Evaluation of the kinds of hazard and risk management encountered with explosive when blasting in surface and underground

1. Evaluation of the kinds of hazard and risk management encountered with
explosive when blasting in surface and underground
Kinds of hazard and risk management:-
What is a hazard?
The meaning of the word hazard can be confusing. Often dictionaries do not give specific
definitions or combine it with the term "risk". For example, one dictionary defines hazard as "a
danger or risk" which helps explain why many people use the terms interchangeably.
There are many definitions for hazard but the most common definition when talking about
workplace health and safety is: A hazard is any source of potential damage, harm or adverse
health effects on something or someone. The CSA Z1002 Standard "Occupational health and
safety - Hazard identification and elimination and risk assessment and control" uses the
following terms:
Harm - physical injury or damage to health.
Hazard - a potential source of harm to a worker.
Basically, a hazard is the potential for harm or an adverse effect (for example, to people as
health effects, to organizations as property or equipment losses, or to the environment).
Sometimes the resulting harm is referred to as the hazard instead of the actual source of the
hazard. For example, the disease tuberculosis (TB) might be called a "hazard" by some but, in
general, the TB-causing bacteria (Mycobacterium tuberculosis) would be considered the
"hazard" or "hazardous biological agent".
Hazard type defines and describes the nature of the hazard arising from an explosive in
manufacture and storage conditions.
Hazard
type
Definition(regulation 2 ER2014) Explanation
Hazard
Type 1
An explosive which, as a result of, or as a result
of any effect of, the conditions of its storage or
process of manufacture has a mass explosion
hazard
a mass explosion is one in
which the entire body of
explosives explodes as one
Hazard
Type 2
An explosive which, as a result of, or as a result
of any effect of, the conditions of its storage or
process of manufacture has a serious projectile
hazard but does not have a mass explosion
hazard
Hazard
Type 3
An explosive which, as a result of, or as a result
of any effect of, the conditions of its storage or
process of manufacture has a fire hazard and
either a minor blast hazard or a minor projection
hazard, or both, but does not have a mass
explosion hazard
ie those explosives which give
rise to considerable radiant
heat or which burn to produce
a minor blast or projection
hazard
Hazard
Type 4
an explosive which, as a result of, or as a result
of any effect of, the conditions of its storage or
process of manufacture has a fire or slight
explosion hazard, or both, with only local effect
those explosives which
present only a low hazard in
the event of ignition or
initiation, where no significant
blast or projection
offragments size or range is
expected

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Hazard type represents the potential behaviour of the explosives in the form in which they are
manufactured or stored. This means that explosives do not have inherent hazard types that can
be automatically ascribed without consideration. Hazard type will be dependant on:
• the quantity of explosives
• the types of explosives
• the loading density
• packaging (if any) or containment
• the presence of barriers or other controls that will prevent rapid communication of an event
between explosives;
• orientation
• how an event involving the explosives might progress or degrade any controls
Hazard Identification and Evaluation
Before beginning the hazard evaluation and risk assessment process, a researcher must define
the scope of work. What are the tasks that must be evaluated? A well-defined scope of work
is a key starting point for all steps in the risk assessment and hazard analysis.
The next step after identifying the scope of work is to identify the hazard. A HAZARD IS A
POTENTIAL FOR HARM. Hazards can be identified as an agent, condition, or activity that
has the potential to cause injury, illness, loss of property, or damage to the environment. The
table below has been adapted from Identifying and Evaluating Hazards in Research
Laboratories, which you can find in the Resource tab to the right.
Table 3-1: Examples of Hazards Commonly Identified for Research Activities
Hazard
Types
Examples
Agent
Carcinogenic, teratogenic, corrosive, pyrophoric, toxic, mutagenic,
reproductive hazard, explosive, nonionizing radiation, biological
hazard/pathogenic, flammable, oxidizing, self-reactive or unstable,
potentially explosive, reducing, water-reactive, sensitizing, peroxide-
forming, catalytic, or chemical asphyxiate
Condition
High pressure, low pressure, electrical, uneven surfaces, pinch points,
suspended weight, hot surfaces, extreme cold, steam, noise, clutter,
magnetic fields, simple asphyxiant, oxygen-deficient spaces,
ultraviolet radiation, or laser light
Activity
Creation of secondary products, lifting, chemical mixing, long-term
use of dry boxes, repetitive pipetting, scale up, handling waste,
transportation of hazardous materials, handling glassware and other
sharp objects, heating chemicals, recrystallizations, extractions, or
centrifuging
Hazard Controls
When evaluating the risks associated with specific hazards, the results of this evaluation should
guide the researcher in the selection of risk management techniques including elimination,

