Are Proprietary Systems Still Used in UK SuDS?

While there have been well-publicised international efforts to reduce carbon emissions and lower the impact of climate change (Kyoto 1997, Paris 2015, and most recently COP26 in Glasgow), it seems unlikely that UK rainfall levels will decline any time soon. So, there is still a pressing need to better manage what will continue to be higher volumes of surface water, particularly in urban areas.

Sustainable Urban Drainage Systems (SuDS) are designed to manage surface water run-off by controlling both flow rates and volumes of water, as well as remove contaminants to help support a better, more sustainable use of rainwater.

SuDS techniques can be broadly categorised into natural and proprietary systems. Both are highly effective at managing surface water, and they can be used either solus or in combination within a so-called SuDS Management Train. SuDS Management Trains are designed to capture, control, treat and finally discharge the surface water to a receiving water course or allow it to seep underground. 

While a lot has been written about natural systems, including the use of swales, ditches etc., there has been less attention paid to proprietary systems of late, but that should not detract from the vital part they can play within an effective SuDS solution.

Guidance for specifiers who are considering installing SuDS proprietary systems – which include rainwater harvesting systems, fuel/oil separators, pump stations (where gravity flow is not possible) and attenuation tanks or crates - is included within The Design and Construction Guidance for foul and surface water sewers offered for adoption in England, 2020 (DCG).

Unlike most natural systems, proprietary SuDS techniques are largely installed underground. This means they are ideal for locations where there is limited space.

And they play an important role in lowering local pollution, by removing from run-off. Separators, for example, are highly effective at removing hydrocarbon pollutants (petrol, diesel, engine oil) which are typically found in rainwater run-off from roads. Indeed, under section C7.13 of the DCG, where locations have a high pollution hazard level, then the advice is that a “treatment device should be part of the private drainage system, or the street drainage system, as appropriate.”

It is our firmly held view, backed by our 60 years’ experience as industry-leading experts in the wastewater industry, that all water management solutions including SuDS techniques (natural or proprietary) need to be regularly maintained if they are to continue to work to their maximum potential.

We welcome all regulatory stipulations that support this view.

But it’s also worth highlighting that proprietary systems are particularly easy to service and maintain, ensuring that their performance remains unchanged over the long-term. This makes them a good candidate for adoption by a water and sewerage company (WaSCs). 

Foul and surface water systems in England are adoptable under the DCG and in accordance with Section 104 of the Water Industry Act 1991. In fact, the DCG aims to speed up the mandatory uptake of SuDS in new developments through a transfer of ownership and management responsibility to WaSCs, a role which is far easier if the system itself is easy to maintain.

The full process of adoption is described within the DCG.