Objective

Relationships between (fractional) mass flux reduction and (fractional) mass removal measured for two field systems of different degrees of complexity. The TIAA site is very heterogeneous with a nonuniform DNAPL distribution, while the Borden site is relatively homogeneous.

Chlorinated solvents occur in the form of nonaqueous phase liquids (NAPL) and are long-term sources of vadose zone and groundwater contamination. Given their toxicity, widespread occurrence, and complex behavior, chlorinated solvents pose a risk to human health and the environment. As such, significant effort is focused on risk assessment and remediation of contaminated sites. The recalcitrant nature of these NAPL source zones, however, limits the feasibility of groundwater remediation without source control, and there is significant uncertainty in how source zone architecture controls contaminant mass flux and mass removal in heterogeneous systems.

The objective of this project is to enhance understanding of the relationships between source zone architecture, mass-transfer dynamics, and contaminant mass flux for heterogeneous dense nonaqueous phase liquid (DNAPL) source zones. Specific objectives include: (1) investigate the impact of source zone aging on the relationship between mass removal and mass flux reduction; (2) investigate the impact of source zone architecture and mass-transfer dynamics on contaminant removal, mass flux, and plume response at the field scale; (3) apply mathematical models to evaluate the impact of porousmedium heterogeneity, nonuniform DNAPL distribution, and mass-transfer processes on mass-flux behavior at multiple scales; and (4) assess the efficacy of methods for estimating mass-flux-reduction/mass-removal behavior.