chapter 4: temperature inside the landfill

_ _
t >
T −Y
− Tt
+ Y
then a significant temperature drop event has occurred.
X
_ _
(3-7)
Where T t−Y
is the mean of the temperature readings over Y days before time t, T + is the
temperature averaged over Y days after time t and X is the difference between the two averages.
The value of X and Y is dependent on the sensor location (injection well or monitoring
location). The sensitivity of the results with respect to Y was tested by using different values of
Y varying from 4 days to 20 days. Fifteen days for monitoring wells and twenty days for
injection wells gave a good match to injection data.
The value of X also affected the number of events. The various values of X tested were
0.1, 0.2, 0.3 and 0.4 0 C for the monitoring locations and 0.4, 0.5 and 0.6 0 C for injection wells.
Again the use of a small number overestimated the number of events while a large number
underestimated it. Finally it was decided to use 0.5 0 C for the injection wells and 0.2 0 C for the
monitoring locations. The larger value of X for injection wells reflects the higher temperature
drop at injection wells.
3.4.2 Monitoring wells – resistance readings
In order to compare the moisture sensors to temperature sensors, it was necessary to
correlate resistance drop (R-drop) events with the injection events. Resistance at the moisture
sensor drops as a result of an increase in electrical conductance when the moisture arrives. This
drop in resistance was identified and compared to temperature injection events.
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t Y