August 18, 2007
It Really Happens: Heat Causes Mulch to Ignite
By Linda A Moore [email protected]
Last week wood chips spread on an Arlington, Texas playground got hot enough to spontaneously combust.In March 1995 Romano's Macaroni Grill in Germantown was damaged in a fire officials believed started when mulch ignited all by itself.
It may sound bizarre, but experts say the right recipe of heat, decomposition and a little bit of wind can combine to start a fire, even in two inches of mulch around a flower bed.
"It's possible and I've seen it happen," said Michael McPeak, owner of Digger O'Dell's Nursery in Arlington .
So has Chief Jerry Ray of the Fayette County Fire Department.
"Anything that is decomposing generates heat. Mulch is more susceptible, especially the black because black absorbs heat," Ray said.
Black mulch may be more susceptible but the mulch fires at Digger O'Dell's have been from brown mulch.
"First we noticed it smoldering. By the time we noticed that and approached the area there were flames," McPeak said.
He's seen it ablaze while in transport.
"There have been instances where a vehicle hauling mulch going down the interstate and that air starts circulating," McPeak said. "I've seen it ignite on people's trailers."
Spontaneous combustion occurs when a substance generates enough heat to ignite without an outside source, Ray said.
"The fire triangle is heat, fuel and oxygen. You get those three together in the right combination and it will burn," Ray said.
Compost piles, like mulch, can also spontaneously combust, they said.
Mulch and compost don't have to be in a huge pile to catch fire, although it's doubtful the mulch will ignite in a flower bed that is watered regularly, Ray said. It also doesn't have to be hot outside.
"I've seen it happen in the winter," he said.
Most of the mulch fires Gary McDonald, manager at mulch producer Nature's Earth Products in Arlington has seen have been in the fall and winter.
"We very seldom have any problems in summer," McDonald said.
He also hasn't heard of mulch fires in flower beds that weren't helped along by something else.
"Personally, I don't believe it's a problem unless it's a huge pile or somebody throws a cigarette on it or something," McDonald said.
Nevertheless, as a precaution, homeowners should turn their mulch and compost piles and sprinkle them with water a few times a week, cooling the bed enough to discourage a fire that could get out of control, McPeak said.
"As dry as the grass is if a compost pile does ignite it could spread to the grass easily," McPeak said.
- Linda A. Moore: 529-2702
Originally published by Linda A. Moore [email protected] .
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