Andrew Simms and Lee Vandervis argued for the project to be either paused or stopped.
Sophie Barker, Carmen Houlahan and Jules Radich said development of the landfill should proceed as planned.
Cr Houlahan had first go at the Smooth Hill question, referring to an $80 million construction cost if contingency money is not used.
"And all the research and information we've had is that over the 20-year period, it's going to be way cheaper to keep it here and build Smooth Hill," she said.
"Also, we've had a lot of business owners ask us to keep it here as well, because they're afraid their costs will go up."
Cr Vandervis noted the figure included in the council’s 2025-34 long-term plan was $92.4m.
He appeared to expect Smooth Hill would end up costing more.
Mr Simms said he had put 400 hours of research into the issue, including reading the resource consent.
"I've been contacted by numerous other experts throughout New Zealand who believe that Smooth Hill will be incredibly expensive to operate because of its proximity to Dunedin Airport, and it will be under-utilised," he said.
"It is bonkers, and it needs to be reviewed, and it needs to be put out for full consultation."
Mr Simms said the council could use regional waste facilities at Kate Valley in Canterbury or Winton, Southland.
Cr Barker said it was important for the city to control its waste stream.
"Smooth Hill has been carefully looked at, carefully managed, carefully planned," she said. "To delay that would cost us more money."
Incumbent mayor Mr Radich said operating costs over 20 years at AB Lime in Winton could be double such costs at Smooth Hill.
Homelessness was another prominent issue discussed during the evening.
Mr Simms said, as mayor, he would pledge part of his mayoral salary and the car allowance to fund a dedicated homeless outreach service for Dunedin.
City council candidate Russell Lund received a series of shout-outs during the evening for his work in community housing.
