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chapter 4: temperature inside the landfill

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Scenario<br />

#<br />

Injection Temperature<br />

Drop<br />

1 YES YES YES<br />

2 YES NO YES<br />

3 YES NO NO<br />

4 YES YES NO<br />

5 NO YES YES<br />

6 NO YES NO<br />

Table 4-1. Hypo<strong>the</strong>sis * testing Scenarios<br />

Resistance<br />

Explanation<br />

Drop<br />

Moisture has been injected and arrived as indicated by both sensors supporting<br />

<strong>the</strong> hypo<strong>the</strong>sis.<br />

If <strong>the</strong> waste has been wetted by previous injection, increased biological activity<br />

has led to heating of <strong>the</strong> waste which in turn leads to liquid being heated while<br />

traveling through <strong>the</strong> waste. The heated liquid did not lead to substantial<br />

<strong>temperature</strong> drop at <strong>the</strong> <strong>temperature</strong> sensor while <strong>the</strong> resistance reading of <strong>the</strong><br />

moisture sensor indicated moisture arrival. The explanation refutes <strong>the</strong><br />

hypo<strong>the</strong>sis.<br />

(a) Moisture sensor was already saturated; or<br />

(b) Because of an increase in biological activity due to earlier wetting, liquid was<br />

heated while traveling through <strong>the</strong> waste; or<br />

(c) The liquid was not able to reach <strong>the</strong> sensor at all because it took a preferential<br />

path around <strong>the</strong> sensor due to heterogeneity of <strong>the</strong> waste.<br />

The explanations nei<strong>the</strong>r support nor refute <strong>the</strong> hypo<strong>the</strong>sis.<br />

(a) The moisture sensor did not work because it was saturated; snd<br />

(b) Temperature senses moisture arrival.<br />

The explanations support <strong>the</strong> hypo<strong>the</strong>sis.<br />

Although <strong>the</strong>re is no injection, still both sensors are showing a drop in <strong>the</strong><br />

readings, suggesting a moisture arrival. This may be <strong>the</strong> liquid injected in ano<strong>the</strong>r<br />

cluster of injection wells and traveling through preferential paths to this<br />

monitoring location. The explanation supports <strong>the</strong> hypo<strong>the</strong>sis.<br />

There is no injection event but <strong>the</strong>re is a drop in <strong>temperature</strong> reading <strong>the</strong>n <strong>the</strong>re is<br />

a very high probability of false indication by <strong>temperature</strong> sensors. The<br />

explanation refutes <strong>the</strong> hypo<strong>the</strong>sis.<br />

7 NO NO YES<br />

A drop in resistance suggests moisture arrival. Again liquid may be arriving from<br />

ano<strong>the</strong>r cluster of injection wells. The <strong>temperature</strong> sensor was not able to detect<br />

moisture arrival so <strong>the</strong> explanation refutes <strong>the</strong> hypo<strong>the</strong>sis.<br />

*<br />

Hypo<strong>the</strong>sis: <strong>temperature</strong> sensors can be used to track moisture arrival in <strong>landfill</strong>ed waste<br />

49

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