Specialist
Drainage & Flood Risk Surveys
Where the water goes. Levels, falls, outfalls, culverts and the capacity of the ground to take it, measured on site rather than assumed from a desktop layer.
Typical accuracy · ±10mm vertical on outfall and feature levels; surface water level observations to the millimetre. Peat depth from drone-based GPR is typically ±100mm at the transect points themselves, and is a measured depth at those points rather than a continuous model between them.
When you need it
- →A planning application needs drainage or flood risk evidence.
- →Surface water is standing on the site and nobody can say why.
- →You need to size a drainage connection or attenuation feature.
- →An Environment Agency flood zone check needs confirming against actual levels.
- →The site is on fen or peat and nobody knows how deep the peat actually is.
What you get
- Flood zone and drainage constraint annotation
- Spot levels, falls and outfall invert levels
- Existing drainage feature locations and condition notes
- Drone-based GPR peat depth transects, on fen and peat sites
- Run-off and capacity observations with recommendations
- Drawing and data for drainage design
How it runs
- 01
Desk review of flood zones, permissions and historic drainage.
- 02
Site survey of levels, features and any standing water.
- 03
Drone-based GPR transects where the peat depth or substrate boundary is in question.
- 04
Analysis against your proposed scheme or layout.
- 05
Issue with clear recommendations and stated limitations.
- Horizontal control
- ±10mm typical
- Vertical control
- ±8mm typical
- Datum
- OSGB36 · EPSG:27700
- Area covered
- Norfolk base · 6 regions
Questions we get asked
Is this the same as a flood risk assessment?
No. A flood risk assessment is a study against the mapping. A drainage and flood risk survey measures the actual site, which is what tells you whether the mapping is right for your plot.
Why measure peat depth rather than dig a trial pit?
Because a trial pit tells you about one point and usually costs a machine to get there, and a peat profile that is 300mm of embanked mineral soil on one side and 2m of fen peat on the other is a site-wide problem, not a point problem. Drone-based ground-penetrating radar gives a depth and substrate interface along a transect without disturbing the ground or taking a peat core through a habitat you may be trying to protect.
Often needed alongside
Where we cover
Norfolk based, working nationwide. Site-based surveying, so distance is rarely the constraint.
Most requested in Norfolk, Kent & Medway, Suffolk, Cambridgeshire & Essex.
Every town, district and borough we cover is listed in full on each region page. See the full service area.
All 18 other services
Start here
Send the address and what it is for.
You will get a straight answer on whether this survey is the right one, and what it should cost. If it is not, we will say so.
info@prospaplans.com · Norfolk, Kent, London, East Anglia and the Midlands