Pilot study of in-situ thermal treatment for the remediation of pentachlorophenol-contaminated aquifers.

A field pilot study of a steam injection method for the treatment of pentachlorophenol (PCP)-contaminated soil and groundwater has shown potential advantages over the traditional pump-and-treatment method. Low-pressure steam was injected 10 m below the ground surface. The ground water temperature was raised to 118 degrees C over a period of 3 months. Five soil and groundwater sampling events were performed during the pilot test. Results of sample analysis showed that the PCP concentrations in deep aquifer soil decreased dramatically whereas those in shallow aquifer soil increased. It was concluded that raising the groundwater temperature caused PCP in deep aquifer soil to be desorbed, and as the hot, deep groundwater circulated upward, it brought the desorbed PCP to the shallow aquifer. By using steam injection, PCP can be desorbed from soil and moved upward to the ground surface so that it can be removed more easily through pump-and-treatment.