The buried corrugated steel tunnel in the boxcut to the portal of the Z55 underground mine at the Yaramoko project in Burkina Faso unexpectedly collapsed in April 2023 leading to a pause of operations. The direct cause of the failure was not determined but several bolts pinning two rings of the corrugated steel panels were sheared through with minimal signs of corrosion, which allowed 20 t of backfill material to force its way between the sheets, irreparably damaging the tunnel and blocking the single access decline. To reopen the mine, the backfill material around the steel tunnel was partially excavated to expose the damaged area but due to the short remaining mine life it was decided not to fully replace the steel tunnel, thereby leaving an open-air gap where the damaged panels were removed. This necessitated a geotechnical assessment and a plan for remediation works, involving the construction of sumps, diversion walls and earthworks to limit the impact of run-off from the sudden increase in catchment area of the new open boxcut. The designed remedial works were successfully completed, and a prism monitoring program put in place which has so far shown no signs of displacement even through rainy season. The failure highlights the need for proper installation practices of corrugated steel liners and periodic inspections of the panels which if performed may have caught the shearing and deformation of the bolts early enough to prevent the collapse.