About the Guidance Document:
The ISC-1 Guidance Document synthesizes the knowledge of DNAPL site characterization and remediation acquired over the past several decades, and provides guidance on the simultaneous characterization of contaminant distributions, hydrogeology, and attenuation processes to allow for improvements in the following areas:
- assessment of ongoing contaminant exposures
- quantification of contaminant transport, storage, and attenuation patterns
- prediction of future exposures that would occur without intervention
- prediction of changes in future exposures that would occur in response to remedial actions
- selection and design of remedial actions
Team Background:
Dense, non-aqueous phase liquids (DNAPLs), which are typically chlorinated organic compounds, are one of the most widespread and high-risk types of subsurface contamination. Understanding the subsurface behavior of DNAPLs is technically challenging and methods for site characterization have evolved. The goal of this project was to summarize emerging DNAPL site characterization methods, their applicability in various geological settings, and where they fit into current regulatory processes.
Sites contaminated with dense nonaqueous phase liquids (DNAPLs) and DNAPL mixtures present significant environmental challenges. Despite the decades spent on attempts to characterize and remediate DNAPL sites, substantial risk remains. Inadequate characterization of site geology and the distribution, characteristics, and behavior of contaminants—by relying on traditional monitoring well methods rather than more innovative and integrated approaches—has limited the success of many remediation efforts; however, the amassed experience and applied research have resulted in a better understanding of subsurface science, including recognition of the complexity of subsurface geologic conditions (in particular, system heterogeneity).