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Blitz Results: Ground Control Blitz

Safe At Work Ontario
  • Issued: April 10, 2015
  • Content last reviewed: April 2015

Workers face health and safety risks from hazards that can lead to the collapse of excavated rock areas in underground and surface mines. These hazards can result in serious injuries, and even death, to workers.

In October and November 2014, mining inspectors and engineers conducted an enforcement blitz to check that Ontario mines have proper control measures in place to prevent the collapse of “ground” (rock) as well as to prevent “rockbursts” (bursts of rock from mine roofs and walls). They also looked at stockpiles and working faces at surface mines. In particular, they focused on the stability of the:

  • “face” (wall surface) where mining work is taking place in underground mines. For example, if a “drift” (tunnel) is being blasted to reach ore areas, the face would be the solid rock wall surface that lies directly ahead as blasting progresses to extend the tunnel
  • “slope” (edge) of a mound of mined material that has been dumped on the ground in open pit / surface mines

Inspectors checked that employers were complying with the Occupational Health and Safety Act (OHSA) and Regulation for Mines and Mining Plants.

The goal was to:

  • raise awareness of ground control hazards
  • promote compliance with legislation and best work practices
  • encourage employers to identify and control hazards
  • improve the health and safety of workers in underground and surface mines

Protection of mine workers is part of the government's continued commitment to prevent workplace injuries and illness through its Safe At Work Ontario strategy.

Report summary

Falls of ground and rockbursts are among the leading causes of serious injuries and deaths in Ontario mines.

Since 2000, 10 workers have died and about 47 workers have been critically injured in underground mines in Ontario as a result of falls of ground or rockbursts.

Hazards involving ground control mainly involve workers being struck by falling or toppling rock or by rock that is violently ejected from an excavation’s roof or walls. During the October and November 2014 blitz, ministry inspectors conducted 74 visits to 61 mining workplaces. Some of the mines were visited several times. Inspectors issued 228 orders under the OHSA, including 13 stop work orders.

As of January 13, 2015, about 85 per cent of the orders issued during the blitz had been complied with.

Full report

Workplace inspection blitzes

Inspection blitzes are part of the province's Safe At Work Ontario compliance strategy. They are announced to the sector by the ministry in advance, although individual workplaces are not notified in advance. Results are posted on the ministry's website. The blitzes raise awareness of known workplace hazards and promote compliance with the OHSA and its regulations.

Inspectors' findings may impact the frequency and level of future inspections of individual workplaces. Inspectors may also refer employers to health and safety associations for compliance assistance and training.

Blitz focus

Inspectors focused on:

  • recently reopened or new mines
  • mines where previous ground control hazards were observed
  • mines with a poor compliance history

They focused on:

Mine design: Inspectors checked that a proper engineering analysis had been conducted to predict issues that could lead to falls of ground and rockbursts in new or existing excavations in mines. This included how excavations would be dug out and supported. The analysis was to be conducted prior to the start of the excavation. Inspectors and engineers checked that adjustments were made to the excavation design if the analysis identified any potential problems.

Engineering report: Inspectors checked that a professional engineer had analyzed and prepared a report indicating an excavation would not endanger workers’ safety in cases where there was no ground support. The report’s findings were to be included in the mine design for work being performed in or around the unsupported ground.

In surface mines, inspectors and engineers also focused on:

Slope stability: Inspectors checked that stockpiles of loose material were being maintained at a safe angle of “repose” (natural slope). They also checked that the vertical height of the “face” was not too high and the face was not “undercut” (the floor was not formed of loose unpacked material that was less solid than the walls and ceiling). Inspectors and engineers also looked for hazards involving loose material created by blasting at the working face. Inspectors also confirmed that there was a mine design using sound geotechnical practices for metallic open pit mines.

Face hazards: Inspectors checked that supervisors had examined the face for any potential or actual hazard to workers' health and safety of a worker.

Inspectors took enforcement action, as appropriate, in response to any violations found under the OHSA or its regulations.

Inspection activity summary

Table 1: Blitz activity at a glance

Tableau 1 : Visites de mines
Inspector Visits 74
Workplaces Visited 61
Orders Issued 228
Stop Work Orders 13
Requirements 1
Orders and Requirements Per Workplace Visited 3.75
Orders and Requirements Per Field Visit 3.09

Order analysis

Orders were issued under the Occupational Health and Safety Act and Regulation for Mines and Mining Plants for various violations.

Table 2: Most frequently issued orders under the OHSA and Mining Regulations during the blitz
Reason for Order Number of Orders Percentage of Orders Issued During Blitz
Failure to ensure equipment, materials and protective devices provided by employer are maintained in good condition (OHSA S. 25 (1)(b)) 38 16.59%
Failure to take every precaution reasonable in circumstances for protection of workers (OHSA S. 25 (2)(h)) [1] 21 9.17%
Failure to provide safe means of access when workers are required to work, operate, maintain or service equipment (Mining Regulations S. 46(2)) 20 8.73%
Failure to perform work, as required, at face of surface mine (Mining Regulations S. 88) 12 5.24%
Stop work on any place, equipment, machine, device, article, thing, process or material until order is complied with (OHSA S. 57 (6)(a)) 11 4.80%
Failure to equip motor vehicle in mine with wheel chocks (Mining Regulations S. 107(1)) 10 4.37%
Failure to examine workplace for dangers and hazards before work begins and, if required, make safe (Mining Regulations S. 66) 3 1.31%
Failure to ensure mine design contains drawings, plans, specifications or procedures to be used and is prepared under direction of competent person (Mining Regulations S. 6(2)) 2 0.87%
[1] Three orders issued under (OHSA S. 25 (2)(h)) were related to working at the face.


The Ministry of Labour has undertaken a Mining Health, Safety and Prevention Review with a report to be delivered to the Minister of Labour in Spring 2015. An interim progress report in 2014 outlined a number of initiatives to improve health and safety in Ontario mines.

During the review, the ministry launched a risk assessment initiative in an effort to gain better insight into the risks facing workers in underground mines. Ground control hazards were identified as the hazard of highest concern by the workplace parties and, as a result was one of the five topics studied by the review’s hazards working group. The working group studied the effectiveness of current control methods in underground mines and how these methods could be improved.

In the future, the risk assessment result will focus on development of further training and guidance information on high risk topics such as ground control.

Conclusion and next steps

The results of this blitz confirm the ministry’s need to continue focused enforcement on ground control hazards in underground and surface mines.

Compliance help for employers

Please contact Ministry of Labour health and safety partners for more information on identifying, preventing and controlling these hazards.