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Podcast: Deadly Dust -- Lessons Learned From The 2017 Didion Milling Explosion

May 30, 2022
Indictments leveled against a few key players are charging conspiracy to commit federal offenses in order to conceal violations and unsafe conditions from auditors and government agencies.


Traci: Welcome to the "Process Safety With Trish & Traci" podcast, the podcast that aims to share insights from past incidents to help avoid future events. I'm Traci Purdum, executive digital editor with Chemical Processing, and as always, I'm joined by Trish Kerin, the director of the IChemE Safety Center.

Hey, Trish, what is new in your world of process safety?

Trish: Wow. There's certainly lots happening at the moment. I'm about to head off from Australia to the UK, and Europe for the next couple of weeks to go to a series of different process safety events and activities. So, I'm looking forward to catching up with my European colleagues and understanding what's happening over there.

Traci: Sounds great. Crisscrossing the world and you'll be in all sorts of different time zones. So, hopefully, you won't be too confused.

Trish: Hope not.

Traci: Well, today we are going to look back at the deadly dust explosion that occurred at Didion Milling in Cambria, Wisconsin on May 31st, 2017. The explosion killed five workers and injured 15 others. In mid-May, just this year, a Federal grand jury indicted the operator and six management officials on nine criminal counts, including two counts related to willful violations of federal workplace safety standards for grain handling. Trish, can you give us some background on the incident itself.

Trish: Sure. So, the CSB are still currently investigating this incident. So, there's still, believe it or not even all these years later, some unknown pieces of information here. What we do know is that shortly before the explosions occurred at the mill, workers reported that some of them saw or smelled some smoke on the first floor of one of the mill buildings. And in trying to find it source, they started to focus on a piece of equipment called a gap mill. Now, while they were inspecting that equipment, one of the filters on the air intake blew off, and that created a corn dust cloud that filled the air. Then, there were flames coming out from the air intake line that then resulted in an explosion. And as is the case with dust explosions that do occur, then we saw more explosions because the first explosion started to liberate even more dust. And so the shock wave creates more dust, which then propagates another series of explosions that occurred. So, it was quite a substantial explosion that occurred. If you see the photos or the video, this building was absolutely destroyed by this particular incident. To my knowledge, they have not yet determined what the initial fire and ignition source was for this incident though yet.

Traci: Now, let's talk a little bit about the violations, what were they, and how are they going to be able to determine if they're willfully violated?

Trish: Okay. So, this is a really interesting part to look at, and it was fascinating to read some of the articles and activities going on in this space. So, as you mentioned earlier, six personnel have been indicted, and they will stand criminal trial for this. So this is no longer a civil matter. This is a criminal matter for them. Now, criminal does mean that, obviously, they do need to be found guilty beyond all reasonable doubt. So, they do have...the prosecutors, the government have a higher burden of proof because it is beyond all reasonable doubt, not on the basis of probabilities as in a civil case. But these crimes relate to alleged worker safety, fraud, air pollution, and obstruction of justice. So, they're quite substantial charges that we are hearing about here. And there are six people, from as senior as the vice president, all the way down to some of the shift superintendents. So, they weren't only just the senior management here that has been indicted in this particular instance, either.

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Now, apparently, the company was required to regularly clean the dust accumulation from the inside of the mill for, not only safety issues, because of combustible dust, but also for food safety and quality issues as well. And they were required to operate and maintain air pollution control devices and have documentation around the maintenance of these things. Now, according to the indictment, they allegedly didn't have a proper log of the important cleaning procedures of the plant. So, that's one particular issue, first of all. So they didn't have a proper log that was being kept. Now, supervisors allegedly made requests of employees to backdate the cleaning logs so that they'd be compliant when it came time for auditing. So, now we're starting to talk about fraudulent behavior here. Apparently, according to the indictment, the managers were aware that the cleanings were not getting frequently done.

In a 2014, email from the food safety superintendent, so this is one of the people that has been indicted. He cited approximately 300 tasks not completed entry. And in 2016, there were another 130 tasks not completed. And 36 blank entry. That was obvious that they knew the tasks weren't being documented. Whether they knew the tasks weren't being completed is a different matter, and that's for the prosecution to prove. But they knew the tasks weren't being documented. Now, early on in my career, I worked in the aviation fueling sector. And one of the things that was drummed into me at every instance was, if it's not written down, it never happened. So, you always have to document all of these sorts of checks. If it's not written down, you got to consider it never actually happened.

