So I read an article about a landfill where they have ten to fifteen foot compost piles full of organic material that caught fire. Here is the article about [url=https://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/07/24/BA1311UPN6.DTL&type=printable]Flammable Compost[/url].
So what's the deal? Are compost piles a fire hazard?
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hendi_alex
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Almost every week I read of one or two yards and houses that get burned down as compost piles spontaneously burst into flame. Quite a serious problem. Think that congress is looking into the matter so as to propose some kind of safety legislation.
Just kidding
As a kid, we used to have a large sawdust pile, like a mountain, within walking distance behind our house. We used to climb and play all over that thing. One day as my brother and his buddies were on it, the thing start collapsing from the inside. The heat would build up so high inside those old piles that the pile would smolder and burn in the middle, creating a cavern which would then collapse and continue burning. Those piles were often fifty feet tall and a hundred feet wide, and even they never really caused a fire problem as I can recall. A compost pile is just not likely to ever be large enough to let that kind of heat accumulate. Further, a compost pile holds quite a bit of moisture, and that IMO would limit any combustion from migrating outside of the hottest core area where some burning and ash could perhaps form. So I vote no. Have never heard of a fire originating from a compost pile not even from large commercial piles, but in the event that such could perhaps happen, would have to be a fairly rare event and would have to be a pretty big pile. Of course my compost pile is on a concrete slab, so no matter even if it did catch fire.
Just kidding
As a kid, we used to have a large sawdust pile, like a mountain, within walking distance behind our house. We used to climb and play all over that thing. One day as my brother and his buddies were on it, the thing start collapsing from the inside. The heat would build up so high inside those old piles that the pile would smolder and burn in the middle, creating a cavern which would then collapse and continue burning. Those piles were often fifty feet tall and a hundred feet wide, and even they never really caused a fire problem as I can recall. A compost pile is just not likely to ever be large enough to let that kind of heat accumulate. Further, a compost pile holds quite a bit of moisture, and that IMO would limit any combustion from migrating outside of the hottest core area where some burning and ash could perhaps form. So I vote no. Have never heard of a fire originating from a compost pile not even from large commercial piles, but in the event that such could perhaps happen, would have to be a fairly rare event and would have to be a pretty big pile. Of course my compost pile is on a concrete slab, so no matter even if it did catch fire.
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hendi_alex
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While it is true that water would make the pile less likely to catch fire, an adequate amount of water is also part of what causes the chemical processes to work so quickly and generate so much heat. Conversely, if the pile begins to dry, the chemical activity slows, therefore that also should make the pile less likely to catch fire. Large commercial compost piles have sufficient mass for this to be a potential problem, but IMO the risk at a relatively small home compost pile is almost non existent.
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Charlie MV
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It's not compost per se; but at least once every couple of years in my general area I hear of someone's barn burning down because they baled hay while it was green still, not dried enough in the fields; and instead of letting them age outside went ahead and stacked them in a barn. A day or two later = burned barn.
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hendi_alex
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It is all related to mass. Get the pile big enough, or the bales piles closely enough, and with poor air circulation such that the heat can't dissipate and the chance for spontaneous fire goes way up. Outside the pile would have to be pretty large and the conditions almost perfect for the rate of heat production and accumulation to exceed the kindling temperature.
Remember what we are talking about here is slow oxidation. What is the difference between that and fire? Well, fire if often called rapid oxidation. Both generate heat, but slow oxidation generally does not generate heat fast enough to cause a fire. This only happens in circumstances where the heat can slowly build, causing the chemical processes which generally move faster at higher temperatures, to generate even more heat, and the process feeds on itself until the kindling temperature is reached and the item busts into flame, provided sufficient oxygen is present. So where does this happen? Is most often associated with oily rags bundled closely in a storage area, as the oil tends to oxidize fairly rapidly anyway, so it is pretty easy for the heat generated to ignite the rags. In something like a sawdust pile, large trash pile, or even large compost pile where the mass of the pile insulates the interior sufficiently for the heat generated to accumulate and accelerate the heat generating processes sufficiently to ignite the combustables. Most piles don't have sufficient mass and the heat simply dissipates fast enough to prevent any fire problem. A compost pile may possibly get hot enough in the interior, but most often the exterior acts as a wet blanket that would not be overly combustable therefore would smother any coals that might form. So IMO, it would take fairly special conditions for most any home compost pile to actually burst into flame.
Remember what we are talking about here is slow oxidation. What is the difference between that and fire? Well, fire if often called rapid oxidation. Both generate heat, but slow oxidation generally does not generate heat fast enough to cause a fire. This only happens in circumstances where the heat can slowly build, causing the chemical processes which generally move faster at higher temperatures, to generate even more heat, and the process feeds on itself until the kindling temperature is reached and the item busts into flame, provided sufficient oxygen is present. So where does this happen? Is most often associated with oily rags bundled closely in a storage area, as the oil tends to oxidize fairly rapidly anyway, so it is pretty easy for the heat generated to ignite the rags. In something like a sawdust pile, large trash pile, or even large compost pile where the mass of the pile insulates the interior sufficiently for the heat generated to accumulate and accelerate the heat generating processes sufficiently to ignite the combustables. Most piles don't have sufficient mass and the heat simply dissipates fast enough to prevent any fire problem. A compost pile may possibly get hot enough in the interior, but most often the exterior acts as a wet blanket that would not be overly combustable therefore would smother any coals that might form. So IMO, it would take fairly special conditions for most any home compost pile to actually burst into flame.