HR: 0800h
AN: H21E-1066    [Abstracts]
TI: Analysis of a Micro-Pumping Test Conducted Within a Saprolitic Aquifer
AU: * Spane, F A
EM: frank.spane@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999 MS K9-36, Richland, WA 99352 United States
AU: Scheibe, T D
EM: tim.scheibe@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999 MS K9-36, Richland, WA 99352 United States
AU: Brooks, S C
EM: brookssc@ornl.gov
AF: Oak Ridge National Laboratory, P.O. Box 2008 MS 6038, Oak Ridge, TM 37831-6038 United States
AU: Kamolpornwijit, W
EM: kamolpornwiw@ornl.gov
AF: Oak Ridge National Laboratory, P.O. Box 2008 MS 6038, Oak Ridge, TM 37831-6038 United States
AB: Field research on biostimulation for remediation of uranium contamination in groundwater is ongoing at a field site near Oak Ridge, TN. As part of the site characterization program, a low-stress pumping test was conducted within a relatively low-permeability fractured saprolite aquifer underlying the site. Despite the low pumping rate used (~25 ml/min), clearly discernable water-level responses were observed as far as 30 meters from the stress well. The pumping test provided areal characterization information in the presence of observable natural stress effects from barometric pressure fluctuations and precipitation events. Although the aquifer is shallow (less than 10 meters), a strong barometric pressure response was observed in all wells. The response model patterns are indicative of a dual-porosity medium, which is consistent with the fractured character of the saprolite materials. The observed water levels were successfully corrected for barometric response, which exhibited time-lag dependences extending to 44 to 48 hours for the four wells analyzed. A variable, areal drawdown dependence for test responses was exhibited at observation wells as a function of direction from the stress well, indicating horizontal anisotropic aquifer conditions. Most of the monitor wells also exhibited a distinct loading response to significant rainfall events that occurred during the pumping test characterization period. This loading phenomenon can be analyzed to determine the vertical hydraulic diffusivity of the overlying bed.
DE: 1829 Groundwater hydrology
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting