A controlled release experiment for investigating methane measurement performance at landfills

We assessed the performance of various methane measurement solutions in landfill applications. Our study involved full-scale multipoint- and area-source (dispersed) controlled releases of methane from the ground surface of a closed 25-hectare landfill with collection system and a background rate of 24 kg/hr. Most quantification methods performed well, but the Mobile Tracer Correlation Emissions Assessment method performed the best with an uncertainty of ±20%. The drone-based, drone flux plane method also performed well with an uncertainty of ±34% with very few outliers in the best-case scenario. For leak detection, AirLiDAR demonstrated a 100% detection probability down to the lowest emission rates whereas drone column sensor emulating EPA 21 Surface Emissions Monitoring (SEM) were 100x less sensitive. Continuous sensors, trucks, and other methods were also assessed. Results indicate that many of the current quantification methods are effective, and potentially more accurate than first-order decay models, though still need to be applied in a replicated fashion for robust site level estimates. Detection outcomes were variable and questions remain, such as how the evaluated methods would compare the against regulatory SEM method, the impact of spacing and trigger thresholds (which differ regionally in regulation), and what detection level is actually necessary for effective landfill gas management. This site provides a future test bed for answering these other questions.