Air Dispersion Modeling for Landfill Gas Emissions and Facility Siting

Air dispersion modeling studies how the air pollutants disperse in the ambient atmosphere using computer simulation. The dispersion models are used to estimate or predict the concentration of air pollutants or toxicants emitted from various sources such as industrial plants, road traffic vehicles or accidental chemical releases.

Landfill gas is a complex mixture of gases generated by anaerobic decomposition of biodegradable waste in landfills, which includes methane, carbon dioxide, and trace constituents of volatile organic compounds (VOC), hazardous air pollutants (HAPs), and hydrogen sulfide. In recent years there are more and more concerns about the acute toxicity, chronic hazards, and risks associated with landfill gas emissions. Emission estimating is an important step in conducting risk evaluations, obtaining permits, demonstrating compliance with regulatory limits, and designing emission control systems for solid waste landfills. A landfill site case study is demonstrated, and different screening and refined modeling tools are used for the modeling of landfill gas emissions and their resulting ambient air concentrations.

Facility siting is for managing the risk to on-site personnel located in new and existing buildings intended for occupancy. Air dispersion models are used to determine the consequences of accidental releases of hazardous or toxic materials. The results of dispersion modeling, using worst credible case accidental release source terms and meteorological conditions, can provide an estimate of the location of impacted areas, ambient concentrations, and be used to determine mitigation actions appropriate in the event a release occurs. Computer Fluid Dynamics (CFD) software is used for a chemical gas plant permanent building location study.