Can a pile of fresh wood chips spontaneously combust?

[Egon]

Many a barn with slightly damp hay in the loft has burned down.

 

[Alien]

I saw a hay barn go up once. Took the tractor and other machinery with it. Dad used to sprinkle salt between each layer of hay to prevent it from happening.
I saw a string mop that burnt up once. It was leaning against a wall on a concrete floor. Fire dept came to check it out. Quite intriguing.
If people can spontaneously combust, no reason a pile of compost wouldn't.

 

[Davegc2]

These people say the piles need to be bigger than 60'x100'x10' or so so you might be safe. https://s0.hfdstatic.com/sites/the_hartford/files/wood-chip-mulch-storage.pdf
I know I had a 6' deep pile that was steaming hot the other day so I was wondering too.

 

[turnkey4099]

For the last ten years or more - I thin and chip my "baby" pine stands. 900 to 1200 small pines every spring. So......... I have piles of chips all over my 80. The piles will never get as big as what you have there Sixdogs. I let the chips fall where they may. A "pile" could be 20 feet long - 3 feet wide - have a MAX depth of one foot.

Bottom line - I've never had any of them get any hotter than the prevailing conditions. No smokers - no flames.

However - I HAVE seen the results of a hay stack "explosion". THEY said it was spontaneous something or other.

I would keep an eye on that five foot pile. If it starts getting warm/hot - - spread it out to a much thinner pile. Maybe a foot deep and spread out.

I built a compost pile (my first) with shredded bark mixed in with lots of cow pats. Wasn't long before it was smoldering.

I "noodle" firewood rounds too big for me to lift. That produces lots and lots of shavings that look like noodle. Neighbor raises chickens and loves those for bedding and nesting material. I pack it tight in big black garbage bags and warn her about the possibility of spontaneous combustion. Hasn't happened yet but any combustible material cut down into shavings or sawdust can do it given a bit of moisture.

 

[turnkey4099]

I worked at an agricultural equipment factory. Final step in the process was into the paint shed for a good coat. The floor had to be scraped periodically toremove the builup of paint. Painter did that one day and put the scrapings into the dumpster. Yep, fire dept came put it out and barely saved the building.

 

[mapper]

I'm the OP on this and decided the risk of spontaneous combustion is a risk I don't want to take. As mentioned, I'm chipping understory branches deep in rows of shelter belt trees and it's too tight to get anything more than the tractor w/chipper in. No trailer for the chips. I figured to leave the chips in the trees to dry for a while and then bucket out to burn. A fire deep in those trees would be an inaccessible mess. So, I'll chip now and bucket them out ASAP.


For other spontaneous issues, when we baled small square hay bales I remember an exact number number of days and temperature to watch for. We had a12" probe thermometer and you had to watch for a temperature range that I've forgotten but it was around the 11th day +/- after baling and maybe 125 ish degrees with a probe in the center of the bale. If a fire was to occur it was around the 17th or 18th day, more or less but I can't recall the exact days. I know those are pretty exact numbers but I double check things and it was spot on for small bales of timothy/grass hay. Advice would have come from Univ of Maine @ Orono or Maine Extension Service if you want to check it out.

Why not just spread them around where you chip them, they will feed the trees as they break down and help build up the soil?

 

[CobyRupert]

Yes. I think many a wood/chip yard at a paper plant has caught fire. I believe they can burn for days/weeks/months and many places have fire pumps and hose systems nearby.

 

[jyoutz]

Yep. I’ve seen several chip pile fires at sawmills. In fact many mills have sprinklers on the chip piles.

 

[jyoutz]

Why not just spread them around where you chip them, they will feed the trees as they break down and help build up the soil?

As long as they aren’t more than about 2” deep. Otherwise they impede growth of forest plants and don’t break down very fast.

 

[orangetree]

our fresh piles of wood chips, one large utility truck's worth (maybe 5'tall, 8'wide, 12' long) would smoke, and be uncomfortably hot inside. This in a mild climate, with plenty of water, and never covered.

