Big Plume; Little Remediation – Smart Characterization in Action

The best remediation strategy begins with a new approach to site investigation. Traditional site investigation methods assume a uniformity of conditions in the subsurface, and the result is a conceptual site model based on a relatively small dataset collected from a monitoring well network. Because monitoring wells simply report contaminant concentrations, rather than mass flux, the monitoring well dataset fails to provide the information necessary to accurately evaluate potential risks and liabilities or understand likely clean-up timeframes.

We recommend the Smart Characterization approach, which creates a mass-flux based conceptual site model by integrating dynamic, real-time, high-density soil and groundwater sampling with hydrostratigraphic interpretations and 3D permeability mapping. By classifying the subsurface into transport, slow advection, and storage zones, we can tailor characterization approaches based on the mass transport behavior. We capture the high resolution flux data into a digitalconceptual site model, which is linked with a business decision framework we call Return On Investigation, or ROI. When applied correctly, Smart Characterization methods result in an ROI through reduced total cost of remediation, better definition of uncertainty and risk, and understanding achievable endpoints before remediation commences.

As a case study, we present a site with a one-mile long, 10 PPM TCE plume, which was rapidly characterized using real-time, high-resolution Smart Characterization methods. These characterization data were used to build a 3D digital CSM and ultimately obtain site closure pending in 2017. The most significant finding is that human health and the environment could be protected largely using administrative methods. It is certain that this conclusion would not have been reached with traditional characterization methods. Therefore, this project also demonstrates the ROI concept: the site characterization for the project cost far less than decades of useless active remediation which would not result in any further reduction of risk.