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SH1 Mangamuka Gorge slip repairs

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December 2024

Aerial view of Mangamuka Gorge
Slips A27, A12 and A13
Slip A27 mural - Hawaiki
Slip A7 – Road surface reinstatement and barrier installation are complete. Anchor work will be completed in the new year
Newly paved section of road through Mangamuka Gorge
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November 2024

Over 5km of asphalt is being laid throughout the gorge with repairs being undertaken while the road is closed
Slip A1 and A2 – Asphalt has been installed and is ready for barriers and line marking
Slip A6 – Asphalt has been laid and is now ready for line marking
Slip A7 – Asphalt has been laid, and crash barriers have been installed
Slip A8 – Asphalt has been laid and is now ready for line marking
Slip A9 - Asphalt has been laid and is ready for the crash barriers. The last remaining anchors will be installed in the new year
Slip A9 – Grading and rolling the basecourse prior to asphalt
Slip A11 – Linemarking complete
Slip A12 – Smaller drill rig has been brought in to drill the final anchor
Slip A13 – Various protections are in place to protect the fresh asphalt, and sediment controls are installed around the drilling and grouting of anchors.
Slip A26 – Ready for line marking. Swale drains are being installed on the side of the road
Slip A47 – Lagging is complete. Road surface reinstatement is nearing completion
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October 2024

Slips A1 and A2 – Anchors being installed and tested
Slip A3 - The guardrails have been installed
Slip A4 – Ready for the road resurface to be reinstated
Slip A6 – Road surface installation. Subsoil drains are being installed to improve drainage under the subbase.
Slip A7 – Piling, lagging and back filling is complete and ready for road reinstatement
Slip A8 – The road has been milled and the bitumen membrane has been laid ready for asphalt
A section of completed pavement repairs between Slips A9 and A26
Slip A9 – Base course installation
Slip A10 – Road reinstatement and drainage is complete, and the guardrail has been installed
Slip A11 – Drainage and road surface installation under way and is now complete
Slip A11 – Roadside drainage is now complete. The rip-rap rock inset into the concrete is designed to slow the flow of water to prevent it overflowing onto the road
Slip A12 – Asphalt installation is now complete
Slip A13 – Asphalt installation is now complete
Slip A26 –The wall is now complete. The wearing course membrane has been installed and ready for asphalt
Slip A47 – Pouring the last piles
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September 2024

Slips A1 and A2 – Capping beam is complete
Slip A4 –Anchor installation underway
Slip A6 – Anchor installation continues. The guardrails have been covered to protect them during drilling
Slip A7 – Piling is complete with dig out, and wooden lagging is nearing completion
Slip A8 – Drilling the final pile
Slip A9 – Anchor installation
Slip A10 – Pavement and drainage is complete, and the guardrail is being installed
Slip A11 – Road reinstatement is complete
Slip A12 – Subbase being installed
Slip A26 –The wall is now complete, and road reinstatement is underway
Slip A47 – The crew installing the casing and H-piles
Milling of the old road surface in preparation for new asphalt to be laid between slips A8 and A9
With the completion of piling on A8, we are now saying goodbye to much of the equipment used for the piling repairs. Here, the last of the smaller drill rigs awaits collection
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August 2024

Slip A4 – Capping is now complete, and anchors have commenced
Slip A10 – The upslope stormwater chutes installed as part of the stormwater upgrades
Slip A7 – The final H-beam pile has been installed for this site
Slips A1 and A2 – Formwork being installed for the capping beam
Slip A26 - The concrete panels been installed and the ground behind the wall backfilled. The next step is reinstating the road
Slip A6 - Anchor installation has now started
Slip A3 – Guardrails have been installed. Last step – pavement and disestablishment around the site
Slip A11 – Pavement installation is underway to reinstate the road. Barriers are in place to ensure our teams are working outside of the buffer zone
Slip A12 – Complete and ready for the pavement crews, with A27 on the right-hand side complete
Slip A13 – Anchor teams ballet as they install the anchors
Slip A47 – The crew installing stormwater and sediment controls around A47
Slip A5 – Guardrails have been installed. Last step – pavement and disestablishment around the site
Slip A8 – Piling in the narrow carriageway
Slip A9 – Installed anchors before testing and trimming
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July 2024

Slips A1 and A2 - SR-45 piling rig during night works
Slips A1 and A2 – Crane setting up the tremie extensions to assist with the concrete pour
Slip A3 – Guardrails have been installed
Slip A4 – Drilling the final pile and setting down the tremie rack after the concrete pour at the same time
Slip A6 – The finished product - the capping beam has been poured and anchor installation is up next
Slip A7 – The team are set-up and drilling the first H-beam pile
Slip A8 – Pouring one of the ‘test’ piles
Slip A9 – The team are set-up and have begun drilling the anchors
Slip A11 – Rocks being delivered to begin the rock spall wall
Slip A12 – Anchors being installed
Slip A13 – The scaffolding works platform installed ready for the anchor machinery to start installing anchors
Slip A26 –The concrete panels have arrived and are being placed at the southern end of the slip
Slip A47 – CPT (Cone Penetration Test) tests carried out and the area barriered off
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June 2024

Slip A12 – Anchors being installed
Slip A4 – Mangamuka rush hour. Space is at a premium with both piling and concrete pouring underway at the same time
Slip A13 – The final section of this capping beam being poured
Slip A1 and A2 – LB 24 Piling rig during night works
Slip A1 and A2 – Concrete pour underway on one of the piles
Slip A6 – Steel and formwork in place in preparation for the capping beam concrete
Slip A9 – The capping beam is now complete
Slip A11 – Stage 1 cut is now complete
Slip A26 – The last of the UC piles have been installed
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May 2024

Slip A3 – Anchors installed waiting for testing. This will be fully complete at the end of the month.
Slip A4 – Pile cages being installed.
Slip A4 – Pile casings being spliced and screwed in place.
Slip A6 – Pile cages being installed.
Slip A9 – First half of the capping beam has been completed. The second stage cages with the anchor portals can be seen at the top of the picture, ready to be poured.
Slip A11 – Excavation is well underway.
Slip A11 – vegetation clearance 30 April 2024.
Slip A11 – progress with excavations 14 May 2024.
Slip A12 – Anchors being installed.
Slip A13 – Completed capping beam at the bottom, installed cage in the middle and the final stage to be completed at the top of the picture.
Slip A26 – UC piling is continuing.
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April 2024

Slip A3 – Final anchors have been installed.
Slip A4 – Pile Casings screwed in place ready for piling.
Slip A6 – Night works drilling piles in preparation for the day team to install the reinforcing cages.
Slip A6 – Driving the lagging plates behind the piles using a giant compression hammer.
Slip A9 – Cages and formwork in place to pour the top half of the capping beam.
Slip A11 – Wildlife relocation is underway. The teams carefully clear the site of vegetation and relocate any wildlife that they find.
Slip A12 – Anchors are now being installed.
Slip A13 – Cages being installed in preparation for the first capping beam pour.
Slip A26 – Universal Columns (UC) being installed.
A kauri snail (pupurangi) crossing the road by the worksite.
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March 2024

Slip A3 – Anchors being installed
Slip A4 – Pile locations marked out for coring and casing install
Slip A5 – complete
Slip A6 – All casings have been installed and piling has begun
Slip A7 – Site preparation for the installation of the UC piles
Slip A9 – The bentonite plant has been set up at the northern yard to help stabilise the A9 piles
Slip A11 – Safety barriers in place around the work area to the right
Slip A12 – the capping beam is now complete
Slip A26 – Universal Column (UC) installed and waiting for concrete
Slip A26 – UC Column piles being drilled.
Slip A27 – All piling and precast installation are complete
The biggest rig currently on site, the Liebherr LB24 Drill Rig, being moved to slip A6 after completing Slip A3
Rain rain and more rain
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February 2024

Slip A3 – formwork for the capping beam has been installed
Slip A4 – enabling works are complete
Slip A5 – anchors being installed
Slip A6 – splice casings being installed during the night shift
Slip A6 – Spliced casings for installation. These have all now been fully installed.
Slip A9 – completed piles waiting for the capping beam cages to be installed
Slip A11 – 3D modelling of the area that needs to be cleared
Slip A12 – piling is finished, and the capping beam is nearing completion. Anchors will need to be carefully installed around A27 being built on the opposite side of the road
Slip A13 – permanent piles being installed
Slip A26 – Universal Column (UC) beams onsite for installation
Slip A27 (right) – platforms, Universal Column (UC) beam and precast wall installation
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January 2024

Slip A27 (right) – platforms, Universal Column (UC) beam and precast wall installation. Work has to be carefully coordinated around the A12 and A13 slip repairs
Slip A26 – coring has been done in preparation for the piles. However, work has been temporarily paused to allow access to other operational sites
Slip A13 – permenant piles and casings being installed
Slip A12 – installed section of capping beam. The holes are where the ground anchors will be installed
Slip A10 – test anchors being installed
Slip A9 – reinforcing cages that were lowered into the pile hole and filled with concrete. There may be 2 or 3 of these spliced together in a single pile
Slip A6 – enabling works are complete and permanent works are underway. Here you can see the temporary piles and the layout for the permanent pile casings
Slip A5 – capping beam and work platforms are in place
Slip A4 – enabling works were completed over the holiday period. Here you can see the capping beam being installed
Slip A4 – enabling works were completed during the holiday period with 102 piles installed in just 6 days!
Slip A3 – preparation for the capping beam to be installed
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December 2023

Slips A12 and A27 - these slips present unique challenges, as work on both needs to be undertaken at the same time
Slip A27 – platforms and Universal Column (UC) beam installation is ongoing. UC beams are H shaped columns that the precast concrete retaining panels slot into to form the wall. This design was successfully used during the 2020 repair
Slip A26 – stormwater and drainage upgrades are complete with the permanent work platform installation beginning
Slip A13 – permanent piles are being installed. The enabling works can be seen behind the permenent piles. The enabling works will support the heavy machinery required for the permenant works.
Slip A12 – capping beam on the upper section is being installed
Slip A11 – while it may not look like much, A11 is a sizable slip area over several hundred metres and 21m deep
Slip A9 – permanent works are underway including piling, cages and concrete being poured
Slip A6 – enabling works capping beam is complete. Spall walls and drainage upgrades are underway
Slip A5 – the final level of the capping beam is now being installed
Slip A4 – enabling works are underway. Due to the access constraints, work on A4 will continue over the Christmas break
Slip A3 – reinforcement cages being installed prior to concrete being poured
Mangamuka Summit - weekly health and safety toolboxes are held with the whole team as part of the ongoing commitment to keep everyone safe
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November 2023

Slip A5 – the capping beam is now being installed. PVC pipe has been installed to support the installation of the ground anchors once the capping beam is installed.
Slip A3 – permanent piles being poured. The tremie pipe in the middle is used to pour concrete to the bottom of the pile and push any water at the bottom up to a level where it can be sucked out.
Slip A3 – permanent piles being poured. Movement around site can be challenging while major tasks like concrete pours are underway.
Slip A6 – enabling works are nearing completion with the capping beam being installed
Slip A9 – permanent works have commenced with casings being splices and secured
Slip A26 – slot drains
Slip A12 – capping beam is being installed and A13 permanent piles are underway
Slip A27 – foundations and Universal Column (UC) beam installation has commenced
Slip A27 – platforms and Universal Column (UC) beam installation has commenced
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October 2023

Slip A6 - enabling and drainage works are continuing
A third large piling rig arrived on site, meaning that we are now able to complete the larger permanent piles on three sites at a time
Slip A3 - permanent pile casings have been spliced and are being installed
Slip A5 - piling and lagging plates have been installed. The capping beam is now being installed.
Slip A9 - permanent works have commenced with casings currently being installed
Slips A1 and A2 - casing installation is complete. Completion of the piling is scheduled for after several more critical slips have been completed
Slip A12 - concrete pouring for the permanent piles is complete and work will continue on to Slip A13
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September 2023

Example of the TARP controls that are constantly monitoring ground movement to keep our teams safe
Example of the TARP controls that are constantly monitoring ground movement to keep our teams safe
Example of the TARP controls that are constantly monitoring ground movement to keep our teams safe
Mangamuka Gorge slip map that shows the locations of all of the current slips in the Mangamuka Gorge
Slip A1 and A2 - piling sleeves installation is now complete
Slip A3 - permanent pile casings are being spliced and installed
Slip A5 - permanent piling is nearing completion
Slip A6 - enabling and drainage works are underway
Slip A9 - enabling works and environmental control reinstatement is nearing completion
Slip A12 - concrete for the permanent piling for 12 is progressing well
Slips A12 and A13 permanent piles. The piling rig and crane are in place and underway with the permanent works on A12
Water runoff is diverted into a series of clean industrial bins
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August 2023

