Local Planning Authorities and the national environmental agencies are increasingly asking developers to show how they’ll manage surface water for their development in the form of a surface water drainage strategy systems or a sustainable drainage strategies (SuDS) report. In some cases you may also be required to provide a second-stage report known as a detailed surface water drainage design.
A sustainable urban drainage system (SuDS) or surface water drainage strategy is a report into how surface water, usually caused by rain, affects a site and the surrounding area. It establishes how water behaves on a site, and determines the runoff rate, flow pathways and infiltration potential (the likelihood of water being soaked into the ground).
It then investigates what effect the development will have on these issues, and outlines measures the developer can take so that runoff rates meet the requirements for the site set by national and local planning policy.
As of April 2015, a change in National policy requires that developments of more than ten units (including residential, industrial, commercial and mixed-use sites) review the potential use of sustainable drainage strategies (SuDS) to achieve betterment on brownfield sites or restrict run-off rates to the greenfield. You may also need a surface water drainage strategy if you’re increasing the footprint of an existing site.
If your development’s within an area designated as Flood Zones 2 and 3, or an area identified as having a surface water flooding problem, you’re also likely to need a drainage strategy.
Even if your development doesn’t meet these criteria, Local Planning Authorities have the final say on who needs a strategy. It’s best to speak to your local planning office before you submit a planning application.
To check if your site is in Flood Zone 2 or 3, you can contact us or take a look at national flood maps:
You may only need a surface water drainage strategy for your planning application. But you may also need a second-stage report known as a detailed surface water drainage design.
The detailed drainage design provides construction details, such as pipe diameters, manhole locations and the results of on-site soil testing. Whether or not you’ll need it very much depends on the location, size and type of your development, as well the views of the EA, local utilities (water company) and your local planning authority.
Our team have a wealth of experience in civil engineering, including drainage and infrastructure design, highway alignment, and waterside and marine developments. We use the specialist Microdrainage software for our designs and can advise if you need detailed drainage design.
“Ambiental produced a Surface Water Drainage Scoping Report to guide a masterplan for one of our projects. They understood the brief and proposals immediately and the Report was produced promptly and in line with the timeframe they gave us.
The Report was prepared to a high standard. It was easy to read and understand and covered everything that was expected. Any questions we had that arose from the Report were promptly and comprehensively answered. I would certainly recommend Ambiental to clients for similar work in the future.”
Chris Wojtulewski, Parker Dann
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