Pellet Plant Safety Rooted in Planning, Practice

The lines of communication between pellet facility employees, management and local fire and emergency response personnel begin with robust training and planning. But even the best-laid plans are only as good as a plant's practice regimen.
By Anna Simet | May 26, 2020

In the aftermath of a 2019 grain silo fire and explosion that resulted in the death of a firefighter and serious injury of an employee, many conclusions were made in a subsequent OSHA investigation report. Discernible from those conclusions was that each violation had a common thread: “inappropriate or incomplete lines of communication.” Unfortunately, inadequate communication extended beyond the worksite, having detrimental effects on the emergency response outcome. Specifically, “definitive roles and duties within the incident command system were not clear or appropriate,” and essential information firefighting personnel needed in the event of the emergency was not collected. This included the amount and type of grain in the silo and that it had been smoldering for two days, the assessment of explosion risk and height of bridged product, and the existence and configuration of an inspection port along the side of the silo. This lack of information caused changes to the emergency response and limited strategies to fight the fire, resulting in a catastrophic outcome.

Working with a highly combustible material is the nature of wood pellet manufacturing, and while there is no across-the-board instruction manual on how to prepare for and respond to emergencies, as a jumping off point, there are general recommendations and guidelines for both firefighting personnel and facilities with combustible dust. “OSHA’s publication, Firefighting Precautions at Facilities with Combustible Dust, indicates that a pre-incident survey forms the basis of how emergency responders plan for and handle incidents,” an OSHA spokesperson tells Pellet Mill Magazine. “Employers and firefighters must understand that the more specific the information that is shared, the more comprehensive and valuable the pre-incident survey will be.”

OSHA does not mandate communication between an establishment processing combustible dusts and emergency responders, the spokesperson adds, but strongly encourages communication and coordination to ensure employees and emergency responders remain safe during emergency situations. Doing so could prevent injury or deaths, but also citations and fines. “To abate hazards at facilities processing combustible dusts, OSHA may issue citations for violations of OSHA standards and Section 5(a)(1), the General Duty Clause, which requires employers handling combustible dusts to comply with several agency standards, including housekeeping, exit routes, emergency action plans and fire prevention plans, as well as materials handling and storage, and toxic and hazardous substances.”

Even abiding by professional guidelines and recommendations, it leaves the responsibility of formulating, practicing and executing a plan up to each individual facility. “There are a lot of unique components for every specific plant, but there are some things all of them can be prepared for,” says Fahimeh Yazdan Panah, director of research and technical development for the Wood Pellet Association of Canada. “Development of fire and emergency response is very important, as a lot of conventional practices to extinguish fires are not really applicable in general for biomass storage.”

For high-capacity facilities, a heavy focus should be placed on silos, according to Panah, and that includes outreach to local fire departments to ensure they have the knowledge and equipment needed in the case of an emergency.

Preparation and Communication
“Wood pellet storage tends to self-heat, and is prone to spontaneous combustion,” Panah says. “It very much depends on the condition of the storage and environment around the storage—for example, the temperature, and if the pellets are exposed to moisture. These fires don’t happen often, but when they do, they are usually a catastrophic event.”

 Panah underlines many “don’ts” that may not be obvious when it comes to combatting self-heating or fires in silos, including that they should never be opened, water shouldn’t be used, and employees or emergency personnel should never work on top of the silo. “When self-heating happens, gases are being produced—carbon dioxide (CO2), carbon monoxide (CO), and methane. The CO is an early sign; you may not even see any smoldering, especially if the self-heating is happening deep in the silo. That’s why it’s very important to constantly measure the concentration of gases in the headspace of the silo and around it—if you read a higher concentration, you know something’s happening.”

In the event the incident has accelerated to visible smoldering with a strong odor—an indication pyrolysis has begun—plants should take immediate action, following an emergency response plan that has been practiced with their local fire department. “When the fire department comes to the plant, personnel should be able to explain the observations made, the gases measured and whether there is smoke, so they have a good idea of the scenario,” Panah says. “Other things firefighting personnel should know include the type of silo, whether it’s connected to a ventilation system (which should be shut down), access points for nitrogen injection and the rate of flow it should be sent into the silo.

 In some cases, firefighters may not be aware that liquid nitrogen, rather than water, is needed. “They should know—in advance of an incident—that they need to bring this and a vaporization unit with them,” Panah advises. “Things like this are what they should practice, or at the very least, be aware of.” This knowledge could make a significant difference in the amount of damage a facility undergoes during an incident, especially in locations that are long distances from mobile nitrogen systems. “For some plants in British Columbia, it’s an eight-hour drive to get nitrogen to the plant,” she says. “And there have been some cases where there has been smoldering, but two days’ time to get nitrogen. The very first 24 or 48 hours are critical to have access, and the fire department needs to know this. Nitrogen inerting should be done from the bottom of the silo, discharging material to break down the hot area in the silo.”

CO2 can also be used, Panah adds, but nitrogen is highly recommended for a variety of reasons. Perhaps most importantly, if the silo temperature is very high and CO and methane are being produced, CO2 may change the direction of some reactions, producing an excess of hydrogen. In that case, if the silo is opened and exposed to enough oxygen, it will explode. “This is another thing the fire department and plant need to review together and have a system or plan in place in the case something happens,” Panah says.

