A Systematic Approach to in Situ Bioremediation of Carbon Tetrachloride in Groundwater

The historical use of carbon tetrachloride (CT) as a fumigant at grain silos has caused groundwater contamination at numerous sites. The Interstate Technology Regulatory Council (ITRC) – In Situ Bioremediation (ISB) Team has recently completed a guidance document that describes a systematic approach to ISB for CT in groundwater (ITRC, 2002). Contaminant reduction of CT through ISB typi­ cally occurs through a reductive process whereby an electron donor is introduced into the subsurface. Primary reductive pathways for CT have been documented to occur primarily through direct reductive dechlorination, cometabolic reductive dechlorination, and cometabolic denitrification. CT found at silos may be in conjunction with nitrate contamination that serves as an electron acceptor during ISB of CT. ITRC’s ISB team guidance document describes regulatory concerns, provides a description of treatability tests, and feasibility; and defines the contaminant’s pervasiveness, risks, sources, and site parameter criteria important to the evaluation of ISB for CT. ITRC is a state-led coalition of more than 40 states working together with industry and stakeholders to achieve regulatory acceptance of environmental technologies. ITRC brings together a diverse mix of environmental experts and stakeholders from both the public and private sectors to broaden and deepen technical knowledge and streamline the regulation of new environmental technologies.