Since the 1980s, various approaches have been developed to address contaminated sites and old landfills, ranging from excavation to advanced in-situ treatment technologies. There is a need post evaluate such sites. While significant progress has been made, ongoing challenges such as the long-term sustainability of these methods and impacts of climate change call for a rethinking of strategies. Emerging contaminants like PFAS (per- and polyfluoroalkyl substances) and microplastics have recently gained attention due to their persistence in the environment and toxicity. New techniques are needed to monitor and treat these. Urban infrastructure projects commonly encounter contaminated soils. For such situations soil washing is becoming an increasingly common ex situ technology to remove contaminants from the soil with a combination of physical separation and chemical leaching by aqueous solutions, creating valuable materials such as gravel and sand. This also reduces the need for waste deposits. Supported by appropriate regulations and sustainability assessment tools, we can push towards a more circular mass handling.