Mixed Connection, Toxic Result

Summary

On October 21, 2016, a chemical accident at the MGPI Processing facility in Atchison, Kansas, caused a toxic cloud to drift into the community, injuring over 140 people. The incident occurred when sulfuric acid and sodium hypochlorite were mistakenly mixed due to improper chemical unloading procedures. The CSB's investigation highlighted human errors, inadequate labeling, and lack of emergency shut-off systems as contributing factors. The case emphasizes the need for chemical facilities and distributors to reevaluate safety protocols, improve equipment design, and ensure proper communication to prevent similar incidents in the future.

Takeaways

• 😀 The MGPI incident occurred on October 21, 2016, when sulfuric acid and sodium hypochlorite were mistakenly mixed, creating toxic chlorine gas that affected over 140 people.
• 😀 The incident was caused by a delivery of sulfuric acid, where a driver connected the wrong hose to the sodium hypochlorite line due to similar-looking, unmarked lines.
• 😀 The lack of proper labeling and close proximity of chemical lines contributed to the operator’s and driver’s failure to properly connect the unloading hose.
• 😀 The CSB identified human factors deficiencies, including poor communication and unawareness of safety procedures, which led to the chemical reaction.
• 😀 Over 4,000 gallons of sulfuric acid mixed with 5,800 gallons of sodium hypochlorite, causing the release of chlorine gas that required the evacuation of 11,000 people.
• 😀 The incident highlights the risks associated with routine chemical deliveries, which, though simple in theory, can have severe consequences due to the large quantities of chemicals involved.
• 😀 The lack of automatic shutoff systems in the chemical transfer process prevented an immediate halt to the chemical flow, prolonging the release.
• 😀 The CSB urges facilities to improve the design and labeling of chemical transfer systems to reduce the likelihood of operator error and chemical mixing.
• 😀 Facilities should implement physical safeguards, such as differentiating hose couplings, separating lines, and automating shutdown processes to improve safety.
• 😀 The MGPI case emphasizes the need for comprehensive safety training, clear procedural guidelines, and collaboration between facilities and chemical distributors to prevent future accidents.

Q & A

What caused the toxic cloud at the MGPI facility?

The toxic cloud was caused by an unintended chemical reaction when sulfuric acid and sodium hypochlorite, two incompatible chemicals, were accidentally mixed at the MGPI facility.

What are the potential dangers of routine chemical deliveries in facilities like MGPI?

Even routine chemical deliveries can be dangerous because large quantities of chemicals are involved. Incorrect handling or chemical reactions, such as mixing incompatible substances, can result in severe incidents, as seen in the MGPI case.

How did the chemical transfer mistake happen at MGPI?

The mistake occurred when a truck driver, following instructions from an operator, connected the sulfuric acid unloading hose to the wrong fill line, which was meant for sodium hypochlorite. This resulted in a chemical reaction that released chlorine gas.

What human factors contributed to the MGPI incident?

The proximity and similarity of the sulfuric acid and sodium hypochlorite fill lines, lack of clear markings, and insufficient operator training on procedures were key human factors that contributed to the incident.

What was the immediate effect of the toxic gas release on the MGPI workers?

The toxic gas quickly overwhelmed the workers in the control room, and some were unable to access their respirators before evacuating. This delayed the response to stop the chemical transfer.

How long did the chemical transfer continue after the incident began?

The transfer of sulfuric acid into the sodium hypochlorite tank continued for nearly 45 minutes before emergency responders were able to stop the flow.

What were the consequences of the incident for the community?

Over 140 people, including MGPI employees, emergency responders, the truck driver, and members of the public, sought medical attention due to the toxic exposure. The incident also led to the evacuation or shelter-in-place order for 11,000 citizens in Atchison.

How common are unloading incidents like the MGPI case?

While less common than incidents involving compatible chemicals, incidents like the MGPI case, where incompatible materials are mixed, have occurred at least eight times since 2014, resulting in injuries and evacuations.

What lessons did the CSB identify from the MGPI incident?

The CSB emphasized the importance of properly evaluating and designing chemical unloading systems, ensuring clear labeling and separation of incompatible chemicals, and installing safeguards like alarms and automatic shutdowns to prevent similar incidents.

What procedural issues were identified at MGPI that contributed to the incident?

MGPI's procedures were not followed as intended. For example, operators were supposed to verify the connection of the fill line but were not present during the actual hose connection. Additionally, some operators were unaware of the correct procedures, leading to unsafe practices.