Application of in-situ horizontal barrier risk control technology in the treatment of a decommissioned industrial contaminated site

In order to meet the goal of human health risk control, targeted risk control schemes were designed for indoor and outdoor areas in combination with the working situation of later site development scenarios of a decommissioned industrial contaminated site. For the −2 m contaminated soil under the foundation of indoor regional buildings, the soil gas barrier control project was adopted. The soil gas was blocked by spraying a film between the foundation and the air guide layer of the building, and the negative pressure of the air guide layer below the building was controlled to be −5-−2 Pa. The soil gas was collected by the extraction system, which was treated by the tail gas treatment system to reach the standard before discharge. HDPE film (two cloth and one film) was used as a horizontal barrier for contaminated soil with an original ground elevation below −3 m in outdoor areas, and clean clay was used for cover and compaction above the barrier layer. The results of the risk control effectiveness evaluation carried out within one year after project completion showed that the engineering performance indicators and pollutant indicators of the indoor and outdoor areas met the evaluation standards and achieved the expected effect. The project passed the acceptance of the ecological environment department in December 2021 and entered the later stage of environmental supervision.