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EVALUATING MONITORED NATURAL ATTENUATION FOR RADIONUCLIDE AND INORGANIC CONTAMINANTS IN GROUNDWATER
Citation:
FORD, R. EVALUATING MONITORED NATURAL ATTENUATION FOR RADIONUCLIDE AND INORGANIC CONTAMINANTS IN GROUNDWATER. Presented at NARPM 2007 Meeting, Baltimore, MD, May 21 - 25, 2007.
Impact/Purpose:
To inform the public.
Description:
Monitored Natural Attenuation (MNA) for inorganic contaminants is dependent on naturally occurring processes in the subsurface that act without human intervention to reduce the mass, toxicity, mobility, volume or concentration of contaminants. EPA is developing a technical reference document for the regulated community to utilize MNA as a ground-water remedy based on the previous definition with emphasis being placed on reliance of radioactive decay and/or immobilization as the predominant mechanism(s) for attenuation. A tiered approach for site characterization is outlined that allows for a graded approach that is dependent on addressing the following technical issues: (1) demonstrating removal from groundwater, (2) identifying the mechanism(s) of removal, (3) demonstrating long-term capacity for attenuation and stability of the immobilized contaminant, (4) design of a monitoring program, (5) defining regulatory points for failure, and (6) establishing a contingency plan. Frequently occurring inorganic contaminants that represent as many fate and transport situations as possible will be included. The document structure will contain three volumes: 1) description of EPA policy, scientific basis, and the general technical framework for site characterization to assess the potential to use MNA for remediation of inorganic contaminants in ground water, 2) a collection of individual chapters that provide the current state of knowledge and practice for assessing MNA for non-radionuclide contaminants, and 3) a section that addresses issues specific to radionuclide contaminants, including individual contaminant chapters. The chapters dedicated to specific inorganic contaminants will address: occurrence and distribution, geochemistry and attenuation processes, radioactive decay, and site characterization in a tiered approach. EPA’s Office of Research and Development is the lead Office with the Office of Solid Waste and Emergency Response and the Office of Radiation and Indoor Air providing review, support, and information.