About the project

Ambiental were appointed by our client to undertake a National Planning Policy Framework (NPPF) compliant Flood Risk Assessment (FRA).

The project involved the change of use of a former warehouse into a biodiesel plant at the Kingsnorth Industrial Estate on the Hoo Peninsula, Rochester.

A little more about the project

The property was located in Flood Zone 3 and approximately 1km away from the closest waterway.

The site itself was considered to be at high risk of flooding with a 0.5% chance of annual tidal flooding. It was also considered to be “Highly Vulnerable” under the NPPF due to the plant utilising hazardous materials such as potassium hydroxide, methanol, cooking oil, and biodiesel.

However, the site was already elevated by over 1m above ground level and protected by defences that were demonstrated to be effective up to a 1 in 1000 year flood event, according to the EA.

Flood Map for Planning showing the Flood Zones of the site

The Problem

The property was located in Flood Zone 3 and approximately 1km away from the closest waterway.

The site itself was considered to be at high risk of flooding with a 0.5% chance of annual tidal flooding. It was also considered to be “Highly Vulnerable” under the NPPF due to the plant utilising hazardous materials such as potassium hydroxide, methanol, cooking oil, and biodiesel.

However, the site was already elevated by over 1m above ground level and protected by defences that were demonstrated to be effective up to a 1 in 1000 year flood event, according to the EA.

The Solution

Under the NPPF the development had to undergo an Exception Test and therefore a Flood Risk Assessment was required to demonstrate the development could be achieved in a sustainable manner with an overall reduction of flood risk to the site and surrounding area.

There were numerous social and environmental benefits found for the proposed development, such as the avoidance of use of finite resources and utilising an otherwise waste material, reducing overall waste. This meant that it could be shown to be of benefit to the wider community.

The topographical survey information provided demonstrated that the existing building was constructed upon a plinth, elevating it above the existing ground level. When our Flood Risk Consultant reviewed the modelled flood levels against the topographic data it was demonstrated that the finished floor levels of the existing building would be located at a level acceptable for the Environment Agency.

The Outcome

The site was found to be located in a high risk flood zone however through the use of data and our expertise, it was demonstrated that the flood risk to the asset would be low.  As a precaution , any hazardous materials that were kept on site were to be positioned at a greater level (where possible), mitigating the flood risk and pollution risk even further.

The development also passed the exception test, showing it provided a wider sustainability benefit to the community and the FRA demonstrated that the development will be safe and not increase flood risk elsewhere.