Landfill, as an indispensable part of every waste management system, is subject to a critical revision. The existing scientific, technical, and regulatory concepts are discussed in group reports on the basis of 14 review papers. Landfills are considered as chemical and biological reactors, which can be active over a time span of several centuries. Thus the common goal of the participants of the workshop was to define both scientific and technical criteria for landfills with final storage quality. This new concept is of fundamental importance for environmental engineers and scientists.