This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply the law based on the facts in the workplace.

Purpose

The purpose of this guideline is to assist workplace parties with understanding the requirements under the Occupational Health and Safety Act (OHSA) and Regulation 854 (Mines and Mining Plants) regarding explosives storage and security in Ontario mines.

Objectives

The objectives of this guideline are to:

  • provide information to assist workplace parties to assess hazards relating to the storage and security of explosives at mines
  • reduce incidents relating to explosives, thereby reducing the risk of injury and illness to workers
  • provide guidance on what to consider when establishing and maintaining written procedures regarding explosives security, access, and inventory control

Legal requirements

Sections 121 to 129 of Regulation 854 set out the relevant requirements regarding storage and security of explosives.  Additional requirements for explosives are set out in sections 131 to 154 of the regulation.

Regulation 854 also requires all employers to conduct risk assessments of the workplace for the purpose of identifying, assessing, and managing hazards, and potential hazards, that may expose a worker to injury or illness. The risk assessment requirements are outlined in sections 5.1, 5.2, and 5.3.

Under these provisions, an employer must develop and maintain, measures to eliminate, where practicable, or control, where the elimination is impracticable, the hazards, and potential hazards, identified in the risk assessment. These measures must be developed in consultation with the joint health and safety committee (JHSC) and health and safety representative (HSR), if any. This would include any measures the employer has put into place to mitigate hazards associated with explosive handling and storage.

The results of these risk assessments should be considered in the development of measures to protect the health and safety of workers. The Ministry of Labour, Immigration, Training and Skills (MLITSD) has developed a Risk assessment and management for mines and mining plants guideline to help workplace parties understand how to identify, assess, and control workplace hazards.

Background

Explosives are used extensively in Ontario mines and can pose a hazard if not stored, secured, and used in a proper manner. Incidents have shown that worker safety can be compromised when measures for the control, security and storage of explosives have not been established. Properly stored blasting explosives, detonating cords and initiation systems will help ensure the safety and security of workers as well as the workplace itself.

Explosives can be generally considered to be any substance that is made, manufactured, or used to produce an explosion or detonation and includes:

  • gunpowder
  • propellant powder
  • dynamite
  • detonating cord
  • blasting agent
  • slurry
  • water gel
  • detonator

Explosives suitable for use underground

Subsection 121(a) of Regulation 854 requires that an owner of an underground mine must ensure that explosives are suitable for use underground. More specifically, no explosive may be used in an underground mine unless the Explosives Regulatory Division of the Department of Natural Resources Canada has determined it is suitable for use underground.  It is important to note that fume class, which is a measure of the amount of toxic gases produced by the detonation of explosives, is no longer assigned by Natural Resources Canada.

Explosives manufacturing companies are required to submit an oxygen balance calculation for explosives that are used underground where workers may be present after blasting has occurred. Ideally, to minimize the amount of toxic gasses produced, commercial underground explosives will have an oxygen balance that is close to zero and which will result in low fume generation. Based on these calculations, and if the criteria are satisfied, underground explosives packaging is labelled by the manufacturer as suitable for use in the underground environment. The markings on the explosives packaging will indicate “1-Suitable Underground”. 

To ensure the worker’s health and safety is protected, employers must adequately ventilate the workplace of post blast contaminants by means of mechanical ventilation systems in accordance with section 252 of Regulation 854 before workers are permitted to enter the workplace. For more information review the post-blast examinations in mines guideline.

For more information on explosives used in mining, see National Resources Canada.

Storage and security of explosives underground

Section 124 of Regulation 854 requires mines, in consultation with the joint health and safety committee (JHSC) or health and safety representative (HSR), if any, to establish and maintain written procedures to manage the hazards associated with the safe use, storage, transport and delivery of explosives used in underground mines. The procedures should clearly indicate the responsibilities of each workplace party from the owner of the mine to the end user that is loading explosives to prepare to blast.

To support the development of these procedures, mines need to conduct a risk assessment to identify mitigating controls for hazards associated with explosive handling and storage. The results of the risk assessment should be considered in the development of the required written procedures.

As a general matter, the written procedures required by section 124 must set out procedures concerning:

  • security of explosives (including during transport, delivery, storage and use)
  • the control of access to explosives
  • the control of inventory (including the return of, and the temporary storage of, explosives)

This includes:

  • how explosives will be secured during delivery
  • how to safely secure explosives in magazines
  • how to safely secure explosives in temporary storages
  • how to secure explosives being delivered from surface magazines to underground, including between their arrival at the shaft station and delivery to the magazine
  • how inventory will be controlled
  • how to return unused explosives

A copy of the written procedures must be provided to the joint health and safety committee or the health and safety representative, if any. The written procedures may be stored in electronic format in accordance with the Electronic Commerce Act, 2020, however they must be kept readily available at the mine site.  They should be revised and updated as required and should be reviewed at least annually.  All workers in a mine who use or handle explosives must be provided with information and trained in the applicable procedures, specific to the roles or responsibilities of each worker.

