Ministry of the
Solicitor General

Hazard Identification Report 2019 - Section G - Structural Hazards


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Hazard Identification and Risk Assessment Program

Hazard Identification Report 2019
Section G: Structural Hazards

Office of the Fire Marshal & Emergency Management


The Hazard Report contains information profiles for hazards, including a high-level overview of possible consequences. It is divided into 10 parts; an introduction and 9 sub-sections labelled A-I as follows:

  1. Agriculture and Food
  2. Environmental
  3. Extraterrestrial
  4. Hazardous Materials
  5. Health
  6. Public Safety
  7. Structural
  8. Supply and Distribution
  9. Transportation


Structural Hazards: Hazards related to full or partial structural failures.

Dam Failure

Go to next hazard: Fire/Exlposion


The uncontrolled release of stored water due to the breaching or destruction of a dam or barrier intended to hold back water or other fluids.


A dam or barrier is an obstacle that disturbs or impedes the flow of surface water, excluding beaver dams, water crossings, and culverts. Some of these structures are used for control of water, while others are power-generating[1].

There are over 15,000 dams in Canada of which 933 are categorised as “large” dams under the International Commission on Large Dams definition.[2] These dams are owned by the federal and provincial governments, electric utilities, industrial and mining companies, irrigation districts, municipalities and private individuals. Some of the largest dams in the world are associated with Canadian hydroelectric and mine tailings developments.

In Ontario, Ontario Power Generation (OPG) operates 66 hydroelectric stations, including 29 small hydroelectric plants, and 241 dams on 24 river systems. Other dam structures in Canada include small and medium embankments for agricultural and water supply usage. In all cases the dams must be designed, operated and maintained so that they do not pose an unacceptable risk to the downstream populations. In Ontario, during Dam Safety Reviews (DSR) of existing dams or the design of new dams, flow control structure operating conditions and capacity are evaluated according to criteria laid out by the Lakes and Rivers Improvement Act (LRIA)[3].

The Lakes and Rivers Improvement Act, administered by The Ministry of Natural Resources and Forestry, provides safety standards and guidelines for dam owners, and regulation of “the protection of persons and of property by ensuring that dams are suitably located, constructed, operated and maintained and are of an appropriate nature”. However, it is the ultimate responsibility of the dam owners to ensure that their dams are safe.

The Ontario Lakes and Rivers Improvement Act requires dam owners to obtain approval from the Ministry of Natural Resources and Forestry for[4]:

  • the construction of new dams
  • certain repairs and alterations to existing dams
  • certain water crossings and channelization works

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically the riverbed of the dammed river itself. The primary purpose of a spillway is to discharge flows that cannot either be used immediately or stored in a reservoir for future use. A service spillway is the primary flood discharge structure that would be available to handle discharge under any conditions. The spillway is operated either automatically or by personnel assigned to the site. Emergency spillways (also known as auxiliary spillways) are used during unusually high flow conditions[5].

The main methods of Dam failure are generally as follows[6][7]:

  • Overtopping: water spilling over the top of a dam.
  • Movement and/or failure of the foundation supporting the dam: Foundation defects, including settlement and slope instability, cause about 30% of all dam failures.
  • Settlement and cracking of concrete or embankment dams: caused by movements like the natural settling of a dam.
  • Piping: seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam.

Others include:

  • Deliberate acts of sabotage.
  • Structural failure of materials used in dam construction.
  • Inadequate planning or design of structure.
  • Inadequate maintenance.
  • Operational error.

Other influences on Dam use and resilience include[8]:

  • Changes in land use: Development, which can turn forests into farmland or tracts of housing, can lead to more runoff going to dams. It may also result in more developments downstream of the structure, and thus at risk from a potential failure.
  • Changes in weather patterns: Shifting weather patterns can also put more strain on dams, as some areas get wetter while others get drier.
  • Outdated design: Dam design has also improved over the past century, although many communities can’t afford to replace their old dams with the latest technology.

According to the Ministry of Natural Resources and Forestry, flooding is the primary cause of dam failure since it can result in water levels that exceed the carrying capacity of the dam.[9]

Spatial Scale, Timing and Warning Period

Spatial Scale: A dam failure may result in the full or partial destruction of the dam and may damage the area downstream.

Timing: A dam failure may occur at any time of the year.

