Projects
Geochemical and Physical Aquifer Property Heterogeneity
The goal of this project is to determine if the geochemical processes that control reactive transport of carbon tetrachloride in the Ringold Formation aquifer vary with lithology and stratigraphy. If so, researchers will determine the effect of the geochemical and physical heterogeneity of the aquifer on reactive transport velocities.
PNNL researchers are testing the hypothesis that geochemical and physical hydrologic properties that control reactive-solute transport in sedimentary aquifers are correlated to the distribution of sedimentary facies types in the saturated zone at the Ringold Formation on the Hanford Site. The geochemical and physical aquifer properties selected for measurement in the project are the properties that control carbon tetrachloride transport: hydraulic conductivity (K) and reactivity (sorption distribution coefficient [Kd] and anaerobic transformation rate constant [kn]). Geochemical measurements are being performed by collaborators at the University of Buffalo, New York.
PNNL is conducting the following activities:
- Providing scientific expertise on the sedimentology and stratigraphy of sediments at the Hanford Site
- Developing geostatistical realizations of Ringold Formation aquifer properties conditioned on numerical realizations of the lithofacies distribution provided by the University of New Mexico
- Performing flow and transport modeling to explore the control of the sedimentary architecture on the reactive transport of carbon tetrachloride in the 200 West Area of the Hanford Site.
This work will provide reactive transport data relevant to transport of carbon tetrachloride in the aquifer at the Hanford Site and determine if those properties vary with lithology and stratigraphy. This activity will provide valuable information needed for assessing the potential for long-term transport of carbon tetrachloride in the aquifer at the Hanford Site and innovative approaches to better predict this movement.
These studies will result in published journal articles that will include measurements of Kd and kn categorized by geologic facies, numerical grids of geologic facies and geochemical and physical properties and reactive flow and transport results.
Conceptual model for lithofacies control on reactive transport.
Widespread iron-oxide staining and carbonaceous matter were described and sampled in cores from the Ringold Formation. The distribution of these and other features are being studied in lithofacies of the Ringold Formation for their potential impact on the reactive transport of carbon tetrachloride.