As noted, the written procedures required by section 124 must deal with how the security of explosives will be addressed. Among other things, security of explosives means that all explosives will be in the care and control of workplace parties as identified in the written procedures. The procedures should identify the measures of how explosives will be secured from the time of their arrival on site to the loading operation.  These measures could include:

  • providing physical observation so that explosives are not left unattended
  • using electronic surveillance such as cameras or entry monitors
  • fencing temporary storage areas to limit access
  • implementing access controls such as locks and keys or electronic security cards
  • maintaining accurate inventory control of explosives upon entry, removal, and the return of unused explosives to the magazines
  • supplying only the required quantity of explosives as per the engineered design at loading operations
  • creating specific locations for temporary storage of explosives as part of the mine design.
  • using suitable lockable temporary storage containers, a common industry term for this type of container is a “day box” (for example, a suitable storage container for temporary explosive storage that is made of an outer non-combustible material and an inner surface that is made of wood or other non-sparking material with no exposed metal and equipped with a locking mechanism to secure the explosives)

Storage of explosives on surface

Subsection 123(1) of Regulation 854 states that explosives on surface must be kept and stored in compliance with the Explosives Act (Canada) and its regulations. The term “surface” includes surface mines, surface areas of an underground mine, and surface areas at mining plants. 

A surface mine is defined under Regulation 854 as a pit or quarry where metallic or non-metallic rock, mineral bearing substance, earth, clay, sand or gravel is being, or has been removed by means of an excavation open to the surface to supply material for construction, industrial or manufacturing purposes and includes any work, undertaking or facility used in connection therewith but does not include a cutting for a right of way for a highway or a railroad.

Surface areas of an underground mine include all areas within the physical boundaries of the footprint of the mine, such as:

  • the yard
  • material delivery zones
  • out-buildings
  • headframe

Mining plants are defined under OHSA to include any roasting or smelting furnace, concentrator, mill or place used for, or in connection with, washing, crushing, grinding, reducing, leaching, roasting, smelting, refining, treating or research on any substance mentioned in the definition of a mine. Surface areas at mining plants include all areas within the physical boundaries of the footprint of the mining plants such as the yard, material delivery zones and laydown areas. 

Clause 123(2)(a) and (b) of Regulation 854 require that all surface magazines be constructed to conform with the requirements in National Standards of Canada CAN/BNQ 2910-500/2015 (Explosives – Magazines for Industrial Explosives) and be located in conformance with CAN/BNQ 2910-510/2015 (Explosives – Quantity Distances), as they may be amended from time to time.

CAN/BNQ 2910-500/2015 sets out the minimum requirements for the construction and surveillance for the safe and secure storage of industrial explosives that will be licensed under the Explosives Act (Canada).

CAN/BNQ 2910-510 standard applies to all locations in which a quantity of stored manufactured explosives has the potential to, if the inner contents were to explode, create a blast that could be associated with the projection of fragments and debris or create a fire hazard.  The intent of this standard is to reduce potential risk to life and property by establishing the minimum separation distances to be used between both potential explosion and exposed sites using quantity distance tables as a measure of calculation.  It is important to note that this standard does not apply to the use of “day boxes” being used as temporary storages of explosives for blasting operations.

Surface magazines also require fire breaks as per clause 123 (2)(c) of Regulation 854.  For the purposes of compliance, the requirements as outlined in section 17 of the Forest Fires Prevention Act should be considered.

Storage of explosives in magazines underground

As a general rule, section 125 of Regulation 854 requires that all explosives in an underground mine must be kept or stored in magazines. However, where less than 160 kg of explosives are kept or stored in the underground mine, they may be kept or stored in suitable storage containers away from drilling and blasting activities. For long hole blasts or similar blasting operations, an amount of explosives that can be loaded within a twenty-four hour period and the quantity necessary to maintain that supply may be kept outside the magazine in a suitable storage location.  Further, explosives may be kept or stored outside of a magazine on a temporary basis if: the written procedures required by section 124(1) are followed; and any unused explosives are transferred or returned to the magazine as soon as practicable.

Section 126 of Regulation 854 requires that explosive magazines, temporary explosive storage containers and temporary explosive storage areas in an underground mine must be conspicuously marked by a “DANGER EXPLOSIVES” sign and located at least 60 metres from:

  • the main access into or from a mine
  • key mechanical and electrical installations that remain in service during a mine emergency
  • areas of refuge or other areas where workers may congregate
  • storage areas for fuels or other potential sources of fire

They must also be located and designed to protect explosives from vehicle impact or vehicle fires.

Additional Requirements

Section 128 requires the employer to establish, in consultation with the joint health and safety committee or health and safety representative, a procedure for safely disposing of damaged explosives.

Section 129 requires that all wiring and electrical equipment installed or used in an explosive storage area or a magazine complies with:

  • the requirements of the Ontario Electrical Code with respect to Zone 22 locations
  • the National Standard of Canada CAN/BNQ 2910-500 Explosives Magazines for Industrial Explosives
  • be protected against lightning strikes and electrical surges

Section 134 requires explosives to be delivered without delay from near the shaft collar, entrances to underground workings and or shaft stations; and transported from a magazine to other magazines or place of use without delay and by the most direct and safe route.