Stabilising work on a massive urban landslide has begun in earnest this week, three months after a slip took out much of an Auckland car park.
A footpath collapsed into the landslide in last week’s wild New Year’s storm, worsening damage from two earlier slips in October and November.
Now Auckland Council has taken over management of the site from Auckland Transport and started drilling sheet piles to stabilise the landslide, which is creeping ever closer to buildings in the North Shore shopping centre.
Geotech lead Ross Roberts said Auckland Transport initially took control because it could mobilise quickly for the emergency response, but now the site was in the “recovery” stage.
Roberts said he expected more slips, so the sheet piles were being put in to protect the properties in the area.
The sheet piles were long blocks that were moved into position by a crane, and then drilled into the rock beneath the earth. They were acting as a retaining wall.
There were spaces between the piles, so as not to risk creating an underground dam.
Birkenhead’s Mokoia Rd shops were currently at a low-risk status, Roberts said.
“Once the sheets are in, the ground will be the same as for a new build. It is safe to be there [Mokoia Rd] and we are monitoring the situation.”
There has not yet been an attempt to retrieve the Hiway Stabilizers machine, the remotely operated drilling apparatus that was swallowed by the second slip in November.
Focus is still stabilising the top of the slip, Roberts said.
Roberts said the emergency works had interfered with how much engagement had been with the community, and as the next “strategic phase” was initiated, there would be more engagement.
Auckland Council had carried out a comprehensive review of the Birkenhead landslide, and regular updates were available on Our Auckland.
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Article by Laine Moger
Published 13 January 2018 > Auckland – stuff.co.nz