Cover systems for landfills and brownfields

Some 25 to 30 years after Western nations, the emerging economies in Asia and South America, as well as the countries of the former Soviet Union now have to address the environmental problems of waste management, and to establish long-term safe landfills as a first step towards a waste management regime governed by recycling and waste-stream reduction. A cover system as part of the landfill design should permanently prevent the uncontrolled release of landfill gas (primarily methane gas (CH4)) and pollutants, as well as the infiltration of precipitation water into the body of the landfill. Active degassing of municipal landfills takes on particular significance in the light of current climateprotection objectives, and can also provide energy by utilizing the captured gases. This paper describes current problems with classic compacted clay liners (CCLs) and their still unquestioned use in landfill legislation and landfill construction around the world. This paper focuses on dehydration/desiccation and deformation cracking when CCLs are used in landfill-capping applications. As alternative solutions, it is shown that modern capping design using geosynthetics such as certified geomembranes and certified geosynthetic clay liners (GCLs) are more than ‘equivalent’, and have proven to give better long-term, reliable solutions. The authors recommend the replacement of CCLs by certified geosynthetic components such as geomembranes and GCLs.