DANGER! 

Written by Don Dugger 

Warnings like this one are common sights in the industry, and they are meant to identify dangerous areas, equipment and chemicals that can create great harm. Having a nice large label telling you of a hazard is a good idea, right? But the mulch on your site doesn’t come with labels.  

The reality is that large-scale raw or processed materials catch on fire every year at manufacturing sites. A simple search will return multiple stories about mulch fires across the United States this year alone. There are still others that did not generate news coverage.  

We all know that our raw material when stacked up will cause self-heating. 

If the piles are too large, too tall and stay in place too long, conditions for spontaneous combustion occur and may ultimately lead to a fire.  

LOOK FOR THE SIGNS 

Mulch/Compost/Raw Material fires typically start small in a single area. There are multiple ways to manage a hot pile, but it all starts with key monitoring principles. Training, monitoring and inventory management can help you avoid a large fire. Here are some keys to prevent a fire risk within large piles.  

#1 MONITOR TIME 

Piles that have been stacked for over 90 days contain significant heating and pose a higher fire risk. Know your inventory and log it; keep track of how long the pile has been static. 

#2 MONITOR TEMPERATURES 

Using temperature probes weekly and logging the data will show you a steady temperature rise, and when the temps exceed 140 degrees Fahrenheit, closer monitoring is required. Temps that reach 160 degrees are entering the “Danger Zone,” and it usually aligns with the 90 days of static stacking. Probe weekly, record and monitor the temperature and take appropriate action. 

#3 VISUAL MONITORING

Any signs of smoke, or anything other than steam, should be investigated for a smoldering fire. Look for the difference between steam leaving the piles versus bluish smoke. Steam rises fast and is clear. Smoke has a blue tint and lingers. Train your staff to look for this, and take action.  

#4 ODOR MONITORING 

Mulch plants typically smell quite “earthy.” Wood products, bark products, mulches and compost all have a particular smell. Piles that are beginning to heat to a point that risks spontaneous combustion start to have an odor that smells like something is smoldering or burning. Know your site and what it smells like, and train loader operators to report anything that smells like smoldering.