Back in 2018, the UK Government gave itself a hearty slap on the back in its review of the adoption of Sustainable Drainage Systems (SuDS) policies in local planning authorities (LPAs).
The SuDS approach makes intelligent use of ground absorption, water storage, rainwater recycling, and other features, to reduce drainage discharge into the sewage system, and lower the flooding risk. It was, the review said, being consistently prioritised in well over 80% of LPAs’ planning policies, not only for areas at particular risk but in all major new developments.
At Clark-Drain, we’re no stranger to successful, sustainable drainage solutions, so we applauded the findings.
But another report released earlier this year by the House of Commons Environment, Food and Rural Affairs Select Committee (EFRA) has accused the Government of ‘playing catch-up’ on SuDS, and recommends legal enforcement of such systems to protect the country from the effects of climate change.
So, what are some of the issues, here – and the possible solutions – seen from the viewpoint of a business with over 60 years’ experience in drain design, manufacturing, and innovation?
Engage early, explore new options
Firstly, it seems possible that engagement with planners and other stakeholders may not systematically be happening early enough in the process.
Early engagement is vital to ensure a more coordinated drainage approach across multi-functional spaces such as car parks, footpaths and verges, gardens, landscaped areas, driveways, courtyards, and communal spaces, so that what results is a “collective maximisation” of drainage across all drainable elements of a development – not just the usual selected surfaces.
This is critical, as over 80% of the UK population now live in urban areas where there has been a huge reduction in the amount of land where rainfall can soak naturally into the ground.
But other benefits of this approach should not be ignored, either. A coordinated approach to planning drainage across an entire development will naturally lead to smoother, more predictable, more cost-effective sourcing and procurement of drainage products, too.
Focus on product performance
Harnessing every available drainable asset to squeeze maximum value out of SuDS is all well and good, but the wrong choice of drainage products can do much to undo the benefits conferred by SuDS planning, damaging its credibility and, ultimately, slowing the system’s adoption, as per the EFRA report.
Which products, then, are truly up to the job?
Geocellular solutions play an important role here. Rather than drainage as such, these products are more about storage. Their cellular structure enables them to store, and delay the discharge of, excess water, in circumstances where heavy rainfall means that the volume of water flowing from a site is too high to go immediately into the main drainage or sewer system.
But here again, effective performance at one level can be undone by poor performance at another.
For geocellular storage to play its part effectively in the SuDS approach, the drainage channels that work with and around it must, themselves, perform effectively.
An average shallow drainage channel, as just one example, has an internal depth of about 75mm, which results in a hydraulic performance of about 88mm per hour.
But far better performance can be obtained from an optimised channel with an internal depth of 105mm, which will have a hydraulic performance of some 172mm per hour – and this option requires no more external space than the traditional shallow variant, as its intelligent structural design enables a much larger internal width relative to the external dimensions.
SuDS is, after all, a system – and a system’s performance is always affected by the performance of each sub-system within it.
Get it into the ground quicker!
Design and theory aside, the practical success of SuDS depends on much the same factors as any other drainage installation – namely, the speed and ease with which drainage components can be installed and laid.
With increasing levels of rainfall (and increasingly frequent rainfall) driving an urgent environmental agenda, the quicker the assets are in the ground, the quicker they’ll be doing their job in time for the next deluge.
Modularity, lightness, and resilience are key here. Traditional, heavy drainage products are difficult to handle, slow to install, and require proportionately much more (costly!) labour and machinery on-site.
But if drainage products can be made from light, tough materials, such as polypropylene, and supplied in modules that can simply be clicked together, installation is more rapid, costs less to manage, and, pound for pound in weight, results in the use of far less fuel (fuel pollution being, of course, one of the factors that has contributed extensively to climate change and rainfall increase in the first place!)
The view from Westminster
What, then, are we to make of the SuDS debate raging in Westminster?
It seems that this is largely about the speed of change – and the only way we, as a drainage manufacturer grounded in expertise, can influence that is to ensure that effective and affordable drainage products are available that not only deliver in conventional drainage environments, but transfer those same benefits seamlessly to the application of the SuDS strategy.
And by making drainage channels that are tougher, lighter, higher-performance, and easier and cheaper to install than the alternatives, we are doing precisely that.