Evaluation of deep vadose zone contaminant flux into groundwater: Approach and case study
| Autor: | M. Oostrom, M.J. Truex, G.V. Last, C.E. Strickland, G.D. Tartakovsky |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Washington
Hanford Site Environmental remediation Soil vapor extraction 0208 environmental biotechnology 02 engineering and technology 010501 environmental sciences 01 natural sciences Vadose zone Water Movements Environmental Chemistry Groundwater 0105 earth and related environmental sciences Water Science and Technology Hydrology Technetium Groundwater recharge Models Theoretical 020801 environmental engineering Plume Groundwater model Geology Water Pollutants Chemical Environmental Monitoring |
| Zdroj: | Journal of contaminant hydrology. 189 |
| ISSN: | 1873-6009 |
| Popis: | For sites with a contaminant source located in the vadose zone, the nature and extent of groundwater contaminant plumes are a function of the contaminant flux from the vadose zone to groundwater. Especially for thick vadose zones, transport may be relatively slow making it difficult to directly measure contaminant flux. An integrated assessment approach, supported by site characterization and monitoring data, is presented to explain current vadose zone contaminant distributions and to estimate future contaminant flux to groundwater in support of remediation decisions. The U.S. Department of Energy Hanford Site (WA, USA) SX Tank Farm was used as a case study because of a large existing contaminant inventory in its deep vadose zone, the presence of a limited-extent groundwater plume, and the relatively large amount of available data for the site. A predictive quantitative analysis was applied to refine a baseline conceptual model through the completion of a series of targeted simulations. The analysis revealed that site recharge is the most important flux-controlling process for future contaminant flux. Tank leak characteristics and subsurface heterogeneities appear to have a limited effect on long-term contaminant flux into groundwater. The occurrence of the current technetium-99 groundwater plume was explained by taking into account a considerable historical water-line leak adjacent to one of the tanks. The analysis further indicates that the vast majority of technetium-99 is expected to migrate into the groundwater during the next century. The approach provides a template for use in evaluating contaminant flux to groundwater using existing site data and has elements that are relevant to other disposal sites with a thick vadose zone. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect