Simulation Study of Groundwater Polluted by Landfill Leachate in Subsidence Areas

The subsidence caused by mining was used as domestic waste landfill, due to the lack of anti-seepage treatment at its bottom, the internal leachate not only contaminated the surface water, but also the goaf groundwater continuously. Therefore, taken the Datong landfill in Huainan, Anhui Province as an example, the similar simulation test was chosen to simulate the temporal variation of the concentration of pollutants in the goaf. The formed mechanism of leachate pollution of groundwater was also discussed. The results show that the leachate still caused serious pollution to groundwater after the closure of the landfill. Pollutants in groundwater mainly move from west to east under the action of convection-dispersion and adsorption. In the process of pollutant migration and diffusion from west to east, it is controlled by the boundary of the aquifer in the goaf, resulting in a large accumulation of pollutants at the end of the goaf and causing the high concentration of pollutants. In addition, due to the influence of geological environment in goaf, the pollution rate and concentration are constantly changing. The results of the test provide some reference for the groundwater remediation and treatment in the coal mine subsidence area.