Soil water characteristic curve test and saturated-unsaturated seepage analysis in Jiangcungou municipal solid waste landfill, China

Abstract

In this study, an analysis of municipal solid waste (MSW) is undertaken at the Jiangcungou landfill in Xi’an, China. Using waste specimens gathered from the landfill, the soil water characteristic curve (SWCC) is determined at the laboratory, and the effects of landfill age and dry density on the SWCC parameters are analyzed. Leachate level trends during the landfill lifecycle are examined by performing saturated-unsaturated seepage analysis with the consideration of precipitation, as well as the inner source of water. These results are then summarized into three primary points. First, the shallow waste in the Jiangcungou landfill lost its water relatively quickly at small negative pressure heads, while the deep waste lost its water much more gradually. In addition, the deeper waste exhibited a lower volumetric water content when the matrix suction was less than 1.4kPa, but the result was opposite when the matrix suction was more than 2.0kPa. Second, the saturated volumetric water content and steepness of the SWCC decreased as the dry density increased, and the residual volumetric water contents increased and the inverse of the air-entry pressure decreased with increasing landfill age. Third, layers three, five and six demonstrated the highest leachate levels in the eighth landfill stage especially layer five, and these merit the greatest attention in monitoring and construction. These findings may provide a basis for the management of the Jiangcungou landfill.