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substitution, engineering controls, administrative controls, and personal protective
equipment. This is known as the Hierarchy of Controls.
Elimination and Substitution
The most preferred method of controlling risk is to eliminate the hazard altogether. In most
cases, elimination is not feasible and when possible, substitution is the best approach to hazard
mitigation. When possible, substitute less hazardous agents in place of their more hazardous
counterparts. This also applies to conditions and activities. Examples include substituting
toluene for benzene, non-lead-based paints for lead-based ones, or SawStop table saws for
existing traditional table saws.
Engineering Controls
Engineering controls consist of a variety of methods for minimizing hazards, including process
control, enclosure and isolation, and ventilation.
• Process controls involve changing the way that a job activity is performed in order to
reduce risk. Examples of this include using wet methods when drilling or grinding or
using temperature controls to minimize vapor generation.
• Enclosure and isolation are targeted at keeping the chemical in and the researcher out,
or visa versa. Glove boxes are a good example of enclosure and isolation. Interlock
systems for lasers and machinery are other good examples of isolating processes.
• The most common method for ventilation in research laboratories is localized exhaust
systems. Fume hoods, snorkels, and other ventilation systems are discussed at length
in the Laboratory Equipment and Engineering Controls section of this site.

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Administrative Controls
Administrative controls are controls which alter the way work is performed. They may consists
of policies, training, standard operating procedures/guidelines, personal hygiene practices,
work scheduling, etc. These controls are meant to minimize the exposure to the hazard and
should only be used when the exposure cannot be completely mitigated through
elimination/substitution or engineering controls.
What is risk?
Risk is the chance or probability that a person will be harmed or experience an adverse health
effect if exposed to a hazard. It may also apply to situations with property or equipment loss,
or harmful effects on the environment.
The CSA Z1002 Standard "Occupational health and safety - Hazard identification and
elimination and risk assessment and control" uses the following terms:
Risk – the combination of the likelihood of the occurrence of a harm and the severity of that
harm.
Note: In risk assessment terminology, the word “likelihood” is used to refer to the chance of
something happening, whether defined, measured, or determined objectively or subjectively,
qualitatively or quantitatively, and described using general terms or mathematically (e.g., a
probability or a frequency over a given time period)
Types of risk
There are two generic types of risk that may be considered during the risk management process
for explosive facilities:
a) individual risk (IR). This is the chance of a fatality or serious injury to a particular
individual in a specific location as a result of an accidental initiation of explosives; and
b) societal risk (SR). This expresses
the probability of the largest number of
people that might be fatalities or
seriously injured as a result of an
explosives accident.
As the criteria for IR or SR are derived
from different sources the risk levels that
have been estimated during the risk
management process shall be clearly
annotated to indicate whether the
estimate is for IR or SR. The respective
limits of tolerability for IR and SR are
usually independent of each other. In
practice, IR would normally be used
during the risk assessment process as SR
is often more difficult to estimate. This is
because societal risk concerns often

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involve a much wider range of potential outcomes.
It is possible that tolerable risk may be achieved using one set of criteria but not achieved using
the other criteria. In this case remedial action should be taken to ensure that both sets of criteria
are met. If this is not possible or practicable then the national technical authority shall exercise
best judgment and also seek formal political approval for the continued use of the explosives
facility.
Determining tolerable risk
Tolerable risk is determined by the search for absolute safety contrasted against factors such
as:
a) the inherent explosive safety hazards of storing, handling and processing ammunition;
b) available resources;
c) the conventions of the society where the ammunition is being stored; and
d) the financial costs.
It follows that there is therefore a need to continually review the tolerable risk that underpins
the concept behind stockpile management operations in a particular environment.
The level of tolerable risk shall be determined by the appropriate national authority, but it
should not be less than the tolerable risk accepted, for example, in manufacturing or industrial

