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StoneSet Australia

Subsurface Drainage Paving

Subsurface Drainage Paving

Project QuickStats

Location 12 Chester Hill Rd, Chester Hill, New South Wales
Cost $15,576
Stone Colour 6mm Tan
Total Area 177
Date Installed 28-11-2013

One of the great things about Porous paving is its practical, and it looks good!

There was no better example of this than an innovative subsurface drainage solution installed at the entry of Chester Hill library in Sydney.

Limited options?

The trouble working in Sydney is so many buildings are heritage listed and the geology of the Sydney basin is such that roads and development have evolved in a haphazard way. Many buildings have had to work in with limitations of existing stone foundations and established drainage.

Such was the case in this situation for this public building in Canterbury Blacktown council. The entrance to the library had limited depth and so limited provisioning for new stormwater drainage.

There was not enough fall to allow for a standard strip drain, and the depth too shallow to go putting in a ‘french drain’ style perforated pipe in a channel. The video below demonstrates the concept of the subsurface drainage ‘french drain’ pipe.

A versatile product

The work around in this case was larger porous ‘drainage gravel’ pits just below the surface, designed with a fall that channel water collecting in these pits (where water collected) and guide it towards the single large stormwater drain (off to the left of the entranceway).

The below photos (unfortunately have a lower resolution) demonstrate the stages of installing a new gravel-only subsurface draining system designed to specification, before finishing the paving off with StoneSets’ 25mm layer of permeable paving.

The black plastic grid seen below is a HDPE cell, clipped together in segments in a similar manner to children’s foam mats. Basically a hard wearing durable moulded plastic, these grids give structure to the loose, larger drainage gravel.

Drainage gravel is used because its hard wearing, doesn’t biodegrade (thus lead to the pavement sinking) and when vibratory compacted, locks and holds together whilst still allowing water to trickle thorugh the gaps in between.

Subsurface Drainage Paving

In this situation the majority of the foyer area was under cover and didn’t experience direct rainfall. Given there was no steep/incline leading down to the foyer, there was not the potential of ‘volume runoff’ one might see flood the area during significant rainfall events.

Can StoneSet Act as Drainage?

The short answer is, when overlaying existing surfaces then no, 16mm layer of porous resin bound stone is not suitable to be relied upon as drainage during heavy downpours. Similarly, for commercial applications, resin bound stone can not be used in place of the consulting engineers drainage provisions.

The longer answer – if the paved area is for foot traffic and graded to the correct falls, StoneSet can certainly be used to facilitate free-draining movement of water down below the surface. There it follows a subsurface drainage channel or point floor waste system for foot traffic areas.

Regardless, StoneSets porous surface is a far safer approach to reduce chance of pudlle slip hazards, a good example of this was the StoneSet applied in Sydney marina club foyer.

Now You See It

Subsurface Drainage Paving 6 Subsurface Drainage Paving 7

Subsurface Drainage Paving 3 Subsurface Drainage Paving 5

The council were amazed with the final result, no additional surface drainage strips – no potential trip hazards, no collection points for leaf or rubbish litter. Just continuous natural stone paving and a beautiful new entrance way to the library.

If you would like more information on this particular Porous pavement project, please get in touch with us at 1300 392 155 and quote the job reference number POT19603, we would be more than happy to discuss similarities in your patio, foyer or pathway project. We can fast-track how StoneSet porous paving may suit your specific paving project.

Resin-bound stone is not one of the first things that come to mind when looking for Pathway ideas and particularly when paving over existing hard surfaces.

Learn More About Permeable Footpaths

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