Field-Scale Assessment of Desiccation Implementation for Deep Vadose Zone Contaminants

Journal Article · Thu Nov 01 04:00:00 EDT 2012 · Vadose Zone Journal, 11(4)

DOI:https://doi.org/10.2136/vzj2011.0144· OSTI ID:1057831

Truex, Michael J; Oostrom, Martinus; Strickland, Christopher E; Chronister, Glen B; Benecke, Mark W; Johnson, Christian D

Desiccation of the vadose zone has the potential to reduce the flux of contaminants to underlying groundwater by removing moisture and decreasing the aqueous-phase permeability of the desiccated zone. However, data to evaluate implementation of desiccation are needed to enable consideration of desiccation as a potential remedy. Implementation of desiccation was field tested by injecting dry nitrogen gas to a target treatment zone and monitoring the spatial and temporal progress of the drying process. Aqueous waste discharges to disposal cribs approximately 50 years ago distributed water and contaminants, including primarily technetium-99 and nitrate, within the 100-m deep vadose zone at the test site. A field test location was selected adjacent to one of the former disposal cribs. The test was conducted in a contaminated portion of the vadose zone dominated by fine sands with lenses of silt material. Desiccation reduced volumetric moisture content to as low as 0.01. The lateral and vertical distribution of drying from the injection well was influenced by the subsurface heterogeneity. However, over time, desiccation occurred in the initially wetter, lower permeability lenses.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1057831
• Report Number(s): PNNL-SA-83775; 42793; 830403000
• Journal Information: Vadose Zone Journal, 11(4), Journal Name: Vadose Zone Journal, 11(4)
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory
remediation
vadose zone