Incident Investigation: Vacuum Truck Explosion Injures Worker | WorkSafeBC

WorkSafeBC

7 Nov 201604:54

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

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🔥 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

An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. In the context of the video, an explosion occurred due to the ignition of flammable gases and vapors that were drawn into the vacuum truck's engine air intake, resulting in a fireball and serious injuries to the driver.

💡Vacuum Truck

A vacuum truck is a specialized vehicle designed to transport liquid or gaseous waste materials by creating a vacuum within its tank. In the video, the vacuum truck was involved in the transportation of hazardous liquid waste from a natural gas production plant to a waste facility, where the incident occurred.

💡Hydrocarbons

Hydrocarbons are organic compounds consisting entirely of hydrogen and carbon atoms. They are often found in petroleum and natural gas and can be both toxic and flammable. In the video, the liquid waste contained hydrocarbons, which contributed to the flammable nature of the waste being transported.

💡MSDS (Material Safety Data Sheet)

An MSDS is a document that provides information on the potential hazards of a chemical product and how to handle, store, and dispose of it safely. The video emphasizes the importance of having an MSDS for hazardous waste, as it was not provided in this case, leading to a lack of understanding of the waste's properties and safe handling procedures.

💡Hazardous Waste Manifest

A hazardous waste manifest is a document used to track the movement of hazardous waste from the point of generation to the point of disposal. In the video, a manifest was provided but incorrectly stated the waste as 'Petroleum crude oil NOS,' which did not accurately describe the waste's composition and potential hazards.

💡LEL (Lower Explosive Limit)

The Lower Explosive Limit is the lowest concentration of a flammable gas or vapor in air that can form an explosive mixture. The video script mentions that the LEL alarm went off, indicating that the concentration of flammable vapors had reached a dangerous level, which is a critical point in understanding the risk of explosion in such situations.

💡Risk Assessment

A risk assessment is the process of identifying potential hazards and analyzing the likelihood and consequences of those hazards. The video suggests that a proper risk assessment could have identified the fire or explosion hazards associated with the offloading of the hazardous waste, potentially preventing the incident.

💡Engineering Controls

Engineering controls are methods of controlling hazards by modifying the source of the hazard, such as through the design of equipment or processes. The video mentions pump-equipped closed hoppers as an example of engineering controls that could have been used to minimize exposure to flammable gases and vapors during waste offloading.

💡Ignition Source

An ignition source is any object or condition that can cause combustion or an explosion. In the video, the truck's engine, which was left running, is identified as the likely ignition source that caused the explosion by igniting the flammable gases and vapors.

💡Offloading Procedures

Offloading procedures refer to the steps and methods used to safely transfer materials from one container to another. The video discusses the importance of having safe offloading procedures that prevent the concentration of airborne flammable gases or vapors from exceeding 20% of the LEL, which was not adhered to in this case.

💡Hazardous Waste Profile Sheet

A hazardous waste profile sheet is a document that provides detailed information about the hazardous ingredients in waste and outlines safe work procedures. The video emphasizes the necessity of such a document for ensuring that all parties involved in the handling of hazardous waste are aware of the associated risks and how to mitigate them.

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.