Estimating Mobile-Immobile Mass Transfer Parameters Using Direct Push Tools

Back diffusion of contaminants stored in zones with lower hydraulic conductivity (K) can slow aquifer recovery, greatly extending the time to reach remediation goals. In this project, a suite of field and modeling approaches are developed allowing users to better characterize low-K zones in the field, more accurately simulate mass transfer between low-K and high-K zones, and evaluate the impact of these processes on the time to reach groundwater cleanup goals following source removal. Work included: 1) development of low-cost direct push (DP) methods for high-resolution characterization of K; 2) high-resolution characterization and solute transport modeling to evaluate ability to simulate back-diffusin processes; 3) development of methods to calibrate existing and new mobile-immobile zone models; and 4) development of simplified methods for estimating the impact of matrix diffusion on cleanup time.