Warning Period: In some cases, warning may be possible, however, in many cases the failure occurs with little or no advanced warning.

Potential Impacts

Potential impacts of a dam failure may include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reputational Damage.
  • Illness, injury or death of domestic or livestock animals.
  • Implementation of water use restrictions.
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Harm to wildlife populations, domestic or livestock animals and related industries, if susceptible. May result in loss of income, effects on hunting, tourism.
  • The need for debris management.
  • The need to evacuate or shelter in place.
  • The need for damage assessment.
  • The need for financial assistance.
  • The need for emergency provision of essential needs, including food.
  • The need for emergency shelter services.
  • The need for site or area access restrictions.

Secondary Hazards

Secondary hazards may include:

  • Flooding
  • Erosion
  • Building/Structural Collapse

Past Incidents

There are two significant examples from Ontario:

  • Gorrie Dam, 2017: Maitland Valley Conservation Authority (MVCA) advised of the failure of the Gorrie Dam, which occurred due to historically high water levels and the failure of the emergency spillway. The incident had the potential to affect all municipalities downstream. MVCA provided maps of potential downstream surge and the more than 150 property owners at risk from rising waters. These properties were evacuated as a precaution, though damage was minimal.
  • Matachewan Consolodated mines, 1990: A release of about 150,000 cubic metres of tailings occurred when a tailings dam failed at the abandoned Matachewan Consolidated Mines property on October 17, 1990. This occurred after water levels rose in Otisse Lake. The tailings turned the water in some areas mud-brown and raised lead levels above the Ontario Drinking Water Standards, Objectives and Guidelines.

In addition, two additional incidents of national importance include:

  • Mt Polley, BC, 2014: The Mount Polley mine disaster in the Cariboo region of central BC began in August 2014. It is among the worst incidents of Dam breach in Canadian history. A breach of the copper and gold mine tailings pond at the Imperial Metals facility released Twenty-four million cubic metres of mine waste into Polley Lake. The spill devastated the downstream river system, including Polley Lake, its outflow Hazeltine Creek, and nearby Quesnel Lake and Cariboo River. The incident was caused by an inadequately designed dam that didn't account for drainage and erosion failures beneath the pond, as determined by an independent, government-ordered panel of experts.[10]
  • Springbank Dam, 2008[11]: While being rehabilitated in 2008 with new steel gates, a gate failed to function properly. All gates are needed to be working in order to maintain a higher water level east of the dam so the remaining 3 gates were also lowered so the water would flow freely. The river has been without a functioning dam since.

Provincial Risk Statement

Ontario has strict protocols that include geotechnical design and factors of safety when considering applications for approval. This includes considerations for permafrost; which can cause special problems in tailings facilities as the condition of the frozen ground can change.

It is possible to use models to predict and estimate failure of dam infrastructure, including the potential for human and property loss. This, along with numerous policy measures, infrastructure maintenance and improvement programs, and legislation, enable effective design, construction and management of dam infrastructure in Ontario.


The impact depends on available shelter, local flood depths, flood velocities and debris. A dam failure that occurs with little to no warning may result in fatalities and injuries, primarily from interaction with water or debris. Contamination of water could also impact potable water systems and environmental conditions, which in turn have potentially serious health effects.

Social Impacts

There may be a negative effect on support networks and systems if the impacts of dam failure result in social isolation, or the cessation of formal services.

Property Damage

A dam failure may result in damage to properties downstream from the dam, including ground contamination. Additional damage from mold or chemicals may occur. Agricultural property, including crops may be damaged.

Critical Infrastructure Disruptions

Critical infrastructure may be damaged during a dam failure or may have to be shut off following a failure to ensure safety. Roads and bridges may be blocked by debris or washed out.

Environmental Damage

A dam failure may result in the destruction of aquatic ecosystems and damage to land based ones.


Businesses downstream from a dam failure may be damaged. Others may be impacted by associated critical infrastructure disruptions.

Fire / Explosion

Go to previous hazard Dam Failure

Go to next hazard: Mine Emergency


Fire: A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities. Any instance of destructive and uncontrolled burning, including explosions.[12]

Explosion: The sudden conversion of potential energy (chemical, mechanical, or nuclear) into kinetic energy that produces and violently releases gas.


Fires can pose an immediate threat to the safety of life or damage to property. Among a range of effects, they can cause extensive damage to property, evacuations of large numbers of people, restrictions on the re-entry of homes and businesses.

Fires can pose a significant public safety risk, both from the direct effects of the fire such as smoke and burn damage, and from the secondary effects.

The environment created by fires and explosions can include any of the following conditions:[13]

  • Smoke: Which impairs visibility and the ability to breathe.
  • Oxygen deficient atmosphere: Oxygen is vital for humans and animals to breathe.
  • Elevated temperatures: Even without direct contact with the flames, conductive heat and radiant heat can cause serious burns even from great distances.
  • Toxic atmospheres: Combustion produces atmosphere that is harmful to humans and animals.

Structure fires and explosions can result in fatalities, injuries and significant property damage. However, large-scale and mass fatality fires have decreased due to advances in fire prevention and suppression since the 1970s, when smoke alarms became widely available.

Fire Protection and Prevention Act, 1997 (FPPA) is the overall governing legislation in the Province for fire protection matters at both the municipal and province level. Under this Act, “fire protection services” includes:[14]

a) fire suppression, fire prevention and fire safety education,

b) mitigation and prevention of the risk created by the presence of unsafe levels of carbon monoxide and safety education related to the presence of those levels,

c) rescue and emergency services,

d) communication in respect of anything described in clauses (a) to (c),

e) training of persons involved in providing anything described in clauses (a) to (d), and

f) the delivery of any service described in clauses (a) to (e).

Municipal fire departments enforce the Fire Code, though local zoning and land use bylaws also help to limit the potential impact of industrial accidents or fires through distancing requirements and other limitations of use.

The Ontario Building Code work together with the FPPA and other regulations in Ontario, including the Fire Code, by providing building requirements designed to limit and prevent the spread of fire. Specific requirements vary depending on building use.

In addition to legislation, standards and regulation, fire prevention activities are important to mitigate fire and explosion risk, and core to the mandate of the Ontario Office of the Fire Marshal. An example of such initiatives is the extensive public safety education program provided by the OFM, including the addition of new curriculum specifically for vulnerable populations such as seniors.[15]

Spatial Scale, Timing and Warning Period

Spatial Scale: Fires and explosions can affect one or multiple buildings or structures.

Timing: Explosions and fires can occur at any time of the year.

Warning Period: Explosions and fires often have little to no warning. The presence of proper sensing equipment such as smoke detectors can provide people with enough warning to evacuate.

Potential Impacts

Potential impacts of an explosion/fire may include:

  • Injury, illness or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • The need for emergency shelter services.
  • The need for site or area access restrictions.
  • The need for debris management.

Secondary Hazards

Potential secondary impacts of explosion/fire may include:

  • Building/Structural Collapse
  • Hazardous Materials Incident

Provincial Risk Statement

Human Impacts

There is a risk of fatalities and injuries caused by explosions/fires. From burns to smoke inhalation, the health risks are varied. Toxins contained in smoke can also cause severe respiratory and other longer-lasting health effects.

Social Impacts

Social impact is likely to be limited and localized, though psychological or lasting social effects are possible.

Property Damage

Damage is often isolated to the building/structure affected, however nearby buildings may suffer serious damage. Larger scale events may impact multiple buildings. Damage may range from cosmetic to severe. Smoke may result in additional damages.

Critical Infrastructure Disruptions

Gas is likely to be turned off to the affected area to prevent explosions. Electricity and water infrastructure may be damaged. Roads near the affected area may be blocked by debris.

Environmental Damage

Environmental damage is likely to be fairly localized. Air quality can be impacted by toxins or particulate being released as a result of an explosion and/or fire.


Since this is often a localized hazard, damages are often restricted to economic impacts in the immediate area or within the affected building.

Mine Emergency

Go to previous hazard: Fire / Explosion

Go to next hazard: Building/Structural Failure


An unplanned event that jeopardizes the structural integrity, ground stability, or normal conditions of a mine site or mining plant that presents a risk to the safety of workers, people near the mine, the property of the mine, the environment or the economy.

This hazard can be divided into two parts;

  • operational mine emergencies, and
  • abandoned mine emergencies.


