HR: 14:10h
AN: H43H-03    [Abstracts]
TI: DNAPL Source Zone Morphology and Mass Flux: the Role of Aquifer Heterogeneity
AU: * Page, J W
EM: jwep2@eng.cam.ac.uk
AF: University of Cambridge, Engineering Department, Trumpington Street, Cambridge, CB2 1PZ United Kingdom
AU: Soga, K
EM: ks@eng.cam.ac.uk
AF: University of Cambridge, Engineering Department, Trumpington Street, Cambridge, CB2 1PZ United Kingdom
AB: To design and implement successful remedial actions, it is necessary to understand the dissolution behaviour of the DNAPL. Remediation cannot be assessed purely in terms of mass or volume removed, but must focus on the mass flux leaving the source zone on completion of cleanup. This study considers the significance of DNAPL spill morphology on source zone dissolution and subsequent mass flux using a combination of numerical simulations and 2-D laboratory experiments. Using the Turning Bands method and assumption of a log-normal distribution of natural aquifer permeability values, a number of stochastic aquifer realizations have been generated using a range of mean, variance and correlation scale parameters. In each test aquifer, a 500L release of PCE was simulated followed by a 3000 day dissolution period using a multi-component, multi-phase simulator. Temporal variations in mass flux leaving the source zone were recorded, and the vertical PCE distribution within the source zone was found to be the dominant controlling factor. This value was then used in a new method for normalising mass flux values. These simulations were repeated for aquifer realisations with different variance and correlation scale values, and corresponding normalised flux values also followed a similar trend. Any exceptions could be explained by examining the PCE spill morphology, which could then be directly related to the aquifer heterogeneity. Six heterogeneous aquifer fields were generated with the same Turning Bands technique and used in a series of laboratory tank experiments. The experiments involved multiple surfactant flushes and a suite of partitioning tracer tests. Following periods of surfactant flushing, vertical PCE mobilization occurred by reduced interfacial tensions and aqueous PCE concentrations in the tank effluent had increased. The measured PCE mass flux values at different stages of remediation were normalised by the observed vertical DNAPL distributions, and the resulting data showed close similarity with the trends seen in the numerical simulations.
DE: 1803 Anthropogenic effects
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1869 Stochastic processes
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting