The death of an upstate New York firefighter earlier this year is a stark reminder of the hazards of fighting fires in agricultural silos. Firefighters responded to a call at about 9 a.m. on April 11 for a silo fire in Sackets Harbor, N.Y., at the same farm where 100 cows perished in a barn fire four days earlier. It is likely that the heat from the original barn fire caused the silo contents to heat up.

Garrett Loomis, 26, was on the silo when it exploded. He received serious injuries and was pronounced dead at the hospital. Loomis had just been promoted to his volunteer assistant chief position the previous week. He also was a career firefighter with the Fort Drum (N.Y.) Fire Department.
This article will discuss agricultural silo fires and recommended means to safely handle them.

Don't be Fooled

Agricultural silos account for much of what we envision in an idyllic farm scene. Indeed, it’s almost impossible to picture a farmhouse without a barn and silo nearby.

Silos typically are used to store forage crops used for animal feed. But that seemingly innocent use can mask a considerable variety of dangers. These dangers can be hazardous not only to the farm’s workers and residents, but to the fire and rescue personnel who are called to the farm.

The hazards faced by farmers and rescuers involving agricultural silos include falls from heights; electrocutions; entrapments in unloading machinery; IDLH atmospheres; fires; and explosions.
Several firefighters have been injured or killed during fireground and rescue operations involving agricultural silos. These injuries and deaths typically result when responders aren’t familiar with the structures and their hazards, or when rescuers fail to follow proper confined-space or firefighting procedures. This article will describe agricultural silos, their hazards and the proper manner in which to assess and handle them when they are on fire.

Agricultural silos must not be confused with grain bins or grain elevators, which are used to dry and store grains like wheat, corn, oats and barley. These other structures have different properties and hazards. Fire departments need to be educated and perform preplanning on all of these structures in their districts.

Let’s now examine the myriad types of agricultural silos.

Vertical silos, also called tower or upright silos, are the recognizable round cylinders on farms. The fact that there are 1 million tower silos in North America, coupled with the multiple hazards of these structures, make silo rescue and firefighting an important issue for many rural rescuers. Fires can occur in silos regardless of whether they actively are being utilized by the farmer.

Vertical silos are subdivided into conventional, oxygen-limiting and modified types. Each type presents different problems and challenges, so rescue personnel need to be able to distinguish between these types. Misidentifying a silo and employing incorrect procedures can result in needless firefighter injuries or deaths.

Conventional silos are constructed from poured concrete, concrete staves (curved concrete blocks held in place by steel rings) or steel. Older ones were made of tile blocks or wood. Conventional silos usually can be identified by the 3-foot-diameter chute that runs the length of the silo. However, be aware that some modified oxygen-limiting silos have been retrofitted with exterior unloading chutes. The chute allows the silage to fall down into the barn, wagon or conveyer during unloading operations. Conventional silos may have no roof at all, or a hemispherical domed roof.

Oxygen-limiting silos are designed to limit the amount of oxygen in the structure, a feature that can rapidly kill farm workers and rescuers. Farmers and firefighters have asphyxiated by entering from the top and the bottom of these silos. Many firefighters also have died when the oxygen-limiting silo exploded while they were on top of the structure during firefighting operations. The term "exploded" is being used in this article liberally as the violent destruction of these silos is actually caused by a detonation.

Oxygen-limiting silos are constructed of steel or poured concrete. The blue-colored Harvestore brand is the most common. These silos generally have a flatter roof than conventional silos, and most will have roofs with two 18- or 24-inch openings with hatches. Unmodified oxygen-limiting silos have no exterior unloading chute, as they unload from the bottom.

Modified silos are a catch-all grouping of silos that have been modified from their original design. These modifications can change the tactics employed in rescue/recoveries and firefighting. One example of these silos is an oxygen-limiting silo that has been modified for top unloading, with unloading doors and an exterior chute. Another example of a modified silo is the conventional silo that has a center unloading system that replaces the exterior chute. Identifying these structures can be difficult. Calling for technical advice is strongly recommended when you encounter a modified silo.Preplanning specific to silos is essential and should include the following:

• Type and brand of silo and silo unloader.
• Silo owner, manufacturer and local dealer.
• Normal types of contents.
• Dimensions and age.
• Modifications, if any.

Silo fires occur when the contents heat up independently or secondarily to an adjacent barn fire. Controlling fires in silos depends on the kind of silo involved. Misidentification or failure to account for modifications of a silo can result in firefighter injuries and deaths. Explosions in agricultural silos are caused when oxygen enters a smoldering fire inside the structure and causes the carbon monoxide to detonate.

Conventional silos. Historically, fires in conventional silos have posed little threat of explosion. This is because the silos are not designed to be sealed structures. Time also is in the firefighters’ favor, unless exposure problems to attached or proximal buildings develop.

On arrival at a conventional silo fire, the officer in charge should:

• 
Establish incident command and an accountability system.
• Perform a 360° evaluation, inspecting for exposure issues.
• Confirm preplan information.
• Have the farmer and silo dealer respond to the incident.
• 
Check for and extinguish any hot embers that may have left the silo.
• 
Have the farmer move any livestock or machinery from the area and adjacent structures, if possible.
• 
Raise the silo unloader machine as far as possible via a hand crank or electrical switch at the base of the silo, in order to minimize damage to its parts from heat and fire.
• 
Disconnect the electrical supply to the silo unloader.

