Book excerpt: This book contains the results of a three-year research programme by a joint team of experts from four different EU countries. The main focus of this research was on investigating the possibility of using abandoned underground mines for the disposal of hazardous chemical waste with negligible pollution of the environment. The contributors address many aspects that are common to underground disposal of nuclear waste, such as: the properties and behaviour of waste-isolating clay materials and practical ways of preparing and applying them, development of tools/software to assess the stability, performance, transport of contaminants inside and outside the repository, and risks associated with different repository concepts considering the long-term safety of the biosphere. Information is also included on the selection of site location, design and construction of repositories, predicting degrees of contamination of groundwater in the surroundings, estimation of isolating capacity of reference repositories, cost estimation of this approach in comparison with some other approaches, and many other relevant issues.Invaluable to researchers and engineers working in the field of hazardous (chemical) waste disposal, this title will also significantly aid experts dealing with nuclear waste.