UNDERSTANDING AND CONTROLLING LANDFILL FIRES

Extinguishment Methods

Water Application:

Water is an effective fire fighting agent, but only if it can reach the burn zone in large quantities.  0.18 GJ of energy are consumed in raising one m³ of water from 55°C to 100°C.  A further 2.25 GJ of energy are consumed in the phase change from liquid to vapour.  From an energy balance perspective, three or four m³ of water are required to absorb the thermal energy released by the combustion of one tonne of burning refuse.  In practice, somewhat less water is required since the rate of energy release in an underground fire is slow; nevertheless, as a rule of thumb 0.5 to 1.0 m³ of water is required for each m³ waste that is involved in the fire.

During the recent Vancouver Landfill DLC fire in October, 2000 three large earth moving trucks were utilized to deliver 20 m³ (5,000 gallon) payloads of fire fighting water to the burn zone.  Photo 5 shows one of the Mack trucks delivering it’s payload.  An agricultural water cannon capable of delivering a steady stream of 250 L/minute (60 GPM) was brought on line near the end of the fire fight.  In total, 4,300 m³ of water were applied over seven days to extinguish the fire involving approximately 4,000 m³ of burning DLC.  As a result of the very high permeability of DLC waste, the entire payload penetrated the DLC waste in seconds each time a truck was unloaded.  In this case, water application was successful because the DLC landfill was only 8 m high and no intermediate cover layers were present to prevent penetration of the water to depth. 

           
   PHOTO 5. MACK TRUCK WITH 20 000L PAYLOAD                Photo 6. LIGHT MIST APPLICATION 30GPM 

At the Delta Shake and Shingle DLC Fire (November 1999 – April 2000), over 250,000 m³ of DLC was ultimately involved in the fire.  Since the waste was piled up to 20 m high and the fire was burning intensely at depth, extinguishment by application of water was not effective.  Application of water from monitors capable of delivering 360 L/min (90 GPM) was throttled back to 120 L/min m³ per minute (30 GPM) to apply the water as a dispersed wetting mist rather than a concentrated stream (see Photo 6).  This method of application proved more effective in controlling open flame at surface. 

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