HR: 0830h
AN: H31B-0462    [PDF]
TI: 3D Inversion of a Self-Potential Dataset for Contaminant Detection and Mapping
AU: * Minsley, B J
EM: minsley@mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Sogade, J
EM: sogade@erl.mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Briggs, V
EM: vbriggs@mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Lambert, M
EM: mbl@mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Reppert, P
EM: reppert@erl.mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Coles, D
EM: dac@mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Morgan, F
EM: morgan@erl.mit.edu
AF: Earth Resources Laboratory, MIT, 42 Carleton Street, Cambridge, MA 02142 United States
AU: Rossabi, J
EM: joseph.rossabi@srs.gov
AF: Westinghouse Savannah River Company, Savannah River Site Bldg. 773-42A, Aiken, SC 29808 United States
AU: Riha, B
EM: brian.riha@srs.gov
AF: Westinghouse Savannah River Company, Savannah River Site Bldg. 773-42A, Aiken, SC 29808 United States
AU: Shi, W
EM: wshi@shellus.com
AF: Shell United States, n/a, New Orleans, LA 70139 United States
AB: Due to the complicated nature of subsurface contaminant migration, it is difficult to determine the spatial extent and severity of contamination, which can provide essential information for efficient remediation efforts. Self-potential (SP) geophysics is employed to provide a minimally invasive, fast, and inexpensive method for remote {\em in-situ} detection and three-dimensional mapping of subsurface DNAPL (Dense Non-Aqueous Phase Liquid) in conjunction with inverse methods. The self-potential method is commonly used to detect a variety of phenomena that are typically related to thermoelectric, electrochemical, or electrokinetic coupling processes. Surface self-potential surveys have been documented to show anomalies over areas known to be contaminated, but interpretation of these datasets is often mostly qualitative, and can be plagued with problems of non-uniqueness. In this study, oxidation-reduction (redox) reactions, one of the mechanisms associated with the attenuation of chemicals released into the environment, provide an electrochemical source for the SP signal. Electrochemical potentials associated with subsurface zones of redox activity are analogous to localized 'batteries' buried within native earth materials, and produce an electric field that is remotely detected using electrodes placed at the surface and in nearby boreholes. Three-dimensional inversion of the self-potential data incorporating resistivity information is the necessary step in characterizing the source parameters, which are directly related to the redox activity, and therefore to the contaminant itself. Surface and borehole SP data are collected in order to help constrain the solution in depth, and resistivity information is taken from an induced polarization survey performed over the same area during this field excursion. Inversion results are correlated with contaminant concentration data sampled from a series of ground-truth boreholes within the region of interest.
DE: 0903 Computational methods, potential fields
DE: 0925 Magnetic and electrical methods
DE: 1099 General or miscellaneous
DE: 1875 Unsaturated zone
DE: 5109 Magnetic and electrical properties
SC: Hydrology [H]
MN: 2003 Fall Meeting