Waka Kotahi is boring into the ground above the slip on State Highway 25A with a 10-tonne drilling rig.

The goal is to gather soil samples which will give them the information they need to decide how to restore the road, according to a post by Waka Kotahi on Facebook.

"These photos show the rig making boreholes on the northern part of the slip, expected to be finished by the end of the week.

"The rig has so far reached 15 meters deep and will continue until it gets to 20 meters. As yet, no rock has been found.

"Earlier the rig drilled a borelog on the eastern side of the slip where the road still exists — five metres of rock was found there. Another drilling rig will be brought to site next week and will start work in the lower slip area."

Last week, Waka Kotahi posted an update video on the slip, which can be found here.

For the latest updates on the roads around the country, visit the Waka Kotahi Journey Planner at https://www.journeys.nzta.govt.nz/.