Selected Wells
What a healthy vs. a developing SET Event looks like, for these three measures
As a SET (Subsurface Elevated Temperature) Event develops, the wellhead signature for these three measures shifts in a predictable direction, away from healthy anaerobic decomposition. Shaded bands on the charts below mark the same thresholds.
Temperature
Typical operating range for healthy anaerobic decomposition.
Methanogenesis slows once temperatures pass 131°F and is severely curtailed above 160°F. Desirable microbial activity halts near 170°F. At 160°F and above, site infrastructure is also at risk: PVC/HDPE piping, geosynthetic liners, and gas/leachate collection systems can soften or melt.
Oxygen (O₂)
Should sit near zero at a healthy wellhead.
Detectable O₂ above baseline signals air intrusion feeding the reaction, the top SET Event trigger.
CH₄:CO₂ Ratio
Methane and carbon dioxide track together in stable landfill gas.
The ratio collapses well below 1.0 as methanogenesis slows while thermal oxidation keeps CO₂ elevated, a clearer signal than either gas alone. Below 0.6 is a warning, below 0.2 is a smoldering signature.
Table view (accessibility fallback, selected wells' raw readings)
| Well | Date | Temp (°F) | O₂ (%) | CH₄:CO₂ |
|---|