A sinkhole that keeps opening near a Glace Bay, N.S., apartment complex has residents worried they're living above an old bootleg coal mine.

Jessica Bainbridge lives in one of the buildings. She said the hole first appeared last year and was a metre in diameter. Metcap Living, the owner of the four-building complex on Dominion Street, filled it with loose rocks and refilled it again in January.

On Monday, it opened up once more.

"It opened up to about a metre wide, the next day it was a metre and a half, and the day after it was just under two metres," said Bainbridge.

She and some others in the apartment complex wonder if the sinkhole is being caused by an old illegal mine. While the locations of official mines are known, the many bootleg mines poor people once dug for coal to sell during hard times are not.

'It's a Band-Aid'

Cathy Crosby, who also lives in the complex, said simply filling in the sinkhole with gravel is not a solution.

This is what the sinkhole looked like. (Submitted by Jessica Bainbridge)

"They need an engineer with ground-penetrating equipment to come in and assess the situation. Someone independent, not connected to Metcap. They filled it in now, but that's not fixing it, it's a Band-Aid," she said.

Metcap Living does not have a Cape Breton office; the closest office is in Dartmouth. The company said it didn't know about the area's history of unmarked mines.

The company said it has hired an engineer to to do an underground assessment.

'I've actually had nightmares'

The uncertainty surrounding the sinkhole has Crosby and Bainsbridge worried about the safety of everyone living in the building.

"People in here have grandchildren and pets. If it's underneath the building, what's to say there's not going to be a tragedy, with a building collapsing into a sinkhole?" said Crosby.

"I've actually had nightmares about the apartment breaking off outside of my bathroom, because I'm on the far side, and the rest of the building going into a cavern underneath," said Bainsbridge.