Now, in terms of the way that they were filling in, the indictment has basically said that there were several overt acts showing times when supervisors sent emails, requesting empty logs to be filled in for upcoming audits so they would pass them. And the indictment actually reads, "DMI willfully violated two federal safety standards promulgated under the Occupational Safety and Health Act. By one, failing to develop and implement a written program to effectively prevent and remove combustible grain dust accumulations. And two, by failing to install explosion venting or explosion suppression on a dust filter collector." So, they're the two willful violations that they have been charged with. So, there's certainly a lot of issues around what was going on there. The indictment also said that they failed to follow procedures, and that caused the death of the five employees due to the combustible dust explosions that occurred because of the failure to follow those procedures.

So, basically, they're being charged predominantly with fraud and taking deceptive measures to conceal their failure, to meet the OSHA standards, which are really quite substantial charges to be laid. In terms of some of the other charges. So, a couple of the people are charged with conspiracy to commit federal offenses in order to conceal violations and unsafe conditions from auditors and government agencies. So, you know, there were comments in emails stating things like, I just need everyone to make sure the logs are up-to-date, not actually to make sure the checks are done. And I think that's where the government is going to be trying to push for the charges in that. As I said, it is a criminal charge that they've been indicted on. And so they actually could be sentenced up to 20 years in prison for these crimes, should they be proven in court, quite substantial.

Traci: Well, yeah, these are very serious allegations. And I'm trying to think back of any, obviously, process safety incidents. There are serious allegations in past process safety incidents, but this seems pretty...they're pretty good. They're going full hog on them on this.

Trish: They are. The only other one I can think of that really sort of sticks in my mind of something similar in terms of the magnitude of the allegations would be the Upper Big Branch Mine incident that occurred several years ago, where I believe they might have had some charges of willful. And I believe they were found guilty. That was testing my memory.

Trish: That was testing my memory. I think someone was prosecuted and sent to jail over Upper Big Branch.

Traci: I think, and we had discussed this, and I think you are correct. And I will go back and link to that in the transcript of this podcast so we can...because we did discuss that at one point [See: Podcast: Are Corporate Manslaughter Charges Too Much For Safety Incidents?] And chemical processing dedicates a fair amount of content to process safety. And in particular, for this incident, preventing dust explosions, we have webinars and articles and, in fact, this podcast. From my seat, it appears that it's well known that accumulated dust is a big hazard. Is there a disconnect in facilities not grasping the same concept? Obviously, I would think that they would know the ramifications.

Trish: We need to remember that sometimes some of these facilities are smaller in nature, and they might not have the staff on hand that actually have that technical knowledge. Now, that is in no means an excuse for not knowing. Ignorance is not a defense. And they certainly will not be able to try and rely on that, I would suggest. But the fact is that we see a lot of places that have dust explosions, just really don't get that dust can be explosive. And one of the challenges is we often think if we think about, you know, combustibles or flammables, we think petrol, gasoline, we think those sorts of things. We don't necessarily think about flour, sugar, corn, these are all things we eat. And I think that actually puts us into a false sense of security. Because how dangerous can flour be? How dangerous can corn be or sugar? The fact is very dangerous when it actually is in the right conditions for an explosion.

And so we also tend to get into this false sense of security in that, certainly, in the process safety world, we often just sort of, to a certain extent, maybe dismiss housekeeping a little bit because that's an OHS thing that they need to worry about. That's not a process safety thing. When we're talking dust, housekeeping is clearly a process safety aspect. Because dust accumulates over time. As you know, I mean, I'm sure if you've got a shelf anywhere in your house with knickknacks on it. Dust accumulates over time, doesn't it? So, you need to make sure that you actually are maintaining your housekeeping to keep the surfaces dust-free. And one of the challenges is that sometimes there are surfaces we don't see. If there's a mezzanine roof on a building inside a larger building, how are you cleaning the roof of that area?

That's why things like you should be... If you have beams in your facility, ceiling beams, they actually need to be fully encased. You can't have an eye beam or a sea channel exposed because the flanges are perfect for the accumulation of dust that you can't see because it's up in the air and it's on a surface facing the ceiling. So, you can't see it from the ground. So, things like having enclosures around your beams are really important as well to make sure that you can't accumulate dust on them. Keeping your housekeeping up-to-date and making sure that you're doing things like vacuuming the dust, not blowing the dust. Because, you know, it can be a lot quicker if we just get the leaf blower out and start moving the dust around. We can move it much quicker, but that's not the right thing to do, that will potentially create a hazardous environment for you. So things must be vacuumed, not swept, vacuumed. That's the only way that you can actually make sure that you can contain the dust. You've got to make sure you've got your bag filters in place and they're being regularly changed, so you're not getting breakthrough of the dust coming through them either.

