CANMORE, ALTA. -- Canmore council began hearing public feedback on TSMV's vision for two large developments that could add up to 14,500 residents to the mountain town.

"It is so large and of such a scope that it will forever change the character of Canmore," says Tracey Henderson, an opponent and organizer of a loose coalition of community members concerned with the potential impacts.

Council will consider what the next steps are for Three Sisters Village and Smith Creek developments, which if approved, would be built out over the next 20 to 30 years.

"We've been very careful to listen for five years to collect these two plans together and make them happen," says Chris Ollenberger, director of strategy and development at TSMV.

A previous version of the plan was rejected in 2017, with council at the time asking for a more comprehensive plan that would allow them to understand what a completed project would look like.

"They wanted to see how we could address some of the towns' concerns on a number of areas such as affordable housing, co-existence with wildlife, climate change considerations," says Ollenberger.

However opponents to the proposal say it would restrict wildlife movement through the busy Bow Valley, create so-called "dark communities" consisting of mostly vacation homes and poses a financial risk because of underlying abandoned coal mines.

The mines left large underground rooms supported only by a grid of aging timbers. This has led to slumping and sinkholes around the former mining town in the past. Some opponents say they fear the town will be left paying for the cost of future collapses.

The developer says they've drilled more than 500 bore holes to help map and evaluate the risk of sinkholes, saying 60 per cent of the development area lies over the network of underground rooms.

Last year the province approved the developer's proposed designated wildlife corridor which critics said was too narrow and relied on slopes too steep for regular use.

TSMV says if approved the project will create 2,300 jobs during construction, paying $95 million in wages annually.

But former Canmore mayor Ron Casey said while vacation homeowners are an important part of the local community, benefits don't match the risks.

"You can't turn this back, once this is done you can't turn it back. You can't undo it," Casey said.

"Second home owners use their properties about 34 days a year," he said. "So that means they can't coach hockey and they can't coach soccer and they can't really be part of a neighbourhood."

Late Tuesday, a delegation from Stony Nakoda told councillors they had not been properly consulted on the plan and voiced their opposition.

Public comments are scheduled into next week. Once complete, council will consider the feedback and could either come back with requests for changes, approval, or deny the project outright once again.