Forty miners were trapped underground at PotashCorp Rocanville after a magnitude 3.8 earthquake hit early on Labor Day Monday morning and knocked out power to the mine.
The earthquake took place at 4:40 a.m. Labor Day Monday, and was centred 32 kilometres southeast of Yorkton.
The PotashCorp mine near Rocanville had to switch to backup power when a power outage occurred.
Normally the mine’s backup generators would have switched on automatically, but in this case a switch failed and there was no power for the hoists.
Randy Burton of PotashCorp said the miners underground did as they were trained to do and went to underground refuge stations in the mine with power, air, and water until the power came back on.
The workers were then brought back up to the surface. The last person arrived at the surface at about 11:30 a.m. that day.
The power outage happened just as PotashCorp Rocanville was stopping mining operations for a maintenance shutdown.
“We’re just starting our annual maintenance shutdown, so this happened just by coincidence at the same time,” said Burton.
Everyone was all right after the incident.
SaskPower reported a widespread outage in the area that impacted Moosomin, Rocanville, Whitewood, Esterhazy, Stockholm and Wapella.
According to SaskPower, the quake caused problems at the Tantallon switching station, taking out power to about 2,000 residential customers.
This isn’t the first time an earthquake has been felt in the area. There have been 12 earthquakes in the region at magnitude 3.0 or higher since 1981.
Burton said the power outage normally wouldn’t cause any difficulty as backup power generation normally comes online automatically.
“Under normal circumstances we would have backup power which would kick back in when the main power goes out. We had a switch problem at the mine and so our backup generator would not kick in,” he said.
“I don’t know if we could run absolutely everything on it but in this instance it would be enough to run underground operations or certainly the hoist. And that was the issue—the emergency power to the hoist wasn’t available because our backup power wouldn’t kick in properly.
“It was an automatic transfer switch and it didn’t work. It faulted and shut the generator down. So we had to get that fixed which we did, and it took awhile.
“As a result, because we couldn’t run the hoist, we had about 40 people who had to stay underground for a period of several hours until we got the switch repaired.”
PotashCorp Rocanville employees were able to repair the electrical backup problem on their own.
The incident didn’t affect production.
“We were in the process of shutting down production anyway, because Rocanville is now on its annual maintenance shutdown,” said Burton. “That was scheduled to start on the same day. They were essentially trying the clear the decks for the maintenance shutdown.
“For safety’s sake the 40 people underground all went to one of the refuge stations—they’re essentially a big underground room. They are separate from the main shaft area. For example, in the event there is a fire underground it is a separate air supply. You are not part of the main shaft. There is a lot of room in there, water and a clean air supply essentially out of harm’s way there. That’s where the crews went and when the power came up they came up.”
He said PotashCorp employees are now reviewing how to avoid a similar situation in the future.
“Crews at the mine are now reviewing what’s happened here and we will take corrective action to hopefully prevent a reoccurrence in the future.
“We’ve got safety protocols—if there should be an incident of any kind in the mine that makes it unsafe to continue, then production shuts down and people go to the refuge stations if there is an issue of people having difficulty getting out, what ever that may be.”