The reopening of State Highway 1 Brynderwyn Hills has been pushed to the end of June following a delay caused by an active slip.

The road had been on track to reopen 13 May until two significant slips occurred on 26 and 30 April.

NZ Transport Agency Waka Kotahi said that while contractors are urgently working toward the end of June to reopen the road, if there is a significant amount of unexpected rain, or further instability is found, that could delay the timing.

“Our priority has been to undertake geotechnical and safety assessments to determine the best option for stabilising the hillside and getting State Highway 1 Brynderwyn Hills open as quickly as possible,” said NZTA national manager of infrastructure delivery, Mark Kinvig.

“We are committed to completing these vital recovery works as quickly as possible to ensure a safe and reliable SH1 Brynderwyn Hills for the short to medium term.”

Excavation has already started, with operators working from a platform at the top of the ridge. Removing soil from the top of the ridgeline reduces the likelihood of further slips, which will then enable safe work to be undertaken from the bottom to remove material.

Up to 55,000 cubic metres of earth will be excavated to stabilise the site where the two slips occurred at Kauri Tree Corner.

“Our team is working seven days a week, where weather allows, to get the road open,” said Kinvig.

“We are maximising the number of trucks, diggers and workers on site to ensure the soil removal is a continuous operation, utilising daylight hours, to get it clear.”

The remaining planned works, including drainage and pavement works, are on track and continue in parallel; with night works where it is safe to do so.

“We have built in contingency for poor weather, however the ground conditions remain unstable and continue to be actively monitored by staff and GPS sensors. There is a risk of further slips until we complete the stabilisation works,” Kinvig said.

“While the closure is in place we continue to have crew proactively monitoring the three official detour routes to ensure these are safe and as high quality as possible and NZTA will be undertaking essential repairs on these routes.”