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Dissertation
GROUT DEVELOPMENT AND HYDROLOGIC MODELING OF A LANDFILL COVER SUPPORTING CLOSURE FOR HANFORD’S FIRST SINGLE-SHELL TANK FARM AND ASSOCIATED WASTE MANAGEMENT AREA C
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004364
Handle:
https://hdl.handle.net/2376/124731
Abstract
The Hanford Site, managed by the U.S. Department of Energy (DOE), is undergoing the world’s largest environmental cleanup. Sixty percent of the nation's chemically toxic, highly radioactive wastes are stored in 177 deteriorating underground storage tanks. In 2018, waste retrieval was completed for sixteen tanks in Waste Management Area (WMA) C. WMA C will be the first to undergo closure and set precedence for future closures.
This dissertation presents three crucial studies that contribute to resolve key data and knowledge gaps for advancing closure, a unique and challenging venture. For “closure,” tanks will be removed from service and WMA C placed in a condition protective of human health and the environment. To date, DOE has not specified WMA C closure engineering tasks and field actions for their regulatory framework. Therefore, policy indecisions and data gaps remain, confusing regulators and stakeholders, resulting in extended schedules and increased costs. I conducted a high-level Systems Engineering analysis to identify short- and long-term closure engineering functions and performance requirements, determine preliminary engineering tasks and field actions, and develop recommendations to optimize this “first-of-its-kind” effort.
Residual wastes within WMA C tanks and ancillary equipment pose a threat to the Columbia River, the lifeblood of the interior Pacific Northwest. Residual wastes must be physically stabilized to prevent subsidence, solidified, and encapsulated to meet regulatory requirements. In the second study, I developed cementitious flowable-fills through formulation, laboratory assessment, and field testing. For flowable, self-leveling structural and non-structural fills, slump flow, bleed water, and shrinkage measurements guided reformulation efforts. I ultimately identified self-consolidating grouts, which met WMA C closure engineering performance requirements.
WMA C closure will include placement of a landfill cover once the tank system is filled with desired grout(s). The cover must isolate and contain the waste, minimize its leaching, and limit it from reaching the deeper vadose-zone and groundwater. I performed Hydrus-1D modeling to determine the thickness of a viable cover and assess placement scenarios for an evapotranspiration cover. Potential and actual evaporation, precipitation leakage through the cover, and recharge of wastewater to groundwater were estimated and contrasted to determine favorable placement.
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Details
- Title
- GROUT DEVELOPMENT AND HYDROLOGIC MODELING OF A LANDFILL COVER SUPPORTING CLOSURE FOR HANFORD’S FIRST SINGLE-SHELL TANK FARM AND ASSOCIATED WASTE MANAGEMENT AREA C
- Creators
- Michelle Lynn Hendrickson
- Contributors
- Joan Q Wu (Advisor)Stephen F Dwyer (Committee Member)Markus Flury (Committee Member)Christine A Langton (Committee Member)Claudio Stockle (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Agricultural, Human, and Natural Resource Sciences, College of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 111
- Identifiers
- 99900883038701842
- Language
- English
- Resource Type
- Dissertation