Ōtaki Gorge Road slips
Ōtaki Forks and Tararua Forest Park is a taonga that has provided opportunities for recreation, education, fun, adventure, peace and much more over a very long time. It’s also on the Te Araroa Trail route.
Work is underway to clear the two slips.
The slip at Blue Bluff on Ōtaki Gorge Road is nearly cleared.
The clearing work revealed a natural spring on the cliff face. Engineers are designing a method to manage the spring's flow to prevent future slips.
The original retaining wall was found to be in fit-for-purpose condition, but an additional section needs to be built to support the road near a steep drop-off.
This extra work is likely to extend the project by a few weeks, with the road now expected to reopen in June or July.
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The slip on the Ōtaki Gorge Road at Blue Bluff - View larger image. [PNG 1.19 MB]
Restoring access
Slips on Ōtaki Gorge Road in 2020 and 2021 at the area known as Blue Bluff, closed the road to vehicles and pedestrians.
After a significant period of monitoring and investigation Council opted to proceed with reopening the road.
A range of options were explored and presented for consideration. These included:
- closing the road completely
- building swing bridges across the river
- building long-term walking access over the existing slips.
Staff recommended reinstating the road access and this option was adopted by Council.
More information on all the options and the proposed construction methodology for rebuilding the road is available in the Agenda for the Council meeting on Thursday 9 May 2024.
Timeline
- September 2020 – Slow slip detected at Blue Bluff, Ōtaki Gorge Road closed for safety reasons.
- Early 2021 – Geotechnical monitoring and investigation into restoring access to Ōtaki Forks commences.
- June 2021 – Heavy rain reactivates slow slip, causing significant deformation of the road and the slip face to slump into the river.
- October 2021 – The road stabilised enough to reopen part of it for a walking and cycling track along the wall side of the road. Site works had progressed to allow this to happen.
- December 2021 – Heavy rain on 6–8 December triggers over slip across the road. Cycling track destroyed.
- June 2022 – Walking track built to allow for monitoring and geotechnical work. Plans to open it to the public put on hold due to continuing instability on the over slip.
- 2023–May 2024 – Ongoing investigations into options for restoring access.
- May 2024 – Council adopts plan to restore road access.
- October 2024 Detailed design work finished. Consent applications lodged.
- Early 2025 Physical work to begin
- June/July 2025 Road due to reopen
About Blue Bluff
The Blue Bluff section of the Ōtaki Gorge Road, 12 kilometres inland from the Peka Peka to Ōtaki Expressway, is an area that becomes active during wet weather.
The road is on a steep embankment above the Ōtaki River, which is naturally degrading the riverbed and embankments. The Ōtaki Forks area receives intensive rainfall further adding to the challenges of this road.
- Council opts to re-open Ōtaki Gorge Rd at Blue Bluff (10 May 2024)
- Improving access to Ōtaki Forks (30 June 2022)
- Investigative work to restore access to Ōtaki Forks kicks off (20 April 2021)
- Ōtaki Gorge Road to remain closed at Blue Bluff for summer peak (3 Nov 2020)
- New damage at Blue Bluff, Ōtaki Gorge Road causing concern (25 Sept 2020)
- Minor slip cleared at Ōtaki Gorge Road (24 August 2016)
- Ōtaki Gorge Road reopens after seven-month closure (15 July 2016)
- Council urges people to stay clear of Blue Bluff slip (22 Feb 2016)
- Fresh slip at Blue Bluff, Ōtaki Gorge Road (20 Feb 2016)