Analytical Study on the Performance of a Novel Barrier: Cut‐Off Wall and Permeable Reactive Barrier Dual‐Domain System

ABSTRACT An alternative structure with an up‐gradient permeable reactive barrier (PRB) and a down‐gradient cut‐off wall is proposed to enhance plume capture and degradation while optimizing material use. A 2D analytical model is developed to predict the contaminant transport through the dual‐domain barrier system. The proposed analytical solutions are verified by comparing their predictions with results from numerical solutions and from previously published 1D analytical model. The derived analytical solution is used to explore how the arrangement of PRB and cut‐off wall structures affects the system's performance. We show that the cut‐off wall domain can direct flow and reduce the contaminant flux through the system due to its low permeability. The system performance can be best improved with the decrease of the contaminant half‐life in PRB, whereas the impact of the PRB retardation factor on the system performance is less important due to the quick saturation of the adsorption for the PRB material. The average flux through the total system can be decreased to 5.4 × 10 −4 mg·m −2 ·s −1 (3.7 times lower than the limited value) when the contaminant half‐life in PRB is 1 h. Additionally, the pumping/recharge wells are suggested to be together used to control the contaminant flow velocity since high equivalent head losses can lead to poor remediation efficiency of the system. The proposed alternative PRB structure and analytical solution are expected to be effective tools for the management and remediation of the organic contaminated sites.