Slip A12 enabling works - enabling works continue as the permanent works commence further down the hill
Slip A9 - enabling works piling is nearing completion
Slip A1 and A2 permanent piling - night works are underway to install the pile sleeves in preparation for the main piling rig
Slip A12 and A13 - piling rig and crane for the permanent piles are now underway
Slip A12 - piling rig and crane for the permanent piles are underway
Slip A12 - permanent piling is underway
Slip A12 and A13 permanent piles - the piling rig and crane are now in place and underway with the works
Slip A5 - the capping beam for the enabling works is now complete
Slip A1 and A2 - permanent piles casings installed
Slip A3 - permanent pile casings have been installed
Slip A8 - eight other rock spall walls are being installed along the site
Slip A12 piling - some piles are up to 27m deep
Long tailed bat - pekapeka-tou-roa (chalinolobus tuberculatus) - Image Sabine Bernert (Department of Conservation)
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Enabling work

Aerial image of enabling work being carried out at slip 5 - May 2023
Work progressing at slips 12 and 13
Work progressing at slips 12 and 13
Work progressing at slips 12 and 13
Team toolbox meeting where the crew comes together to plan the day ahead and talk about health and safety requirements
Slip 9 - April 2023
Progress on Slip 5 – 25% of the piles have been installed at this location - March 2023
Progress on slip 3 – all of the temporary piles have been installed and approximately 50% of the permanent piles
Levelling work at Slip 9 - March 2023
Levelling work at Slip 9 - March 2023
Improved drainage near slip number 12
Earthworks at slip 5 - March 2023
Crews working at slip 5 - March 2023
Capping beam installation on Slips 1 and 2
A pile ready to be installed at slips 12 and 13
North Auckland worms (some up to 70 centimetres long!) were found during our biodiversity walkover
Several pupurangi (Kauri Snail) were found during a biodiversity walkover and safely relocated deeper into the forest
A kēwai (freshwater crayfish) which was found and relocated during a biodiversity walkover
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Emergency protection work

Crews installing bunds around slips to divert rainfall and prevent further movement
While this hole may look small, the road has actually fallen away beneath the road surface almost 2 metres deep and 4 metres wide
Crews preparing to install drainage on the southern end of the Mangamuka Gorge
Crews installing culverts under the road to to collect the rainwater running off the hillside and ensure it doesn't impact the road surface
Crews have removed loose debris and have stabilised the big slip above the road on the Southern end of the gorge to prevent further material falling
Bunds and crack sealing completed around one of the slips on the southern end of Mangamuka Gorge
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August 2022 slip damage

An underslip on the northern end of Mangamuka Gorge
An underslip on the northern end of Mangamuka Gorge
A large overslip on the southern end of Mangamuka Gorge which has now mostly been cleared
An underslip on the northern end of the Mangamuka Gorge
An underslip on the Southern end of the Mangamuka Gorge
Geotechnical investigations underway on one of the main underslips on the northern end of Mangamuka Gorge
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Works underway

Road surface work between new upper and lower retaining walls at main slip (eight) - May 2021
Upper retaining wall in progress at main slip (eight) - May 2021
Upper retaining wall and new road alignment at slip three - May 2021
Small lower retaining wall and pavement work at slip seven - May 2021
New road alignment at slip five - May 2021
Drilling anchors into lower retaining wall under roadway at main slip (eight) - May 2021
Lifting beams and concrete panels into place for upper retaining wall at main slip (eight) - May 2021
The big rig and crane arrive to install permanent piles up to 20m in length - November 2020
Staff observing installation of temporary piles - October 2020
Medium sized rig at work installing 8m piles - October 2020
Work begins to install piles under the road at the main slip - 30 September 2020
Work begins to install piles under the road at the main slip - 30 September 2020
Work begins to install piles under the road at the main slip - 30 September 2020
Casing going in at the main slip - 24 November 2020
Night works at the main slip - 1 December 2020
Drone image of main slip - 4 December 2020
Drone image of main slip [2] - 4 December 2020
Pulling down road closure barrier to open road for holidays - 18 December 2020
Road open for the holidays past the main slip - 22 December 2020
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Slip areas

1950s image showing an old slip that sits above the main slip site
Second slip aerial view
A major slip that has been cleared
Mangamuka Gorge second biggest slip
Mangamuka Gorge main slip from below
Main slip aerial view
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Official detour map

SH1 Mangamuka Gorge official detour map
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