Unit XXVIII, page 129 Pile Fires

1. Unit XXVIII, page 129 Pile Fires 1 Reproduced with permission of the US Composting Council

2. Fire Basics Oxygen The Fire Triangle Self- Sustaining Fire Fuel Heat 2 Reproduced with permission of the US Composting Council

3. Oxygen Self- Sustaining Fire Fuel Heat Ignition temperature . . . the temperature at which more heat is generated by combustion than is lost to the surroundings, so that the combustion process becomes self-sustaining (Energy Technology Handbook, Considine). The ignition temperature for most organic materials is 205 to 400°F (96 to 205°C ). 3 Reproduced with permission of the US Composting Council

4. Heat Sources in a Composting Pile 1. Biological respiration a) releases heat during biological degradation that is b) driven by compostable material (nutrients), moisture, air and organisms. 2. Chemical oxidation a) begins at about 122°F/50°C, b) can be accelerated by heat released during active composting, and c) releases heat during chemical breakdown of organic matter. 4 Reproduced with permission of the US Composting Council

5. Oxidat ion Ranges • Thermal Oxidation • CO2 • H2O • Heat Celsius Fahrenheit 205-1850°F 100 212 90 194 80 176 • Chemical Oxidation • CO2 • H2O • Heat 70 158 60 140 122-400°F 50 122 40 104 30 86 • Biological Oxidation • CO2 • H2O • Heat 20 68 39-172°F 10 50 0 32 Reproduced with permission of the US Composting Council

6. Oxygen Self- Sustaining Fire Fuel Heat How does the fire triangle close in a pile of combustible material . . . spontaneously? Reproduced with permission of the US Composting Council

7. 70 14 60 140°F Bacteria 12 Temperature 50 10 40 Temperature (°C) 8 Actinomycetes 30 6 x 20 4 Fungi 10 2 0 6-weeks 3-weeks 2-weeks 0 Simulated Microbial Population Dynamics During Composting #5 Log # CFU's/g A simulation based on: Beffa, Blanc, Marilley, Fischer, Lyon and Aragno “Taxonomic and Metabolic Diversity during Composting” 1995; Jeong and Shin “Cellulosic Degradation in Bench-Scale Composting of Food Waste and Paper Mixture” 1997; Whitney and Lynch “The Importance of Lignocellulosic Compound in Composting” 1995. 7 Reproduced with permission of the US Composting Council

8. High porosity in the pile allows an increased supply of oxygen through accelerate convection Self- Sustaining Fire Oxygen Combustible material - large high pile (self- insulating) - decreasing pile moisture percent - pile dry spots Fuel Heat Vigorous bacterial activity drives chemical oxidation accompanied by rising pile temperature >94°C/200°F Reproduced with permission of the US Composting Council

9. 3’ 3’ Turned Windrow Fresh Debris (Feedstocks) 3’ 3’ Static Pile 3’ Enclosed Vessel Agitated Bin 3’ 3’ Curing Pile Rotating Vessel Piles of Compostable Material Combustible 9 Reproduced with permission of the US Composting Council

10. Feedstocks and Conditions Most Susceptible to Pile Fires • Raw, green feedstocks that may have already begun decomposing, such as a large brush pile. • Bark chips if given enough moisture to start biological activity. • Large piles of coarse compost, feedstock and screened over-sized material (particle size ~4”), such as bulking material, wood chips and mulch products. 10 Reproduced with permission of the US Composting Council

11. Monitor pile temperature! Oxygen Self- Sustaining Fire Fuel Heat Prevention of Fires • Allow pile heat dissipation by keeping pile height below 2 1/2-meters (8-9 feet) • Keep pile moisture above 40%, and • Keep moisture uniformly distributed 11 Reproduced with permission of the US Composting Council

12. Pathogen and Seed Management @ 55°C+/131°F Thermophilic 45 - 78°C 113-172°F Upper Control Limit Target Lower Control Limit Mesophilic 25 - 45°C 77-113°F Psychrophilic Composting High Rate & Stabilization Feedstock Preparation Compost Curing Compost Screening & Refining Compost Storing Composting Process Control #5 Characteristic Continuum Curve - Temperature Impact 80 75 70 65 60 55 Temperature, ° C 50 45 40 35 30 25 20 15 Reproduced with permission of the US Composting Council

13. Oxygen Self- Sustaining Fire Fuel Heat Sources ofHeat Spontaneous combustion Lightning strikes Cutting torches, welding sparks; vehicle sparks Grinding sparks; shovel sparks; turning sparks Cigarettes Wildfires Arson Reproduced with permission of the US Composting Council

14. Oxygen Self- Sustaining Fire Fuel Heat Sources ofFuel Feedstocks and product Compost Curing piles Woody bulking material piles Piles of screened “Overs” Methane Dust Lubricants and fuels Refuse and debris piles Paper-bag packaging materials Office supplies Reproduced with permission of the US Composting Council

15. Pile Fires Oxygen Self- Sustaining Fire Fuel Heat To Extinguish Pile Fires • Reduce pile height to one foot to allow water to get in pile, then • Wet down to remove heat 15 Reproduced with permission of the US Composting Council

16. Oxygen Self- Sustaining Fire Fuel Heat Question: When a pile fire develops, and the Fire Department is called and arrives on the scene, who is in charge? Answer: The law says the Fire Department is in charge of dealing with fires. 16 Reproduced with permission of the US Composting Council

17. Oxygen Self- Sustaining Fire Fuel Heat Conclusion: Facility owner/operators should insure Fire Department personnel understand how to deal with pile fires at your facility and firefighters are trained in advance. 17 Reproduced with permission of the US Composting Council

18. Oxygen Self- Sustaining Fire Fuel Heat Fires: Site Design Implications • Provide enough space to avoid exceeding the fire-safe height of piles. • Provide access to piles for fire fighting equipment (full perimeter access). • Provide access to adequate supply of water. • Provide space to spread • piles out. 18 Reproduced with permission of the US Composting Council

19. Oxygen Self- Sustaining Fire Fuel Heat End Unit XXVIII Pile Fires 19 Reproduced with permission of the US Composting Council