Engineering topics

Yonkofski, Catherine M.R.

Publications and source records attributed to Yonkofski, Catherine M.R..

3 records

DOE OSTI2019

Hanford Surface Barrier Design Guidance

This status report presents results of progress made during fiscal year 2019 towards developing a software tool for designing surface barriers in the Central Plateau. This tool is intended to be used to support feasibility studies and remedy applications. This status report summarizes the methodology followed to develop preliminary vadose zone reduced order models (VZ-ROMs) for use in such a tool. The ROM development process required generation of a training and testing dataset representing an example waste site in the Central Plateau. This training data was prepared via eSTOMP simulations that simulated variable drainage through hypothetical surface barriers into waste sites within the Central Plateau. Prior to regression analysis, these numerical results were analyzed to understand the behavior of contaminant solutes under different drainage conditions in the vadose zone. Results from eSTOMP simulations provided an understanding of the effectiveness of hypothetical surface barriers in isolating the subsurface system and mitigating contaminant transport. The primary objective of the work was to establish an appropriate ROM methodology. Further development is required to adapt the ROMs presented here to appropriately couple surface barrier construction design. Future iterations will be used to predict the performance of different surface barrier engineering designs. Future development will follow a similar process to the one demonstrated in this document.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

Dust Control Planning

At the Hanford Site, dust control is required during many activities for health and safety purposes and to prevent contaminant dispersal via atmospheric transport. Water is commonly used to reduce dust dispersal, but can mobilize contaminants and facilitate transport through the vadose zone to groundwater as observed with past activities within the River Corridor. To prevent contaminant mobilization associated with remediation activities in the Central Plateau, alternative approaches for dust suppression are presented considering site-specific requirements at Hanford. There are two high-level categories of approaches to dust control: proactive work strategies to minimize fugitive dust generation and reactive engineered controls to mitigate dust generation and/or capture fugitive dust. Because a variety of activities have the potential to generate fugitive dust at a given site, there is no unique response to dust prevention and control. In fiscal year 2018, an evaluation was completed to identify alternatives, determine limits on surface water additions, and develop information suitable for consideration in feasibility studies. The technical basis detailed in the 2018 evaluation has been condensed into this document that provides a practical Dust Control Plan template and site-specific guidance in the appendices. This Dust Control Plan template specifically provides a workflow to 1) identify key project information, 2) identify fugitive dust sources, 3) assign dust control methods, and 4) determine appropriate monitoring practices to mitigate impacts to groundwater.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Information on Technical Impracticability for Remediation of Iodine-129 Contamination

Groundwater in the 200-UP-1 operable unit (OU) is contaminated with carbon tetrachloride, uranium, nitrate, chromium (total and hexavalent), iodine-129, technetium-99, and tritium, associated with past nuclear weapons production activities at Hanford. The preferred alternative described in the 2012 Record of Decision (ROD) for the 200-UP-1 OU Interim Remedial Action includes 35 years of active remediation using a combination of groundwater pump-and-treat and monitored natural attenuation (MNA) for portions of the contaminated groundwater, followed by institutional controls until cleanup levels are met for unrestricted use. As noted in the 200-UP-1 OU interim ROD, no treatment technology for iodine-129 had been found that could achieve the drinking water standard (DWS) of 1 pCi/L for the iodine-129 concentrations present in the 200-UP-1 OU groundwater. Therefore, the 200-UP-1 OU interim ROD specified hydraulic containment of the iodine-129 plume, update of the conceptual model for iodine-129, and further evaluation of potentially applicable iodine-129 treatment technologies. The 200-UP-1 OU interim ROD further stated that in the event a viable treatment technology is not available, the use of a technical impracticability (TI) waiver may need to be considered as part of the final remedy and that this information be gathered concurrently with the technology evaluation. Hence, this report provides information relevant to a TI waiver consideration on the current federal 1 pCi/L DWS for iodine-129 in the 200-UP-1 groundwater OU of the Hanford Site.

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