Instructions
1. You are the chief fire inspector in your community, and there has been a recent sharp increase in the number of clandestine drug lab incidents, one of which involved a firefighter being exposed to a hazardous material. The fire chief has directed you to develop a short presentation for all investigators and suppression personnel.
2. For this assignment, you will produce a PowerPoint that you would use for this presentation. In the presentation, you will identify and describe the following elements:
· potential indicators that a clandestine drug lab may be involved,
· first responder safety precautions,
· other resources that may be called upon for assistance in the response and/or investigation, and
· special safety precautions and considerations that need to be addressed in hazardous materials and explosion investigations.
Your presentation must be a
minimum of 12 slides in length
, not counting the title and reference slides. At least one reference must be used, and at least three graphics should be used in the presentation.
FIR 4305, Fire Investigation and Analysis 1
Upon completion of this unit, students should be able to:
8. Analyze explosions and explosive combustion.
8.1 Explain key safety considerations when investigating clandestine drug lab or explosive fires.
Course/Unit
Learning Outcomes
Learning Activity
8.1
Chapter 3
Unit VII PowerPoint Presentation
Chapter 3: Chemical Fires and Explosions
Unit Lesson
Experienced firefighters and risk managers know that low-frequency/high-risk incidents present many
difficulties for responders as the stakes are high, and we often lack experience in dealing with these types of
situations, which can lead to unsatisfactory outcomes. This unit will cover the topics of explosions, chemical
fires, and hazardous materials, which certainly meet the definition of high-risk and low-risk occurrences. We
will not only look at the distinct nature and at features of these fires, but we will also focus on the increased
safety measures that these situations require of the fire investigator.
Investigating Explosions
Safety is paramount when investigating a scene that could involve any type of explosive. The fire investigator
must first verify that there are no secondary devices. The scene should be rendered safe by those with
explosive ordinance training, such as by Explosive Ordinance Disposal (EOD) personnel or teams. The
National Fire Protection Association (NFPA, 2017) recommends using specialists whenever explosives may
be involved.
Once the scene has been cleared for secondary devices, the investigator must determine if any structures
involved in the incident are safe to enter and inspect. Here again, outside expertise may be required before
proceeding with the investigation. The support of experts in building construction and/or structural engineering
may be needed before entering a structure.
An explosion is described as the sudden conversion of mechanical or chemical energy into kinetic energy. In
an explosion, gases are produced and released under pressure (NFPA, 2017). Some explosions can be
accidental, occurring as the result of mechanical defects or natural gas leaks. Some can be set to appear
accidental, and some may be intentional as in a terrorist activity. In the intentional explosion incidents, special
care must be given to ensure that there are no secondary devices aimed at first responders. In all three of the
aforementioned scenarios, the safety issues regarding explosions remain the same. Please see Table 3-1 on
page 187 in the textbook to review common types of explosives.
UNIT VII STUDY GUIDE
The Investigation of Explosions
and Explosive Combustion
FIR 4305, Fire Investigation and Analysis 2
UNIT x STUDY GUIDE
Title
The objective in an explosive scene examination is largely the same as in a fire scene, which is to determine
the spot that the explosion originated from and then the cause. This is often further complicated by the size of
the blast area, which often covers large areas, and fragments being thrown anywhere from several feet to
miles away from the seat of the blast.
The following video shows the violence that a natural gas explosion can muster. In Sun Prairie, Wisconsin, a
4-inch natural gas line was hit by contractors doing work in their downtown area. The resulting explosion,
which was captured on a dashboard cam, resulted in 25 buildings being damaged, but more importantly, 13
injuries and a firefighter being killed in the line of duty. First responders had evacuated approximately 250
people from the area before the explosion. Please click the link below to view the video.
Madison.com. (2018, December 20). Sun Prairie gas line explosion [Video]. YouTube.
https://www.youtube.com/watch?v=5Efo_Bsgs1I
There are two characteristics of explosive damage: low-order damage and high-order damage. With low-order
damage, which is created by a slower pressure rate, you will notice damage such as bulged out walls, roofs
partially lifted, dislodged windows with the glass still intact, and large pieces of debris or fragments. With high-
order damage, which is created by a rapid rise in pressure, the investigator will observe such damage as
shattered wall and roof members, shattered debris, or fragments that are pulverized and thrown great
distances. The smaller the pieces and the further they are thrown, the higher the energy of the explosion,
combustion, deflagration, or detonation.
There are seated and non-seated explosions. The difference between the two is very distinct. In a seated
explosion, there is a crater or area in which the greatest damage can be found. These types of explosions are
typically generated by boilers, explosives, or a boiling liquid expanding vapor explosion (BLEVE). In contrast,
non-seated explosions occur when fuels are diffused or dispersed across a large area. Such explosions can
reach subsonic velocities. This type of explosion was illustrated in the Sun Prairie, Wisconsin, video above.
