NZ Transport Agency Waka Kotahi (NZTA) has reiterated that SH6 between Haast and Lake Moeraki in South Westland remains fully closed – next update Sunday 17 November, 5pm
Heavy rain overnight Friday and the weekend resulted in a significant number of slips in the Knights Point and Moeraki areas. The most significant issue is at the Epitaph Rift* and Epitaph Underslip sites where rockfall and road movement has occurred, says NZTA.
A large rockfall, releasing several thousand cubic metres of material came down overnight Friday. Access to the site was hampered due to other slips closing the road north and south of the site, and heavy rain and cloud reduced helicopter access.
“The initial inspection on Sunday identified concerns with unstable material above the road, the source of the rockfall material. This rock needs to be removed or stabilised to provide a safe worksite and road access. Immediate arrangements were made to have a rock scaling team establish on site first thing Monday morning,” says Mark Pinner, System Manager for NZTA in the Central Region of the South Island.
“After the initial assessment, a further rockfall occurred overnight on Sunday, creating a new scarp/steep bank. The roped access inspection Monday also identified that the rockfalls have destabilised the Rift feature in between, which means there’s significantly more scaling work that needs to be tackled before teams can come in to begin clearing rockfall from the rockfall catchpit. (See photos).
“A scaling crew, with a helipad established, is now working on removing loose and unstable rocks from these two new rockfalls, as well as the remaining unstable feature between, estimated to weigh five tonnes,” says Mr Pinner.
Any large rocks threatening to drop or roll onto the highway need to be prised loose or popped out using air bags or explosives. As of the end of Tuesday between 60 and 70 cubic metres of rock had been removed from the southern end of the site and vegetation concealing loose rock removed off the main bluff. There is still a lot of work to do to make this bluff safe before the road reopens, says Mr Pinner.
Before rock scaling starts – Tuesday this week, first full day.
The face after rock popping using airbags to remove unstable features.
Tuesday after the first day of scaling/rock removal, showing why people cannot be on the road while work is underway given the distance the rocks travel, bouncing over the highway into the bush.
The heavy rain also caused movement at road level at the Epitaph Underslip.
“While people may have seen photos of cracks in the road, the good news is that there hasn’t been any movement since recording started late on Saturday,” says Mr Pinner.
“We are continuing to monitor this part of the slope, with more active monitoring going in in the coming days. This will help us manage the site while work continues on a business case for more significant stabilisation work through the Epitaph area.”
NZTA needs to make the slope safe before crews can remove any of the accumulated material in the catchpit below and spilling out to the south. Some of this material will be used to create rock bunds to protect road users, the rest will be trucked away in coming weeks after the route reopens.
The team will continue scaling and preparing for blasting on Wednesday and through into Thursday morning. As much rock scaling/removal work as possible will be completed on Wednesday with checks made on any areas of overhanging trees to ensure no rock is dammed behind them.
Co-ordinating with the scaling team, drainage work at road level will also get underway this week. Cracks in the asphalt above the underslip area at the southern end will be filled, stormwater piped away from the site and a swale made more impermeable.
Heavy rain is forecast on Thursday and Friday with potentially 60-70mm over those two days. The ground is still saturated with elevated volumes of water flowing from the slip drainage, and the further rainfall will likely increase this further. “We need to take this time to understand how the site might react to the rainfall since the weekend movement,” says Mr Pinner. “There will be teams onsite monitoring, but it won’t be safe to work on the slope in these conditions. As soon as the site is safe after the weather clears, work will be underway again to make the slope safe.
“Confirming the programme ahead depends on how rock scaling goes through Wednesday and Thursday and how the rain affects the site. Once the bluffs are made safe enough for crews to work under them, we’ll be able to provide a better indication of when the road may re-open. Whether to not that will be Sunday or early the week after will depend on whether the large and unstable rock mass adjoining this section of highway can be safely removed. A further update will be provided as soon as this is understood.
“We do understand how important this route is for West Coasters and that it is a key route into and out of Otago for visitors but we also need to protect people from the possibility of another rockfall.
“At this stage most of the risk appears to be from above the road – the rift/split in the rocks - rather than the 2012 Epitaph Underslip but we will need to monitor the road in coming weeks and months to be certain there is no more movement.”
NZTA encourages all people planning on getting to the West Coast’s SH6 and South Westland to access it from either end – Makarora to Haast and Hokitika south as far as Lake Moeraki, while this work is underway.
The route into the glacier towns and further south as far as Paringa is fully open from the north/Hokitika on SH6.
Drivers can access Haast from the southern Otago/Makarora side of SH6.
People cannot drive between the two at this stage.
The section of highway north of Lake Moeraki to Paringa is open daytimes this week, between 9 am and 6 pm, but drivers are restricted to journeys on the hour with up to 60-minute delays. The next update for this section is Sunday, 17 November.
Ongoing slip clearance at five slips along Lake Moeraki is the reason for these daytime restrictions this week.
Outside of these hours, overnight, ie before 9 am and after 6 pm, this section of road will remain closed until slip hazards are fully cleared.
*A rift is a major fault/split separating blocks of rock/ land.
Below left: 3D model of the Epitaph site taken from the NZTA survey on Sunday 10 November, 2024 – courtesy WSP. The rockfall on the left, to the north of the site, is clearly visible with additional rockfall occurring Sunday night on the southern end.
Below right: is from 2022 when the last 3D model was done at the site for comparison, with the Epitaph Underslip, below road level present on both.
