The NZ Transport Agency has reiterated that a slip which occurred in 2012 south of Knights Point on State Highway 6, South Westland, is being closely monitored and the safety of all road users is the guiding priority.
“There has been a very small amount of deep-seated movement detected – around 50mm – which is not unexpected in this sort of environment,” said Pete Connors, the Transport Agency’s Regional Performance Manager.
If there had been any concerns around the safety of the slip, emergency work would be underway to mitigate the risk.
The Transport Agency has been monitoring the Epitaph Slip site south of Knights Point with instruments that measure groundwater and ground movement since 2012 when the slip occurred.
“These readings indicate that the slip is largely unchanged since then,” said Pete Connors. As well as these instrument readings, the site is visually inspected at least weekly, with road users’ and local residents’ safety the guiding priority, he said.
The road itself is separated from the head of the slip by at least five metres, the same as it was back in 2012.
The Transport Agency has plans to look at design options for this road if it has any cause for concern based on the geotechnical information and wider understanding of the geology of the area.
“Options include lowering the highway with an anchored retaining wall structure on the seaside, or cutting into the hillside above the road, or a combination of the two,” said Mr Connors. “These would only be considered if the results of geotechnical investigations identified concerns about the road’s safety.”
Photo showing the groundwater and ground movement instruments being installed deep into the rock in 2012 by the Transport Agency’s contractor.