Can a pile of fresh wood chips spontaneously combust?

[sixdogs]

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?

 

[EarPlug]

Can Compost Get Too Hot - Hazards Associated With Hot Compost Bins

 

[Dftodd]

Yes, they can retain moisture and after baking in the sun, they can go up in flames just like a bale of hay.

Local pallet mill had their sawdust mountain do just that.

Pile smoldered for several months.

They rigged up a fire suppression system so they could soak the sawdust down before loading it in dump trucks to hall it off.

They would dig into the pile with the loader, spread it out, soak it down good to put it out. Then load into trucks.

I actually set up the pump, and fire lines for that place. It was one of the more interesting jobs I've been on.

I was a little concerned when I realized the mountain my truck was parked on top of was actually burning inside

 

[rademamj1]

Yes it can, but it's mainly a late summer type occurrence and even then very rare. Our local fire station put out a spontaneous fire in a huge saw dust pile located inside an abandoned warehouse previously used for mobile home assembly. They went out of business over 3 years ago, but that fire started just this summer...August on a day it was 102F.

 

[oosik]

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.

 

[workinonit]

Yes, I passed by a pile 2 days ago and saw it burning. Theirs was in an open area where it couldn't hurt anything.

 

[Gem99ultra]

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?

Perhaps there is a thread of truth in this, especially if you have a lot of greenery. Most of the reports refer to sawdust and/or compost. However, last Spring I chipped up over 40 piles of pine and spruce pretty much the size you're doing, and never had anything like enough heat for a fire.

The 'belt AND suspenders guys' no doubt will disagree, but that's just not been my personal experience.

 

[s219]

This is definitely a true thing, I've read about fires before.

I've seen my piles give off some sort of vapor on a cold morning, and if you dig in to the middle of the pile it is noticeably warmer. I know they can burst into flames, but I don't think my piles are big enough or around long enough for that to happen. My biggest piles are maybe 6' high and 15' around at the bottom, and they get used within a week or so.

We have a place down the road that processes mulch and when you drive by there on a cool morning, all the big piles are giving off a pretty serious stream of vapor. At least I think it's vapor!!

 

[stuckmotor]

We used to play in sawdust piles when it was common for timber to be sawed on location with circular sawmills. I remember a fresh one steaming when we dug into it after a rain.

 

[jaxs]

It happens but only if material is wet (green) and doesn't flame unless there's dry material mixed in.

 

[sixdogs]

We used to play in sawdust piles when it was common for timber to be sawed on location with circular sawmills. I remember a fresh one steaming when we dug into it after a rain.

I would be chipping spruce limbs from the dark center of rows of trees. Not much sun in there so some are dead and some are living but very little green involved. Just chipped branches.

 

[Jstpssng]

It's becoming a practice here to grow Cole products in greenhouses in winter, with only compost for heat. When I worked for a landscaper years ago we would pack grass clippings into trash bags after mowing clients lawn. We never had a fire, but at the end of a hot day could see that the clippings were turning to ash. I don't believe that should be as much of a concern in the OP's case unless he's adding a lot of water and green manure. Wood is a bit more stable.

Here's an interesting story about heat from compost... in early horse racing days the jockeys were required to stay under a certain weight. A track down in Mexico had a huge manure pile from all of the race horses there. Jockeys would go out and bury themselves to the neck, letting the heat from the composting manure act like a sauna to sweat some weight off.

 

[stuckmotor]

I've read of people burying water tubes in piles of wood chips to extract heat and looping the tubes under trays in greenhouses. If there's a fire hazard I don't know that it's worth the risk.

 

[MoKelly]

It's becoming a practice here to grow Cole products in greenhouses in winter, with only compost for heat. When I worked for a landscaper years ago we would pack grass clippings into trash bags after mowing clients lawn. We never had a fire, but at the end of a hot day could see that the clippings were turning to ash. I don't believe that should be as much of a concern in the OP's case unless he's adding a lot of water and green manure. Wood is a bit more stable.

Here's an interesting story about heat from compost... in early horse racing days the jockeys were required to stay under a certain weight. A track down in Mexico had a huge manure pile from all of the race horses there. Jockeys would go out and bury themselves to the neck, letting the heat from the composting manure act like a sauna to sweat some weight off.

That is just disgusting. Hard to imagine.

MoKelly

 

[RalphVa]

Yep. With the right amount of greenery to start things cooking, especially if out in the sun with its help.

 

[stuckmotor]

That is just disgusting. Hard to imagine.

MoKelly

They must have smelled awful.
Another thing I've read about is tramps in Victorian times burying themselves in manure piles to stay warm. I hope the manure was rather dry and they were between some kind of blankets.

 

[Alan W.]

There was a mulch pile that spontaneously combusted in Lexington this last year.
So yes it can happen. How likely who knows.

 

[user.69169]

20 acre leaf mulching site here where towns all dump yuppie leaves dat can't be chopped into lawn of house about to get foreclosed. Guy walks around every other day wid thermometer taking pile temperature. Pile gets hot dey bring in machine dat stirs de pile so it don't light off.

 

[jaxs]

The sulution is quite simple,rather than piles 10w x 5T,spread to no higher than 3'. Put you hand inside 2 days later to check heat. If you can stand to keep your hand buried for 60 secounds you can proceed to pile higher. If it feel's super hot,weight until composting slows before building higher piles. What will you eventually do with wood chips?

 

[sixdogs]

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.