Vapors of such ignitable liquids or fuel gases are the most commonly encountered explosion. However, non-
seated explosions can also be triggered by a workplace hazard as simple as dust. Many types of dust from
organic materials such as flour, sugar, or wood, are just as flammable as inorganic dust sources such as
paint, plastics, and pharmaceuticals. Click the link below to access a short video that explains this common
workplace explosion hazard.
Aurora Pictures. (2013, March 13). Combustible dust [Video]. YouTube.
Click here to access a transcript for the video.
Processing the Scene
A preliminary search of the scene will often reveal the direction of the spread of blast fragments or the blast
pattern and the seat of the explosion. The use of aerial drones to survey and document the scene from above
are of particular use in explosive scene investigations. If you do not have access to a drone, the use of an
aerial apparatus and news or law enforcement helicopters to photograph and record the scene would provide
a much better overall view than ground photography can capture. As mentioned earlier, safety is paramount
in these types of incidents, and a rule of thumb for a preliminary perimeter is 1.5 times the distance from the
seat of the explosion to the furthest fragment. This may be adjusted as more information becomes available,
but it is a good rule of thumb. The perimeter should be marked with scene tape, ropes, or barricades—just as
in a structure fire. Technology is rapidly evolving in the investigative field, and we now have access to better
tools to assist us in documenting these types of scenes. Total Station survey systems and 3D laser imaging
instruments are now replacing tape measures and are more accurate and can pinpoint the position of
evidence using GPS.
Another aid to the investigator in these situations are the following mnemonics: the Four Rs and the Four Cs.
The Four Rs are recognition, recovery, reassembly, and reconstruction. The Four Cs are container,
concealment, content, and connections (Icove & Haynes, 2018). These are simple memory aids to help the
investigator. The Four Rs are a way of keeping a scene search in logical order. The Four Cs remind the
investigator what to examine and look for (i.e., what type of container, how or where it was concealed, what
https://online.columbiasouthern.edu/bbcswebdav/xid-113825663_1
FIR 4305, Fire Investigation and Analysis 3
UNIT x STUDY GUIDE
Title
the contents were, what explosive materials were used, and by what method or connections [including any
sequence of events] that could have caused the explosion).
Dealing with Chemical Fires and Hazardous Materials
The textbook suggests that, for numerous fires, hazardous material either starts the fire or, at some point,
becomes involved in a fire. Of the two, it is more likely that hazardous material was involved in the ignition of
the fire, causing it to burn more intensely due to hazardous material being involved. Fires involving a
hazardous material can also increase the fire spread rate and make the suppression efforts even more
dangerous.
Hazardous gases, liquids, and solids are commonly found within any structure. Natural gas and liquid
propane are among the most common gases found in residential structures. Many residences heat or cook
using one of the aforementioned gases. Consider the vapor density of these gases when investigating a fire
where they are possibly involved. For instance, two of the most common gases encountered are natural gas
and propane. Natural gas is lighter than air, and propane is heavier than air. What does this mean for the fire
investigator? When examining a scene where either of these gases could have been involved, consider
possible ignition locations either near the floor level or slightly higher. For example, an ignition source for
propane would more than likely be at or near floor level since propane, being heavier than air, will sink toward
the floor.
Fire investigators will come across even more hazardous liquids than gases during an investigation.
Flammable liquids can become more volatile and explosive when exposed to the high temperatures of a
structure fire. Because flammable or combustible liquids, such as cleaning solvents, mineral spirits, or similar
liquids, are so common in both residential and commercial buildings, extra attention should be paid to verify
that these, in fact, belonged in the building at the time of the fire; if not, then an intentional act may have
occurred.
Due to the ease at which drug manufacturing supplies can be obtained, more and more explosions and fires
are occurring at surreptitious methamphetamine labs. These drug manufacturing sites can be set up
anywhere—from a bathroom of an occupied residence, to the back of a station wagon, or in an abandoned
structure. These types of explosions and fires require extra vigilance, and you should always beware of their
indications when investigating a fire. Some hazardous materials used in manufacturing these illegal drugs
could include ammonium nitrate, lye (drain cleaner), lithium (lithium batteries), anhydrous ammonia (liquid
fertilizer), ethyl ether, or white gas. Not only are these materials fire hazards, but they also may prove
dangerous, even after being involved in a fire. Use extreme caution when in these environments. Some
jurisdictions have designated units or teams that specifically deal with these clandestine labs; they can assist
in identifying them and will handle dismantling and disposing of the remaining hazardous chemicals.
References
Icove, D. J., & Haynes, G. A (2018). Kirk’s fire investigation (8th ed.). Pearson.
National Fire Protection Association. (2017). NFPA 921: Guide for fire and explosion investigations.
