The long-awaited repairs to broken sewer pipes in Wellington are being described as "incredibly technically challenging work" that has never been done before in Australasia.
Trucks have been transporting human waste from the Moa Point treatment plant to the landfill since the pipes failed in January.
The cost of the repairs and trucking is expected to be at least $15 million.
A specialist team of engineers flown from Germany to complete the repairs have finished their 14-day quarantine and begin work next week.
Wellington councillor Sean Rush, who holds the water portfolio, said the repairs - requiring material to be pulled through nearly 2km of tunnel to line the walls - was very technically challenging.
"The fellows that are coming here they know what they're doing, they've done it before in different parts of the world," Rush said.
"But not here in New Zealand, not in Australasia and not during a level 3 pandemic lockdown. So all that adds to the complexity."
Rush said the engineers were heroes for coming here during a pandemic to do the work.
Wellington Water manager major projects Stephen Wright said the first of the two liners would go in early next week.
"Winching the liner carefully through the pipe is a tricky process. Once we get started, we can't stop until it's all the way through the pipe. That's about an 18-hour process."
He said there would be a considerable amount of noise from the winch at the Kilbirnie end of the tunnel that would likely carry on into the night.
"We're very grateful for the understanding of the community as we carry out this work.
"We'll do our best to keep everyone informed as we go.
"The prize is to be able to stop the sludge trucking; we'll know more by the end of next week about when we should be able to do that."
The second pipe liner has been made and will be on its way to New Zealand shortly. The technicians will remain in New Zealand until it arrives and can also be installed.