Review on penetration of barriers by contaminants and technologies for groundwater and soil contamination control

Barrier systems are the most important structures for landfills in terms of groundwater pollution control. Analytical solutions to one-dimensional models of transport of heavy metals and organic contaminants in clay barriers and composite barriers were summarized in order to evaluate the service life of the barrier systems. The analytical solutions include the solution to a one-dimensional model of diffusion of contaminants in clay barriers under piecewise linear adsorption conditions, the solution to a one-dimensional model of transport of contaminants in composite barriers with geomembrane defects, and the solution to a coupled model of transport of pollutants in clay barriers under thermal effects. The reliability of high-gravity centrifuge tests of long-term transport of contaminants through barriers was assessed. Field investigation was carried out in a 17-year old landfill in Anhui Province. The results showed that the maximum migration depth of chloride ion reached 9 m, and the maximum migration depth of sodium ions and COD reached 3 to 4 m. The technologies of vertical barriers for control of groundwater and soil contamination were summarized and assessed. It was found that the application of soil-bentonite cutoff walls in China generates prosperity, and further research areas were discussed.