Innovative in-situ determination of unsaturated hydraulic properties in deep loess sediments in North-West Bulgaria

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Abstract

In the framework of selecting a suitable site for final disposal of low- and intermediate level short-lived radioactive waste (LILW-SL) in Bulgaria, site characterization is ongoing at the Marichin Valog site, North-West Bulgaria. The site is characterized by a complex sequence of loess, clayey gravel, and clay layers, of which the first 30-40m are unsaturated. Proper knowledge about unsaturated water flow and concomittant radionuclide transport is key input to safety assessment calculations. Constant-head infiltrometer tests were carried out at several meters below ground surface to determine the unsaturated hydraulic properties of silty loess, clayey loess, and clayey gravel layers. Infiltration tests provided data on cumulative infiltration and progression of the wetting front in the initially unsaturated sediments surrounding the infiltrometer. By means of an inverse optimization routine implemented in the finite element code HYDRUS-2D, fieldscale soil hydraulic parameters were derived for all layers. Results show a great consistency in the optimized parameter values, although the test sites were several meters apart. Apparently the size of the affected volume of soil was large enough to reduce the effect of spatial variability and to produce average field-scale hydraulic parameters that are relevant for large-scale predictions of flow patterns and radionuclide migration pathways.

Details

Original languageEnglish
Title of host publicationThe 11th International Conference on Environmental Remediation and Radioactive Waste Management
Place of PublicationFairfield, NJ, USA, United States
Pages1-7
Publication statusPublished - 13 May 2008
EventICEM 2007 - 11th International Conference on Environmental Remediation and Radioactive Waste Management - American Society of Mechanical Engineers (ASME), Bruges, Belgium
Duration: 2 Sep 20076 Sep 2007

Conference

ConferenceICEM 2007 - 11th International Conference on Environmental Remediation and Radioactive Waste Management
CountryBelgium
CityBruges
Period2007-09-022007-09-06

Keywords

  • low-level waste disposal, site characterization, Kozloduy, Bulgaria, unsaturated zone, in-situ infiltration, HYDRUS-2D model

ID: 216928