Slip A12 repairs at the southern end of the gorge from the air. The temporary piles and anchors are now complete.

SH1 Mangamuka Gorge Slip Repairs - June update

Kia ora koutou,

Despite an extremely wet month the enabling works at SH1 Mangamuka Gorge are progressing well, with a couple of exciting milestones achieved.

We are continuously monitoring ground conditions for additional slip movements, including during weather events. There has been some movement due to significant rainfall, including several new slips that are being cleaned up and repaired.

Our crews have put extra measures in place to keep everyone safe, and at times we needed to stop work when conditions become unsafe, or the numerous sensors positioned through the gorge have indicated ground movement.

Despite the disruptions, our crews have remained busy on site and are confident we’re on track for reopening in May 2024.

In parallel to the physical works in the gorge, we are continuing to collaborate with a Far North working group which includes hapū, local stakeholders, technical experts, and elected representatives to highlight the key priorities for the district. This feedback will be included in a business case which will be presented to the Waka Kotahi Board for consideration, and we’ll share more about this long-term planning in due course.

We appreciate your understanding, patience, and support as we work through this.

Slip 13 hard pile installation through the central slip area.

Progress update

We’re continuing with enabling works which will ensure the gorge is safe and stable enough to accommodate the large machinery needed to carry out permanent slip repairs.

This has included installing hundreds of soft piles (drilled and filled with concrete) and hard piles (reinforced with steel casings) across the critical slip sites and we are now onto installing capping beams (these tie all the piles together) on multiple sites.

The permanent walls will be built adjacent to these and will then be anchored with rods drilled into the sturdy material in the mountainside to hold the road which will be built on top.

With approximately 700 temporary and permanent piles to install across all sites this is a large and complicated piece of work. We have completed 90% of all the temporary piles and are progressing ahead of schedule with capping beams and ground anchors.

Over the next month, we’ll continue installing piles for enabling work capping beams on two other slips. Check out the images at the bottom of this newsletter to see what our team have been up to.

This month sees a major milestone with the permanent slip repairs commencing on the northernmost  slips 1 and 2. These are 2 of the most complex slips to repair with 40 piles, each over 1m wide, forming 1 large worksite. The repair work at this site is expected to be completed late this year and will be carried out at night so the remaining slips can continue to be worked on during the day.

The work is being carried out like an assembly line, where our crews begin installing piles from the outermost slips and work their way toward the summit. Capping beam installation follows behind that.
 

News and media

Check out the links below to view drone footage from a recent flyover, and our Project Director Norman Collier provides a project update on Te Hiku Radio.

Mangamuka Gorge drone update June

Te Hiku Radio - Norman Collier: SH1 Mangamuka Gorge Update

Need more information for your local community group?

Our latest flyer ensures you and your community are kept up to date.

If you would like some printed copies to hand out to your whānau or community group, send us an email at northlandproject@nzta.govt.nz with your name, mailing address and the number of copies you need. We’ll then pop them in the post directly to you.

To view the electronic version of the flyer, click here.

Slips 1/2 temporary piles and capping beam are complete with the permanent piles now being installed.

Progress on Slip 5 – 60% of the hard piles have been installed at this location.

Slip 8 rock wall work by Far North Roading.

Slip 12 soil anchor installation nearing completion

More information

For more information on the SH1 Mangamuka Gorge slip repairs, contact us at northlandproject@nzta.govt.nz

Visit our website www.nzta.govt.nz/mangamuka