More than a million litres of sludge has to be transported every day by truck from Moa Point Treatment Plant and the landfill at Carey's Gully. Photo / Georgina Campbell.
More than a million litres of sludge has to be transported every day by truck from Moa Point Treatment Plant and the landfill at Carey's Gully. Photo / Georgina Campbell.
Repairs to a major wastewater pipeline in Wellington have been delayed due to business restrictions imposed by the German government as part of its Covid-19 response.
In January, a pipeline failed in a wastewater tunnel beneath Mt Albert in Wellington.
As a result, more than a million litres of sludge has to be transported every day by truck from Moa Point Treatment Plant and the landfill at Carey's Gully until the pipeline can be repaired.
The sludge pipeline from the treatment plant to the landfill runs for 9km and consists of two pipes, which usually operate one at a time to allow for maintenance.
Wellington Water considered it "highly unusual" both pipes failed at the same time, especially because the infrastructure was only about 25 years old.
To repair the problem, a polyester woven liner will be winched from one end of each pipe to the other, then expanded to essentially act as a new pipeline within the old one.
The liner will be installed through the full length of the pipelines under Mt Albert, where they are most inaccessible.
It will be the largest-scale deployment of this technology in Australasia.
Once in Wellington, the estimated timeframe for installation of the pipe liner is eight days.
But Wellington Water chief executive Colin Crampton said due to restrictions on business imposed this week by the German government, delivery of the liners by the supplier has been pushed back.
"This is a high-quality, robust and resilient solution that will get the pipelines back up and running, and reduce the risk of further bursts.
"It's a high-tech specialist product which is not manufactured in New Zealand. Unfortunately, due to the importance of protecting their workforce and community from the spread of Covid-19, production at our supplier's factory has slowed."
At this stage, it's expected the liners will arrive in Wellington by mid-May.
"We appreciate the ongoing patience and understanding of the communities in the area. Trucking operations are not ideal from anyone's perspective, but they are successfully keeping millions of litres of wastewater from flowing into Cook Strait," said Crampton.
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The repair solution only has a working life of 10 years and a long-term approach to the failure will likely be to decommission the underground sludge pipes altogether.
"We are now developing alternative options for the council to consider, which would enable us to stop disposing of sludge into the landfill entirely," Crampton said.
Wellington mayor Andy Foster launched a mayoral taskforce into Wellington's water woes in February following a string of failures in the network over just a couple of months.
The task force officially met for the first time this week.
A Wellington Water briefing subsequently made public on Wellington City Council's website advised the taskforce that sludge represented 20 per cent of total waste into the Southern Landfill.
It said disposal rates recently increased by 400 per cent and odour from the landfill and sludge was affecting neighbouring properties.
