The industrial accident that killed two workers and injured several others at Domtar’s Windsor plant on October 26, 2021 was caused by a scaffolding design that had safety deficiencies. security.
Posted yesterday at 3:07 p.m.
This is what the Commission for Standards, Equity, Health and Safety at Work (CNESST) concludes in its 91-page report released on Wednesday.
The plant in the Estrie region was on extended shutdown to allow for maintenance work in the digester. To carry out this interview, scaffolding had to be installed.
The accident occurred when the scaffolding of 16 levels, in all 39 meters (128 feet), installed inside the digester, collapsed.
The accident caused the death of a welder and a handyman. Other workers were also injured.
The digester looks like a silo; it is pressure equipment in which wood chips and certain chemicals are mixed to form paper pulp.
It is completely emptied at regular intervals for preventive maintenance.
No less than eight companies were involved in the investigation, notes the CNESST. Domtar, a pulp and paper manufacturing and distribution company that employs 850 union members there, was the “client”. She had hired other companies for the scaffolding and maintenance work.
The CNESST report indicates that the first cause relates to the very design of the scaffolding.
The investigation of the structure reveals an “insufficient design safety factor”, as well as a mass of the scaffolding which was underestimated and the “absence of element stabilizing the post under level 7”.
“These three causes alone would be sufficient to cause the scaffolding to collapse,” reads the detailed report.
The second cause is due to a load that is too heavy to bear.
“The ultimate load of one of the rosette uprights is reached, which causes it to break and the scaffolding to collapse,” the report concludes.
“The collapse originated at the level of one of the four vertical posts located under the projecting floor of level 7. It was shown that this post, loaded in compression/flexion, was stressed at 121% if two workers were at the end of the floor, i.e. directly above the diagonal,” the report states.
After the accident, the CNESST had ordered the suspension of work, then ordered Domtar to develop a safe work method for erecting the scaffolding. “The company having complied with the requirements, the resumption of maintenance work has been authorized”, reports the Commission.
The CNESST will send a copy of its report to several bodies, including the Order of Engineers, the Association de la construction du Québec, the Association of building contractors, as well as the civil engineering faculties of universities.