The newly released price tag for a citywide composting program has made Mayor Naheed Nenshi question the wisdom of Calgary’s mission to cut landfill use.

The new organics processing facility, equipment and other startup costs will be $158 million, beyond the annual $35 million to run a green cart service that begins in 2017, a city report states.

Taken with project savings from picking up black carts less often, the monthly cost of composting will be about $6.50 per household, Calgary’s waste and recycling director Dave Griffiths said.

Asked about these numbers Friday, Nenshi questioned the whole premise of the city goal of keeping 80 per cent of all waste out of city landfills by 2020.

“I’ve asked the question very clearly: if we don’t have the same kind of landfill constraints that they have in places like Toronto, why are we doing this?” the mayor said in an interview.

“Can we quantify the environmental benefit? Can we quantify the social benefit and can we quantify the financial benefit? Because it’s a lot of money.

“If the answer’s only that we need to divert more from the landfill, that’s not a good enough answer.”

The mayor, who wasn’t on council a decade ago when “80/20 by 2020” became the waste management mantra at city hall, insisted he doesn’t want to suddenly change course — unless research said Calgary should.

“I don’t know that there’s a lot of demand either from council or the public to do that, but I am always worried about path dependency,” Nenshi said. “I’m always worried that we’re doing stuff just because we’re doing it.”

His comments led Ald. Gord Lowe to caution against “short-term thinking,” and Griffiths to reason that Toronto is the horror story Calgary should strive to avoid.

Toronto, after running out of its own landfill space 11 years ago, had to haul trash to Michigan until 2006. But then the state closed the border to Toronto trash, and the city spent $220.3 million on a landfill in St. Thomas, Ont. — 200 kilometres from the city.

Calgary landfills have 30 years of capacity left at current rates, and Griffiths said he doesn’t want to have to buy more landfill space or come anywhere near the limit.

“Places like Toronto hit those walls. They had no choice,” he said.

There are also ever-rising costs of capturing landfill gases that come up and the liquids that leach down, Griffiths said.

Lowe expressed worry about greenhouse gas emissions and the risk of environmental cleanups or public health concerns like the city faced at its Spyhill Landfill.

It’s “the biggest liability the city faces,” said Lowe, an early advocate for composting and recycling.

“To simply say it’s too expensive and we shouldn’t do it is short-term thinking.”

Council will decide next year whether the green cart service and repaying the startup costs will be recouped through user fees or added into general taxes. Blue cart recycling is fully covered by a $7.40 monthly fee, while homeowners pay part of black cart garbage pickup through the $4.70 charge and the rest through taxes.