Our July feature on road runoff prompted an interesting email from someone who knows the pages of Drain Trader rather well – our retired features writer and industry legend, Ian Clarke. Retirement, it seems, hasn't quite cured Ian of the drainage bug.
Having read our look at the growing concern surrounding pollution washed from our roads, Ian delved into his own archives and unearthed two articles he wrote for Trenchless Works back in 2015 and 2016.
More than a decade ago, he was already writing about a technology designed to tackle part of the problem we're discussing today. It was called SmartSponge and, perhaps more interestingly, it's still around.
SmartSponge was developed by US company AbTech Industries and, at the time of Ian's 2015 article, was available in the UK through Naylor Environmental.
The polymer-based material was designed to selectively capture hydrocarbons from water, turning liquid hydrocarbon pollution into a solid material rather than simply allowing it to continue downstream.
But it's the application Ian highlighted that now seems particularly relevant today. “One of the largest potential areas of application,” his 2015 article noted, was road surface water run-off.
The Smart Gully incorporated the material within the road drainage system using a replaceable Smart Gully Adaptor. Fitted into the gully's rodding eye, it was designed to allow normal surface-water flows to continue while intercepting oil and hydrocarbon contamination close to source.
Ian also reported on trials undertaken by Wiltshire County Council which, according to the information available at the time, reduced hydrocarbon concentrations in road gullies from 8,000 ppm to just 1 ppm. The replaceable units were designed to remain in service for around 12 months or longer, depending upon contaminant loading.
By the following year, Ian was reporting on SmartSponge again – this time in use.
A Bellway Homes development at Oxlease Farm in Romsey bordered a Site of Special Scientific Interest canal, meaning stringent measures were required to prevent polluted construction runoff entering the watercourse.
The solution combined several technologies. Runoff passed through Naylor's Enviroflow material to remove sediment before entering Smart Filter Chambers containing SmartSponge to capture hydrocarbons.
Bellway's longer-term plan was to install Smart Gully Adaptors into every road gully on the completed development, providing continued protection for the canal and surface-water drainage system.
The idea wasn't simply to clean up pollution once it reached a river. It was to stop it much earlier in its journey.
A decade on...
The pollutants attracting attention today extend well beyond oil and fuel. Tyre and brake wear, microplastics, heavy metals, sediment and numerous other contaminants can all be washed from highway surfaces into drainage systems and ultimately the wider environment.
So SmartSponge certainly isn't a complete answer to today's road-runoff challenge.
But Ian's articles pose an interesting question.
Do we always need another new innovation – or do we also need to get better at deploying some of the solutions the industry has already developed?
SmartSponge hasn't disappeared. Naylor continues to offer the technology today, including Smart Gully Adaptors designed to capture hydrocarbons from stormwater. And it is no longer alone.
The stormwater treatment market has developed considerably during the intervening decade, with filtration systems, hydrodynamic separators, sediment treatment, SuDS and other technologies now providing engineers with an expanding toolbox for tackling different elements of polluted runoff.
The real opportunity then isn't finding one product that solves road runoff, it’s recognising the pollutants present, understanding the risks at a particular location and assembling the right treatment train to prevent as much of that contamination as possible ever reaching the receiving water.
And that treatment train needn't be entirely engineered. Nature-based solutions can have an important role to play too, slowing and treating runoff before it reaches our rivers and streams. The answer may ultimately lie in combining these approaches – tackling pollution as close to source as possible, rather than relying on one final line of defence downstream.
In fact, there are echoes of that thinking in the case study Ian covered back in 2016. Rather than relying on a single solution, sediment was removed before the runoff reached the SmartSponge filter chamber, where hydrocarbons were then targeted. Different stages tackled different elements of the problem.
There's something rather satisfying about an article written more than 10 years ago resurfacing because the problem it discussed has finally moved much further up the industry's agenda.
Technology has advanced, and the regulatory and environmental pressures surrounding water quality have certainly changed. But some of the thinking was already there.
Our thanks to Ian Clarke for digging into the Trenchless Works archives and continuing to keep an eye on the industry despite supposedly retiring from it... Apparently, once drainage gets into your system, there's no getting it out.
And Ian, if you're reading this issue of your favourite magazine over breakfast again, we'd strongly recommend finishing the cornflakes before turning to any pages involving fatbergs.
[This story appeared in Issue 341 of Drain Trader, September 2026. You can view it here]