Groundwater pollution management with source remediation and composite geomembrane cut-off wall: an analytical model and field investigation

Abstract

This study proposes a two-dimensional analytical model for contaminant migration through the composite GMB cut-off wall (CGCW) and aquifer system considering the effects of the leakage and source remediation. A comprehensive sensitivity analysis based on the Sobol's method is conducted to investigate the key impacts of contaminant distribution and degradation rate in the source, cut-off wall retardation factor and Darcy velocity in CGCW. The results show that the performance of the CGCW significantly is controlled by the leakage. The peak contaminant concentration at the outlet of CGCW for large leakage (10^-8 m/s) can be 77.1 times larger than that for small leakage (10^-11 m/s), with a performance deterioration of 98.7%. Additionally, the performance of the CGCW can be significantly enhanced by the source remediation technique. The CGCW will not be broken through when contaminant source degradation rate is larger than 2.9 × 10^-8 /s. Increasing the cut-off wall retardation factors (> 14.7) and decreasing the standard deviation of contaminant source distribution (< 0.1) can also improve the CGCW performance. Moreover, the analytical model coupled with the genetic algorithm is used for the CGCW leakage detection and performance prediction at an abandoned pesticide site based on the monitoring data. Accurate leakage detections in the field (with errors of < 5 m) can be achieved through the analytical solution, which is validated by the non-destructive high-voltage technique. The analytical solution can be an easy-to-use tool for the design, installation and construction of the CGCW at polluted sites.