1 Department of Civil & Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee 32310, FL, USA. Electronic address: abichou@eng.famu.fsu.edu.
2 Department of Civil & Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee 32310, FL, USA.
3 Dept. of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee 32310, FL, USA.
4 Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G1M8, Canada.
5 Department of Earth and Environmental Sciences, St. Francis Xavier University, Antigonish B2G2W5, NS, Canada.

The Tracer Correlation Method (TCM), when applied to quantify landfill methane emissions, relies on previously developed stringent quality control thresholds (R² = 0.80 and Emission Rate Deviation (ERD) = 20 %, hereafter referred to as the Gold Standard. However, these thresholds often exclude a substantial portion of the collected data, limiting wider use of TCM. We evaluated TCM during a controlled release campaign at the Petrolia landfill (Ontario, Canada), where methane was emitted at known rates (27.1-179 kg/h), though these were not disclosed to the measurement team during testing. Emission estimates from the TCM (slope-based and area-based) were compared to the true releases using the Symmetric Mean Absolute Percentage Error (SMAPE). While transects fulfilling the Gold Standard threshold showed strong agreement with actual emissions, several non-Gold Standard transects also yielded emissions estimates within 20-30 % of the released rates. These results were used to propose an expanded classification framework introducing a Silver category (R² = 0.60, ERD = 30 %), that retained additional valid transects under moderate conditions. These results demonstrate that TCM can provide accurate total landfill emission estimates supporting a more flexible, performance-based framework to improve its utility in landfill monitoring programs.