The Occupational Health and Safety Act (OHSA) defines a mine as follows:

“any work or undertaking for the purpose of opening up, proving, removing or extracting any metallic or non-metallic mineral or mineral-bearing substance, rock, earth, clay, sand or gravel”

In addition to removal of materials, mines also host other facilities, known as ‘mining plants’. This is any “roasting or smelting furnace, concentrator, mill or place used for or in connection with washing, crushing, grinding, sifting, reducing, leaching, roasting, smelting, refining, treating or research on any substance” in a mine[16]. The main two types of mines are surface mines (above ground) and underground mines.

Ontario produces approximately 43% of Canada’s nickel and 46% of Canada’s gold, 28% of Canada’s copper and 79% of Canada’s platinum group metals. Ontario is the leading producer of gold, cobalt, nickel, platinum group metals, silver, salt, clay products, cement, and stone in Canada. Ontario is the second leading producer of sand and gravel as well as the only producer of nepheline syenite. Internationally Ontario ranks 3rd in platinum group metals, 9th in nickel, 13th in cobalt, 13th in gold, 17th in copper, 19th in zinc and 19th in silver production[17].

Mining in Ontario is a well-developed industry with safety standards that are in place. Ontario regulations strictly regulate the health and safety requirements of mine operators, workers and rescue operations. Rescuers are required to be trained, well-equipped, and available at all mining operations at surface and underground mining operations.[18] Currently mines rescue operations are under the control of Workplace Safety North. Regulations also require each underground mine to have trained rescue personnel and equipment under Ontario R.R.O.1990, Reg.854 s 17 Regulations for Mines and Mining Plants.[19]

Some possible causes or contributors to a mine emergency include:

  • The accumulation of lethal gases (e.g. methane, carbon monoxide, carbon dioxide and hydrogen sulphide).
  • Malfunctioning or misuse of explosives
  • Water inrush/flooding
  • Ground instability and collapse of mine openings
  • Fires and explosions that can result in creation of lethal gases
  • Power outage 

Abandoned mines

Abandoned mines, in addition to operating mines, can also pose a threat to the safety of a person who intentionally or unintentionally enters the mine. The term “abandoned mine” describes sites where advanced exploration, mining or mine production has ceased without rehabilitation being completed. Some of the dangers of abandoned mines are:

  • Active explosives that have been left behind.
  • Aging and/or unstable structures which may collapse.
  • Poor air quality or lack of oxygen.
  • At the surface, shafts may be unprotected, hidden by vegetation or covered by rotting boards.
  • Rotting timbers, deteriorating ground control (rock bolts, rebar and cable bolts) and unstable rock formations can lead to cave-ins.
  • Darkness and debris add to the hazards making escapes and rescues more difficult.
  • Mine subsidence.
  • Vertical cliffs in open pit mines and quarries can be prone to collapse.
  • Water-filled quarries and pits may hide rock ledges, old machinery and other hazards. The water can be deceptively deep and dangerously cold. Steep, slippery walls can make exiting these ground openings extremely difficult.
  • Maps of the mine and workings may no longer exist or may not include updated features which could hinder a rescue operation.

In 1991 the Mining Act was amended to require that mining companies submit closure plans and financial assurance to return lands to their natural or other acceptable state upon completion of exploration and mining activities. After various stages of production, mine features including but not limited to surface structures are removed, underground stability is assessed, tailings areas are evaluated for both physical and chemical stability, and distrurbed areas are re-vegetated.

Some abandoned mine sites in Ontario are over a century old, and standards for safety and closure were not comparable to current mine closure requirements. Some mining companies abandoned mine sites due to business failure circumstances which has resulted in some of these mines not having been properly rehabilitated/secured.

In the past, members of the public have intentionally entered abandoned mines for recreational purposes. Due to unknown or unforeseen dangers inherent to abandoned mines, entry is strongly discouraged[20].

Lethal gases

Ventilation, the use of air-purifying respirators and many other measures significantly reduce the risk related to air quality and the accumulation of lethal gases. However, these hazards remain, particularly in underground and enclosed spaces.

The Ontario Ministry of Labour issues strict controls relating to protection of workers from all kinds of workplace hazards. This includes the presence of common contaminants in mines and mining plants that can affect workers’ breathing and lung health.


The risk of explosions in mines has decreased due to advances in explosive technology. In particular, nitro-glycerin based explosives have been replaced with water gel explosives. However, forgotten or abandoned nitro-glycerin based explosives may still pose a risk if people re-enter an abandoned mine. As well, explosives detonation has become more technical and sophisticated, bringing with it the need for greater understanding in order to use them safely.

