Human waste sludge being trucked to treatment plant in southern landfill # update 2 (20/03/2020)

Carl from Brooklyn Residents Association Incorporated

High-tech repair solution for Moa Point pipelines delayed by Covid-19 response

"Wellington Water has worked with a leading international engineering firm to develop an innovative solution to repair the high pressure sludge pipelines between the Moa Point Wastewater Treatment Plant and the Carey’s Gully landfill. However the global response to the Covid-19 pandemic will delay its installation.

The repair presents a significant engineering challenge, as it must be completed within the 1.8 km section of the pipelines running through a tunnel deep beneath Mt Albert. The solution that has been developed is a polyester woven liner which will be winched from one end of each pipe to the other, then expanded to essentially act as a new pipeline within the old.

The liner will be installed through the full length of the pipelines under Mt Albert, where they are most inaccessible. This 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.

Wellington Water CEO Colin Crampton says due to restrictions on business imposed this week by the German government, delivery of the liner 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 the importance of protecting their workforce and community from the spread of Covid-19, production at our supplier’s factory has slowed.”

Mr Crampton says that current estimates are for the liners to 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,” says Mr Crampton.

Mr Crampton says the long-term approach should be to decommission the underground sludge pipelines entirely.

“The solution we have developed has a working life of 10 years. This provides an opportunity for Wellington City Council to receive advice on what is the best way to manage sludge going forward. We are now developing alternative options for Council to consider which would enable us to stop disposing of sludge into the landfill entirely.”

Alexander van Paassen Manager, Community Engagement
Wellington Water