There's a range of different things. The other thing to remember is we understand the science of this. There's a thing called the Dust Pentagon, that explains perfectly well why dust explosions happened. But first of all, you have to have a combustible dust. And some of them are the ones that we dismiss as being harmless because their food substances, but they're still combustible dust. But you could also have, metal dust is combustible, wood dust is combustible. A number of other different dust are as well. There's certain characteristics that go with whether a dust actually is a combustible substance. So, combustible dust has to be present. So, if you've got a dusty environment or if you are handling dust in any way, you've got combustible dust. Then you need something that actually is going to disperse the dust into the atmosphere. So, whether that is sweeping, blowing, a jolt of some sort of small explosion or incident that happens that starts to shake dust around, equipment damage that can cause dust to be put into the air, whatever it is, you got to disperse the dust.

And then you need some form of confinement as well. So, dust explosions typically happen within buildings. There's a form of confinement around it. Or they can also occur where you've got other buildings around. So you might still be outside, but there is still that confinement that deals with how the explosion actually propagates. And then, obviously, you need an oxidant air is around. So we've got the oxidant and the ignition source. So, if you've got all five things in place, at any one point in time, you can have a dust explosion. You need to make sure we are removing as many of these fibers that we can because some of the others can sneak up on us at times if we don't realize it. So, we can't just say, "Well, we'll make sure that we don't have confinement." If you've got the other four in place, then some part of that dust could well be confined somewhere. So, we need to make sure we're covering off on all the areas.

Obviously, the inherently safer way is let's not have dust at all. If you're handling a product, can you handle it as a slurry? Can you handle it as a palletized form? Does it have to be a dust? Now, in some instances, you are making dust deliberately. If you're making sugar, flour, corn, mill, you are making dust for a purpose. But in other instances, there are times when you don't need to handle a dust at all. So, why don't we actually stop making dust and start using, as I said, pellets or flurries to move things around rather than potentially have that dust accumulate. There's a lot of things that we can be doing differently and better in this space. But it does start with people need to be aware of the dust Pentagon and make sure that we address all five elements of it in the situations where we could have dust. And one of those key areas is make sure you have good housekeeping. And as I said, housekeeping is not only an OHS issue when it comes to dust. Housekeeping is a process safety-critical task when it comes to combustible dust.

Traci: Absolutely. And you talking about the false sense of security. And the Pentagon you're talking about, everybody has those things within their plants if they're creating something that causes dust. So, it's not out of the realm for any of this to happen. So, keep things in check is the best way to mitigate. And I was wondering if you had any other sorts of resources available for plants to better mitigate these dust hazards. Is there something... I know the NFPA is a source, are there other resources they can go to?

Trish: Yeah. So, there's certainly several standards out there in terms of managing and handling dust. So, obviously, NFPA have their standards. In Europe, it's ATEX standards that cover it. And the key elements here are, in a similar way to flammability, you have to make sure that you are controlling your ignition sources. So, if you have electrical equipment within areas where you could have dust accumulation, then they actually need to be rated for dust. And it's a different rating as the one for flammable vapors. So, make sure you've got the right equipment, follow the standards here. They're well and truly clearly established in terms of what you need to be doing to have the right hazardous zones established around the equipment you have, where you could have dust accumulating. None of this is new. There is an enormous amount of information out there on dust. There are a number of different training courses around the world on safe handling of powders and dust. And they happen in so many different industries as well.

And you've also, as I said, you know, go back and check the standards. There's a lot of standards on this stuff, making sure you've got the right equipment in place, and then you're maintaining it correctly as well. Again, I talk about maintenance a lot. We can install the right equipment, but if we don't maintain it, it's not worth the cost of installation. Because if we're not maintaining equipment for hazardous zones, we can no longer consider it as being safe for hazardous zones.

Traci: That's an important distinction.

Trish: And one that's often missed.

Traci: Absolutely. Absolutely. And that maintenance to make those things are working is just paramount. Out of tragedy can come lifesaving lessons learned, what can we gain from this incident?

Trish: I think one of the key things when you look at... If we look at this incident as it's unfolded, and potentially where it could go for the six individuals that are being prosecuted here, we see a situation where people deliberately, allegedly have broken the law. And that's what they're being charged with willful violations, in an effort to get the product produced, to get the material out the door, to get the corn milled down, to keep production running. So, there's a whole cultural issue around production over safety, I would suggest potentially in this facility. Five lives were lost in this incident, and we could see another six people spend 20 years in jail because of it, too, because they allegedly pushed to get things done in a certain way that resulted in these fatalities occurring.