Explosions and fires can have many causes including methane gas or chemicals used in the extraction and purification processes and equipment, and secondary explosions may occur. Many explosions have been caused by the ignition of methane gas or coal dust. As Ontario does not have any coal mines, surface or underground, this risk is low

Water inrush/flooding

The presence of many large water bodies and aquifers in Ontario means that flooding will always present some degree of risk to miners in Ontario, although that risk has been decreased due to monitoring and advances in technology. Additionally all mines in Ontario are required to have refuge stations under Ontario R.R.O.1990, Reg.854 s 26 Regulations for Mines and Mining Plants. Such stations provide shelter and provisions for miners to until the situation is no longer dangerous or they are rescued.

Water can cause a range of stability, safety and operational problems depending on the water volume, the location of the leak, the layout of the mine and the speed at which it enters the mine.[21]

Structural instability

Structural instability and collapse can have many different causes. Among the more common:

  • Errors in mining practices.
  • Rock bursts, falls of ground, geological features such as slips and faults.
  • Seismic events (see “past events – Sudbury 2007”)

A rockburst/bump is a sudden and violent failure of a large volume of overstressed rock, resulting in the instantaneous release of large amounts of accumulated energy. On the surface, a large rockburst may sound like an explosion and can even generate impact waves[22].

Seismicity and rockbursting are becoming a more prominent issue as Ontario mines become deeper. Measures known as "ground control" must be taken to stabilize the structure of new excavations in underground mines and prevent falls of ground. The ‘Unusual Occurrence Report for Groundfall/Rockburst’ was developed to provide Ontario mining operations with a standard means of collecting and reporting pertinent information on these types of occurrences.[23]

Advances in technology and the understanding of geology have contributed to a decrease instances of structural collapse. However, this still presents a significant risk in both operating and abandoned mines.

Spatial Scale, Timing and Warning Period

Spatial Scale: A mine emergency is usually confined to the mine and surrounding property.

Timing: A mine emergency can occur at any time of year.

Warning Period: The amount of warning depends on the cause of the emergency.

Potential Impacts

The potential impacts of a mine emergency may include:

  • Injury or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reports of missing individuals. The need for search and rescue, family reunification operations.
  • Reputational damage.
  • The need for debris management
  • The need for damage assessment.

Secondary Hazards

Potential secondary hazards of a mine emergency may include:

  • Human Health Emergency
  • Building/Structural Collapse
  • Hazardous Materials Incident
  • Explosion/Fire
  • Flooding

Past Incidents

Past occurrences of Mine Emergencies include:

  • Sudbury 2007: October 7th, 2007, Creighton Mine in Sudbury district experienced 3.7 magnitude earthquake, resulting in rockbursts.

Rockbursts have been reported in the Sudbury region as early as 1935[24].

Mining emergencies can also occur as a secondary hazard of an electrical power outage, among others. For example, during the widespread blackout of 2003,140 miners were stranded underground in Sudbury when the power went out. They were safely evacuated by the following morning when power was restored.

Provincial Risk Statement

Human impacts

Mine emergencies can result in fatalities, injuries or miners being trapped. Should a mine emergency occur in Ontario and miners subsequently become trapped, equipment and trained personnel are available to respond.

Should an abandoned mine emergency occur in Ontario where member(s) of the public become trapped, there are no dedicated emergency response resources who are equipped, trained and available to respond. Mine Rescue personnel may be able to assist local police and fire fighter members to attempt a rescue if the mine workings and environmental conditions are stable enough to do so.

Social Impacts

Social impacts are generally limited to the mine workers and families during the event in this type of emergency. The affected population may experience mental health symptoms or illness during and after such an emergency, such as anxiety disorders or Post traumatic stress disorder.

An abandoned mine incident could cause some social anxiety with the number of abandoned mine hazards and their present state of protection/securing.

Property Damage

Property damage is a possible impact arising from a mine emergency but is likely confined to the mine property.

Abandoned mines and their associated mine hazards including but not limited to potential underground mine workings subsidence, groundwater and surface water impacts could have a negative effect on adjacent lands or even surface rights.

Crown intervention to acquire impacted properties to avoid potential future emergencies has and is likely to occur again in the future. The risk of property damage although unlikely can have serious consequences.

