16 / Apr / 2020

International technicians arrived in New Zealand yesterday to help Wellington Water repair a critical wastewater sludge pipelines using an innovative high-strength liner solution.

Wellington Water Manager, Major Projects Stephen Wright says the five technicians, who arrived on the return leg of a German-government sponsored repatriation flight, are in 14-day quarantine in Auckland.

They will then be driven to Wellington to start work in early May aiming to complete the first pipe repair by mid-May and completing the project by the end of the month.

“Despite the ongoing Covid19 restrictions, we’ve committed to getting this fixed as one of our critical projects for the region,” says Mr Wright.

“Bringing these technicians out is an essential part of the project, and at a total cost of $12,000, it’s a small fraction of the costs for each day that the trucking continues.”

The two high-pressure pipes that carry sludge, a by-product of wastewater treatment, both burst in late January. This prompted 24/7 trucking of sludge from the Moa Point treatment plant to the Southern landfill dewatering plant.

Wellington Water has worked with a German engineering firm to design the innovative repair solution for the technically challenging repair job.

“The burst pipes are encased in concrete on the floor of a 1.8km-long tunnel deep below Mt Albert, in Wellington’s town belt. Added to that is the fact that the tunnel itself serves as a live wastewater pipe making it a highly difficult and dangerous space to work in.

“This is also the second time in seven years these pipes have failed. So, the solution that has been designed aims to not just fix the current bursts but provide greater strength to the whole 1.8km section within the tunnel.

“That is where the technicians come in. Once the burst section has been patched, they will insert the high-strength polymer liner, that has been custom-made in Germany, within each pipe. When connected and operating as designed, they should have a lifespan of well over 10 years.”

Mr Wright says the pipe lining process is complex, and preparations are already well under way at each end of the Mt Albert tunnel.

“All going well, with the specialists coming out of quarantine by the end of the month, the first pipe should be repaired and operational by the middle of May.”

To help bring the specialists here under extremely challenging circumstances, Wellington Water has worked with the Ministry of Business Innovation and Employment, Immigration NZ, national crisis management teams and Air New Zealand to take advantage of the specially arranged repatriation flights. 

The five technicians are currently booked to return to Germany in mid-June, this may change due to the changes in international flight schedules.