It always comes back to the old Trevor Kletz quote, "If you think safety is expensive, try an accident." And we're not only just talking about the financial cost here, but we are talking about potentially, not only the five lives lost and the impact on those families but also another six lives impacted potentially here, too, because of the actions that they have allegedly taken. So, you know, what can we gain from this incident? It is far better to get it right the first time, do the work that needs to be done, make sure it's adequately documented. Because if it's not written down, it never happened. And that way prevent the situation that led to the tragedy that killed five people here. So, you know, keep your facilities clean of dust, if you handle dust.

Understand what the standards are, and make sure you are following them. Make sure your equipment is maintained adequately. All of that, surely, has to be a lot easier and cheaper than 20 years in jail, and not forgetting the five lives that were lost in this strategy.

Traci: Now, what about the folks listening to this podcast that maybe aren't management, but they are the workers that see what's happening is...what I'm getting at is, is there a whistleblower line that they can call into to alert people that these types of things are happening? Or is know, you mentioned that they put this facility, obviously, was putting production over safety. Is there a safe place for people to report things like that?

Trish: At the end of the day, you'd like to think that people could report it through their own company lines and say, "Hey, there's a problem here. We need to fix it." In reality, some facilities and some companies don't have that culture where people are safe and have the psychological safety to be able to stand up and say, "There's a problem we need to fix this, this is unsafe." In those instances, if you can't get it through the channels internally, then that is where we need the regulators to become involved in it. And that is where a call to OSHA to say, "Hey, there's a problem here. I have seen something. I think there's a safety breach." You know, if we can bring in the regulators before the incident occurs and get the changes made, then no one has to die for this. And that is one of the key aspects of it. When you see something unsafe, if you are not in a position to take action on it yourself, to fix the situation, you need to be courageous enough to call the people that are.

And sadly, that last line then is going to be the regulators. And if we need to bring the regulators in, then that is something that should potentially occur. I mean, I have known of instances where I have seen workers believe that they weren't getting what they wanted from the management in terms of resolving a safety issue, and they have called in the regulator. I've seen that occur personally. I've also personally picked up the phone, in some instances, where, you know, walking past the construction site, I had no influence to be able to change it. In fact, there was one I was watching from my office window, a construction site in the city of Melbourne. And I looked out the window and I thought, "Oh, my. Someone is about to die on that construction site with the work they're doing." I phoned the regulator and called the regulator into that site because of what I was witnessing. I had no way to access that site, so I had no other way to communicate with them. But if I hadn't have done that, there was a very real possibility that someone could have fallen to their death on that site.

So, sometimes we just need to stand up, pick up the phone and make that call. If we can't influence it directly internally, we should try to influence it directly, internally. That would be the best way to try and resolve the issue. But if we just don't have the agency to be able to do that, then we need to be going to the regulator, I think.

Traci: Some sound advice. Trish, you know my last question is always, is there anything that you would like to add that we maybe have not touched on?

Trish: We've covered a lot of things today, haven't we?

Traci: Yes, we have.

Trish: Look, I think I just want to go back to a couple of points of making sure that, not only are the checks that need to be done but that they're documented. And whilst we all have a lot of paperwork to do and checklists, and it's really annoying to get all those documents done. At the end of the day, the documentation is the evidence that said you did something. Assuming that the documentation is not fraudulent, that's why you need to do the checks and document the checks, not just document something you didn't do. So, make sure you are doing the cleaning, the checking, the maintenance activities that you need to be doing to keep your facility safe, then make sure you've got it written down. Because sadly, if something does occur, you are going to need to rely on that. And you don't want to be in the situation where a court starts to accuse you of having fraudulent documentation in that instance.

Traci: As always, you are the voice of reason letting us know that it is far better to get things right the first time so that we can prevent these tragedies. Unfortunate events happen all over the world, and we will be here to discuss and learn from them. Subscribe to this free podcast so you can stay on top of best practices. On behalf of Trish, I'm Traci. And this is "Process Safety With Trish & Traci."

Trish: Stay safe.

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Trish Kerin, director, IChemE Safety Centre, Institution of Chemical Engineers, spent several years working in design, project management, operational, safety and executive roles for the oil, gas and chemical industries. She currently sits on the board of the Australian National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) and is a member of the Mary Kay O'Connor Process Safety Center steering committee. You can email her at [email protected].
Traci Purdum, an award-winning business journalist with extensive experience covering manufacturing and management issues, joined Chemical Processing as senior digital editor in 2008. Traci is a graduate of the Kent State University School of Journalism and Mass Communication, Kent, Ohio, and an alumnus of the Wharton Seminar for Business Journalists, Wharton School of Business, University of Pennsylvania, Philadelphia. You can email her at [email protected].

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