Age dating of a chlorinated solvent plume in groundwater

Groundwater in a well in southern New Jersey exhibited elevated concentrations of trichloroethylene (TCE), cadmium (Cd) and lead (Pb). The contaminant source was suspected to be wastewater lagoons at an industrial site located 550 m upgradient. Wastewater discharges were active at the site until the mid-1970s and TCE, Cd and Pb have been detected in underlying soils. The age of groundwater in the well was used to confirm the source of the contamination. To determine the age of the contaminants present, tritium (H-3) analyses and groundwater migration rate calculations were performed. H-3 analyses performed on the sample revealed that the age of the groundwater was about 24 years. Groundwater flow calculations confirmed that the travel time between the lagoons and the well for TCE and metals is between 20 and 25 years. Accordingly, the contaminant source was confirmed and the owner accepted liability.