Silo explodes at ready-mix plant...The top (cap) of the silo was thrown into the air, across a road, landing in an adjacent property. Fortunately, no injuries occurred as a result of this incident.

1. Health & Safety Alert
November 2018
Silo Explosion
Silo explodes at ready-mix plant
On November 5, 2018, an explosion occurred at a ready-mix concrete plant owned by a
Lafarge Joint Venture company in Nova Scotia, involving a fly ash storage silo installed on the
property. The top (cap) of the silo was thrown into the air and travelled over the road, landing
in an adjacent property. Fortunately, no injuries occurred as a result of this incident.
Upon investigation, it was found that the 90-ton steel silo, originally installed in 1985, was only
filled to 1/3 of its capacity at the time of the event. Initial indications suggest over-
pressurization and inability to release pressure may have contributed. An investigation to
uncover the root causes related to this failure is currently underway.
What have we learned from this incident?
Regular inspection and maintenance of storage silos in our ready-mix operations is critical for
the continued safety and operational efficiency of our plants. Plant staff must complete a
daily inspection of all silos, ideally before batching activities begin, to ensure that deficiencies
that could impact the integrity of the silo, and thus the health & safety of people both on and
off the property are identified and corrected promptly.
It is equally important that cement tanker drivers arriving at ready-mix operation to unload
cement products into our silos are trained and knowledge of site-specific silo filling
procedures, including maximum blow-off pressures and shut-down procedures when upper
cut-off limits are reached.
Eastern Canada
November, 2018
Fig. 1. Image of the explosion, captured
by a member of the public
Fig. 2. Image of the top of the silo, at its resting place
across the road from the ready-mix plant.

2. Health & Safety Alert
November 2018
Silo Explosion
What do we do now?
In light of this event, all Lafarge ready-mix operations in Eastern Canada are advised that the
following actions are required with respect to all storage silos in use on their properties:
 Signage indicating maximum blow-off pressures must be posted at all silo filling points,
and communicated to cement tanker drivers upon arrival at the site and prior to
unloading. In most cases, blow-off pressures should not exceed 12 PSI;
 Dust collectors must be viewed daily while in operation, inspected monthly and
serviced regularly, according to schedules listed in the Plant Maintenance Logbook;
 Pressure relief valves must be installed on all storage silos to allow accumulated
pressure to dissipate so as not to create a risk of silo explosion. It is recommended
that relief valves are inspected regularly and a secondary safety cable be installed on
the pressure relief valve cap to prevent the cap from being ejected in the event of an
over-pressurization;
 Plant staff must ensure that there is adequate capacity in the silo to receive the full
cement load, before unloading begins. Cement tanker drivers must be reminded upon
arrival that silo filling must stop immediately if alarms sound or high-lights illuminate;
 All daily, monthly and annual inspections of the cement storage systems (silos) must
be recorded on the Plant Maintenance Logbook, and deficiencies logged and actions
tracked to completion; and
 Plant staff must periodically walk their yards and check in with cement tanker drivers
during off-loading to ensure all applicables rules are followed.
Please ensure this type of incident cannot happen in your site!
An ALERT provides information to Lafarge operations concerning a health & safety incident that
occurred within Eastern Canada. The ALERT contains preliminary findings from incident
investigations that may be subject to change. Lafarge’s ECAN Health & Safety Department
issues such ALERTS to all sites in order to promote rapid learnings from such incidents and to
further our commitment to health & safety performance improvement and injury avoidance.
For more information, please contact the Eastern Canada Health & Safety OR RMX
Manufacturing Department
Eastern Canada
November, 2018