Inspire : Public Works Professional Sept - Oct 2013
31 POROUS PAVEMENT Porous pavement technology has long languished in the bottom drawer of Australia's toolbox when it comes to water sensitive urban design (WSUD). However, as WSUD gains traction, this alternative to imper meable concrete and asphalt pavements may be poised for a renaissance. Certainly, one of its abiding proponents, Rodney Swil of FPP Industries, thinks so. Swil champions a product called FiltaPave, made from a ﬂexible proprietary binder, graded aggregate and recycled tyres, which give it a certain eco-friendly cachet, along with a claimed resilience to cracking or trip hazards caused by tree root intr usion. "Porous pavements are increasingly being used overseas for mitigating stormwater because they promote inﬁltration, improve water quality and often eliminate the need for detention basins and other drainage str uctures," he says. "Plus, they replenish aquifers and protect waterways from run-off. The key is to provide the water with a place to go by laying an open-graded aggregate bed. "Then, as the water drains through the porous surface and percolates through the stone bed, it slowly inﬁltrates into the soil. This subjects any contaminants to a natural cleansing process as they ﬁlter through the pavement, substrate and soil." Swil says that's far better than channelling contaminated stormwater through a series of drains and pipes for bulk treatment further down the line. Plus, it can lessen the need for installing those drains and pipes in the ﬁrst place. Two years ago, FPP Industries installed a porous surface for the City of Sydney at Cook and Phillip Park near St Mary's Cathedral, because the city was concerned that sections of decomposed granite paving were being washed into drains and hence into Sydney Harbour during heavy storms. Moreover, the maintenance of tree surrounds and footpaths was becoming increasingly difﬁcult. The project involved excavating an 80m2 area to a depth of 80mm, laying a 40mm underdrain of blue metal, with a 40mm topping of FiltaPave. Two years on, according to Swil, and the surface has performed to expectations, with the material still stable and porous, and no washaways into storm drains or water visible after signiﬁcant storm events. Installations for other clients have included driveways, parking areas and pedestrian walkways, which in most cases have eliminated kerbs, gutters, drains and pipework. ••• SOAKING IT UP Porous paving absorbs rain as it hits the ground, meaning less need for drains and pipes. As impervious surfaces continue to reduce watershed integrity, this soak-it-up solution could be set for growth. BY BRIAN MCCORMACK The key is to provide the water with a place to go by laying an open-graded aggregate bed. Top: Porous pavement goes into place at Cook & Phillip Park in Sydney's CBD. Le : Porous driveway at Corpus Christi School in St Ives, Sydney.
Public Works July Aug 2013
Public Works Nov Dec 2013