HR: 11:20h
AN: H42A-05    [Abstracts]
TI: Designing flushing-based remediation systems for maximum reduction in contaminant mass discharge
AU: * Fure, A D
EM: adfure@ufl.edu
AF: Department of Environmental Engineering Sciences, University of Florida 217 Black Hall , Gainesville, FL 32611 United States
AU: Jawitz, J W
EM: jwjawitz@ifas.ufl.edu
AF: Soil and Water Science Department, University of Florida 106 Newell Hall , Gainesville, FL 32611 United States
AU: Annable, M D
EM: annable@ufl.edu
AF: Department of Environmental Engineering Sciences, University of Florida 217 Black Hall , Gainesville, FL 32611 United States
AB: The complexity of sites contaminated with dense nonaqueous phase liquids (DNAPLs) presents significant technical challenges to the successful design of source zone remediation. The restoration of DNAPL contaminated sites such that dissolved-phase contaminant concentrations within the source zone are below drinking water standards is often technologically infeasible. An alternative approach for evaluating the success of source zone remediation technologies is in a risk-based framework where the technology is evaluated for its ability to reduce the contaminant mass discharge from the source zone to the dissolved plume to a level where the risk to down-gradient receptors is lowered below a certain threshold. The evaluation of source zone remediation technologies in such a flux-based paradigm requires the re-analysis of current design protocols that have been developed to maximize reduction in DNAPL mass, as opposed to maximizing reduction in contaminant mass discharge to the plume. In this work numerical simulations were conducted to investigate flushing-based (e.g., cosolvents, surfactants) source zone remediation design protocols for achieving maximum reduction in contaminant mass discharge. Design protocols investigated included well configuration and mass transfer rate discrepancies between natural-gradient conditions and flushing conditions. Results indicate that line drive type configurations oriented in the mean direction of groundwater flow are the most effective. Line-drive configurations best exploit the similarities between `flux creation' under natural flowing groundwater conditions and efficient flux reduction during flushing. Such well configurations also allow for the prediction of remediation effectiveness prior to implementation of source zone remediation. Simulation results also indicate that consideration of the discrepancy in mass transfer rate coefficients between natural-gradient and flushing conditions, often several order of magnitude, is of paramount importance when designing systems to yield maximum reduction in contaminant mass discharge.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting