Mayor Brian Bowman's Executive Policy Committee has endorsed new seven year garbage and recycling contracts.
Starting in October of 2017, Miller Waste and GFL Environmental will take over collection from Emterra and Progressive Waste Solutions.
A report said the two deals could cost up to $251 million.
Department staff said the federal carbon tax could impact the overall price tag because both companies will use diesel trucks to deliver the service.
In a letter to the city, Emterra estimates a carbon tax would cost an extra $902,000 a year or $6.6 million over the lifetime of the deals.
CUPE and some councillors want the contracts put on hold in order to explore the option of bringing some of the collection back in house for city workers.
A Probe Research poll done for CUPE shows 58 per cent of Winnipeggers support a public model if costs were similar.
Water and waste officials said it would increase the costs by 25 per cent for city employees to provide pickup.
