Landscaping. Sea defences. Art.
Three seemingly unrelated topics all share one thing in common – they are a direct result of a community no longer prone to flooding, and a side benefit of work to enable about 800 new homes.
They are outcomes from a nearly-completed infrastructure project in Ōwairaka – a neighbourhood in the 11,000-home Kāinga Ora Roskill Development.
“In one-in-a-hundred-year rain events before our system was installed, there was between 12 and 26 overflows of raw sewage into Oakley Creek Te Auaunga, the awa,” says Andrew Sandlant, Senior Development Manager.
“It’s a disaster environmentally.”
Nearly five kilometres of new stormwater network, separated from sewerage lines into pipes sometimes big enough to walk through, have brought an end to that disaster.
As a result, Oakley Creek is cleaner. Ōwairaka homes and streets have remained free of floodwaters as Mother Nature continues to test the upgrades.
“This new network is a crucial first step in us delivering more homes for Ōwairaka, but Kāinga Ora infrastructure upgrades are for the whole community, whoever calls it home,” says Andrew.
“Existing residents have been incredibly patient during some pretty disruptive earthworks, so it’s great that we can make sure they experience some early benefits.”
Those disruptive earthworks came from contractors having to break large chunks of basalt, ancient volcanic rock, sometimes digging up to six metres in order to upgrade the stormwater system.
It was challenging work – close to homes, existing pipes and power lines – so the team used ‘pepper drilling’, where rock is broken in place and filled with an expanding grout, to reduce noise and minimise disruption.
About 7,000 cubic metres of rock was pulled from the earth – or nearly 150,000 loads in your trusty wheelbarrow – and donated to be reused in streams, water courses, to build sea defences and, in at least one case, to create art.
As a result, a large basalt shard carved into a beautiful sculpture now sits in the courtyard of a new housing development in another Auckland suburb.
That rock was once an example of a community sacrificing peace and quiet for a brighter future. Now, it welcomes residents home.
Ōwairaka – by the numbers
- 4.7km of new stormwater pipes
- 99 manholes
- 1650mm – the diameter of some of the new stormwater pipes
- 800 new homes enabled
- 1.3km of new wastewater pipes
- 9km of power and communications cables moved underground
- 3 new stormwater outlets
- 13,000 new plants and trees
- 68 new streetlights
- 2km of upgraded roads
- 6.2km of new concrete footpaths
- 650m of new roads
- 435m – the length of sliplined and cured-in-place pipes, fed underground without the need to dig trenches
- $35 million – the total cost of the infrastructure upgrades
