By Erika Mathieu
Sunny South News
Fire departments around Lethbridge County were busy last week dealing with several fires in close proximity to one another in a short timeframe on the morning of Aug. 17. Nobleford and District Emergency Services provided an update that morning.
“Early this morning around 02:00hrs, crews were called out to a large outside fire, upon arrival it was discovered that a large stack of hay bales was on fire out in the Lethbridge County.”
At the time of the update, the crews were still working to extinguish the blaze several hours later with the assistance of both Picture Butte Emergency Services, Coaldale and District Emergency Services, as well as the Coalhurst Fire Department. According to the update, while fire crews were still on scene finishing cleaning the site of the first fire, Nobleford and District Emergency Services reported they were notified of a second large bale stack fire just a few minutes away from the first scene, roughly five kilometres south. “All units from the original fire went out to work on extinguishing this second location.” Following the second fire, emergency services staged fire crews at a third location to ensure further potential flare-ups could be contained quickly.
Some residents took to social media to express scepticism over whether the fires in close proximity were in fact, spontaneous. As most farmers are aware, there is a scientific explanation for hay bales spontaneously combusting. According to a paper by Lester R. Vough titled, Hay Combustion, “spontaneous combustion is always a possibility with stored hay but particularly if the hay was bailed too wet or too green.
If hay is not able to sufficiently dry in the field, it will undergo a curing process, or a “sweat” in storage whereby heat is produced. Vough said, “This heat buildup is caused from live plant tissue respiration coupled with bacteria and mold activity.” this can lead to a higher moisture content throughout the bale, without good ventilation. “Plant and mold respiration also generate heat. If the hay heats to 100°F or higher, browning reactions begin,” where proteins and plant sugars react. This releases heat which results in “an upward spiral in temperatures of the hay mass. If the water generated by plant and mold organism respiration is not able to escape from the bale, mow or stack, then what initially may have been a relatively small wet spot becomes bigger and bigger as the heating drives moisture into hay surrounding the spot.”
According to Vough, bale density and mass also affect heating potential for heating increases with bail density and size and the surrounding hay mass, The higher the bale density and larger the bail. The drier the hay needs to be at the time of baling.
The paper also says the interface between dry and wet hay creates an ideal environment for spontaneous combustion. As the wet area heats up, moisture moves into the surrounding dry areas of the bale. “The area where the wet and dry hay touch, has the heat, dampness and insulation necessary to start a fire. If there is enough hay mass around the hot spot to prevent the escape of heat and there is a slow infiltration of damp air, conditions for fire exist.”
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