Remediation of Mercury Contaminated Groundwater Using a Permeable Reactive Barrier

A permeable reactive barrier (PBA), composed of a mixture of activated carbon and a medium quartz sand, was designed as a cost-effective remediation alternative to control a mercury contaminated plume with concentrations as high as a 1 ppm. Laboratory tests were undertaken to establish the ideal mixture of the reactive material that could be best suited for treating the mercury plume by offering a high sorption potential and, at the same time, have a high permeability. Numerical modeling was used during the design phase to optimize the location of the PRB as well as to assess the relative efficiency of a funnel-and-gate versus a continuous wall. The permeable barrier, composed of confining and reactive portions, was executed during a 4-month period and was finally installed in July/2005. It is 186m long, 5.5m deep (starting 3.5m below waterable) and 0.6 m wide (at the confining walls).