an FRA isn't completed, or isn't correct.

Therefore, it is essential to work out if you need an FRA early on in your preparation for planning permission.

An FRA will point out the flood risk from all water sources, such as rainwater and drainage or rivers and sea levels. Areas will naturally already be in a flood zone level. 

Sites in Flood Zone 1 are at a low risk of flooding, with less than 1 in 1,000 annual probability. Sites in Flood Zone 3 have more than a 1 in 100 chance of flooding each year.


When Do You Need a Flood Risk Assessment?

The government's national policies on the requirements for a Flood Risk Assessment are detailed in Planning Policy Statement 25: Development and Flood Risk (PPS25). It explains that the Environment Agency and a Local Planning Authority (LPA) must consult on planning applications for any sites located in Flood Zones 2 and 3 if they are more than one hectare in size.

If any proposals are put forward for development in the flood plain, the Environment Agency has the power to challenge the LPA, as it is its responsibility to enforce the regulations included in PPS25.

In this document, it states that LPAs have to prepare Local Development Documents (LDDs) that establish how sites are allocated and discuss their development so that the risk of floods to both people and property can be avoided where possible.

The report notes that the risk of flooding should be considered along with other issues such as economic growth, housing, transport and natural resources, among others. Climate change and the potential threat it could have on flooding should also be considered by LPAs. When they are preparing LDDs, they must ensure the potential relocation of construction developments - including housing projects - to locations that are less risky is considered.

When applications are being drawn up, PPS25 states that any construction projects must be supported by flood risk assessments for the specific site. This includes a consideration of whether any developments in flood risk areas are resilient to threats and whether they need to include access and escapes routes if necessary.

The sequential approach refers to the process of determining the suitability of land at potential risk of flooding for development, with the more vulnerable aspects located in less at-threat sites.

When drawing up plans for their project, the report explains developers have a responsibility to incorporate the flood risk into their designs and consider suitable drainage systems and resilience measures wherever possible.

Full guidance on when assessments are needed can be found on the gov.uk website.


Can You Get Planning Permission for New Homes on Flood Plains?

There is a possibility permission for new homes can be granted on flood plains, but under certain circumstances.

Development should be designed so homes are away from the areas at greatest risk. Where development is necessary in areas at greatest risk, homes should be designed to be safe from flood waters, without moving the water elsewhere.

This may mean increasing floor levels to above the predicted floodwater levels or raising plugs and other sockets high up on the walls. A choice of water-safe flooring and furniture materials will have to be decided.

Sufficient drainage needs to be in place, and a demonstration as to why homes must be built on that site and nowhere else must be argued.

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