Optimization of groundwater contamination control in decommissioned acid in-situ leach uranium mines

Upon decommissioned acid in-situ leaching (ISL) uranium mining sites, contaminants (e.g. U(VI), SO 4 2- ) tend to migrate downstream under natural groundwater flow, posing significant risks to groundwater quality. Effective containment of the pollution plume prior to full-scale site remediation is therefore an urgent priority. Hydraulic control via pumping wells is a feasible strategy, but its application is often constrained by the high cost of treating extracted groundwater. To address this issue, this study developed a simulation-optimization framework that integrates a numerical simulation model with a genetic algorithm to identify cost-effective hydraulic control designs for a decommissioned acid ISL mine in Xinjiang, China. Four management scenarios with varying spatiotemporal constraints (10/15 years; 100m/150m control radii) were evaluated to optimize hydraulic barrier layouts by minimizing total pumping rate. The optimized scheme reduced total pumping rates by 30.3% on average and ineffective extraction by 20%, while successfully containing contaminant migration. A notable “funnel-and-barrier” effect, in which concentrated extraction at the downstream well J3 (optimized rate: 58.47 m 3 /d) formed an effective capture configuration, significantly enhanced containment efficiency. By leveraging existing wells and aquifer heterogeneity, this approach provides a practical and cost-effective remediation method for sandstone-hosted uranium deposits and may serve as a scalable strategy for groundwater contamination control at similar sites.