ASPEN — A spontaneous combustion fire in a compost heap at the Pitkin County landfill burned for more than five days until crews were able to douse the smoldering blaze Monday afternoon.

Snowmass Wildcat Fire Protection District officials suspect the fire broke out Feb. 6 when recent heavy snows, which blanketed a compost pile, trapped heat from the decomposing wood and leaf material and ignited a smoky blaze.

On Monday at 5 p.m., five days after the fire began, Snowmass firefighters working with landfill crews in earth movers were able to spread the last of the 30,000-square-yard pile of smoldering organic matter and douse the fire. “We got the whole thing buttoned up,” said Chris Hoofnagle, the solid waste supervisor at the Pitkin County landfill.

The pile might still be smoking this morning, Hoofnagle said, but firefighters will search for hot spots and monitor the site.

Hoofnagle dialed 911 to first report the blaze Wednesday, and over the ensuing days county officials and firefighters picked away at a smoldering blaze that proved relentless.

“It’s just a long process and we’ll have to watch it for a while,” said John Mele, deputy chief of the Snowmass-Wildcat Fire Protection District. “It’s a nuisance fire more than anything, but I can see why people are concerned when they drive by there.”

Mele’s office received numerous 911 calls reporting the smoke, but he stressed that emissions from the blaze were no more toxic than any controlled brush fire.

There was never danger that the fire would spread to nearby construction material or any actual landfill material, Mele said, but had the fire been during the summer it would have been a major wildfire threat. Compost-heap fires are common, Mele said, and in larger landfills, similar fires can burn for months.

“We’re really fortunate on this one,” Mele said.

Using earth-moving equipment, landfill staff dragged smoking debris off the smoldering pile and spread it out. Snowmass firefighters, using a 3,500-gallon county water tanker, then doused the material with water and foam. The burnt wood chips and tree material will later be buried in the county landfill.

Crews worked by day and monitored the fire by night and over the weekend, Hoofnagle said.

Steaming piles of decomposing compost are nothing new at the landfill in winter, Hoofnagle said. The interaction of nitrogen in leaf matter and carbon in bits of bark and branches creates heat, and the compost breaks down at 131 degrees.

While snow usually melts on top of the warm composting material, this year’s heavy snowfall blanketed the compost piles, creating an igloo effect, and when the material reaches 307 degrees Fahrenheit, fire erupts, Hoofnagle said.

The burnt compost material was no loss to the compost process, Hoofnagle said. There still is plenty of organic matter landfill crews can combine with solid waste such as septic sludge to create compost, he said.

“It’s really not going to affect us at all,” Hoofnagle said. “In the composting operation, I’ve got more wood than I know what to do with.”