Integrated approach for accurate quantification of methane generation at municipal solid waste landfills

Municipal solid waste (MSW) landfills have been identified by regulators and policy-makers as primary sources of greenhouse gas (GHG) emissions. Landfill gas (LFG) generation is best described as a first order reaction which is the basis of many LFG generation models. These models are tools to predict a landfill’s lifespan methane generation, in lieu of costly full scale quantification methods. Moreover, modeling results are required to properly design LFG recovery and utilization systems. These results are also used by the GHG emission regulatory authorities to establish and enforce regulations, and modify and fine-tune the existing policies, regulations, and inventory reports. However, with a large number of variables affecting the biological decomposition process within landfills, exact quantification of methane generation and/or emission from these sources is literally impossible. Several investigations have raised serious doubts about the accuracy of many existing models, hence, the validity of model-based emission statistics utilized by the national and international organizations. A quick modeling exercise presented in Chapter 1, involving 5 popular LFG generation models showed up to 340% variation for a single site, arguably showing the need for an advanced model which offers more realistic, consistent, and comparable results that could be used by landfill owners, engineers, and regulatory agencies. In this research, an integrated LFG generation model was developed based on the waste decomposition principles and operational and environmental conditions. Methodologies for effective full scale quantification of fugitive methane emissions were also developed. With the unique opportunity which was made available at the Vancouver landfill (VLF), a newly iii developed integrated gas generation model (iModel-110©) was calibrated and verified based on a comprehensive landfill methane mass balance investigation. The field investigations conducted at the VLF consisted of four major phases including: (i) development of an LFG recovery system database, (ii) monitoring the landfill’s behavior in time and with respect to changes in ambient conditions, (iii) measurement of fugitive methane emissions through an innovative approach, and (iv) quantification of the biological methane oxidation in the landfill’s cover soil using the stable isotope technique.Applied Science, Faculty ofCivil Engineering, Department ofGraduat