HR: 1340h
AN: H13G-1667    [Abstracts]
TI: Hydraulic control for manipulating subsurface conditions for in situ experiments of uranium(VI) bioremediation
AU: Kitanidis, P
EM: peterk@stanford.edu
AF: Stanford University, Department of Civil & Environmental Engineering, Stanford, CA 94305, United States
AU: * Luo, J
EM: jianluo@ce.gatech.edu
AF: Georgia Institute of Technology, School of Civil & Environmental Engineering, Atlanta, GA 30332, United States
AU: Wu, W
EM: wei-min.wu@stanford.edu
AF: Stanford University, Department of Civil & Environmental Engineering, Stanford, CA 94305, United States
AU: Carley, J
EM: carleyjm@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN 37831, United States
AU: Mehlhorn, T
EM: mehlhorntl@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN 37831, United States
AU: Watson, D
EM: watsondb@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN 37831, United States
AU: Criddle, C
EM: ccriddle@stanford.edu
AF: Stanford University, Department of Civil & Environmental Engineering, Stanford, CA 94305, United States
AU: Jardine, P
EM: jardinepm@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN 37831, United States
AB: A field test on in-situ subsurface bioremediation of uranium (VI) is underway at the Y-12 National Security Complex in the Oak Ridge Reservation, Oak Ridge, TN. A four-well system, including two downgradient extraction and two upgradient injection wells were installed to create an inner cell, which functioned as the treatment zone, nested within an outer cell, which protected the inner cell from the influence of regional flow. The proposed four- well system has several advantages in the subsurface flow field manipulation: (1) the recirculation ratio within the nested inner cell is less sensitive to the regional flow direction; (2) a transitional recirculation zone between the inner and outer cells can capture flow leakage from the inner cell, minimizing the release of untreated contaminants; (3) the size of the recirculation zone and residence times can be better controlled within the inner cell by changing the pumping rates. A three-phase remediation strategy was applied in this experiment. It included first removing nitrate prior to stimulation of U(VI) reduction, then adjusting the pH to levels favorable for activity of U(VI)-reducing bacteria, i.e., to about neutral values, and finally adding electron donor to the in-situ reactor to foster reduction and immobilization of U(VI). Tracer tests and bioremediation experiments demonstrated that the designed multiple-well system and the experimental strategy were successful in creating favorable subsurface chemical and biological conditions for uranium bioremediation.
DE: 1828 Groundwater hydraulics
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2007 Fall Meeting