Assessing Abiotic Contribution of Contaminant Attenuation with Rate Constants from 14C Assays
Description / Summary:
Abiotic degradation of groundwater contaminants such as chlorinated ethenes and 1,4-dioxane has been historically under-considered during remediation strategy selection. In aerobic aquifers, where reductive dechlorination of contaminants is inhibited, degradation processes have been difficult to document conclusively. The lack of readily identifiable transformation products from 1,4-dioxane makes documenting its degradation at low concentrations in groundwater very challenging. The Clemson University 14C laboratory assay for degradation of PCE, TCE, cDCE, VC, and 1,4-dioxane to non-toxic polar transformation products is a powerful tool to bridge this gap.
Complementing the previous session on the 14C assay, presented by Dr. Freedman (Clemson University) and featuring an introduction by WSP’s Matt Burns, Dr. John Wilson will illustrate the simple calculations used to convert the laboratory rate constants to rate constants that are applicable at field scale. Then case studies will illustrate how the field scale rate constants can be used to provide the U.S. EPA second and third line of evidence for MNA at a site. Finally, an approach will be presented where the rate constants can be used to support the transition of active remedies such as pump-and-treat to monitored natural attenuation (MNA).