Slip A1 and A2 permanent piling. Night works are underway to install the pile sleeves in preparation for the main piling rig.

SH1 Mangamuka Gorge slip repairs - July update

Kia ora koutou,

The wet winter continues up in the gorge, but despite the weather the team up in the gorge is continuing to make huge progress on the repairs.

Now that most of the enabling works are complete, we are seeing less ground movement, however we continue to monitor the ground conditions for additional slip movements, including during weather events.

As usual our crews are very busy onsite, with the permanent works now underway at both ends of the gorge and the enabling works continuing in between. As reported last month there have been 2 new slips over the last couple of months. These new slips are proving challenging above and below the ground, with investigations continuing to establish the scale of the slip areas and come up with suitable design solutions.

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 A12 enabling works. Enabling works continue as the permanent works commence further down the hill.

Progress update

We have completed the enabling works at the northern and southern ends of the gorge and are making good progress further up the gorge to ensure there is safe and stable enough to accommodate the heavy machinery that is starting to arrive to undertake the permanent works.

The permanent works has begun at both ends of the gorge with 40x 6m pile guides being installed at the northernmost slips (A1/A2) to help guide the drill for the permanent piles, some of which need to be drilled up to 22m deep into the ground. These piles will be secured using ground anchors tied into the side of the hill.

The piling rig and crane have now arrived at the southern end of the gorge and are underway on slips A12 and A13. Both slips require a combined 83 piles over 1m in diameter and like A1 and A2, will be tied into the side of the hill using ground anchors.

This is a big moment for the project as both ends are now working on permanent works on the mission towards the summit.  Due to the amount of space required to safely operate these machines, these works are being undertaken at night to ensure that access can be maintained for the remaining sites during the day.

In addition to this major milestone, over the next month we will be continuing the enabling works on 4 of the other slips (A3/A5/A8/A9). The teams have also been undertaking preventative work on 8 other sites in the form of rock spall walls.

Check out the images at the bottom of this newsletter to see what our team have been up to.

Upcoming Events

Keep an eye out on out social media channels over the next couple of weeks for upcoming engagement popups in Mangamuka and Kaitaia.

This will be an opportunity to meet some to the team working up here in the gorge and ask questions about what we are doing, to those who are on the ground doing it.

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.

Slip A1 and A2. Permanent Piles casings installed.

Slip A3: Permanent Piles casing being installed.

Slip A5. The capping beam for the enabling works is now complete.

Slip A8. 8 other rock spall walls are being installed along the site.

Slip A12. Enabling works are continuing.

Slip A12 and A13. Piling rig and crane for the permanent piles are in place.

Slip A12 and A13. Piling rig and crane for the permanent piles are in place.

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