chapter 4: temperature inside the landfill

injection events are short-lived. In other words, there were
some cases in which the temperature
sensor did not respond to an injection at all perhaps because the volume injected was
not
sufficient for assumed significant temperature drop of 0.2 0 C. The main reasons for the wetting
percentages being so low and no response at some of the
sensors may be the distance between
the monitoring locations and the injection wells and/or the volume injected was insufficient to
reach the sensors. Alternatively a preferential path existed that led to by passing the sensors.
4.8 Conclusions
Temperature and moisture content data were collected from an anaerobic portion of a
landfill in Florida over a period of about three years. Fifty-six thermocouples were installed in
the bottom of the injection wells. Fifty MTG sensors recorded temperature and moisture content
of the waste twice per day.
The
hypothesis tested was that temperature sensors can be used to track moisture arrival.
After confirming the hypothesis at the injection wells, the hypothesis was applied to sensors at
monitoring locations. It was observed that the hypothesis
is true only for 37% of the time. The
main cause of the failure of the temperature data in sensing moisture arrival was found to be the
heating of the moisture as it travels through waste undergoing augmented biological activity as a
result of moisture from previous injections. Consequently, the first injections were analyzed and
85% of the temp events supported the hypothesis. The findings suggested that the moisture
sensors are marginally better than temperature sensors in detecting the first moisture arrival than
moisture sensors.
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