Abstract: This study focused on the Luzhuangzi site in the decommissioned Tiangang Liulin Industrial Agglomeration Zone in Tianjin. To address the challenges of chlorinated hydrocarbon contamination characterized by complex sources, high mobility, and remediation difficulties, the research carried out engineering practices of contamination tracing, spatial distribution characterization, and low-carbon remediation. The contaminated soil area of the site was 5 099.8 m2, with a contaminated earthwork volume of 39 236.7 m3. The contaminated groundwater area was 21 079.9 m2, with a contaminated aquifer thickness of 14.3 m. The characteristic contaminants of the site were tetrachloroethylene, trichloroethylene, vinyl chloride, cis-1,2-dichloroethylene, ethylbenzene, and petroleum hydrocarbons. Geological conductivity imaging technology was employed to accurately identify the contamination spatial distribution. A zoning-classification-grading remediation strategy was developed based on contamination levels and hydrogeological conditions, and bench-scale experiments were conducted to determine grading benchmarks and remediation technologies. A combined remediation approach of targeted source removal, contamination reduction, comprehensive restoration was implemented, incorporating in situ chemical oxidation, thermally enhanced soil vapor extraction, cement kiln co-processing, and groundwater pump-and-treat. The results demonstrated that the combined process achieved efficient contaminant removal while reducing carbon emissions by 41% compared to single-technology approaches, achieved green remediation of contaminated land. This study provides a technical reference and engineering demonstration for the precise and low-carbon remediation of similar industrial legacy sites.

Key words: chlorinated hydrocarbon contamination, soil and groundwater remediation, low-carbon remediation, precise remediation, industrial agglomeration areas