How do we produce our own flood risk assesment? Are there any examples or templates?

Catrin_O

Hi there,
We are going through the planning process to convert our dairy into an annexe but have been told by Snowdonia National Park Authority that we need a flood risk assesment.

We are next to a tiny river but it has never flooded anywhere near the dairy.

This is what they have said,
I attach a screenshot of the correct Development Advice Map outline, which shows
the development site is in fact within the C2 outline. You will therefore need to
submit an FCA. For a development of this scale, we would not expect any hydraulic
modelling to be undertaken. The FCA is likely to be something you could undertake
yourself. The purpose of the FCA is to seek to ensure the development is as safe
from flooding as it can be by incorporating appropriate mitigation measures and flood
resistant/resilient materials and techniques into the design where possible (e.g.
raised floor levels, tiled or concrete floors rather than wooden, raised electrical
sockets, non-return valves on water inlet and outlet pipes, etc). Any residual risks
should be shown to be manageable.

Does anybody have an example of the kind of thing we need to produce or know of some kind of template? We've been quoted thousands of pounds to get it done for us and simply dont have that kind of money.

Any help with this would be amazing. Thanks, Catrin.

EachPenny

One good source of information/examples would be in the planning documents submitted by other people to the same planning authority. Each planning authority will publish searchable details of planning applications on a website, you just need to do a bit of detective work to find some which relate to similar kinds of development (e.g. small residential) where an assessment was carried out.

The assessments will usually be subject to copyright, so don't copy one, but there is nothing stopping you using someone else's work as a guide to what you need to do.

One of the main factors will be the level difference between the river and the floor of your dairy. You'll need to measure the height difference between the two (a spirit level and pegs or 'water level' is sufficient if you don't have surveying equipment).

You then need to look at what other areas would be flooded before the water level reaches the dairy. If the land falls away steeply in any direction that is also an important factor. Essentially anything which means flood water would go somewhere other than into the dairy would be good evidence to include.

In terms of the building, dairies are often associated with sunken floors. If that is the case with yours then do your plans involve raising the floor level? That is the kind of thing associated with mitigation - firstly that flood water cannot enter, secondly that any flood water that does enter will drain away by itself.