Hydro’s Alex Stephenson looks at SuDS
Controlling the volume and flow of water to reduce the risk of flooding has for a long time been the main focus of surface water management. By comparison, the need to treat pollutants in surface water has been given a lesser priority.
However, surface water treatment can no longer be the ‘poorer’ relation of the SuDS triangle of quality, quantity and amenity. True, there are those who believe it would be easier if we could just get on with tackling surface water flooding with SuDS, at least in the short term.
But the fact is improving water quality by removing silts, sediments and pollutants from runoff is coming to the top of the environmental agenda through developing legislation across the UK, driven by water quality targets of the EU Water Framework Directive.
In future it’s going to be vital for merchants and their customers to fully understand the full range of surface water treatment options available to enable correct specification.
Delivering an effective SuDS solution to meet site requirements will often require multiple stages of techniques used in sequence to achieve a so-called ‘treatment train’. This approach is already established as the preferred method in Scotland and the proposed National Standards for England and Wales are expected to follow a similar pattern.
The basic principle is that a number stages or ‘levels of treatment’ will be required depending on the ground conditions, the sensitivity of receiving waters and potential for the land to be contaminated through infiltration.
As techniques and best-practice knowledge for surface water treatment are still developing, a level of treatment is still not completely defined and is open to interpretation. However, best available guidance suggests that SuDS features can be used to deliver one or more levels of treatment to achieve required discharges into a watercourse.
Choosing from the whole SuDS toolbox of techniques using natural and proprietary features can often be the best way to deliver the optimum outcome for pollutant removal, depending on the site conditions. Manufactured devices can be used to enable, enhance or protect natural features, or can be used by themselves to meet water quality objectives.
In anticipation of the growing need for surface water treatment solutions Hydro International is launching the Hydro StormTrainTM Series of surface water treatment devices, providing a comprehensive toolbox of proprietary solutions.
We have also developed some important new industry resources to help in the selection and combination of surface water treatment techniques. Our unique new Online Treatment Selection Tool helps users explore ‘what if’ treatment train scenarios from the full range of natural and proprietary SuDS features.
An informative new E-Guide to Surface Water Treatment is also free to download from Hydro’s newly created surface water treatment hub. Visit www.hydro-int.com/stormtrain .