The Dunedin City Council says the chimney at the Dunedin Gasworks Museum is in worse condition than first thought. Photo: RNZ / Tess Brunton
Workers will start the careful, brick by brick dismantling of a historic Dunedin landmark - aiming to repair it and put it back together in the future.
The Dunedin Gasworks Museum was closed last month to assess the safety of the 25-metre tall chimney after possible earthquake damage.
Dunedin City Council owns the Category 1 historic place, and said a recent update found it was in worse condition than first thought.
The chimney - a relic of the country's only gasworks - has stood proud over South Dunedin since the 1800s.
But last month, an assessment found there was an imminent risk to public safety.
The latest news painted a grim picture: once work to repair the cracks got underway, the chimney might collapse.
Naylor Love is tasked with the urgent work.
Its project and interiors manager Paul Stevenson said it was a big job ahead.
"The cracks are appearing quite considerably. We're having corrosion inside the chimney, which is expanding, which is opening up those joints now," he said.
A crane carrying what looked like a skip hovered near the top of the chimney, as workers secured the walers - 12 metre long timbers - to minimise the risk of it falling down.
Naylor Love project and interiors manager Paul Stevenson. Photo: RNZ / Tess Brunton
Below the chimney is a no-go zone.
"We have to bring it down piece by piece, record it with the hope in the future of rebuilding it and the concern was if we didn't put the walers around we'd lose a lot of that ... it'll just naturally want to fall out," Stevenson said.
At least the top four to six metres will come down before the chimney is reassessed, but he was not ruling out more going if that was what it took to make it safe again.
He was working within tight rules because the gasworks is a Category 1 historic place.
"So we photograph, we pull them out, we number them, we record them, we bring them down, we put them on pallets and store them so we can, in theory, piece the whole thing back together," he said.
"Each layer, three bricks all the way around, also maintaining the ladder rungs that are in there and all that, we need to record all that with the hope of being able to rebuild it in the future."
Dunedin City Council property services group manager Anna Nilsen said it was trying to save as much of the chimney as possible.
It had been a difficult time for the Dunedin Gasworks Museum Trust, which operates the museum.
"It's not their best news, for sure, but they're supportive of the work that we're doing. They're supportive of keeping the bricks aside for future restoration so we're working together pretty closely," Nilsen said.
Last year, an engineering review recommended the council do a more detailed seismic assessment of the chimney.
Dunedin City Council property services group manager Anna Nilsen said detailed inspections had been carried out using drones and crane access. Photo: RNZ / Tess Brunton
Anna Nilsen did not believe the problems and risks should have been noticed earlier.
"The review that we did last year was a starting point so it was the beginning of a seismic assessment," she said.
"That first step was a desk based seismic assessment where it was just the start, we were getting ready to do the full seismic assessment which would have uncovered these things that we now know."
It was not known how much the work would cost, but she said it had to be done.
"I'd hate to give you a ballpark [be]cause I'd just be guessing at this stage. Look, it's health and safety. It's human life that we're talking about so we're always going to be able to find funds to do that and that's what we're challenged to do," Nilsen said.
The dismantling is expected to take about three weeks.
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