Projects & Programs
Geochemical and Physical Aquifer Property Heterogeneity
Objectives: The goal of this project was to determine if the geochemical processes that control reactive transport of carbon tetrachloride in the Ringold Formation aquifer vary with lithology and stratigraphy. Pacific Northwest National Laboratory (PNNL) researchers tested 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 were the properties that control carbon tetrachloride transport: hydraulic conductivity (K) and reactivity (sorption distribution coefficient [Kd] and anaerobic transformation rate constant [kn]). Geochemical measurements were performed by collaborators at the University of Buffalo, New York.
PNNL is conducting the following activities:
- Provided scientific expertise on the sedimentology and stratigraphy of sediments at the Hanford Site
- Developed geostatistical realizations of Ringold Formation aquifer properties conditioned on numerical realizations of the lithofacies distribution provided by the University of New Mexico
- Performed 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.
Results: This work provided reactive transport data relevant to transport of carbon tetrachloride in the aquifer at the Hanford Site, and found that those properties vary with lithology and stratigraphy. This activity provided 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.
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 were studied in lithofacies of the Ringold Formation for their potential impact on the reactive transport of carbon tetrachloride.