HR: 0830h
AN: H51A-05    [Abstracts]
TI: Estimation of groundwater flow distribution in structured media from non-reactive tracer results under unsaturated condition
AU: * Kamolpornwijit, W
EM: wka@ornl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, K9-36, Richland, WA 99352 United States
AU: Kim, Y
EM: kimy1@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Sciences Division, P.O. Box 2008, Oak Ridge, TN 37831 United States
AU: Brooks, S C
EM: brookssc@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Sciences Division, P.O. Box 2008, Oak Ridge, TN 37831 United States
AU: Scheibe, T D
EM: tim.scheibe@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, K9-36, Richland, WA 99352 United States
AU: Mayes, M A
EM: mayesma@ornl.gov
AF: Oak Ridge National Laboratory, Environmental Sciences Division, P.O. Box 2008, Oak Ridge, TN 37831 United States
AB: Subsurface contaminant transport is a complex process especially within structured media, i.e. saprolite, in which fracture flow dominates matrix flow. The media is made up of components of different pore size ranges and hydraulic conductivity rendering an uneven distribution of water flow and contaminant concentrations. An ability to estimate the distribution of hydraulic conductivity within the media is beneficial in several aspects including providing a better understanding of the mechanisms of contaminant transport and a proper allocation of remedial effort to critically contaminated fractions. In this study pore water velocity and diffusion coefficients of relevant fractions of three intact saprolite samples are estimated from breakthrough curves of non-reactive tracer using a one dimensional transport model. Mariot devices are used to deliver solution at specific tensions and a unit gradient to a fraction of samples that remained saturated within an otherwise partially drained sample. Hydraulic conductivity is then calculated from the model-fitted pore-water velocity and estimated porosity. At a tension of around -10 cm, the hydraulic conductivity of the saturated fraction contributing to flow ranges from 0.01-0.07 cm/hr compared to 0.1-0.5 cm/hr of whole samples under fully saturated condition assuming 40% porosity. The conductivity contrast allows the estimation of 1-6% of saturated flow through the fine pore fraction with tension of -10 cm and higher. The approach is simple yet is a helpful tool in understanding complex contaminant transport in subsurface media.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2005 Joint Assembly