Cement supply company convicted, fined after ‘flash fire’ at Picton plant injures three workers

Picton’s cement plant. – Photo via Heidelberg Materials

An Alberta cement supply company, Lehigh Cement Limited, now operating as Heidelberg Materials Canada Limited, has pleaded guilty and been fined $190,000 after workers were injured in September, 2021 at the Lehigh Cement plant in Picton.

The court also imposed a 25 per cent victim fine surcharge as required by the Provincial Offences Act. The surcharge is credited to a special provincial government fund to assist victims of crime.

The date of conviction was Nov. 15, 2023.

A provincial news release explains that on Sept. 7, 2021, workers contracted from a different company were doing maintenance work at the Lehigh Cement plant. A kiln that had been running on coal dust was set to be switched over to natural gas in order to allow maintenance workers to change the jet air blower in the coal feed system.

In order to remove the jet air blower, workers were required to turn off the kiln’s swirl air fan, located in the same area as the jet air blower that was being removed. The swirl air fan had two valves that needed to be closed before the kiln could switch to natural gas. The purpose of the valves was to prevent natural gas from backing up into the coal system. The two valves were redundant, so that only one needed to be closed to prevent a gas backup. A malfunction with one of the valves would mean the system would keep operating with just one valve rather than shutting down.

When workers attempted to shut both valves, one would not close. An electrician from Lehigh Concrete overrode the signal from the stuck valve so that it would show as closed on the computer program, allowing gas to flow. A second Lehigh Concrete electrician saw the difference in valve position and overrode the signal for the second valve as well, allowing both valves to be open despite showing as closed on the computer. When gas began to flow, it was able to flow through the open valves into the area where the maintenance workers were replacing the jet air blower.

Gas accumulated and caused a flash fire, injuring three workers.

“A reasonable precaution to protect the safety of the maintenance workers would have been to ensure that both valves of the swirl air fan were closed before allowing natural gas to flow into the system,” reads the release.

As a result, it was found that Lehigh Cement Limited, now operating as Heidelberg Materials Canada Limited, failed, as an employer, to take every precaution reasonable in the circumstances for the protection of a worker, contrary to section 25(2)(h) of the Occupational Health and Safety Act.

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