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processes. The levels of tolerable risk (based on individual risk criteria) shown in Table 3 could
be considered as reasonable and practicable:
Tolerable risk is achieved by the iterative process of risk assessment (risk analysis and risk
evaluation) and risk reduction. See Figure

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Explosive when blasting in surface and underground its general effects
General
An explosion is a sudden release of energy caused by a very rapid chemical reaction that
turns a solid or liquid into heat and gas. This reaction takes place in less than a millisecond. In
the process of turning a solid or liquid into a gas expansion occurs, so in the case of an
explosion the expanding gas is produced extremely rapidly and pushes the surrounding air out
in front of it, thus creating a pressure wave, known as the Blast Wave. When an explosion
occurs at ground level there are several effects created that cause damage and injury. The
extent of these effects will be generally dependent on the power, quality and the quantity of
explosive deployed. The six basic effects are:
a) thermal radiation;
b) brisance or shattering;
c) primary fragments;
d) blast wave;
e) ground shock; and
f) secondary fragments.
Each of these effects are summarised in the following sections.
Thermal effects
The thermal effects can be considered to be a ‘ball of fire’ created as part of the explosive
process. It is very local to the seat of the explosion and is very short lived (a few
milliseconds). The thermal effects are particularly hazardous to those very close to the blast
(i.e. taking shelter in a hardened structure) as the heat is able to penetrate small openings in a
structure. For those in the open the blast wave and fragment effects have a greater range for
inflicting damage.
Brisance
Brisance is the shattering effect, and it is very local to the seat of the explosion and is
generally associated with high explosives. The effect of brisance can be severe when an
explosive device is placed directly in contact with a structural component. A small air gap
between the explosive and the target is effective at mitigating the onset of brisance-induced
failures.
Primary Fragments
These are the fragments of the device or container of the device, which have been shattered
by the brisance effect and are propelled at high velocity over great distances. Primary
fragments can travel ahead of the blast wave and have the potential to cause injuries at a
greater range than the blast wave.
Blast Wave
The blast wave is a very fast moving high-pressure wave created by the rapidly expanding gas
of the explosion, which gradually diminishes with distance. The blast wave is capable of
reflecting off surfaces and in the process can magnify itself. This is typically displayed when
large devices are detonated in urban environments and the blast is ‘funnelled’ down narrow
streets. The blast wave has the potential to cause fatalities and serious injuries including lung
and organ damage, rupture of the eardrums and the like. It can also cause injury due to whole
body translation (or throwing) of individuals.

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Ground Shock
Ground shock is produced by the brisance effect of the explosion shattering the ground local
to the seat of the explosion, i.e., creating the crater of the explosion. The shock wave resulting
from the crater’s creation continues through the ground and is known as ground shock. The
ground shock has the potential to cause damage to underground services (e.g. water,
electricity etc) as well as structures below ground. It is not uncommon for floods to occur
after a vehicle bomb attack, caused by the rupture of water mains.
Secondary Fragments
These are the fragments that have been created by the blast wave imparting pressure onto
friable materials that are unable to withstand this pressure or loose articles. The energy
imparted to the fragments created by the blast can be such as to throw them large distances
and at great speed. Typical friable materials that form secondary fragments are glass, roof
slates, timber, metal frames and the like. Due to the human body’s moderate resistance to the
effects of the ‘blast wave’, secondary fragments are likely to cause injury at greater distance
than the blast wave. The formation of secondary fragments can cause fatalities and serious
injury.
Confinement Effects
The detonation of an explosive within a building is more severe than in an open environment.
This is because the blast wave is able to undergo multiple reflections (of walls, floors etc),
which leads to an increase in the amplitude and duration of the blast pressure. This increases
the severity of damage to both structural elements as well as humans. For internal explosions
within robust rooms, it is possible for even more severe confinement effects to occur. This is
a result of the confinement of the extremely hot gases that are produced by detonation. By
suppressing the expansion of the gases, very high pressures/forces are applied to the room
enclosure. The smaller the room the higher the resulting pressure.