Water Resources Research Act Program

Details for Project ID 2007OR81B

Contaminant Transport in Highly Heterogeneous Subsurface Media

Institute: Oregon
Year Established: 2007 Start Date: 2007-03-01 End Date: 2008-02-28
Total Federal Funds: $10,169 Total Non-Federal Funds: $24,280

Principal Investigators: Stephanie Harrington, John Bolte

Project Summary: This proposal focuses on tying together both experimental and theoretical analyses of dispersion through highly heterogeneous porous media. This is an area of interest due to the inability of current methods to adequately describe the tailing phenomena seen in the non-Fickian breakthrough curves, which are thought to be a result of the media having a high variance in the log-conductivities (i.e. highly heterogeneous). Past studies have been conducted in this area, most of which have analyzed 2-D systems and have only dealt with the experimental or theoretical analyses independently. This project hopes to expand this research area by not only conducting new and unique experimental and theoretical analyses co-currently, but also analyzing a 3-D system which is more representative of what would occur in the field.

In order to represent a highly heterogeneous system in the laboratory setting, the 3-D set-up will consist of a high-conductivity matrix material with low-conductivity spherical inclusions placed randomly within the matrix environment. An inert tracer solution of fluorescein and bromide, as lithium bromide, will be used to saturate the system. Data will be collected for the removal of the tracer using deionized water adjusted to a similar ionic strength. A robust experimental dataset of concentration versus time data will be collected at several internal points, as well as an overall breakthrough curve at the outlet of the system. The internal geometric configuration of inclusions will be varied between experimental runs, leading to multiple data sets for the 3-D system.

The final stage of this research will entail deriving and testing an upscaled two-equation time-varying mass transfer model for transport in a two-region system which will represent the experimental environment. It is hypothesized that this research will show a highly time-dependent nature for solute flow due to mass transfer limitations as the solute moves between the low-conductivity inclusions and high-conductivity matrix material.