Coroner concludes May excavation collapse in Blainville was accidental
A Quebec coroner has determined the death of a 31-year-old construction worker who was buried during a retaining wall collapse at a Blainville building site on May 20, 2025, was accidental.
Coroner Steeve Poisson concluded the worker, identified in earlier reports as Alexandre Paris, died from the combined effects of suffocation and mechanical asphyxia due to chest compression after being buried when a section of the wall gave way. The collapse occurred at about 11 a.m. on a two-storey underground parking excavation roughly 10 metres deep.
Recovery difficult because of unstable ground
Firefighters recovered the worker's body shortly after 8 p.m. that day. The coroner's report notes the recovery operation was hampered by continued instability at the site and that an engineer had to design a rescue procedure before recovery could proceed. Two other workers were partially buried in the same incident and were rescued.
A criminal probe was opened by Blainville police after the accident, but it did not result in charges.
Provincial investigation points to design and risk-assessment failures
The Commission des normes, de l'équité, de la santé et de la sécurité du travail (CNESST) also investigated the collapse and identified a combination of factors that led to the failure.
- Underestimation of earth pressures behind the retaining wall during design.
- Overestimation of the structural capacity of the soldier piles used to hold the wall in place.
- Inadequate assessment of collapse risk, which allowed workers to carry out tasks at the bottom of the excavation despite visible signs of instability.
Because of those findings, the CNESST ordered work to stop on the day of the accident until the contractor could produce confirmation from an engineer that remaining sections were safe. The regulator also required an engineer to draw up safe procedures for securing sections still in place, for debris removal and for how the reconstruction and continuation of work should proceed.
Coroner: no new recommendations as measures already in place
In his report, coroner Poisson stated that, given the safety measures already issued by the CNESST, he did not deem it necessary to make further recommendations.
"The death resulted from combined effects of suffocation and mechanical asphyxia caused by chest compression after burial," the report states.
The report reiterates the seriousness of excavation and shoring work, where miscalculations in design or risk tolerance can expose workers to life-threatening hazards within minutes.
Timeline
| When | Event |
|---|---|
| May 20, 2025, ~11 a.m. | Section of retaining wall collapsed at Blainville excavation; worker buried |
| May 20, 2025, evening | Other workers rescued; site remained unstable; engineer drew rescue plan |
| May 20, 2025, ~8 p.m. | Body recovered by firefighters |
| Following investigation | CNESST found design and risk-assessment failures; coroner ruled death accidental |
The findings carry implications for contractors, engineers and municipal authorities involved in deep excavations. The CNESST's conclusions point to technical shortcomings in geotechnical assessment and structural design — areas that typically involve engineers, site supervisors and the contracting companies that employ workers.
For Blainville residents, the case underscores the hazards associated with major construction in urban and suburban areas where deep excavations are common. It also highlights how provincial workplace-safety oversight interacts with municipal permitting and construction inspection, particularly when a collapse threatens public safety or disrupts neighbourhoods.
While the coroner did not call for new measures, the CNESST's directives to stop work and require engineer-certified safety plans remain in force for similar situations. The report may also inform how developers and engineering firms manage risk on future excavation projects in the region.
Questions about civil or regulatory follow-up beyond the CNESST orders — including any internal changes at the subcontracting company involved — were not detailed in the coroner's report.