Critical Infrastructure Disruptions

Critical infrastructure failures due to a mine emergency are unlikely. The province of Ontario is aware of the potential risk of legacy mine features interconnected with municipal infrastructure i.e. sewage and water lines located within historical mine utility tunnels. As infrastructure ages, more potential interconnections may become more apparent and may result in potential infrastructure disruptions.

Environmental Damage

Environmental damage due to a mine emergency is possible but unlikely. The scenario most likely to have a serious impact on the environment is failure of an abandoned tailings facility. Water and tailings contaminated with metals including but not limited to copper, zinc, lead, cobalt, cadmium, arsenic and which may be part of acidic effluent released into the environment during a significant event.


The business that owns the mine may suffer financial losses. Communities dependent on the mine may also suffer financial losses.

Building / Structural Failure

Go to previous hazard: Mine Emergency


The loss of structural integrity in a building or structure that results in the structure losing shape, caving in, or being flattened or reduced to debris.


if the load-carrying capacity within structures such as bridges and transmission towers is exceeded, buildings can fully or partially collapse. The load-carrying capacity is exceeded when the building material is stressed beyond its limit.

Controlled demolitions and routine structural maintenance occur on a daily basis, and do not fall under the purview of this definition, unless aspects of the process did not follow the planned or anticipated effects.

Collapse of structures or buildings can potentially occur at any time. Buildings can be at risk of structural issues if there are flaws in the materials used, issues with the design or construction, or if the structure has deteriorated with age. While all of these aspects are strictly regulated by the Ontario Building Code and Ontario Regulation 213/91, structures which do not meet these and other applicable current standards are at higher risk of such issues. So too are buildings that were not built to code, or built without permits.

Apart from the risks inherent to building design, use, age and construction material, there are many instances where other hazards may put buildings at risk, from technological failures to severe weather. High winds, freezing rain and heavy snow loads as well as other environmental conditions that may stress structures. Most of these events do not result in a collapse; though these extreme events could exceed the threshold defined in the Building Code.

The Building Code further reduces the risk related to building/structural collapse with each revision and update. However, as risk evolves over time, there is no guarantee that a building will remain in compliance throughout its lifespan. The Fire Code, which is applicable here as it regulates items such as building evacuation planning, building occupancy and signage, applies retroactively.

Other structures, such as bridges, can be vulnerable to damage and deterioration. Increases in the volume and weight of traffic over time can increase the rate of deterioration and subsequently, the risk of a collapse. Not all structures that at risk of collapse are large, and many smaller structures can form critical nodes in larger systems.

Vulnerability to building/structural collapse depends on several factors:

  • Type and use of the structure.
  • Size and height of the structure
  • The number of people within or near the building
  • Number of people in the building, compared to legal occupancy limits
  • Access and egress limitations (either for people living or working in the building, or rescue crews and equipment)
  • Amount of time required to rescue trapped people

Administration for public safety through the application of uniform building standards falls in part to municipal departments, while the main responsibility for ensuring compliance to these and other standards fall directly to the structure owner and operator. Building inspectors have the legal authority to administer and enforce of the Ontario Building Code Act and Ontario Building Code, which pertain mainly to building construction, repair, remediation or demolition works. The requirements of the code include the following key areas:

  • Health and Safety
  • Fire protection
  • Structural sufficiency
  • Construction materials
  • Plumbing and Mechanical systems

Typically, in incidents such as these, a variety of agencies respond to address the various public safety and corrective work that needs to take place following such an incident.

Not all structures that risk collapse are large. Many smaller structures such as communications towers and utility poles can also collapse. During the 1998 and 2013 Ice Storms, many such structures collapsed due to the weight of the ice that accumulated on them.

To mitigate damage to infrastructure, such as those caused by aging and severe weather, there are substantial investments made to public infrastructure improvements every year. This includes public works, as well a government buildings and transportation networks.

A Heavy Urban Search and Rescue (HUSAR) team specializes in building collapses in order to provide specialized support to local rescue services. Their training and practices can assist in lowering the response time and increasing the chances of survival of people trapped in the rubble.

Spatial Scale, Timing and Warning Period

Spatial Scale: Building/structural collapses usually only involve a single building or structure; however, additional buildings nearby may be impacted.

Timing: Building/structural collapses may occur at any time of the year; though certain causes may be seasonal (e.g. snow load in winter).

