5 facts every planning consultant, architect or developer should know about flood risk assessments
Fact
Most developments require a flood risk assessment. Your development does not require a flood risk assessment if all of the following statements apply:
- It is less than 1 hectare (100m x 100m area) in size
- It is located in flood zone 1
- It isn’t affected by other sources of flooding (such a surface water run-off, sewers, groundwater etc)
- It is more than 20m away from a main river.
Ideally you will want to know in advance if your development requires a flood risk assessment.
Flood Risk Assessments must evaluate the impact and propose mitigation steps for multiple sources of flooding.
Sources of flooding include: rivers, sewers, surface water run-off, reservoirs and groundwater. The impact from river flooding and surface water is evaluated using the flood level information from the Environment Agency. The rest of sources from flooding are assessed by reviewing the local council’s strategic flood risk assessments.
The mitigation strategies should be based on sound engineering principles given by experienced engineers.
FACT
FACT
The flood risk assessment is approved by either The Environment Agency or The Lead Local Flood Authority (This is usually your local County Council). The LLFA check and approve all the flood risk assessments by following the standing advice produced by the Environment Agency. The flood risk assessments checked by your local County Council are most likely to be the flood risk assessments produced for developments which are:
- Less than 250m2 in flood zone 1 or 2
- Located 20m away from main rivers
- Located in flood zone 1 with no critical drainage problems
- Located flood zone 2 which are water compatible
The list above is not exhaustive and it varies depending on the council’s planning department guidance. All the flood risk assessments produced for developments not listed above are assessed and approved by the Environment Agency.
The Environment Agency can stop your development to progress through planning if their flood or ecology concerns are not fully addressed.
This can happen during the planning application stage as the Environment Agency is a statutory consultee. It can also happen during the environmental permit application. The local planning authority will follow the Environment Agency advice. This is clearly demonstrated in the report “Survey of a Sample of Development Applications within the flood plain” completed for the Committee on Climate change dated April 2014 which concludes that over the period between 2009 and 2013 only 8 planning applications progressed contrary to the EA's advice on flood risk.
Ideally your flood risk assessment consultant should have already consulted the Environment Agency before the project is submitted for planning.
FACT
FACT
You can contact the Environment Agency and the Lead Local Flood Authority (LLFA) in advance in order to obtain their pre-planning feedback on your flood risk assessment.
The initial consultation with the Environment Agency is usually free; however you will need to pay for their additional time. This consultation can take between 20 working days to 2 months, this time depends largely on their feedback.
The local council is usually expected to provide their flood risk feedback for free; although in many cases the LLFA provides their flood risk advice at planning stage rather than before planning. The LLFA expects that the flood risk consultant is up to date with the flood risk assessment standard advice provided by the Environment Agency.