Incident Investigation: Vacuum Truck Explosion Injures Worker | WorkSafeBC
Summary
TLDRA vacuum truck explosion during hazardous waste unloading highlights the critical need for proper safety measures. The incident occurred due to the absence of crucial documents like MSDS or a hazardous waste profile sheet, leading to a lack of awareness about the waste's flammability. The use of an open hopper system and the truck engine running contributed to the disaster. The summary underscores the importance of understanding waste hazards, using proper documentation, engineering controls, and eliminating ignition sources to prevent such incidents.
Takeaways
- ⚠️ A vacuum truck transporting toxic and flammable liquid waste from a natural gas production plant to a hazardous waste facility resulted in an explosion and fire due to improper handling.
- 📄 The hazardous waste generator failed to provide essential documents like an MSDS or a hazardous waste profile sheet, which are crucial for understanding the waste's chemical composition and safe handling procedures.
- 🚫 The waste facility and the driver were not informed about the waste's flammability, leading to a lack of proper safety precautions during unloading.
- 🔍 A hazardous waste manifest was provided but it is not a substitute for an MSDS or hazardous waste profile sheet and does not detail the safe work procedures.
- ⛔ The waste facility routinely used an open hopper system for unloading, which increased the risk of exposure to flammable gases and vapors, instead of a safer closed hopper system.
- 🚨 The waste operator's gas detector and the facility's LEL alarm indicated the presence of flammable vapors, but the situation escalated before appropriate actions could be taken.
- 🔥 The truck's engine, left running to raise the pup tank, became an ignition source when flammable gases were drawn into the air intake, leading to the explosion.
- 🏥 The driver suffered serious burns in the incident, highlighting the severe consequences of not adhering to proper hazardous waste handling procedures.
- 🛠️ Engineering controls, such as pump-equipped closed hoppers, should be used to minimize workers' exposure to hazardous substances and control the release of flammable gases during waste offloading.
- 📋 It is imperative for waste generators, transporters, and receivers to review and adhere to documentation that identifies fire or explosion hazards and to conduct risk assessments to prevent similar incidents.
Q & A
What was the incident involving the vacuum truck?
-An explosion and fire occurred during the unloading of liquid waste from a vacuum truck at a hazardous waste facility, which resulted in serious injuries to the driver.
What type of waste was being transported by the vacuum truck?
-The vacuum truck was transporting liquid waste containing hydrocarbons and other toxic and flammable substances from a natural gas production plant.
Why is it important to provide an MSDS or hazardous waste profile sheet?
-An MSDS or hazardous waste profile sheet is crucial as it provides information about the chemical composition of the waste and safe work procedures, which helps in preventing accidents.
What document was provided by the worker at the production plant instead of an MSDS?
-A hazardous waste manifest stating that the waste was 'Petroleum crude oil NOS' was provided, which is not a substitute for an MSDS or hazardous waste profile sheet.
What are the two offloading options at the waste facility mentioned in the script?
-The two offloading options are a closed hopper system, where the discharge hose is connected to a riser, and an open hopper system, where the waste flows directly into an open hopper.
Why was the open hopper system routinely used at the waste facility?
-The open hopper system was used to eliminate the blockage problem that sometimes occurred with the closed system when solid waste blocked the discharge hose.
What happened when the driver activated the engine's positive air shut-off valve?
-An explosion followed with a fireball coming out of the cab after the driver activated the engine's positive air shut-off valve in an attempt to stop the flow of air and flammable gases to the engine.
What is the significance of the 20% lower explosive limit (LEL) in waste offloading procedures?
-The 20% LEL is the maximum concentration allowed for airborne flammable gas or vapor if it's not practicable to maintain the concentration below the applicable exposure limit during offloading or in an emergency.
What was the likely ignition source of the explosion according to the investigation?
-The truck's engine, which was left running to enable the raising of the pup tank, was identified as the most likely ignition source of the explosion.
What are some preventive measures suggested in the script to avoid similar incidents?
-The script suggests knowing the flammability and other hazards of waste, ensuring proper documentation like MSDS or hazardous waste profile sheets, conducting risk assessments, using engineering controls, minimizing workers' exposure, and controlling ignition sources.
Why were the workers not aware of the flammability hazard of the waste?
-The workers were not aware of the flammability hazard because neither an MSDS nor a hazardous waste profile sheet was provided to them, and they lacked clear knowledge of the waste's properties.
Outlines
🔥 Hazardous Waste Explosion Incident
This paragraph details a catastrophic incident where a vacuum truck, transporting toxic and flammable liquid waste from a natural gas production plant to a disposal facility, resulted in an explosion and fire during unloading. The lack of proper documentation like an MSDS or hazardous waste profile sheet led to the workers being unaware of the waste's flammability. The use of an open hopper system, instead of a closed one, due to blockage issues, allowed flammable vapors to accumulate. The truck engine, left running, drew in these vapors, causing an uncontrollable acceleration that led to an explosion, severely injuring the driver. The paragraph emphasizes the importance of knowing the hazards of waste, proper documentation, risk assessment, use of engineering controls, and controlling ignition sources to prevent such incidents.
Mindmap
Keywords
💡Explosion
💡Vacuum Truck
💡Hydrocarbons
💡MSDS (Material Safety Data Sheet)
💡Hazardous Waste Manifest
💡LEL (Lower Explosive Limit)
💡Risk Assessment
💡Engineering Controls
💡Ignition Source
💡Offloading Procedures
💡Hazardous Waste Profile Sheet
Highlights
An explosion and fire incident during waste unloading from a vacuum truck led to a worker's life-changing injuries.
