Investigating post-remediation management strategies for contaminated sites based on residual pollutant migration risks

Post-remediation management plays a crucial role in risk control for contaminated sites, ensuring environmental safety and facilitating site redevelopment. In this study, we assessed the regulatory status of 469 post-remediation sites, analyzing factors such as spatio-temporal distribution, residual pollutants, planned land use, and regulatory measures. Our findings revealed that current post-remediation management often exhibits a coexistence of insufficient and excessive regulatory oversight. To address these issues, we propose a risk classification framework aimed at refining management strategies and improving resource utilization efficiency. The classification system integrates precedence chart and fuzzy evaluation methods, categorizing the sites into three levels (Level I, II, and III), each corresponding to different treatment measures. Five typical sites were selected to validate the classification method, and the results confirmed its stability and scientific basis. The method was then applied to 104 post-remediation sites, where the classification revealed that 62.5 % of the sites were Level III, 15.4 % were Level II, and 22.1 % were Level I. Notably, the application of this method could simplify regulatory measures for 45.24 % of the sites, as some could shift to institutional control rather than requiring long-term monitoring combined with institutional control. The approach developed in this study provides a critical safeguard for the safe reuse of contaminated land, offers valuable insights for the effective development of post-remediation management, and accelerates the establishment of a post-remediation management system tailored to regional administrative conditions. • Revealed the management status of post-remediation sites in typical regions of China. • Regulatory omissions and excessive oversight coexist in the post-remediation stage. • A risk classification system for post-remediation sites were constructed. • Classification system simplifies regulatory measures of 45.24 % of sites.