Warning Period: The collapse may be sudden or delayed. Collapse usually begins with fractures and deformations of the building or structure but may occur quickly so that these are not noticeable in time to evacuate.

Potential Impacts

Potential impacts of a building/structural collapse may include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • The need for debris management
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for damage assessment.
  • The need for financial assistance.
  • The need for emergency provision of essential needs, including food.
  • The need for emergency shelter services.
  • The need for site or area access restrictions.

Secondary Hazards

Secondary hazards may include:

  • Oil/Natural Gas Emergency
  • Hazardous Materials Incident

Past Occurrences

Unfortunately, as structural issues are routine, data concerning structural failures is dispersed and challenging to catalogue except for extremely serious cases. These include Ontario examples:

  • Elliot Lake 2011: Algo Centre Mall roof collapse. 2 fatalities, 22 injured
  • Toronto 2011: Radiohead stage collapse. 1 fatality, 3 injured
  • Ottawa 2011: Ottawa Bluesfest stage collapse. 3 injured.
  • Sudbury 2003: Big Nickel Road Bridge
  • Latchford 2003: Sgt. Aubrey Cosens VC Memorial Bridge
  • Barrie 1978: CKVR Television Tower
  • Ottawa 1966: Heron Road Bridge Collapse. 9 fatalities.
  • Ottawa 1966: Elgin Street, construction site collapse. 1 fatality, 3 injured.

Provincial Risk Statement

If a structure collapses, the most obvious threat is from falling debris and building materials. Secondary effects could include but is not limited to electrical hazards, the release of chemicals or natural gas, or flooding from broken pipes.

Human impacts

The failure of any structure could cause serious injury or death, as well as indirect hardship. The risk to life is higher in areas with greater population density or high-occupancy structures, or if critical infrastructure is affected. In the event of a fast collapse, no one population group is more vulnerable than another, though some of those affected may be more susceptible to injury than others.

Social Impacts

Some limited impact to social networks or support systems may result. The effects would usually be limited, localized and short-lived. The trauma experienced by those affected, or to an affected community, may be severe.

Property Damage

A building/structural collapse is usually an isolated occurrence, unless it results as a secondary effect of an event such as an earthquake. The immediate building is affected, as well as any other structures that are within the collapse zone: the area that is likely to experience falling debris.

Critical Infrastructure Disruptions

Some critical infrastructure damage may occur if the collapse debris blocks a road or topples power lines; however, this damage is usually also localized.

Environmental Damage

The environment is not particularly vulnerable to building/structural collapses, although hazardous materials spills may cause damage and require a response and clean-up.


The economic impact depends on the type of building or structure that collapses. Since this is a localized incident, the impact is usually limited to building owners, operators, occupants and management.

End Notes

[1] Government of Ontario: Dam Management, 2018.

[2] Canadian Dam Association, 2016.

[3] Canadian Dam Association, 2018.

[4] Lakes and Rivers Improvement Act (LRIA).

[5] Government of Ontario: Spillways and flood control structures, 2018.

[6] Federal Emergency Management Agency (FEMA), 2018.

[7] Association of State Dam Safety Officials, 2015.

[8] National Geographic, 2015.

[9] Ministry of natural Resources and Forestry, 2018. correspondence [via email], June 2018

[10] An Audit Of Compliance And Enforcement Of The Mining Sector, 2016. BC Auditor General.

[11] London, ON, 2018.

[12] National Fire Protection Association, 2018. Glossary.

[13] Essentials of Fire Fighting and Fire Department Operations 5th Edition. 2008.

[14] Fire Protection and Prevention Act, 1997 (FPPA):

[15]Office of the Fire Marshal, Resources by topic. 2018. Accessed November 2018.

[16] Occupational Health and Safety Act, R.S.O. 1990, c. O.1

[17] MNDM, 2016

[18] Minsitry of labour, 2018.

[19] Workplace Safety North, 2017

[20] Ontario Ministry of northern Development and mines, 2018. 

[21] Polak, K., Ró┼╝kowski, K. & Czaja, P. Mine Water Environ (2016) 35: 128.

[22] Feng, Xia-Ting, 2018. Rockburst: Mechanisms, Monitoring, Warning, and Mitigation.

[23] Unusual Occurrence Report For Groundfall/Rockburst, 2010

[24] Geology of the Sudbury Basin, 2009.