Fugitive methane emissions through the cover system of a Brazilian landfill cell

Abstract

This paper evaluates the fugitive emissions of methane through a compacted soil cover layer in a cell of the Metropolitan Center Sanitary Landfill, in Salvador, Bahia, Brazil. Static-flow chamber tests were carried out in cracked and non-cracked soil areas in periods of high and low rainfall. Correlation coefficients between fugitive emissions and variables such as precipitation, moisture content and distance from drains, among others, were tested, and empirical equations are proposed for the estimation of fugitive emissions in both areas. Non-linear multiple regressions were able to fit the experimental results. However, a large number of independent variables were required. The fugitive methane emissions ranged from 0 to 356 (g/m2)/d. During the rainy season, points located in cracked areas showed an increase in emissions, with cracks in the soil acting as preferential flow paths. The opposite occurred in areas with few fissures and cracks. Considering the field biogas recovery rate, fugitive methane emissions accounted for, on average, 12% of the methane produced in the area in the period of analysis.