Worker mistakes chemicalSeems like no matter how well a government report describes, some reporters persist in blaming workers’ “mistakes” and “gaffes” for chemical releases and other incidents.

Last week, the Chemical Safety Board released a final report on a major chemical release at MGPI Processing Inc., in Atchison Kansas in October 2016,  due to the inadvertent mixing of sulfuric acid and sodium hypochlorite. The two materials combined to produce chlorine gas that sent over 140 workers and members of the public to the hospital and required thousands of local residents to evacuate or shelter-in-place.

A lazy worker not paying attention?  No, but it seems like blaming workers is always the first thought of some reporters and others.

Last April, when the CSB released preliminary findings, I criticized an AP article whose headline read: “Feds: Human error, labeling led to chemical cloud in Kansas.”  Again, following the release of the CSB report, a headline from the Kansas City Business Journal proclaims “That toxic fog spread over Atchison because of a gaffe with locks, report says,” and the first sentence of the article reads “A federal agency attributed a toxic fog that enveloped Atchison in 2016 to a mistake by plant employees in unlocking chemical storage tank pipelines.”

Interestingly, if you read the 48 page report, the words “gaffe” or “mistake” never appear.  What does appear is a serious analysis of a series of significant problems with the design of chemical transfer equipment, lack of automated and remote shut off systems, and faulty chemical unloading procedures at the plant.

What Happened

Early on the morning of October 21, 2016, a driver from Harcros Chemicals pulled up to MGPI to deliver 4,000 gallons of sulfuric acid. The MGPI operator unlocked a delivery pipe and went back to the office. The truck driver then hooked his hose up to an unlocked pipe and turned on the valve. Within a few minutes heavy clouds of chlorine gas descended on the truck, got sucked into the control room and began drifting over the heavily populated area. It turns out there were two unlocked pipes, right next to each other and the driver hooked the delivery line into the wrong pipe and got back in the truck to do the paperwork.  By the time he noticed the cloud, he wasn’t able to access the valves on the back of the truck to turn off the flow. The operators in the control room couldn’t access their emergency respirators fast enough  because they were locked in their locker and they weren’t able to open the combination locks with chlorine gas pouring into the room. Because neither the control room operators nor the truck driver could access the shut-off valves, it was 45 minutes before a HazMat team could arrive and finally close the discharge valve on the tanker truck.

This event was not unique. Pipeline and Hazardous Materials Safety Administration (PHMSA) incident data from 2014 through 2017 and found that unloading incidents involving hose connections to incorrect tanks occur frequently but most commonly involve compatible materials and result in tank overfills. Less common are incidents similar to the MGPI incident where two incompatible materials are inadvertently mixed due to incorrect tank connections. However, since January 1, 2014,156 eight incidents similar to the MGPI incident have occurred involving incompatible materials and resulting in a chemical reaction. These incidents resulted in 44 injuries and the evacuation of 846 individuals.


I’ll summarize here, but read the report or at least check out the video below.

When doing any kind of comprehensive root cause analysis, investigators need to keep asking “why” until they get to the real root causes. In this case the inadvertent mixing was the initiating event. But “why” was the line hooked up to the wrong pipe?

The CSB found a number of serious problems with the health and safety systems of both companies. Many of these involved human factors. Human factors is not the same thing as human “error” or worker mistakes. As the CSB explains

“Human factors” addresses the interactions in a work environment among workers, equipment, and processes and includes a broad range of areas that can influence safety, such as the design and physical characteristics of a work area; worker stress and fatigue; and the systems under which work is carried out, such as procedures, training, and communication.

The main problems that caused the release include:

Location, characteristics and labeling of piping: Both the sulfuric acid pipe and sodium hypochlorite pipe were close to each other, neither were labeled or color coded, and both had the same fittings making it possible to mix incompatible chemicals.

Work practices did not match operating procedures: There were a number of areas where written procedures were not followed. For example, the plant operator was supposed to ensure that all pipes were locked except for the one that was to be filled. He was supposed to confirm that the hose was connected to the correct pipe. The driver was supposed to closely monitor the loading to ensure that nothing went wrong. Assuming the procedures are correct, workers need to be trained and their understanding of the procedures needs to be verified.

Personal Protective Equipment Needs to be Accessible: The workers in the control room had emergency escape respirators, but couldn’t access them because they were locked in their lockers. And because they were locked with combination locks, they couldn’t open them with chlorine gas pouring in the room. The truck driver had no respirator and therefore couldn’t access the emergency shutoff valve at the back of the truck.

Automatic Shutoffs: Because (as we’ve seen) humans don’t always act as expected and can’t always access shut-off valves, there be additional layers of protection — an automated control system that can monitor and respond to hazardous process conditions (e.g., temperature, level, pressure, or airborne concentrations) and automatically shut down the transfer of chemicals and other processes in the event of an unintended reaction or release during chemical unloading.

Emergency Response: Hospital staff was not informed as to the composition of the chemicals being released, the status of potential victims and decontamination procedures for the chemicals.

Lessons Learned

One might still ask, why isn’t this just simply human error? Because as I’ve written before, one factor was an error made by a human being. But humans, being humans, always make errors. Sometimes it’s because they’re paying attention or didn’t sleep well last night. Sometimes their mind is elsewhere because they had a fight with the spouse or kids this morning, long day, boss just yelled at you, or you’re rushing because you have 15 more deliveries to make and you’re running late.  Or because you haven’t been trained. Or didn’t understand some of the training, and didn’t understand what you didn’t understand.

Add to those factors a confusing layout, poor procedures and lousy labeling.

That’s why systems that are well engineered for safety assume that fallible humans are running operation. They take into account how humans relate to machines, and seek to engineer or design human error out of the process. And if all else fails, there are also good emergency response procedures.

The problem with labeling the whole thing “human error”  or a “mistake” by a worker is that it leads to the assumption that you can just replace that worker with a different, perhaps more conscientious worker, and everything will be fine. The problem is that if the procedures are bad, the fill lines aren’t well labeled and look the same and are located near each other, and the respirators aren’t accessible and the emergency shutdown mechanisms still don’t work — then the next worker on the job will have the same problem. Maybe not today. Maybe not tomorrow. But soon, and with serious implications for workers and the community.

So beware of headlines bearing messages of “human error.” The safety of our workplaces and  communities shouldn’t depend on humans never making mistakes.


3 thoughts on “Chemical Release Caused by Workers’ Mistakes? CSB Says No.”
  1. Blaming workers is the easy (and lazy) way out of performing a thorough investigation and determining the real root causes of these types of incidents. I was taught (by Bill Bridges and Revonda Tew at the Process Improvement Institute) that root causes NEVER travel alone, and that failures such as these are due to gaps in management systems (which for the chemical industry could be PSM, RMP, RC, etc.).
    “Rather than viewing human performance as a mechanical process, we need to see it more like a weather pattern that can be changed by multiple factors, something that needs to be forecast rather than fixed.” -Terry L. Mathis Founder and CEO of ProAct Safety.
    It really all comes back to a very basic principle of any effective management system; PDCA. Plan, Do, Check, Act.

  2. And why was the driver sitting in the cab of the delivery vehicle during the unloading process? DOT regulations CLEARLY require that during delivery of hazardous materials the driver be “in attendance” and specify within 25′, with an unobstructed view, etc.
    Was this driver trained, and did he understand that requirement? Hopefully the chemical distributor will take a good look at their training programs, and do some occasional monitoring to determine compliance with those regulations.

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