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Management of large dilute plumes of chloroethenes and 1,4‐dioxane via monitored natural attenuation (MNA) and MNA augmentation
Citation:
Rhea, L. AND C. Clark. Management of large dilute plumes of chloroethenes and 1,4‐dioxane via monitored natural attenuation (MNA) and MNA augmentation. Remediation Journal. John Wiley & Sons, Inc., Hoboken, NJ, 32(1-2):97-118, (2022). https://doi.org/10.1002/rem.21710
Impact/Purpose:
Characterization and remediation of large dilute plumes of chlorinated volatile organic compounds (CVOCs) has long been recognized as a continuing concern for maintenance of unimpacted groundwater. More recently it has been documented that the CVOC stabilizer 1,4-dioxane (dioxane) is frequently comingled with these plumes, which also requires remediation. U.S. EPA has generated many documents supporting the use of Monitored natural attenuation (MNA) for CVOC plumes for which no synopsis exists, and many of these documents do not address comingled dioxane. The purpose of the present document is to provide a summary of U.S. EPA MNA documents, to incorporate strategy for concurrent management of dioxane, and to update pertinent environmental monitoring and remediation developments. That work will be of use in characterization, management, and remediation of these mixed plumes by U.S. EPA Superfund remedial project managers (RPMs) as well as responsible parties and the consulting community.
Description:
This product will describe to the Regions and Program Office the processes, applications, and appropriate monitoring of biotic and abiotic attenuation of large dilute plumes containing chlorinated solvent compounds (like perchloroethylene, trichloroethylene, and breakdown products) and 1,4-dioxane. The product will be developed with stakeholders from regional offices involved with the Superfund program. An understanding of natural degradation processes, both those attributed to microbial activity and non-biological (abiotic) activity, is important when determining effective remedial strategies at contaminated sites. For example, large dilute plumes of chlorinated solvents have recently been targeted as an issue in the Superfund program. In addition, 1,4-dioxane is a likely human carcinogen and has been found in groundwater and drinking water supplies throughout the United States. The physical and chemical properties and behavior of 1,4-dioxane create challenges for its characterization and treatment. Large dilute plumes demonstrate biogeochemical conditions that result in slow contaminant degradation and that allow plume expansion, as well as matrix diffusion that results in secondary sources which extends remediation timeframes. A full understanding of the natural degradation mechanisms and rates at such sites will aid in developing strategies to sustainably and cost-effectively enhance degradation rates, potentially mitigating the requirement for an engineered remedy throughout the entire plume. Work in further developing tools, monitoring strategies, and technical guidance that can provide direct measurements of organisms, genes or enzymes involved in contaminant biodegradation; the relative contributions of abiotic and biotic processes; the relative rates of various degradation processes; and, improved fate and transport models are needed.
URLs/Downloads:
DOI: Management of large dilute plumes of chloroethenes and 1,4‐dioxane via monitored natural attenuation (MNA) and MNA augmentation
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