Collaborative Research: Experimental and Computational Investigation of Consolidation-Induced Contaminant Transport for High Water Content Geo-Materials

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The goal of this project is to advance the state-of-the art with respect to our understanding of the mechanisms and significance of consolidation-induced contaminant transport for high water content geo-materials. The phenomenon of coupled consolidation and contaminant transport occurs for a variety of practical applications in geotechnical and geoenvironmental engineering. Such applications include confined disposal of contaminated high water content geo-materials (e.g., tailings, dredgings, sludges, and slurries) in ex situ engineered impoundments, mechanical dewatering of contaminated high water content geo-materials, in situ remediation of source zones contaminated with chlorinated solvents via injection of granular zero valent iron (ZVI) slurry and soil mixing, and in situ capping of subaqueous contaminated sediments. Research has demonstrated only very recently that consolidation-induced transport of contaminants is a valid transport mechanism that may have lasting effects on the contaminant migration behavior for a given system. However, little is known about the general significance of this mechanism for practical applications. Current understanding of consolidation-induced contaminant transport is limited with respect to: (1) the effects of higher chemical concentrations and multispecies contaminants, such that typically occur in field sites; (2) the importance of facilitated transport via colloidal particles, which is likely to be an important mechanism for natural fine-grained materials with highly sorbed contaminants; (3) testing of realistic geo-materials, such as mine tailings or dredged sediments; and (4) absence of work conducted for constant rate-of-strain or centrifuge loading conditions. The proposed research will consist of a fundamental experimental and computational investigation of the mechanism of consolidation-induced contaminant transport for several materials and conditions, and then assess the significance of these findings for relevant geotechnical and geoenvironmental applications. The research plan has six tasks: (1) material procurement and characterization; (2) material property testing; (3) consolidation-induced transport testing; (4) development and validation of computational models; (5) computational simulations; and (6) project collaboration and dissemination of results. The proposed research has both intrinsic scientific merit in terms of a fundamental assessment of this transport mechanism and associated parameters as well as practical implications in terms of improving our ability to predict contaminant outflows from high water content geo-materials during consolidation. As a result, a better understanding of the mechanism and significance of consolidation-induced contaminant transport will be achieved, thereby enhancing the ability of designers and regulators to protect the public health and the environment from the effects of contaminants. Results from this research have the potential to transform the way contaminated high water content geo-materials are currently characterized, handled, dewatered and/or disposed.