HR: 16:30h
AN: H44C-03    [Abstracts]
TI: Geophysical Monitoring of Cr(VI) Bioreduction at the Hanford 100H Site
AU: * Hubbard, S
EM: sshubbard@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Peterson, J
EM: jepeterson@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Chen, J
EM: jchen@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Williams, K H
EM: kwilliams@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Conrad, M
EM: msconrad@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Faybishenko, B
EM: BAFaybishenko@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Long, P
EM: phillip.long@pnl.gov
AF: Pacific Northwest Laboratory, 902 Battelle Boulevard, Richland, WA 99352 United States
AU: Willett, A
EM: anna@regenesis.com
AF: Regenesis, 1011 Calle Sombra, San Clemente, ca 92673 United States
AU: Hazen, T
EM: tchazen@lbl.gov
AF: Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AB: The efficacy of in-situ remediation of contaminated groundwater using injected chemical or biological amendments depends on the ability to effectively distribute the amendments within the contaminated aquifer and to understand the role of heterogeneity on remediation processes. In this study, we investigate the use of geophysical data for providing such information in association with a Cr(VI) bioreduction experiment at the Hanford 100H Site in Southeastern Washington State. Seismic and radar tomographic data were initially used with borehole flowmeter data in a principle components analysis to estimate hydrogeological zonation at the site. Subsequently, pumping was initiated to create a steady state flowfield between an injection and monitoring well, and a slow-release polylactate amendment (HRCTM , Regenesis, Ltd) was injected into a sandy formation to reduce Cr(VI) into insoluble Cr(III) complexes. Laboratory analyses were performed to assess the expected geophysical responses to the injectate, as well as to the formation of gasses and precipitates that often form during such biostimulation procedures. Field-scale, time-lapse tomographic data as well as wellbore geochemical data were collected during and after the cessation of pumping. These datasets were jointly used to assess the spatio-temporal changes in the subsurface system associated with the biostimulation, such as the distribution of an amendment 'plume' and a reaction halo. In agreement with the laboratory experiments, the field-scale geophysical data were useful for detecting chemical transformations associated with the biostimulation. The study also indicated that heterogeneity plays a role in controlling both the amendment distribution and the biostimulation processes. This study suggests that high resolution, field-scale, cross-borehole geophysical techniques hold significant potential for monitoring biostimulation efficacy and for investigating the role of heterogeneity on remediation processes.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1835 Hydrogeophysics
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: Fall Meeting 2005