Flood risk assessments for planning, from a Stage 1 screening to a Stage 3 hydraulic model, signed by a chartered engineer.
A flood risk assessment shows the planning authority that a development is safe from flooding over its lifetime, climate change included, and that it does not make flooding worse for anyone else.
It is asked for where a site sits in or near Flood Zone A or B, where the county development plan's Strategic Flood Risk Assessment. The council's own flood assessment behind its development plan, which flags the lands where a site specific assessment is needed. flags the land, or in a further information request. It goes only as far as the risk does: a screening first, an initial assessment where a risk is found, and a detailed assessment with a hydraulic model where the risk has to be quantified.
We carry out all three stages, and the same office designs the drainage and the SuDS the assessment relies on, so the floor levels, the attenuation and the outfall agree with each other when the council reads them.
The 2009 Guidelines for Planning Authorities zone land by how likely it is to flood from rivers and the sea, drawn as if there were no defences and before climate change. The zone and the use together decide what a planning application has to show.
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| Zone | Chance of flooding | What it means for building |
|---|---|---|
| Flood Zone A | More than 1% a year from rivers, or 0.5% from the sea | The highest risk. Homes, schools and other highly vulnerable uses, and less vulnerable uses such as shops and offices, have to pass the Justification Test. |
| Flood Zone B | Between 0.1% and 1% a year from rivers, or 0.1% and 0.5% from the sea | Moderate risk. Highly vulnerable uses have to pass the Justification Test; less vulnerable uses are appropriate with a flood risk assessment. |
| Flood Zone C | Less than 0.1% a year | Low risk, and any use is appropriate. A site can still flood from surface water or groundwater, which the zones do not map. |
Each stage ends in a report the planner can decide on, and a plain answer on whether the next stage is needed.
Drawings, a specification, or the site address and the programme dates: whatever you have is enough to start. We come back inside two working days, and a written fee proposal against a defined scope follows within three working days of that.