Analytical study for two-dimensional transport of organic contaminant in a polymer material-enhanced composite cutoff wall system

Polymer material (PM) is a novel vertical barrier material, demonstrated to be effective in impeding pollutants. However, the associated transport research is limited. This study aims to develop an analytical solution for two-dimensional transport of organic contaminant in the PM-enhanced composite cutoff wall (CCW) system, where the variable substitution and Fourier transform methods are used. This analytical solution, available in various simplifications, is effectively validated via several comparisons. Following this, the analyses show that an increase in the non-uniformity of pollution source concentration distribution shortens the PM-enhanced CCW's breakthrough time ($t_b$), while exhibits a marginal effect on the total flux at its exit. The increment of aquifer horizontal thickness prolongs the $t_b$ to some extent, whereas an increase in its hydraulic conductivity slightly reduces the $t_b$. Additionally, the PM layer location is found to have a little effect on the PM-enhanced CCW's barrier performance. Furthermore, the equivalent performance assessment reveals that the improvement gained from increasing the PM layer thickness far surpasses that from increasing the single-layered cutoff wall thickness, and this difference may exceed 10. For a PM layer with low hydraulic conductivity, it is more suitable for engineering scenarios with the higher hydraulic head difference. Totally, the proposed analytical solution offers a valuable tool for designing the PM-enhanced CCW.