Numerical study of clustered reactive media cylinders for remediating contaminated groundwater

This study explored the viability of monitoring or low-discharge extraction wells surrounded by clusters of cylinders filled with reactive media to remediate contaminated groundwater. A numerical finite-difference model simulated leakage from a hypothetical waste storage facility above an unconfined aquifer. Linear arrays of clusters around a central monitoring (non-pumped) or low-discharge extraction well were evaluated for contaminant plume containment and removal capability. Pumping schemes involved one or more downgradient extraction wells and an upgradient injection well. Without pumping, a minimum of seven clusters, with centres spaced 1.5 m apart, effectively contained and removed the contaminant plume. The most effective low-discharge schemes, extracting less water to remove the plume, were a 1.5-m-spaced three-extraction well scheme, followed by a single-extraction well scheme. Lacking a well along a downgradient extension of the contaminant plume’s long axis, two-extraction well schemes were less effective overall. The modelled configuration – reactive cylinders around a central monitoring or low-discharge well in the same borehole – is novel, with capability for in situ remediation; performance monitoring; low-discharge extraction; exchanging spent media cartridges; and accommodating a fluctuating water table. Results outlined above indicate that passive or low-discharge reactive cylinder clusters may be viable at some sites with narrow contaminant plumes.