Rescue efforts have been ongoing since the April 16 flood, but there has been no communication with the missing miners and it is unclear whether any survived.
“Given the dry season, we obviously didn’t expect rain and we had absolute torrential rain,” said Hein Frey, vice president of operations at Trevali, adding that the water through the one of their bridges and broke the security barriers.
“It’s not just us who have been affected, it’s also the communities around us who are affected by completely unexpected rain,” he said in an interview with Reuters on the site.
The company immediately called for help and by the next day other mining companies in Burkina Faso had sent rescue teams and pumps, Frey said. Water is still pumped out of the mine.
While most of the workers were safely evacuated, the eight missing were below the 520 level, which is 520 meters (1,706 feet) from the surface, at the time of the flood, the company said.
There are two safety chambers with food and water supplies below this level, but it is not known if the men were able to reach them.
“There is always hope, but we also have to be realistic,” Trevali CEO Ricus Grimbeek said in a separate interview with Reuters.
“These chambers are not designed to be submerged in water. The chambers are designed for landfall accidents and where there are toxic environments such as smoke,” he added.
The company and the government of Burkina Faso have launched investigations to determine the causes of the accident.
“We have to understand what we have to do in the future so that what happened here never happens again,” said Mr Grimbeek.