There are many benefits to composting: the environmentally-friendly practice is fairly simple, it diverts waste materials from landfills, and the resulting material can be used as fertilizer to improve soil conditions. These benefits have resulted in compost piles popping up across the nation, from the backyards of farmers, gardeners, and other eco-minded folks, to the large-scale composting facilities used by large corporations and municipalities. As compost piles grow in popularity, so does the potential for spontaneously combusting compost fires.
Composting occurs when organic materials – including food scraps, yard waste, and manure – decompose. Four main components are needed to support the composting process: organic matter, oxygen, moisture, and bacteria. The bacteria and microorganisms work to breakdown the material in the compost pile. This process creates heat, allowing the center of the compost pile to easily reach temperatures of 160-180 degrees Fahrenheit or higher.
Mismanaged compost piles may be prone to spontaneous combustion, which can occur between 200-300 degrees Fahrenheit for organic materials. Compost piles that are too tall, have reduced moisture content or limited air flow, or include a non-uniform mix of materials are likely candidates of spontaneous combustion, as they prevent composting materials to cool properly. To prevent compost fires, be sure to:
- Keep compost piles small.
Pile height should not exceed 12 feet. Smaller piles allow for airflow, cooling the contents.
- Monitor moisture content and internal temperature.
Smoke, venting, or burning smells are noticeable signs of heat retention and hotspots.
- Have emergency plans in place.
Invite your local fire department to do a pre-incident survey. Create and regularly review written procedures for a compost fire with employees. Consider how water and nutrient runoff from firefighting activities will be handled.
If a compost fire does occur, call your local fire department. Trained firefighters will be able to reduce the pile size, cooling the material, while limiting the amount of oxygen introduced to the fire. Do not attempt to extinguish a fire without having the proper training or protective equipment.
“Fire – Compost and Organic Matter.” Alberta Agriculture, Food and Rural Development.
Gromicko, Nick. “Compost Pile Hazards.” International Association of Certified Home Inspectors.