The final contract to build a new Wellington sewage sludge treatment plant has been signed.
The new facility at Moa Point is designed to significantly reduce the amount of sludge created through the treatment process - which reduces the amount going into the landfill.
The construction contract is a joint venture between Wellington City Council, HEB and McConnell Dowell Construction Ltd.
It is expected the project will stick to its 2026 completion date and cost $370 million.
Deputy Mayor Laurie Foon said it was great to have the final contract wrapped up for Christmas, as the facility was critical to Wellington's waste reduction and emission reduction goals.
"Currently, sludge must be mixed with general waste and buried at the landfill. Reducing the amount of sludge created through the treatment process means less sludge and less waste at the landfill.
"This facility is a key piece in the puzzle to enable the city to reduce general waste going to landfill by 50 percent by 2030.
"The new facility will also reduce the amount of emissions created through the treatment process by 60 to 80 percent, a huge drop and a great step towards our goal of being a carbon-zero capital by 2050."
Chief infrastructure officer Siobhan Procter said signing off the third and overarching contract for the project, within the price that council agreed to earlier this year, was a huge achievement.
"This is an incredibly complex project. What we're doing here hasn't been done in New Zealand before, so to get the contract signed, keeping things on track for completion in 2026, is a great way to wrap up the year."
The joint venture's project director Peter Hodgson said the signing of the final contract brought previous work together and set the project up to stay on target.
"We're committed to building something incredibly important for Wellingtonians. It's a hugely complex project, and a great opportunity for the wastewater industry and the city."
The product created through the new treatment process will be much easier to transport, and the city won't need to pipe raw sludge 9km through the city to Southern Landfill to be partially dried and buried in waste anymore.
In July next year a levy will be introduced to ratepayers as part of a financing initiative to support the construction of the facility.