While people or lightning cause many fires, one source could be festering away in your compost bin or truck, waiting to burst into flame.
When even slightly damp, vegetative matter can build up heat to the point it spontaneously combusts, said Mike Caven, Chief of Eugene Springfield Fire. He told KLCC this can happen in hay bales or compost piles. If not properly dried or tilled, decomposition or microbes can increase heat.
“The problem is, is when it doesn't have a way to dissipate it can kind of run away after it gets past a certain temperature like 140, 150 degrees,” explained Caven. “And once that happens, it can quickly raise the temperature up to that ignition's temperature for certain materials at 400 degrees. And you have a fire. And so that's why we call it spontaneous combustion.”
Fires have erupted in gardens, hay trucks, and grain silos, sometimes explosively if pressure and heat exacerbated significantly. Caven said monitoring for moisture and tilling can help prevent such build-up.
“Most people that deal with or manage hay are pretty diligent about testing it and making sure that the moisture content’s below 15% before they store it,” he said. “And really that's the key before you put it in big stacks or in your barn.”
Caven added that if using natural oils for tool handles and the like, to dispose of the rags in a fire-safe canister or in a contained fire.
This summer, a semi-truck hauling hay became engulfed in flames and was completely destroyed on Interstate 5 near Albany. And on Aug. 14, firefighters put out a fire caused by compost near Eugene’s Hendricks Park.
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