Omoto landslide between Greymouth and Stillwater, SH7, background and where to from here

3 MinutesBy NZ Trucking magazineOctober 21, 2019

Aerial view of the landslide at SH7 Omoto, with the Grey River at high volume at the top to the north and the road and rail links below – 19 October 2019.

State Highway 7 access to Greymouth from Stillwater and Kaiata will remain closed while the landslide at Omoto continues to show signs of ongoing instability, says NZ Transport Agency maintenance contract manager Moira Whinham.

The NZTA closed the highway at 5pm Friday after an acceleration in slumpage was recorded with the heavy rain that day.

The landslide moved around 2.5 metres overnight Friday night to Saturday morning and has continued to move throughout the past weekend.

Whinham warned local people who have been filming at the site that they are putting themselves in considerable danger given its instability and liability to move suddenly.

For background on this slip site, which has been moving since mid-August, please check the project page: 

In the past few weeks, it has moved more than 10 metres, more than half of that accelerated movement in the past fortnight.

“Prior to this current period of instability, the Omoto slip site has been relatively stable since the 1980s, and easily managed by highway crews with minimal disruptions for road users,” says Whinham.

“We are concerned that people have been walking over the site over the weekend. This is a risky place while the slip is moving and people are putting their lives in danger if it was to drop suddenly, as it has done in recent days.”

Detour map.

In the short term, the NZTA is investigating a temporary fix while the permanent repair is worked through. New Zealand‘s best geotechnical advisors are working on this solution currently and gathering all the information needed.

However, until the slip stops moving, short-term solutions are unable to be put in place. Once that movement stops, temporary repairs will get underway.

The NZTA encourages people to drive to the conditions on the detour route that passes through Taylorville, a small settlement on the Grey River‘s north bank.

KiwiRail‘s executive general manager operations Siva Sivapakkiam says the rail line at Omoto will be repaired in the short term. Long-term remediation is being established for the slip site to ensure resilience of the location, but temporary repairs cannot begin until the slip settles.

In the meantime, the TranzAlpine will continue between Christchurch and Arthur‘s Pass, with passengers bussed between there and Greymouth.

“However, we are also investigating whether or not the service could instead run as far as Moana if the line is not able to be fixed within a reasonable time frame.”