A simplified method to determine the wall thickness of GCL composite cutoff wall

• A simplified method to determine the thickness of GCL composite wall is proposed. • The relative error of the simplified method is small (= -7.7% ∼ 5.1%). • The method is easy to use and can provide a tool for design and evaluation. Geosynthetic clay liners (GCLs) have recently been incorporated into the traditional soil walls to form GCL composite vertical cutoff walls for waste containment applications in contaminated sites. This novel cutoff wall has been used in engineering practice; however, the design method of this composite cutoff wall has rarely been reported. Considering the contaminant transport mechanisms of advection, hydrodynamic dispersion and adsorption, this study proposes a simplified method to determine the thickness of the GCL composite wall by decoupling the advective and the dispersive fluxes. Error analyses are conducted by comparing the proposed simplified method with an existing analytical solution. The results indicate that the relative error of the simplified method is small (= -7.7% ∼ 5.1%) for the conditions commonly encountered in cutoff wall design (i.e., breakthrough criterion of C b / C 0 ≤ 0.1 and Peclet number of 1 ∼ 100). The proposed simplified method is easy to use and can provide a tool for convenient design and evaluation of GCL composite cutoff wall in contaminated sites.