Study of Contaminated Soils as a Secondary Source of Groundwater Contamination at the Sites of MSW Landfills

Currently, in Russia, large-scale work is being carried out to close municipal solid waste landfills that have exhausted their capabilities, with their subsequent reclamation. The choice of reclamation method is based not only on the landfill body present state, but also on the groundwater and soil contamination. The contaminants accumulation in the soil near the landfill sites and adjacent territories leads to the formation of a secondary source of contamination. Under changed conditions after the landfill reclamation, the chemical elements contained in the soils in mobile forms can enter the aquifer with infiltrating waters, which can lead to groundwater contamination. In addition, contaminated soils can affect on human health while dusting. Study of contaminated soils is conducted at a number of municipal solid waste landfills in the Moscow region. To assess the hazard of the vadose zone as a secondary source of groundwater contamination, an approach was used that consists in calculating moisture and mass transfer in the vadose zone using the WHI UnSat Suite Plus 2.2.0.2 software package. This allowed evaluating both changes in the content of contaminants in soils. The assessment of the contaminated soils hazard was also carried out using the maximum permissible concentrations, regional and local background contents. The advantages and disadvantages of the approaches used were analysed, the methods of solution were proposed. Various categories of soil contamination were identified based on the obtained data and finally rehabilitation measures were proposed. The research was financially supported by the projects of Russian Science Foundation № 22-17-00045 and Russian Foundation for Basic Research № 20-05-00574.