Breakthrough times for barrier systems at typical municipal solid waste landfills in China

Landfill is the most common disposal method for municipal solid waste (MSW). Composite liners are widely used as bottom barriers in MSW landfills in China to minimize groundwater contamination with landfill leachate. However, little information is available on breakthrough times for bottom barrier systems used in landfills. In this study, breakthrough times for bottom barrier systems used in typical active MSW landfills in four Chinese cities (Hangzhou, Shanghai, Shenzhen, and Suzhou) were evaluated by numerically modelling chemical oxygen demand (COD) transport. The performances of the landfill bottom barrier systems were determined from the COD concentration of the leachate, the landfill operating period, and the leachate head. A leachate head of 0.3 m is specified in the relevant regulations. Using a leachate head of 0.3 m, the breakthrough times for the barrier systems in all of the four landfills were > 50 years. However, using the actual leachate heads, the breakthrough time for the barrier system in the Hangzhou landfill was only 27 years even though the barrier system was a compacted clay liner/geomembrane/geosynthetic clay composite liner. The results of this study provide reference data for designing and managing landfill barrier systems.