UNDERSTANDING AND CONTROLLING LANDFILL FIRES

Extinguishment Methods

Oxygen Suppression:

Three ingredients are required to sustain a landfill fire: 1) fuel, 2) heat and 3) oxygen.  By controlling oxygen within the burn zone it is possible to extinguish a landfill fire over time, but is usually a slow process.  A fire at Campbell Mountain Landfill in Penticton, B.C. had broken out repeatedly in the north ravine area of the landfill, where significant quantities of biosolids had been co-disposed with the MSW stream.  Each time the fire broke out at surface, the area was excavated, flooded with water and overhauled.  Although, this low cost approach provided a temporary fix to the problem, it did not fully extinguish the fire nor did it prevent spontaneous combustion from re-igniting the waste in other areas of the North Ravine.

When a large sink hole developed in the North Ravine in 1998 a decision was made to attempt to permanently extinguish the fire.  To assess the extent of the fire, eight monitoring wells were drilled, each instrumented with two to six thermistors.   The temperature monitoring data, discussed in more detail in the next section confirmed that a deep seated fire was burning at the site.   After a review and cost analysis of a range of extinguishment options, a decision was made to attempt extinguishment using oxygen control.  Since many of the fumaroles were occurring in rock talus at the edge of the ravine, trenches were excavated on both sides of the landfill to solid rock, the fractured rock walls were coated with fibre reinforced shot-crete (Photo 11) and the trenches were than backfilled with silt.

A 1,000 mm thick soil cover was compacted in place over the north ravine.  Subsequently, a 300 mm thick layer of biosolids was added when desiccation cracks started to appear on top of the cover system.  From the onset, the cover system proved effective in inhibiting oxygen entry and venting of combustion gases.  Long term temperature and gas monitoring data collected over the next three years confirmed that the extinguishment strategy was effective.

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