Explosion at Laakso Hospital construction site in Töölö, Helsinki deemed preventable according to report

An explosion accident at the Laakso Hospital construction site in Töölö, Helsinki, in August could have been avoided, according to the Southern Finland Regional Administration. Two workers were injured in early August when an unexploded ordnance, leftover from previous excavation work, detonated at the site. Explosive and excavation activities had occurred from May 6 to May 22, with the area that caused the incident being primed on May 20 and detonated on May 22. As a result, the unexploded device had been in place for over two months.

A report from the administration indicates that the accident was preventable if it had been ensured that all explosives had detonated and that any remaining unexploded ordnance was removed. Following the incident, the excavation team leader informed the administration that unexploded ordnance would have been identified if the site had been deemed safe using an explosive-detecting dog.

The report also noted that the uncontrolled explosion could likely have been avoided by using less sensitive detonators. Multiple explosives were set off at once, interconnected in series. The excavation supervisor provided a report suggesting two possibilities for why the ordnance did not detonate: either the explosion of a nearby device interrupted the firing sequence, or there was a technical fault in the detonator.

The administration could not reliably assess the performance of the detonators since the device log file has “disappeared,” and there is no comment in the report explaining how this could have happened. It was noted that the explosion occurred due to rocks being dislodged from the site’s rock face by an excavator, injuring the operator from flying debris. The report suggested that additional shielding on the excavator’s windshield may have mitigated the injury, although the injured operator considered this more theoretical than practical.