UNDERSTANDING AND CONTROLLING LANDFILL FIRES

Monitoring

Temperature Monitoring:

We have found monitoring of temperatures is very useful for establishing the extent of a fire, but only if the temperatures are measured at depth.  The best way to collect temperature measurements (and gas composition samples) is to drill a number of monitoring wells in and around the suspected fire zone.  The monitoring wells can be drilled with augers, Becker Hammer rigs or Sonic drill rigs.  Air rotary rigs should not be considered since injection of large quantities of air could accelerate the fire and possibly trigger a methane explosion.  Photo 12 shows a drill crew installing a monitoring well at Campbell Mountain Landfill.  Note the safety equipment including respirators and ventilation fans.  Gas composition was also monitored on a continuous basis.

      
    Photo 12. drillingmonitoring wells                        photo 13. thermister assembly

To keep the holes open, the monitoring wells should be cased, preferably with slotted steel casing.  Thermistors can then be lowered down the holes to measure temperatures at various depths within the fill.  We prefer to monitor temperatures at 5 m intervals, typically at 5, 10, 15 and 20 m below surface.  To prevent convective currents between the various temperature intervals, we install foam baffles on the thermister strings.  A multi-channel read out box is used to measure temperatures at surface.  Photo 13 illustrates a typical thermistor assembly.

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