A four-month-long operation to truck millions of litres of sludge to landfill, costing a whopping $650,000 a week, has finally come to an end.

Wellington Water has completed another major repair in the scramble to patch up the city's broken pipes.

In January, two pipelines failed in a wastewater tunnel beneath Mt Albert.

That resulted in more than a million litres of sludge being transported every day by truck from the capital's Moa Point Treatment Plant and the landfill at Carey's Gully until the pipeline can be repaired.

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The trucks have become known as the city's "turd taxis".

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Wellington Water issued a statement last night confirming the first of the two pipe repairs has been successful, meaning the trucking operation can stop and sludge can once again flow underground.

Mayor Andy Foster said it was a major achievement, particularly during Covid-19 lockdown conditions.

"Covid-19 created a number of challenges for these critical and highly technical major projects, from the border closure and disruption of international freight through to the need for social distancing protocols on-site. In that context, Wellington Water and its contractor partners have has done a fantastic job to reach these milestones."

The Government gave approval for five technicians from Germany to enter the country during lockdown to carry out the emergency repair job.

Documents show concerns were raised that a Covid-19 outbreak could spread through the drivers and see Wellington's sewage system collapse and vent, untreated, directly into the sea.

The 1.8km- long liner was manufactured in Germany and shipped to New Zealand under urgency for the repair during lockdown. Photo / Wellington Water
The 1.8km- long liner was manufactured in Germany and shipped to New Zealand under urgency for the repair during lockdown. Photo / Wellington Water

The 1.8km Mt Albert sludge pipeline required one of the largest-scale installations of the innovative pipe liner product anywhere in the world.

The operation took more than nine hours and a four-tonne capacity winch was set up at one end of the pipeline to pull through the liner.

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It has since been subject to extensive testing and given the all clear.

Wellington Water has previously estimated the repair cost could be as much as $5 million and the sludge trucking cost up to $11m, assuming repairs are successful by mid to late May.

Max Vollenbroich, of German firm Amex-Sanivar, helps guide the folded and taped high strength liner towards the sludge pipe. Photo / Wellington Water
Max Vollenbroich, of German firm Amex-Sanivar, helps guide the folded and taped high strength liner towards the sludge pipe. Photo / Wellington Water

Wellington Water Chief Executive Colin Crampton said it was a great result to have the first pipeline up and running.

"We're also deeply appreciative of the patience and understanding shown by the residents who've had sludge trucks going past their homes, which provided us the opportunity to repair the pipeline and ensure sludge did not have to be discharged to the ocean."

A woman living near the sludge trucking operation resorted to wearing face masks to deal with the stench.

Moa Point Rd resident Andrea Cootes said the smell from the sludge operation was revolting.

"It smells like someone's done a poo. I cried and thought if this is how it's going to be, I'll go and stay somewhere else, it's been that bad.

"And it's hot, so you want to leave your bedroom windows open, but I've had to close them because my bedroom smelled like a toilet."

The liner for the second sludge pipeline has arrived from Germany and preparatory works for its installation have already begun.

It is expected to be operational in about three weeks.