|
UNDERSTANDING AND
CONTROLLING LANDFILL FIRES
Characterizing a Fire
Spontaneous Combustion:
Potential
causes of landfill fires include:
- embers
in a hot load;
- careless
smoking;
- methane
flash from equipment spark;
- arson;
and
- spontaneous
combustion.
It
has been our experience that the majority of problem fires that
are difficult to extinguish are initiated by spontaneous combustion.
Off the eight fires experienced in British Columbia in the past
two years, four were very likely caused by spontaneous combustion,
including the Delta Shake and Shingle fire, the Vancouver Landfill,
the Kelowna Landfill and the Cache Creek landfill fires.
Spontaneous
combustion is the outbreak of fire without application of heat
from an external source. Spontaneous combustion may occur through
the storage of organic materials such as wood-waste, coal, tire
chips, compost or hay.
In
organic materials, spontaneous combustion occurs when heat initially
produced through biological degradation is not allowed to dissipate
thus raising the temperature of the material. Biological degradation
will generally cause temperatures to increase to approximately
70 °C.
At temperatures much higher than 70 °C
micro-organisms die. Temperatures beyond 70 °C
are associated with chemical oxidation of organic materials in
the presence of oxygen. For wood, exothermic oxidation of wood
commences around 200 °C
and combustion with open flame commences around 300
°C
(National Fire Protection Association, 1976). Following
is a practical reference summary for evaluating landfill fire
temperatures based on our experience on six major landfill fire
projects.
<60°
C Anaerobic Decomposition
<75°
C
Aerobic Decomposition
80°
C
Microbes Die-off
93°
C
Pyrolysis Starts
149°
C
Exothermic Oxidation of Wood Starts
315°
C
Wood Ignites Spontaneously (Combustion)
    
next page 
continue with Characterizing a Fire
|