The vacuum truck transported toxic and flammable liquid waste from a natural gas production plant.
Hazardous waste generators are required to provide an MSDS or a hazardous waste profile sheet to inform receivers of the waste's chemical composition.
Neither MSDS nor hazardous waste profile sheet was provided to the driver or the waste facility.
A hazardous waste manifest was provided, but it is not a substitute for an MSDS or profile sheet.
Workers lacked knowledge of the waste's flammability due to missing documentation.
Two offloading options existed at the waste facility: closed and open hopper systems.
The open hopper system was routinely used due to eliminating blockage issues with the closed system.
The truck engine was left running during the unloading process, which later contributed to the explosion.
The waste operator's gas detector alarmed, indicating flammable vapors.
An explosion occurred after the driver attempted to shut down the engine, resulting in severe burns for the driver.
Prevention measures include understanding the flammability and hazards of waste being transferred.
Hazardous waste generators must ensure an MSDS or profile sheet is available for the waste.
Receivers should review documentation and conduct risk assessments for fire or explosion hazards.
Engineering controls, such as pump-equipped closed hoppers, should be used to minimize exposure to hazardous substances.
Waste offloading procedures should prevent flammable gas or vapor concentrations from exceeding 20% of the lower explosive limit.
The open hopper was not designed to keep flammable gas or vapor levels below the 20% threshold.
Control of ignition sources is crucial; the truck's engine was identified as the likely source of ignition.
Learning from this incident emphasizes the importance of knowing and controlling the dangers of hazardous waste.
Transcripts
An explosion and a fire while unloading waste from a vacuum truck would change a worker's
life forever.
This is what happened.
A vacuum truck was transporting liquid waste from a natural gas production plant to a hazardous
waste facility for disposal.
Containing hydrocarbons and other substances, the waste was both toxic and flammable.
A generator of hazardous waste is required to inform the receiver of the waste's chemical
composition.
This is done by providing the receiver with an MSDS for the controlled products in the
waste, or a hazardous waste profile sheet that accurately
describes the hazardous ingredients and safe work procedures.
Neither document was provided to the driver or the waste facility.
However, a worker at the production plant did provide
the driver with a hazardous waste manifest stating that the waste was
Petroleum crude oil NOS.
The manifest is used to track the movement of hazardous wastes and is not a substitute
for an MSDS or hazardous waste profile sheet.
The driver filled out a portion of the manifest and a truck ticket used for billing by the
waste facility.
Along with a swamper he then drove there.
At the waste facility, the driver,
the swamper, and a waste operator from the facility
proceeded to unload the waste from the pup tank.
With no MSDS or hazardous waste profile sheet, none of the workers had clear knowledge of
the flammability hazard of the waste.
Two offloading options existed at the waste facility:
a closed hopper system, where the discharge hose is connected to a riser
to offload the waste.
and an open hopper system,
where the waste flows from the truck tank's discharge valve directly into an open hopper.
Solid waste would sometimes block the discharge hose when using the closed system.
The open hopper was routinely used instead of the closed hopper,
partly because doing so eliminated the blockage problem.
The truck was backed in front of the open hopper.
The engine was left running to allow the pup tank to be raised.
The driver opened the isolation valve for the pup tank,
and after receiving the okay from the waste operator,
the swamper opened the discharge valve.
Flammable liquid rapidly flowed from the pup tank.
The waste operator's gas detector's LEL alarm went off.
Vapours moved towards the front of the truck.
The facility's LEL alarm sounded.
The driver yelled, "Get out of here. Go!"
The other workers ran.
Flammable gases and vapours drawn into the truck engine's air intake caused the engine
to speed up.
The driver turned the ignition key to the off position,
but the engine didn't shut down.
Still in the cab, he then activated the engine's positive air
shut-off valve, in order to stop the flow of air and flammable
gases and vapours to the engine.
An explosion followed with a fireball coming out of the cab.
The driver was seriously burned.
How do we prevent similar incidents?
Know the flammability and other hazards of any waste being transferred.
The generator of the hazardous waste must ensure there is an MSDS or hazardous waste
profile sheet for it.
If the waste is transported, a hazardous waste manifest must be completed.
Receivers of the waste should review the documentation.
Ensure risk assessments identify fire or explosion hazards associated with the release of flammable
gas or vapour during the offloading of hazardous waste.
Minimize workers' exposure to hazardous substances.
In the hierarchy of exposure controls, engineering controls should be used before
administrative controls or personal protective equipment.
Engineering controls such as pump-equipped closed hoppers do exist,
but they weren't used at this facility to minimize exposure to gases and vapours from
waste.
Ensure that waste offloading procedures don't allow the airborne flammable gas or vapour
concentration to exceed 20% of the lower explosive limit.
20% is the maximum concentration allowed if it's not practicable to maintain the airborne
concentration of a flammable gas or vapour below the applicable exposure limit such as
in a temporary situation, as during offloading,
or in an emergency.
The open hopper wasn't designed to keep the levels from exceeding 20%.
Control ignition sources.
The investigation found that the truck's engine was most likely the ignition source.
The engine was still running to enable the raising of the pup tank when the waste operator
gave the ok to open the discharge valve.
Learn from what happened here.
If you deal with hazardous wastes, know the dangers and how to control them.
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