Canada-based Trevali Mining said on Monday that it was continuing dewatering efforts at Perkoa in its search for eight workers that went missing when the mine flooded on April 16.

The company has a three-stage dewatering plan, of which the first two stages – the repurposing of existing piping to start initial dewatering efforts, followed by the installation of additional underground pumping infrastructure to facilitate an increase in pumping capacity – are now complete and actively pumping. The third stage, which is currently in progress, involves the installation of 5 000 m of new piping and higher-capacity pumps to increase pumping capacity.  

"Our primary focus is the search for our colleagues and to do this we are getting pumping and other dewatering equipment where it is most needed," said president and CEO Ricus Grimbeek.

"The flood eroded the decline ramp that is the primary access to all levels of the mine and repairing this access ramp for safe use was a critical initial step in our efforts. With the completion of the decline rehabilitation to Level 520, pumping capacity has now increased, including the installation of a new 5 000-m pipeline to surface with multiple teams of welders dedicated to completing the assembly and installation,” he said.

The eight missing workers were working below Level 520 at the time of flooding and there has been no communication with these workers since soon after the evacuation order was given. There are two refuge chambers located below Level 520 that are designed to provide a refuge for workers trapped in a hazardous environment. Trevali said that it did not know if some, or all, of the eight missing workers were able to access these refuge chambers.

Mining and milling operations at Perkoa, in Burkina Faso, will remain suspended for the foreseeable future as the company investigates the cause of the flood event.