Measurement of Saturation-Dependent Anisotropy in Hydraulic
Conductivity of Hanford Vadose Zone Sediments
EMSL Project ID
25448
Abstract
The geologic framework of the Hanford vadose zone is very complex with a high degree of heterogeneity and anisotropy in its physical, hydrologic, and geochemical properties. This complex hydrogeochemical framework, together with waste water and rain water fluxes lead to highly complex three-dimensional movement of moisture and contaminants through the vadose zone. Soil anisotropy is dependent on soil water saturation. Failure to correctly characterize soil anisotropy will often lead to underestimation of later migration and overestimation of vertical movement. For accurate description saturation-dependent anisotropy, the PI and others (Zhang et al. 2003) proposed a tensorial connectivity-tortuosity (TCT) model to describe the hydraulic conductivity of anisotropic unsaturated soil. The TCT concept was tested using synthetic heterogeneous and anisotropic soils. The model has been incorporated in the STOMP flow simulator, which has been used widely at Department of Energy's sites. Recently, the PI and others have extended the TCT concept to multiphase flow system. This theoretical model is unique in the way that it describes saturation-dependent anisotropy of multiple fluids. However, there is almost no experimental data available to test the TCT concept. We propose to test the TCT concept using laboratory experiments at two spatial scales - core scale (~15 cm) and intermediate-scale (50-100 cm) with representative typical Hanford soils, e.g. a silt and a sand. Systematic measurements will be carried out at core scale, whereas one experiment will be conducted at the intermediate-scale. The soils will be packed in the desired patterns as described below. Soil hydraulic properties will be measured in two directions - one parallel and one perpendicular to soil stratification. The anticipated results of this work are a journal article describing all experimental results. This work will also provide key experimental data to support proposals to DOE.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-05-01
End Date
2009-05-03
Status
Closed
Released Data Link
Team
Principal Investigator