Can a pile of fresh wood chips spontaneously combust?

sixdogs · Jan 9, 2021

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 · Jan 9, 2021

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

Dftodd · Jan 9, 2021

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 · Jan 10, 2021

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 · Jan 10, 2021

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 · Jan 10, 2021

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 · Jan 10, 2021

sixdogs said:
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 · Jan 10, 2021

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 · Jan 10, 2021

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.