Remediation of a TCE plume using a three-component strategy

A residual source of trichloroethene (TCE) contamination in a deep, fractured basalt aquifer at the Idaho National Laboratory was generated by direct injection of chlorinated solvent-containing liquid waste and sanitary sewage resulting in an approximately 3-km-long trichloroethene groundwater plume. Due to the size, location, and characteristics of the contaminated area, a three-component remedy was implemented: (1) in situ bioremediation for restoration of the residual source area; (2) pump and treat for containment and treatment of the medial zone; and (3) monitored natural attenuation for restoration of the distal zone of the plume. Ultimately, the in situ bioremediation and pump and treat components will transition into one final remedy, monitored natural attenuation, for the entire plume. This article summarizes the technical basis and development of each component and describes how integration of three components has achieved a more cost-effective and efficient strategy for remediation of the plume within the remedial time frame.