Effects of Impermeable-Zone Diffusion on Continuous and Intermittent Pump-and-Treat Remediation at Dover AFB -- Model Simulations and Field Results
EMSL Project ID
2184
Abstract
Investigators studied the removal of organic contaminants from an aquifer at Dover AFB, DE, using continuous and intermittent pump-and-treat remediation on adjacent segments of a long-extant groundwater plume (Mackay et al., 2000). Principal findings were that the remediation was influenced not only by (1) spatial variability of the transport medium (aquifer), but also by (2) spatial variability in the pre-remediation contaminant distribution, and (3) spatial variability of the sorption properties of the low-permeability media. The sorption and diffusion processes have been confirmed through independent experimentation (Ball et al., 1997b; Young and Ball, 1998) and their applicability to the field has been verified through a follow-on project that examined continuing diffusion after over a year of stagnant conditions in the aquifer (Ball et al., 1998; Liu and Ball, 2001). Although predictions have been made as to how concentration profiles and fluxes vary during remediation (Liu and Ball, 1998; Ball et al., 1997b), simulations to date have been under ideal scenarios. A recent analytical solution (Liu et al., 1998; 2000) provides a means to conduct more realistic simulations. Contamination in sorbing impermeable zones can be viewed either as sequestered or a continuing source, depending on initial conditions, physiochemical properties of the immobile region, extent of remediation, and conditions of subsequent water withdrawal. In the proposed project, we would distinguish these by applying analytical modeling (Liu et al., 1998) toward the simulation of (a) concentrations in the extraction wells and piezometers under conditions of the project (Mackay et al., 2000), and (b) expected concentrations that might develop with more extended periods of operation. The objective is to evaluate and illustrate how mass transfer from impermeable zones of sorption can impact risk and remediation.
Project Details
Project type
Exploratory Research
Start Date
2001-02-15
End Date
2004-01-20
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Liu C, and WP Ball. 2002. "Back Diffusion of Chlorinated Solvent Contaminants from a Natural Aquitard to a Remediated Aquifer under Well-Controlled Field Conditions: Predictions and Measurements." Ground Water 40(2):175-184.