Te Whare Wai Para Nuku hits new heights

While still a couple of years out from being fully operational, people passing Te Whare Wai Para Nuku, the sludge minimisation facility, at Moa Point will see huge progress on the site in 2025. 

In 2024 lots of the activity was in the ground or hard to see but over 3200m3 concrete (filling more than 500 trucks) was poured on the project. This formed the base of the building, and the bases and the walls of the digestors which are the height of a six-storey building now they are complete.

In January those tanks were being tested for leaks. 

Project Engineer Mark O’Hare explains how the test works: “We fill the tank with water, then measure to a certain level. Over time we monitor how much it drops by. If it drops by more than 10 millimeters, we need to check if it’s leaking somewhere. 

“The other test is if you see a leak, to check how bad it is. Concrete in time will heal itself, so we check if it’s healing and is nothing to worry about, or if it needs to be repaired.” 

A leak is not necessarily an issue, Mark says – in fact some are expected.

Because the tanks are 14.5 metres high, the water causes a lot of pressure. The concrete expands and different materials like calcium help fill the gaps, so the leaks close. 

It’s proposed the water from the first tank be re-used in testing the tank next to it.

Soon people will be able to see the stairs being built between the two digester tanks, and pipes that feed the digesters, then take the product created away. 

A big gas bag will also sit on top of each digester to capture methane produced by the digestion process which will be used to help power the facility. 

Sitting alongside the digesters is the main process building, where thermal hydrolysis and thermal drying of the sludge will happen. 

Project Engineer Devin Homan says a massive amount of design has gone into making the main process building likely to withstand a 1 in 1000-year earthquake. 

“Everything you do, the size of bolts, the size of steel or the concrete base, has all been increased to accommodate seismic requirements required when building in Wellington.” 

Devin says Wellingtonians will notice a big change in what they see on site. 

By the middle of the year the main process building will be at its full height and cladding on the outside of the building will be installed to make it watertight.  

“Then we can start putting the mechanical processes inside the building," he says. 

It’s going to be an exciting year for Te Whare Wai Para Nuku, as the project starts to see some of its unique mechanical equipment arriving on site and being installed – ready for the facility to be operational in late 2026/early 2027.