Permeable concrete pavement offers a perfect crossroads for those seeking environmentally friendly alternatives in a higher density living environment
A permeable concrete pavement is a type of pavement that allows stormwater to pass through the top-wearing course (your traditional concrete surface) and be stored in the open grade basecourse beneath. Here, it can either replenish the natural ground aquifer by infiltrating the sub grades or be discharged to the stormwater network via under drains in a measured and controlled manner, reducing the peak flows of a storm event. In essence, it replicates a green fields environment, allowing the stormwater to find its natural paths to either the aquifer or local streams and rivers.
The benefits of using a permeable concrete pavement instead of a traditional impervious pavement are not limited to reducing the stormwater peak flow. Permeable concrete pavement also acts as a passive filtration system, improving water quality and reducing the urban heat sink by cooling the environment through evaporation.
Perfect for planning and consenting
There is a myriad of other benefits, but a substantial one is that, if a permeable concrete pavement is installed as a ‘passive’ system – which means it is only receiving stormwater that lands directly on it and not from other sources (eg, roofs) – it will be considered as pervious surface for planning and consenting purposes.
This is an important consideration as New Zealand embraces more and more infill housing and higher density residential construction.
A common application in New Zealand is on sites where an existing property has been removed and replaced with several new dwellings. In this instance, the installation of a permeable concrete pavement not only acts as the driveway and parking for the properties, but also as a detention device by mitigating run-off and not impacting on the overall site impervious/pervious ratios. This can be scaled up to assist in multi-unit developments such as JOALs (joint-owned access lots), carparks and driveways and larger scale commercial car park applications.
Installation is everything
From a performance perspective, permeable concrete pavements are dealing with two aspects – permeability and strength. There is a direct ratio between these two parameters – the more permeable the concrete, the lower the strength. However, there are no standardised procedures to make and test specimens of permeable concrete, so batching and installation is very important in achieving consistency and should only be undertaken by qualified and accredited companies.
Ticking all the boxes
In today’s environment, where we are seeing a desire for higher density living but an increased focus on sustainability and eco-friendly solutions, a permeable concrete pavement can offer a range of environmental benefits, while helping to minimise onsite hardstand coverage.