I don't think you'd need too many variables 'worse' to get ignition: significantly hotter, drier days (it never got above 90, and had humidity), perhaps a perfect balance of material & moisture in the pile, etc. Or especially a pile twice the size.

 

[turnkey4099]

our fresh piles of wood chips, one large utility truck's worth (maybe 5'tall, 8'wide, 12' long) would smoke, and be uncomfortably hot inside. This in a mild climate, with plenty of water, and never covered.

I don't think you'd need too many variables 'worse' to get ignition: significantly hotter, drier days (it never got above 90, and had humidity), perhaps a perfect balance of material & moisture in the pile, etc. Or especially a pile twice the size.

For oddity. Highway department used ground up tires as fill over a culvert. About a year later it ignited. Washington state som 30 years ago but I don't recallthe location.

 

[mapper]

For oddity. Highway department used ground up tires as fill over a culvert. About a year later it ignited. Washington state som 30 years ago but I don't recallthe location.

Near Ilwaco, on the Columbia river. Deep mucky moist soil. It was determined that the steel wire in the rubber was the cause of the spontaneous ignition. Took a long time to put it out.
It was an experiment in use of tire chips as light weight fill in unstable soils, oops! That didn't work out so well.
A better result in light weight fill was in Seattle on the I90 and SR99 interchange near the stadiums, used giant ecoblocks made of styrofoam for all the ramp structures. Hasn't failed or caught fire yet.......

 

[oosik]

I really question if a pile of chips can retain sufficient internal heat to cause combustion. A pile of sawdust - completely different animal. A pile of sawdust is much more like baled hay in a stack.

 

[mikester]

I really question if a pile of chips can retain sufficient internal heat to cause combustion. A pile of sawdust - completely different animal. A pile of sawdust is much more like baled hay in a stack.

I just moved a large pile of forestry mulcher chips mixed with soil...steaming like crazy. Surprised me. Not small chips and no greens.

 

[rademamj1]

I will say this observation, as my chipper knives dull, the output bin gets finer and finer particles, more like a saw dust. I would not take a chance on large chipper piles, with a high content of small chip particles, doing a spontaneous combustion. Spread that pile to reduce risk.

 

[LouNY]

The process of composting is a heat generator. Most piles of composting materials will "steam" when dug open
as the warmed moisture is released to the atmosphere. Very few piles of composting materials will reach the temperature
required for combustion. They can be too hot to hold or shove your hand in but will be a few hundred degrees from combusting.
You will find it very difficult to hold your hand in a material that's over 110 degree F, but that is still a couple of hundred degrees from combusting.

 

[Bill Guenthner]

Can a pile of fresh wood chips spontaneously combust? Pile would be maybe 5 ft high by 10 ft diameter and be mostly all spruce branches with maybe 15% greenery. I can't imagine it happenning but I plan to leave the piles deep in a row of shelter trees and get them out in the spring and don't need any drama.

Seems like spontaneous combustion is an urban legend or is there a degree of truth in this?

This is a very simple equation. If having it catch on fire where it is would be a catastrophe then either move it to open ground or spread it out so it’s about a foot thick. There is a non-zero chance that it could catch on fire the way you have it now.

 

[BravoXray]

In the last few years we have had chip piles at three different mulch companies in the area catch fire. One on the south side of town had caught fire a couple of times, and they finally had to close up the business and get rid of the piles of mulch. Same thing happend to the one across from the NS Elkhart yard. One that was a few miles north of me burned for over a week before they got it put out.

 

[rademamj1]

From what I understand, initially the methane gas generated by decompose is what catches fire. More importantly, piles with large chip particles, usually allow the methane to ventilate to the atmosphere. Smaller particle sizes and poorly sorted wood piles can seal methane and incur higher risk for combustion.

Locally, I know of 3 fires related to large sawdust piles, associated with mobile home manufacturers.

 

[4570Man]

In theory it’s possible but it would take a massive pile for that to actually happen. I’ve had a tree guy dumping chips and I’ve never had a pile catch on fire or even smoke. They won’t burn very good when set on fire.