Next, if it can be done safely, a firefighter with full protective gear, including SCBA and a full-body harness and lifeline, should assess the fire from above the silage. This task can be performed with a ladder truck or by climbing the silo's exterior or chute. Climbing silos should be done with extreme caution, as the ladders and steel rungs of the silo can be slippery, damaged, loose or broken. The chute also may be full of hot embers. Once above the fire, the firefighter can examine the contents for hot spots. Thermal imaging may be valuable here. If hot spots are located, the firefighter can direct a hose stream onto them.

A fire in a tower silo typically is located around the perimeter, the unloading doors and/or the top few feet of silage. A fire burning for an extended period of time can create hollowed-out cavities in the silage. There is extreme risk with entering a silo that is on fire and should not be attempted. Using adjustable penetrating nozzles from the silo chute is a better choice to reach subsurface burning. Proper confined-space techniques must be followed.

Using carbon dioxide or nitrogen gas to extinguish conventional silo fires is a questionable practice. This is because the structure is open to atmosphere and oxygen usually can still reach the fire. Some departments have had success with these gases, but more experimentation is needed before a recommendation can be made regarding their use.

It's usually impossible to completely extinguish fires in conventional silos. Even when the fire appears to have been extinguished, it often reignites. The farmer must partially or sometimes totally empty the silo. Firefighters may have to be present during this unloading to douse hot spots. When unloading is an extended operation, consider rotating personnel and/or lending the farmer a portable pump, pond and hose. Fire officers, farmers and the farmer's insurance representative need to discuss any further actions.

Oxygen-Limiting. Oxygen-limiting silos can explode when on fire, so it's imperative that firefighters know when this type of silo is involved.

Allowing air to enter the carbon monoxide-rich environment of the silo that is on fire can cause an explosion. Therefore, do nothing that may cause air to be drawn into the silo. Do not attempt to open hatches or spray water or foam inside the silo. Firefighters have been killed when they open doors or inject water and/or foam into a burning oxygen-limiting silo.

Response to a fire in an oxygen-limiting silo should involve the following steps:

• Establish incident command and an accountability system.
• Perform a 360° evaluation checking for exposure issues.
• Confirm preplan information.
• Have the farmer and silo dealer respond to the incident.
• Have the farmer move any livestock or machinery from the area and adjacent structures, if possible.
• Do not increase the amount of oxygen inside the silo. Do not open hatches or unloader doors, and do not inject water or foam.

Firefighters should stay off an oxygen-limiting silo that is shaking, hot, noisy, smoking heavily, or that has been opened within the past few days. The latter the likely cause of the recent fatal New York silo explosion. If the structure is quiet, motionless and cool, has not been opened within the past few days and is smoking minimally, firefighters should close the bottom unloader door and top hatches. Do not lock down these roof hatches, as they allow the silo to vent itself.

Inspect for extension into any adjacent-structures and have the farmer evacuate these structures if possible. If the silo walls next to combustible barn walls are hot, create a space between the two to reduce the likelihood of the silo igniting the barn.

Leave the silo closed. Do not open oxygen-limiting silo doors or hatches. If the structure is well sealed, the fire may self-extinguish. Regular monitoring of the silo and adjacent areas is important. If the fire continues to burn, carbon dioxide or nitrogen may have to be injected. Ask the local silo dealer for assistance.

Modified Silos. Extreme caution should be exercised when dealing with a modified solo. Fire departments that have employed incorrect suppression techniques on these structures have paid a high price in firefighter injury and death. Securing technical assistance is critical. As there are many ways silos can be modified, each case must be managed on an individual basis.

Silo fires are not common, but the possibility of firefighter death and injury always is present. Usually there's no great hurry to extinguish silo fires because they generally are well-contained by the structure. Rushing into fire-suppression activities can be disastrous.

Fire-rescue personnel who can't differentiate between silo types or recognize modifications should solicit outside technical assistance. They should select their sources carefully and consider getting a second opinion. Technical information regarding silo fires should be confirmed by another source. This is a very specialized area of firefighting, and lives depend on good information.

• Read the "Silo Firefighting, Step by Step" sidebar for more information.

Ed.: A fund has been established with the Northern New York Community Foundation to honor Sackets Harbor Fire Department Assistant Chief Garrett W. Loomis. The Garrett Loomis Firefighters Fund will provide grants to assist fire departments in obtaining agricultural-related training. Donations can be sent to the Northern New York Community Foundation Firefighters Fund, 120 Washington St., Suite 400, Watertown, NY 13601.

Ted Halpin, MPA, CEM, is co-founder of FARMEDIC, a program which has been training rural fire-rescue personnel in farm emergencies since 1981. Halpin grew up on his family's farm and has 31 years of volunteer and career fire, EMS and EM experience. He holds undergraduate degrees in agriculture and fire protection and a master's degree in public administration. Halpin can be reached at tedhalpin@hotmail.com.