geomechanical evolution of highly alkaline and saline tank waste plumes during seepage through vadose zone sediments

Jiamin Wan, Tetsu K. Tokunaga, Joern T. Larsen, and Zuoping Zheng

Contact: Jiamin Wan, 510/486-6004, JMWan@lbl.gov

Research Objectives
Leakage of highly saline and alkaline radioactive waste solutions from storage tanks into underlying sediments is a serious problem at the Hanford Site in Washington State. Although it was found from field samples that pH values of the initially highly alkaline (pH 14) waste plumes dramatically decreased (to pH 10–7), understanding of the neutralization process was lacking. Since pH is a master geochemical variable, the behavior of waste plume contaminants, including their speciation, sorption, solubility, precipitation, and transport, can be reliably predicted only when the evolution of the pH profile is understood. This study focuses on the geochemical evolution of major geochemical parameters including pH, and addresses how pH evolved as the plumes propagated.

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