Shallow ground water moving beneath an unlined industrial waste landfill resulted in the generation and migration of leachate to a nearby surface water receptor. The landfill, located on a riverine floodplain, was a legacy site deactivated prior to implementation of the Clean Water Act. Leachate generated from the landfill contained organics, metals and high concentrations of total dissolved solids. A cost effective solution was needed to minimize leachate generation and eliminate uncontrolled discharge to the adjacent river.

Roux Associates developed and implemented a phytoremediation alternative as a component of the closure of an industrial landfill located in Michigan. The overall goal of the remediation was to minimize the volume of water moving through the inactive landfill cells and thus to significantly reduce leachate generation. The design objective of the phyto planting was to minimize infiltration of precipitation into the two largest inactive landfill cells as well as to intercept and evapotranspire ground water migrating into the cells from upgradient portions of the Site. To achieve these objectives 5,000 specially bred hybrid poplar tree cuttings were installed in three planting zones. The hybrid poplar cultivars used at the site (OP-367) are capable of transpiring between 10 and 50 gallons of water per day when mature. Based on the periodic monitoring of the trees growing at the Site, the remedial objectives are being successfully achieved.