Methane gas is one of the significant contributors to global warming. A large portion of methane emissions comes from landfills. Developing reliable measurement methods for methane emissions from landfill sites has become very important. In this paper, the surface emissions of methane gas are quantified using a portable probe having a flame ionization detector (FID), a method proven to be successful in landfill gas measurement. Surface methane emissions from two closed cells in the Halton landfill in Ontario, Canada, were measured using the FID method. By analyzing the emissions within the perimeter of the landfill, hotspots of gas leakage were identified. The closed cells in the Halton landfill are equipped with gas extraction system for flaring and energy recovery and a clay topsoil cover. Emission concentrations of fugitive methane were found to range from 0.1 to 63 ppm. The largest emissions were detected in locations next to the leachate extraction manholes and malfunctioning gas extraction wells. The landfill gas balance showed that the landfill gas recovery efficiency was 44%, resulting in an average amount of fugitive methane from the landfill of 6124 m3/day. The results of the study were used to determine the methane generation potential (Lo) for municipal solid waste to further calibrate the USEPA LandGEM model for Ontario landfills. The model was calibrated by actual methane emission measurement and recovery data. The calibrated Lo was found to be 70 m3/t, which is lower than the estimated values in previous studies.
Keywords: Gas collection efficiency; Greenhouse gas emissions; Landfill gas; Modeling; Municipal solid waste.