Tamping down the flames
Material recovery facility fires can be minimized through good design and safety procedures.
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Tamping down the flames

Features - Safety Focus | MRFs

Battery fires at MRFs are an increasing risk, but good facility design and operating procedures can help minimize the possibility of a disastrous blaze.

September 8, 2022

Fires at material recovery facilities (MRFs) always have been a challenge, but the rise in lithium-ion batteries seems to have led to an upsurge in fires in recent years.

Waste and recycling facility fires have risen from 347 known incidents in 2016 to 1,395 in 2021, according to data compiled by Ryan Fogelman, vice president of strategic partnerships for West Bloomfield, Michigan-based Fire Rover, a company with technology that uses heat detection, remote-controlled suppression and monitoring services to protect businesses from the threat of fire.

The chemical composition of lithium-ion batteries presents a greater fire risk than that of alkaline batteries, says Evan Williams, a design project manager for Cambridge Cos. Inc., Scottsdale, Arizona, a design-build firm that serves the waste and recycling sector.

“If you just have a single battery and kind of crack it open and it starts combusting, it sort of burns itself out. But when it’s at the bottom of a pile of material and it gets that going, that could be a real problem,” he says.

The activities that take place within MRFs and the materials flowing through them make MRFs inherently at high risk for fires, Williams adds.

“A lot of the activities that occur in these facilities are sort of the perfect storm to damage batteries,” he says.

If a battery is crushed or punctured at the bottom of a pile of material, it might not start a fire immediately, which Williams says presents challenges.

“The problem is that it’s not that when you damage a battery that it immediately generates the chemical reaction that causes the fire,” he says. “It can be delayed for an hour, two hours or four hours.”

Entering the MRF

Because of the potential for lithium-ion batteries to spark fires, Williams says he considers MRF design in sections.

He explains, “The best way to approach it … is to sort of segment the risks and areas of the building and try wherever possible to use best-practice approaches to eliminate the risks or make them more manageable.”

The danger from batteries often begins on the tipping floor, Williams adds. “If you dump a load of material on a concrete floor and move it around with the wheel loader or run it over with a tire, you’ve created the perfect [situation] to heighten those risks,” he says.

When loads enter the MRF, Williams says it’s a good idea to have a designated area for hot loads that can present a fire risk.

“As a load comes in and they start dumping it … if they notice smoke coming out, [they should have] a clearly defined space outside the building that’s not close to anything where they can dump that’s adjacent to a hydrant so they can put out a fire if [needed],” he says.

Such areas should be located close to the tipping floor in case employees need to move a pile of material that begins smoldering after they’ve moved it into the MRF, Williams adds.

Because the buckets on wheel loaders can damage batteries, some MRF operators try to take the bite out of the blades that push materials around on the floors.

“There are companies that make … buckets that basically have a bolt-on rubber edge, and that reduces the amount of sparking on the floor,” Williams says. “That’s definitely something that we’re encouraging clients to look into.”

“We wait an hour before people leave the facility—a minimum of an hour. The reason for that is if we ran over a battery or if we ran over something else flammable … we feel an hour is a sufficient time for that [potential fire] to occur before we leave the facility.” — Susan Eppes, corporate safety manager, Waste Connections

Once the day ends, however, the danger is not over, adds Susan Eppes, corporate safety manager for The Woodlands, Texas-based Waste Connections.

“We wait an hour before people leave the facility—a minimum of an hour,” she says. “The reason for that is, if we ran over a battery or if we ran over something else flammable … we feel an hour is a sufficient time for that [potential fire] to occur before we leave the facility.”

To help reduce the risk of a fire occurring after hours, Williams says MRF operators should consider processing all the material they receive on a given day, so the tipping floor doesn’t have piles of material sitting overnight.

Eppes says MRF operators also need to understand where their own risks are and adjust their safety procedures accordingly.

“Wherever you’ve had fires in your bunkers—if you’ve had fires in your metal bunkers or you’ve had fires in your paper bunkers—you need to clean that bunker out before you leave at the end of the day,” she says.

Batteries in Machinery

Batteries that make their way into a MRF’s processing machinery are a greater fire risk than those found on the tipping floor, Williams says.

“It could start combusting in your system as the conveyors are carrying it through the building, and you’re basically sort of distributing the fire throughout the facility,” he says.

However, facilities can take measures to minimize that risk.

First, he says employees who are on the presort lines need to be aware of the possibility of small batteries getting to that stage of the system.

“The problem is, it’s not necessarily as simple as just flipping the system in reverse and sending the material back once it’s on the crossing conveyors,” he says. “An important thing would be, on your presort, for those people essentially to have easy access to a kill switch or an e-stop [emergency stop].”

Using a trommel screen either before or immediately after the manual sorting line also can help remove lithium-ion batteries, Williams adds.

“Most MRFs will have an infeed, and they’ll go through a presort subsystem and run the material through a trommel,” he says. “If you do have a trommel out front, typically those [batteries are] dropping to the bottom, so they would be removed almost immediately. Because they’re round and heavy, they fall easily, so they’re going to drop to the bottom of the trommel.”

If batteries do make it through the end of the processing system, though, they can cause problems in bales, Eppes says.

“I know a couple of companies … that have had issues in bale storage at night,” she says. “A lot of people are putting thermal camera systems in their bale storage areas so they can at least see [signs of a fire] in the first five minutes or so.”

Containing the fire

If a fire does start, Williams says a variety of equipment and facility design choices can prevent its spread.

A system by Fire Rover that includes thermal cameras and features a high-pressure extinguishing system can help detect and control fires that aren’t noticed by employees or that spark overnight, he says.

Fire Rover uses thermal detection to alert its own staff when temperatures rise too high in a given area. Once detected, the staff can then confirm whether a fire danger is present or if a piece of machinery near the thermal camera could be causing a spike in temperature.

“They would be able to then zoom in and check the temperature and how it’s evolving, and if it does appear that there is a smolder starting in there, essentially, they have a fire foam system with an articulated cannon they could spray at the hotspot,” Williams says.

Another option for extinguishing fires and smoldering materials is a deluge system, Williams adds. Those can either be actuated manually or by a increase in temperature. Deluge systems also can be customized to douse fires based on the flammability of various materials.

“A bale of aluminum cans has ... little combustible potential, whereas a bale of plastic containers or cardboard has a much higher combustible potential,” he says.

Many facility operators have a misconception that sprinkler systems are designed to extinguish fires, which they are not. Rather, Williams says they’re designed to prevent fatalities.

Making use of deluge systems is a good idea for protecting property.

When designing a MRF, Williams says minimizing damage from fires should be a top consideration. He says the structural elements of the tipping area, for example, should not span the entire facility. If a fire occurs in the tipping area and heats up a girder spanning the entire facility, that girder could collapse and damage the entire MRF.

Conversely, if separate structural parts are used in the construction of the facility, a girder that heats up and collapses in one area wouldn’t destroy the entire facility.

“Best practice would be a fire separation wall,” Williams says. “We have done that in some facilities where we literally had a floor-to-ceiling, 40-foot-tall concrete wall between the tipping and processing areas, and the structure on each side was independent.”

For those interested in designing a MRF, Williams says it’s important to involve fire suppression contractors early on.

The more involved they are, the more likely an operator will end up with a safe facility.

“If they’re not given all the information about how you want to operate the facility, they won’t know,” he says. “They’re going to proceed based on what they’re told or what they’re given.”

The author is managing editor of Waste Today. He can be reached at bgaetjens@gie.net.