Mulch Fire 1

[UofAGrad]

Hi All,

I'm not finding the reading material I'm looking for online so I was hoping someone here could shed some light on a situation. During a grubbing project completed January 2023, mulch piles were kept below the maximum height (~50') and the advised Length and Width(I forget these dimensions). What would cause this mulch pile to (seemingly) spontaneously ignite 10 months later? Is that not very surprising to someone more knowledgeable on the subject?

Disclaimer: this was caught and put out quickly. it was isolated to an area with no other flammable sources nearby.

Thanks!

 

[cvg]

50 feet is way too high and it should have been expected.

 

[TigerGuy]

Compost and mulch piles can reach internal temperatures in excess of 150 degrees F. Besides, it naturally produces methane, which is slightly flammable. Facilities that handle these have to turn the material over on a regular basis.

 

[CarlB]

This New York guide says 25' max.

https://www.dec.ny.gov/docs/materials_minerals_pdf/mulchregsguidance.20171212.pdf

Another site noted NFPA may allow up to 60', but IFC max is 25'.

 

[UofAGrad]

Thanks CarlB. I was looking for a code to reference.

As far as the pile igniting 10 months later, it sounds like we need to turn over and manipulate the pile at some frequency. Thanks for the recommendation TigerGuy.

 

[phamENG]

Turning it over would be a good idea. A local farmer's hay barn went up a couple years ago - seems the joists supporting some hay collapsed and he didn't pull it out. The reduced airflow let the heat build up and poof.

 

[zelgar]

I would guess the fire occurred due to maintenance issues (e.g., aeration (turning over the pile), moisture content, temperature monitoring, C to N mixture ratios).

Hay bales can spontaneously combust if baled when wet/saturated. If bailed wet, the bales start to decompose and generate heat. I married into a farming family and they'd even salt the bales if they thought they were too wet due to the dew (especially for the last bales in the season in fall).