3 February 2017

Helicopter sluicing of the Kaikoura landslides

Posted by Dave Petley

Helicopter sluicing of the Kaikoura landslides

The latest update on the works to mitigate the impact of the Kaikoura earthquake in New Zealand provides some interesting insight into how the authorities are going about dealing with the landslides on the roads to the north and south of Kaikoura itself.  This is the main north – south highway (SH1) that links the port of Picton, where the ferries to North Island dock, and the main population centre on the island around Christchurch.  The biggest issues lie to the north of Kaikoura.  The work is being coordinate by NCTIR – North Canterbury Transport Infrastructure Recovery – an alliance representing NZ Transport Agency and KiwiRail, on behalf of Government. This is the update:-

  • Work continued this week making safe the slips to the north of Kaikoura ready for removal.
  • Helicopter sluicing has continued on four of the nine large slips to the north of Kaikoura.
  • Up to nine helicopters are dropping more than one million litres of sea water on these slips each day to wash loose rock and material down the slip face and into the sea.
  • This work is critical to make it safe for our crews and machinery to move on site and begin removal. It can only happen once the design work is nearing completion so the crews can make rapid progress on the site.
  • Geotechnical engineers are now assessing secondary slips along this section of the route. These are smaller slips but still need to be stabilised before vehicles will be allowed back on SH1.
  • NCTIR continues to meet with the community to inform them of progress and what lays ahead in this massive task.

The aspect that caught my attention here is the concept of helicopter sluicing, in which water is being dumped onto the landslides to remove debris.  This is a novel approach that is also pragmatic, but I have rarely heard of it before.  The NZ Civil Aircraft blog has some nice images of the helicopters undertaking this work, whilst an article on Stuff from December includes an image of a machine undertaking helicopter sluicing on a landslide:

helicopter sluicing

An example of helicopter sluicing on the Awatere Valley Road, via Stuff


Some of the machines undertaking this helicopter sluicing are those normally used for whale watching.  South Pacific Helicopters have put a video on their Facebook page of these sluicing operations.  These operations show both the challenges faced by these landslides and the ingenuity of the geologist and engineers in responding to them.

And this is of course an excuse to show the amazing video, one of my all time favourites, from 2009 of the use of helicopters to remove loose rock from a steep slope in Norway, which I featured in two posts at that time (post 1 and post 2):-