Numerical Simulation of Solute Migration of Groundwater Remediation under a Chromium Contaminated Site

Abstract

Groundwater remediation technology of Pump-Treat and Vertical anti-Seepage is an effective treatment to retard the migration and diffusion of pollutants. It is widely used to prevent and retard the long-term leakage of pollutants in landfills. Based on the groundwater infiltration, dispersion and source-sink interaction, this research work has established a three-dimensional coupled model of hydrologic and contaminant transport was constructed with Modelflow groundwater modelling. It ultimately provides a scientific basis for the prevention and control treatment of groundwater pollution in the actual construction of the site. According to the data of borehole sampling, stratigraphic section and pumping test, the site is vertically divided into three layers, namely the upper weak aquifer, the sandy pebble aquifer and the mudstone weak aquifer. The groundwater system in the assessment area is generalized as non-homogeneous anisotropy, spatial three-dimensional structure, unsteady groundwater flow system. It takes convection and dispersion of contaminant into consideration when transport characteristics of hexavalent chromium (Cr⁶⁺) contaminant with pump-treat and vertical curtain in groundwater environment were numerically analysed. The retention effects of curtain grouting were researched and predicted. The results showed that the Cr⁶⁺ concentration of groundwater was decreasing from 317 mg/L to 180 mg/L under the condition of continuous pumping without curtain grouting with removal efficiency of 43%; and the Cr⁶⁺ concentration of groundwater was decreasing from 317 mg/L to 80 mg/L under the condition of continuous pumping with curtain grouting with removal efficiency of 75%.