A retired mining engineer is worried about what could happen when — not if — the roof of the Bell Island mine collapses.

Peter Young's house in Portugal Cove-St. Philip's, just west of St. John's, offers spectacular views of Bell Island, but he's concerned about what lurks beneath the bottom of Conception Bay.

Young told CBC Radio's On the Go this week that tunnels under the abandoned mines, going down as far as two kilometres, hold the potential for a large-scale disaster.

My suggestion would be to open up, at the shoreline, some openings into the mine. - Peter Young

"Eventually we're quite sure they'll fall, because you can't leave a lot of big open spaces and have the earth allow them to stay open," he said.

"The question really, is this a Chicken Little problem where you say the sky is falling — or is this something that we needn't worry about for perhaps a hundred years?"

Bell Island is located in Conception Bay, on the northern part of the Avalon Peninsula. The island's iron ore mines closed in the 1960s. (CBC) The method of mining that was used saw large pillars of rock installed to keep the roof of the mine up. About 35 per cent of the rock is left in its place while the rest was mined and taken out.

"But the problem really is that originally, the roof in the mine was quite safe. We're beginning to see failures occurring, and the failures are that the water level in the mine is now appearing to follow the tidal movements in Conception Bay," Young said.

"The effect of that is that clearly there's some failure occurring between the mine roof and the ocean floor. The question is how big is it? Is it going to grow, is it going to remain? We just don't know."

Young said the rock pillars were satisfactory when the mine was in operation, but are now insufficient, what with moving water as well as seawater flowing in and out.

"If you think about it, if the tide in the mine rises and falls by about one foot, the mine is five kilometres wide and two kilometres deep, there's an awful lot of water that's moving in and out every tide ... and so therefore there is serious concern about roof failure," he said.

Potential domino effect

When asked what would happen if the roof failed, Young said since most of the pillars are underwater, it would be difficult to get an exact measurement.

"That's the problem. But from my experience in mining elsewhere, it would appear to me that if one pillar failed, this would then throw a load on the adjoining pillars and they may fail, so there's a possibility, a very small possibility, of a massive collapse of the mine," he said.

"Clearly I hope it doesn't happen, but we have to consider it. I see a sequence of events happening which I hope don't happen, but nevertheless, first of all the collapse would initiate locally an earthquake. We would feel shock and vibration all around Conception Bay," said Young.

Young said if the mine roof collapsed, the water presently in the mine would be forced out of the two open entrances to Mines 2 and 4.

"And if you look at it, the amount of water there is almost sort of a cubic kilometre. The secondary effect is that the water level in Conception Bay around the mine would drop — and unfortunately that's the beginning of a refilling, which would occur in the form of a tsunami from the open ocean."

Comparing to the tsunami of 1929

Young, referring to the tsunami of November 1929 on the Burin Peninsula, said, "It doesn't require a very big disturbance under the water to set up a pretty serious problem on the shore."

"I had a chance to speak to some officials in the department [Resources], and they're certainly aware of this and presumably will tackle it themselves, but I'm hopeful that it's a minor problem. I don't want to alert people like, the sky is falling, it isn't — but we have to be prepared for this eventuality."

Young said the Bell Island mine is similar to the mining operation he worked with in Zambia, in central Africa.

'First of all the collapse would initiate locally an earthquake. We would feel shock and vibration all around Conception Bay.' - Peter Young

"We deliberately pulled out one of the pillars, allowing the other pillars to collapse and allow the roof to come down, but that was done deliberately and under control," he said.

"Most of the mine is away from the Town of Wabana. The effect in Wabana and even elsewhere on the island is going to be potential for serious flooding."

While Young is not sure a roof collapse won't happen, he believes potential serious problems can be prevented.

"My suggestion would be to open up, at the shoreline, some openings into the mine," he said.

"The mine tunnels are in the order of 200 to 300 feet down at the shore level, and this would allow during a collapse the water to flow out into Conception Bay and not onto the island."