There are additional things the fire department and plant personnel should know, including that water can’t be put in a silo of wood pellets or biomass. “It’s not a conventional silo, or an open flame—pellets will absorb the water and expand, and the silo may burst,” Panah says. And, nobody should ever work on top of the silo or open it, as there will be a high level of flammable gas in the headspace of the silo, which is not only poisoning and dangerous, but will explode if oxygen is introduced.

Wood pellet silo fires—which can take days, or even a week to safely extinguish—don’t happen often, so all these things should be communicated with the local fire department, Panah reiterates. She gives the example at an incident at a Prince George, British Columbia, pellet manufacturing facility that had reviewed and practiced its emergency response plan with the local fire department, which resulted in saving the plant and keeping all personnel safe.

Each plant has its own unique scenario, Panah adds. “This is why all of this should be done together with the fire department, with everyone working together. It should be practiced before any incident happens, or it’s going to be quite challenging.”

Industrial wood pellet producer Enviva has eight operating industrial wood pellet plants in the Southeast U.S., and with two more under construction, the company continues to invest heavily in safety, training and professional manufacturing practices, according to Christopher Seifert, Enviva vice president of environmental health and safety. For new employees, safety and emergency training begins on day one.

Industrial Insight
“Beginning at new hire orientation, all Enviva employees receive training on their location’s emergency response plan, as well as our combustible dust and housekeeping standards,” Seifert says. “To gain access to the facility’s operating areas without direct supervision, employees are required to complete the general plant safety certification process, which entails successfully demonstrating procedures for cleaning combustible dust, activating the emergency action plan, identifying evacuation routes, and locating and using fire extinguishers and fire hoses.”

Beyond initial certification, Enviva schedules annual refresher training for all employees, and emergency response drills are conducted annually at each facility for each shift. The local fire department participates in at least one drill per facility each year, according to Seifert, and in conjunction with those drills, employees are required to participate in a walk-through of the facility to flag all fire and explosion hazards, identify where hydrants and firefighting equipment are located, as well as update employees on all entry and exit routes.

The drills with fire departments are reviewed and evaluated by a regional or corporate member of Enviva’s operations management team, and improvements are made after each drill—or actual event, Seifert says. “After each drill or event, we debrief and evaluate what went well and what didn’t with the collective team, and depending on the findings, our employee training, drills and emergency response plans are updated accordingly.”

Seifert says that while safety is a vital objective at all the company’s plants, developing and establishing processes and protocols to safeguard employees across all operating facilities is easier said than done. He emphasizes that a key component in successfully crafting and executing these plans is instilling strict protocol in its safety culture at every level of the company. “This is from the CEO’s office to the factory floor,” he says. “For example, Enviva uses an emergency notification system with predefined templates and distribution groups that all employees can access to initiate a conference call with key leaders within seconds. There are tiered levels of emergency alerts based on the severity of the incident, and the system ensures the right safety, engineering and operations leadership are notified and engaged in a timely manner to assist the on-site team in the event an emergency response is needed.”

Perhaps the most important aspect of emergency response training, according to Seifert, is conducting proactive practice drills critical to ensuring employees are confident in identifying emergencies, know the appropriate steps to take, and follow necessary precautions to keep safe. “When possible, all practice drills should be carried out as if they were happening in real-time,” he adds. “During a drill, we try to simulate a real emergency experience and have all employees run through a full scenario as a team.”

Even if a wood pellet facility doesn’t have a silo or a collective workforce the size of Enviva’s, employees should still become very well-versed and proactive about safety around the plant and material from day one when they come in, says Cory Schrock, general manager of Fiber By-Products, a 50,000-ton plant in White Pigeon, Michigan.

Residential Perspective
Every new employee at Fiber By-Products receives a copy of, and reviews with HR, the facility’s emergency evacuation plan, Schrock says. This includes protocol regarding what to do and where to go, as well as a map that outlines all locations of fire extinguishers, gas and fuel dangers, and shut-off valves. “We also have group meetings and walk-throughs to go over procedures, and what to do in the case of a fire,” he says. “During these meetings, we remind and retrain on things including proper personal protective equipment usage and lockout-tagout procedures, and we have incident report forms that show fire extinguisher use along with other safety or equipment damage-related incidents.

These are turned over to supervisors to review or retrain if necessary, and to ensure that if a fire extinguisher was used, it gets replaced right away. We conduct monthly fire extinguisher checks and replace any outdated or damaged extinguishers, and we have a full-time employee that takes all wheel-loaders out of service in sequence on a daily basis for inspection and cleaning of engine compartments, and anywhere that heat and dust collect during normal operations.”

On collaboration with the local fire department, Schrock says it’s mostly made up of volunteers with close ties with the facility. “The chief works and lives just a couple of miles from the facility and was a full-time employee with us in the past, and we currently employ one of his volunteers on our wood pellet production team,” he says. “Most of their current staff are familiar with our plant, operations and procedures, and have done walk-throughs of our facility and know where our dangers are, as well as electrical and gas shutoffs and fire hydrants.”

Fire department personnel also have the code to the plant’s front gate and access to a master key of the facility, according to Schrock. 

Beyond the facility’s employee education and training and collaboration with the fire department, Schrock highlights the facility’s robust spark and fire detection and extinguishing system. All aspects of employee safety practices, training and emergency response are very important, Schrock adds, but this system plays a vital role in preventing fires, explosions or catastrophic events. “Real protection comes from this very important piece of our facility.”

Author: Anna Simet
Editor, Pellet Mill Magazine