They also say there is wider regional support, following calls for neighbouring councils to help subsidise costs on the project.
The comments came immediately after an official launch for the Te Kaha multi-use arena held at the Christchurch Town Hall on Tuesday.
Te Kaha project delivery board chair Barry Bragg said the cost burden was now with the building contractors BESIX Watpac.
"A significant portion of the risk sits with them," he said.
"They knew that coming into the project; that's why they were selected.
"They have experience in delivering these sorts of projects around the world, particularly in Australia.
"This is about a partnership and we've worked pretty closely with them and they're confident they can deliver."
ATVNZ Q+A Kantar public poll earlier this month revealed only 47 percent believed the project was good value for ratepayers.
Another 41 percent of the 500 surveyed disagreed and the remaining 12 percent did not know or refused to answer.
Bragg said the project's contingency should provide Christchurch ratepayers with some assurances.
"To be frank, we're paying for it, that's why we ended up with such a big project increase," he said.
"In this climate, we've paid to have that certainty."
Public consultation by the city council showed 77 percent wanted the stadium project to proceed.
This is despite average ratepayers being set to pay an extra $144 for two years from 2025 to pay for it.
Bragg said he believed Te Kaha would be a regional asset and confirmed there had been meetings with neighbouring councils.
When asked if he believed those councils should be making a financial contribution, he said it was a decision for "the city council to work through".
"We'll support all those efforts. If you take the results of the public consultation there is a fair amount of support from those regions as well.
"There's no doubt about it, the whole region, even the whole of the South Island, will benefit from this project so we'll see."
"We see this as a Canterbury regional project."
Venues Otautahi chief executive Caroline Harvie-Teare acknowledged local ratepayer fears.
"It's a scary big number and it wasn't one we expected in the early days," she said.
"But this is going to be a venue that our city can be proud of, it's going to do more than what it is probably promising at the minute."
Harvie-Teare said the central city will be transformed when the venue opened.
"This is going to be more than just a venue, this is going to be a precinct and there are going to be other activations which will change the face of that side of the city."
Te Kaha is expected to be opened in 2026.
