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Unclogging permeable pavements’ potential

Award-winning new research has potentially pointed the way to dramatically improving the cost-effectiveness of permeable pavements.

At last month’s Australian Water Association South Australian Water Water Awards, Kelly Hill took home the Postgraduate Prize for her study The development of low-clogging permeable pavements: A laboratory study into the mechanisms of sediment accumulation.

The University of Adelaide PhD student said her findings could help save millions of dollars in carparks and courtyards across the country where permeable pavements are used for stormwater capture and harvest.

“By prolonging the lifespan of permeable pavements there can be significant economic benefits, in excess of $20,000 for every 15m2 – the size of a single car parking area,” she said.

“Just from placing permeable pavements in a more appropriate position, we will be able to reduce maintenance costs and incur economic savings of hundreds of thousands of dollars for each car parking area.”

Permeable pavement typically costs around $5000 per parking space upfront, Hill said.

While previous studies have established the top bedding aggregate layer of permeable pavement is the prime area for sediment retention, few have looked at modern systems which do not use geotextiles.

Hill's research tests the clogging processes involved with mono-sized sediments (sediments of single particle size ±10%) to identify where specific sizes begin blocking the drainage system.

“This research not only provides us with information on which sediment sizes are ultimately responsible for accumulation within which 'problem' layers of the pavement,” she said.

“It also uncovers some of the reasoning behind the principles, based on mineralogical findings.”

The research should help developers, planners and stormwater management agencies select the best location for permeable pavements.

“From this research we are able to suggest that permeable paving is most applicable in built-up urban areas (where there is little fine sediment in the surrounding environment), such as in a car park,” she said.

“I would actively discourage permeable pavement installation in areas where there is loose sediment, such as in a seaside or beach location.

“I would estimate that a permeable pavement car park located in an urban area might last up to 20 years longer than one situated in a beachside location.”

Hill's research is also applicable to those developing the next generation of permeable pavements.

“The outcomes of this research will be able to point mathematicians in the right direction ... to design (new pavements) and set new standards and procedures,” she said.

With roads making up around a quarter of impermeable surfaces in Australian cities, they are a massive generator of run-off water.

As such, Hill said it is clear that permeable pavements have a vital role to play in stormwater capture in Australia.

The expertise and innovation of YWPs like Hill will be in the spotlight at the Association’s Young Water Professionals Conference, to be held in Sydney on February 18-19.

To find out more, click here.