Characterization of unsaturated hydraulic conductivity at the Hanford Site

Rockhold, Mark; Fayler, M.J.; Gee, Glendon W.

doi:10.2172/6970088

Cited by 59 publications

(64 citation statements)

References 17 publications

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“…In the past hydraulic parameters have also been developed from field experiments (Rockhold et al 1988), and from laboratory experiments in which samples were rewet following drainage. The data from these other types of experiments represent conditions that are distinctly different from the drainage data depicted in Figure 2.2, and involve the effects of both hysteresis and entrapped or encapsulated air.…”

Section: 4mentioning

confidence: 99%

A Long-Term Strategic Plan for Hanford Sediment Physical Property and Vadose Zone Hydraulic Parameter Databases

Rockhold

Middleton²

2009

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Printed in the United States of AmericaThis document was printed on recycled paper. AbstractPhysical property data and unsaturated hydraulic parameters are critical input for analytic and numerical models used to predict transport and fate of contaminants in variably saturated porous media and to assess and execute remediation alternatives. The Remediation Decision Support (RDS) project, managed by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) and the CH2M Hill Plateau Remediation Company (CHPRC), has been compiling physical and hydraulic property data and parameters to support risk analyses and waste management decisions at Hanford. Efforts have been initiated to transfer sediment physical property data and vadose zone hydraulic parameters to CHPRC for inclusion in HEIS-Geo, a new instance of the Hanford Environmental Information System database that is being developed for borehole geologic data. This report describes these efforts and a strategic plan for continued updating and improvement of these datasets.v

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Section: 4mentioning

confidence: 99%

A Long-Term Strategic Plan for Hanford Sediment Physical Property and Vadose Zone Hydraulic Parameter Databases

Rockhold

Middleton²

2009

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“…The instantaneous profile experiment was conducted by Rockhold et al (1988). The water content, θ, was monitored using neutron probe, and the pressure head, ψ, was monitored by tensiometers placed at 0.15-to 0.30-m-depth increments, down to 1.8 m. Ponding was facilitated by using planking installed in narrow trenches around which the soil was thoroughly compacted.…”

Section: Reduction Of Parameter Dimension By Parameter Scalingmentioning

confidence: 99%

Vadose Zone Transport Field Study: Summary Report

Ward¹,

Conrad²,

Daily³

et al. 2006

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SummaryA series of field studies were conducted at the Hanford Site, near Richland, Washington, from FY 2000 through FY 2003 at two different locations to develop data sets to test models of flow and transport in the vadose zone. The field studies were also done to investigate advanced monitoring techniques for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. The studies were conducted as part of the Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, managed by the Pacific Northwest National Laboratory (PNNL) and supported by the U.S. Department of Energy, Richland Operations Office. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford's vadose zone. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports in addition to numerous technical notes and papers.Two major field campaigns were performed, one at a well injection test site and a second at a clastic dike test site. Both field studies have resulted in field-scale transport parameters for Hanford conditions, which are useful for improving predictions of subsurface flow and transport at the Hanford Site. In addition, advanced geophysical methods, including high resolution electrical resistivity measurements, were successfully tested and are now being deployed at Hanford for subsurface investigations and tank retrieval detection. The most useful information gained from these studies has been a better understanding of flow and transport in the vadose zone, and this has been specifically related to the impact of small-scale stratigraphic features (e.g., sediment layering) on water flow and contaminant transport. Conceptual models have been developed that take into account the lateral spreading of water and contaminants observed in the field studies. Numerical models of unsaturated flow and transport have been revised to account for lateral spreading of subsurface contaminant plumes.The key results from these studies include: 1) Greater understanding of the complexity of plume migration in the vadose zone at Hanford. Finescale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy.2) Observations of anion exclusion in Hanford sediments. Anion exclusion is a mechanism by which negatively charged ions are repelled from the surfaces of negatively charged soil particles, thereby increasing their velocity. Thus, the travel time of ions like pertechnetate, the stable form of 99 Tc found in oxidized environments, may decrease over that of unsaturated water f...

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“…In this modification, the flux of water into soil columns is controlled with equipment described by Wierenga et al (1986). Details of the experimental procedure are described by Rockhold, Fayer, and Gee (1988). Two acrylic columns ( Figure A.I) were packed with FLTF soil to a bulk density of 1.37 g/cm3.…”

Section: A I Methodsmentioning

confidence: 99%

“…The conductivityfunction is based on Mualem_s (1976) Rockhold,Fayer, and Gee (1988) for more details].…”

Section: A I Methodsmentioning

confidence: 99%

“…The properties for the sand are from Rockhold, Fayer, and Gee (1988 the PORFLO-3code (Magnusen, Baca, and Sondrup 1990). The upstream weighting option was used because Brutsaert (1971) showed that, in the case of sharp wetting fronts advancing into an initially dry medium, it is often necessary to use the relative hydraulic conductivity for the cell from which water is flowing to obtain reasonable results and minimize numerical oscillations.…”

Section: 2mentioning

confidence: 99%

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