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MNA of Inorganic Contaminants: Contrasting Behavior of Base Metals and Oxyanions
Citation:
WILKIN, R. T., S. D. ACREE, AND R. G. FORD. MNA of Inorganic Contaminants: Contrasting Behavior of Base Metals and Oxyanions . Presented at The 10th International In Situ and On-Site Bioremediation Symposium, Baltimore, MD, May 05 - 08, 2009.
Impact/Purpose:
The purpose is to cover aspects of site characterization and assessment of monitoring results.
Description:
EPA’s Office of Research and Development has recently prepared technical resource documents for the application of MNA to inorganic contaminants in groundwater. These documents present a framework and tiered approach for evaluating whether MNA presents a viable remediation option for selected metal, metalloid, and radionuclide contaminants encountered in groundwater. Elements of the tiered approach include 1) demonstrating contaminant sequestration mechanisms, 2) estimating attenuation rates and the 3) attenuation capacity of aquifer solids, and 4) evaluating potential reversibility issues. The tiered decision-making approach is used for determining whether MNA is likely to be an effective remedial approach for inorganic contaminants in groundwater at a particular location. Emphasis is placed on developing a complete understanding of the site through development of a conceptual site model that includes a base hydrologic foundation, an understanding of the site-specific attenuation mechanisms, the geochemical conditions governing these mechanisms, and indicators that can be used to monitor attenuation progress. The presentation will provide an overview of the contents of the technical resource documents and will compare and contrast the MNA approaches taken for inorganic and organic groundwater contaminants, especially with respect to site characterization needs. A case study site with over two decades of groundwater monitoring data will be used to explore the contrasting behaviors of metals (Pb, Cd) and selected oxyanion species (As and Se). The presentation will cover aspects of site characterization and assessment of monitoring results. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.
