HR: 08:50h
AN: H31F-04    [Abstracts]
TI: Hydraulic and tracer tomography for the characterization of DNAPL source zones: A laboratory sandbox study
AU: * Liu, X
EM: xiaoyi-liu@uiowa.edu
AF: The University of Iowa, 423C IIHR-Hydroscience & Engineering, Iowa City, IA 52242, United States
AU: Illman, W A
EM: walter-illman@uiowa.edu
AF: The University of Iowa, 423C IIHR-Hydroscience & Engineering, Iowa City, IA 52242, United States
AU: Craig, A J
EM: ajcraig@engineering.uiowa.edu
AF: The University of Iowa, 423C IIHR-Hydroscience & Engineering, Iowa City, IA 52242, United States
AU: Massi, A
EM: amassi@engineering.uiowa.edu
AF: The University of Iowa, 423C IIHR-Hydroscience & Engineering, Iowa City, IA 52242, United States
AB: Contaminant source zones of Dense Nonaqueous Phase Liquids (DNAPLs) are prevalent at a large number of industrial sites throughout the world. Existing direct approaches of site characterization involving coring and interpolation or geostatistical analysis of DNAPL saturation are considered to be invasive and costly. We present here a laboratory study of an alternative to traditional characterization approaches based on hydraulic and tracer tomography. The main advantage of this new approach is that it requires far fewer boreholes than the traditional coring techniques to image the DNAPL source zones. Specifically, it first analyzes the information derived from hydraulic tomography, a new type of aquifer test, to identify the three-dimensional hydraulic heterogeneity in hydraulic conductivity and specific storage of the aquifer. The newly derived knowledge of heterogeneity is then used to design partitioning tracer tests conducted in a tomographic manner to accurately depict the spatial distribution of DNAPL saturations in source zones. We conducted several laboratory sandbox studies which involved the packing of aquifers with a deterministic heterogeneity pattern, spilling of a known volume of Trichloroethene (TCE) and its subsequent characterization through hydraulic tomography, tracer tomography, and coring at the conclusion of all other tests. For purposes of interpreting the hydraulic and tracer tomography data, we utilize the algorithms developed by Yeh and Zhu (2007) to conduct the analysis of our laboratory results. Our laboratory results to date show that the imaging of DNAPL saturations and estimating their corresponding uncertainties is viable through this approach. In addition, we found that the proper estimation of hydraulic heterogeneity first is of paramount importance in designing, conducting, and analyzing partitioning tracer tests. The proper design of partitioning tracer tests can increase the accuracy of DNAPL saturation estimates in heterogeneous aquifers as it will better sweep through suspected contaminated areas including DNAPL ganglia and pools. Characterization of subsurface heterogeneity has an important additional benefit as it contributes to the lowering of site investigation costs.
UR: http:www.iihr.uiowa.edu/~illman
DE: 1831 Groundwater quality
DE: 1869 Stochastic hydrology
DE: 1873 Uncertainty assessment (3275)
DE: 1894 Instruments and techniques: modeling
SC: Hydrology [H]
MN: 2007 Joint Assembly