A case study of an ongoing remediation project involving the mining of an old landfill in northern Italy is presented. The project was started in 2004 after suspicion of groundwater contamination in the area, probably due to the absence of constructed bottom barriers and to the geology of the site, where the landfill was built in the 1970s, before the first legislation on waste management was enforced. The expected results of the project were the complete excavation of the waste but also the construction in the same site of new landfill sectors, to be designed and built according to the current legislation, for the disposal both of the non-recoverable fractions of the excavated materials as well as of new residual waste. The description of the project is given, considering the steps taken over the past 20 years, highlighting the challenges and the solutions adopted for minimizing the emissions, for reaching safe conditions during the excavation, for the management of excavated waste and for the design and management of new sectors.