Degrading CAHs: A Case Study

Chlorinated aliphatic hydrocarbons (CAH) such as dichloromethane, tetrachloroethene, trichloroethane, tricholoroethene, etc. have been widely used as degreasers and solvents in various industries for more than 50 years. CAHs in general are harmful to human and ecological health. Past disposal methods and handling practices have contributed to wide-spread CAH contamination in soil and groundwater. Under reducing and anaerobic geochemical conditions, chemical and biological degradation processes can significantly contribute to the removal of chlorinated solvents from the subsurface. This process is called In Situ Chemical Reduction (ISCR) or Enhanced Reductive Dechlorination (ERD). Saturated soil and groundwater at an active industrial facility located in Illinois is impacted by CAHs, with the primary constituent of interest being 1,1,1 trichloroethane. The remediation strategy implemented utilized a combined approach, with application of the solid ISCR amendment into the hottest areas for source mass removal, followed by the application of liquid ISCR amendment for plume treatment.