NZ Landscaper Magazine

BEST OF BOTH WORLDS

Permeable concrete pavement offers a perfect crossroads for those seeking environmen­tally friendly alternativ­es in a higher density living environmen­t

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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 ecofriendl­y solutions, a permeable concrete pavement can offer a range of environmen­tal benefits, while helping to minimise onsite hardstand coverage.■

 ?? ?? Permeable concrete pavement can help resolve impervious/pervious ratios in multi-unit developmen­ts such as joint-owned access lots
Permeable concrete pavement can help resolve impervious/pervious ratios in multi-unit developmen­ts such as joint-owned access lots
 ?? ?? Permeable concrete pavement allows stormwater to pass through
Permeable concrete pavement allows stormwater to pass through

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