Mayor Naheed Nenshi continues to question the viability of the Calgary Flames' proposal to build a new arena in the city's West Village area — refusing to even refer to it as a "proposal."

"The whole point is there's no proposal. It's just an idea," Nenshi said in a year-end interview with CBC News Calgary.

"There are a lot of economic questions that need to be answered first."

The group that owns the Flames and the Calgary Stampeders unveiled details in the summer of its $890-million plan to build a multi-use complex that would replace the Saddledome and McMahon Stadium.

To pay for the project — dubbed "CalgaryNext" — the group said it would aim to borrow $250 million (ideally from the city but possibly from a private lender) and repay it with a ticket tax on future events at the complex. It would also kick in $200 million of its own.

It's asking the city for a $200-million direct contribution plus $240 million from a community revitalization levy (CRL) — a sort of loan that is to be paid back by anticipated growth in property-tax revenues in the area in the future, resulting from the project and related development.

Public-use fieldhouse

For the city's direct share of the cost, the ownership group said it would build a public-use fieldhouse as part of the stadium component of the complex.

The city has been planning to build a new fieldhouse with an estimated price tag of roughly $200 million but has yet to identify a source of funding for the project.

But Nenshi said major questions remain about whether a CRL — a financing mechanism that was used to spur the East Village redevelopment — would be financial feasible in this instance.

In addition, he said there are outstanding questions about whether the site, located near the existing Greyhound bus station, could be feasibly prepared for any type of development.

Mayor Naheed Nenshi

Mayor Naheed Nenshi speaks with CBC Calgary News at 6 anchor Rob Brown in a year-end interview for 2015. (CBC)

Before any construction could take place, the site would need to undergo major remediation of decades-old creosote contamination in the soil.

"There's a lot of questions left to be answered but the No. 1 is whether this land is good for building at all," the mayor said.

It's unclear exactly how remediation of the site would be done and who would pay for it; the Flames ownership group is not offering to cover any of that tab as part of its current proposal.

What's next?

Nenshi said the city will openly weigh the pros and cons of the Flames' plan and the public will be asked for input throughout the process.

"It may well be the numbers just don't balance ... but it may be that we go a little further, and we'll do that with the public," he said.

"We have to be very, very clear that we're spending public money on public benefit," Nenshi added.

The issue is set to formally return before council in the spring.