Case studies of methane dispersion patterns and odor strength in vicinity of municipal solid waste landfill of Cluj–Napoca, Romania, using numerical modeling

The study investigates the local characteristics of methane dispersion generated by the Pata Rat non–compliant municipal solid waste (MSW) landfill located in vicinity of Cluj–Napoca, Romania, using a numerical model developed at The Center for Promoting Entrepreneurship in the Sustainable Development Domain, from Technical University of Cluj–Napoca. The model was applied to the analysis of the methane dispersion emitted from the landfill, in two different weather conditions. In the first case the synoptic scale effects were weak favoring local flow development, while in the second case, the synoptic scale effects were predominant. The numerical model takes into account the local orography and daytime heating. In the studied area, the topography presents substantial variation, which affects the airflow dynamics. The initial conditions are formulated using observational data, recorded at the Meteorological and Aerological Station Cluj–Napoca, as well as the Meteorological Station of Cluj–Napoca International Airport. In the first case, wind direction and intensity present diurnal variations due to the thermally induced local circulations. In air layers near the ground, up to 350–400m, these variations are more pronounced and significantly influence the dispersion of methane. In the second case, local effects are blurred by a more intense synoptic scale circulation. In these conditions the area affected by methane dispersion is much lower as compared to the previous case. In addition, the time intervals for presence of unpleasant odor due to landfill gases were estimated. Simulation shows that the dispersion is strongly influenced by the weather conditions and local topography. The results indicate the possibility of using the model as a decisional support in assessing the applications and strategies for air pollution control on local scale. An accurate mapping of pollutant dispersion is useful both for urban planning and residential developers.