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 research work was focused on: the possibility of using abandoned underground mines for disposal of hazardous chemical waste with negligible pollution of the environment; the properties and behaviour of waste-isolating clay materials and practical ways of preparing and applying them; development of software tools to assess the stability, performance and risks associated with different repository concepts, considering the long-term safety of the biosphere; the isolating capacity of reference repositories; the different approaches for handling hazardous chemical waste. The project has demonstrated that hazardous waste can be safely disposed in underground mines provided that adequate assessment, planning and design procedures are employed. 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.