The modeling efforts of Dr. Georgio Tachiev and his team of researchers was recently published in the Spring 2012 edition of the Remediation Journal. The paper describes the development of an integrated surface and groundwater model for flow and mercury transport in EFPC. A model with even greater detail has been developed and is currently being used to predict transport patterns of mercury and evaluate risks during deactivation and decommissioning of mercury contaminated facilities at the Y-12 National Security Complex in Oak Ridge, TN. The following is an abstract which summarizes the publication.
Simulation of Flow and Mercury Transport in Upper East Fork Poplar Creek, Oak Ridge, Tennessee
By Siamak Malek-Mohammadi, Georgio Tachiev, Elsa Cabrejo, Angelique Lawrence
“As a result of nuclear processing activities started back in the 1950s, the environment in the vicinityof the Y-12 National Security Complex (Y-12 NSC) in Oak Ridge, Tennessee, and surrounding watersheds has been contaminated by nearly 1,000 tons of elementary mercury. To comply with the state and federal surface water quality standards, a significant reduction in mercury concentration to parts-per-trillion levels has been proposed. In order to analyze the mercury cycle in the environment and provide forecasting capabilities for the flow and transport of mercury within the Upper East Fork Poplar Creek (UEFPC) watershed, an integrated surface and subsurface flow and transport model has been developed using the hydrodynamic and transport numerical package, MIKE, developed by the Danish Hydraulic Institute. The model has been constructed and calibrated using an extensive collection of historical records (i.e., hydrological data, and mercury concentration measurements in groundwater, soil, and sediment) obtained from the Oak Ridge Environmental Information System database. Daily fluctuations in stream flow, as a result of scattered rainfall, flooding, and flow augmentation, resuspend the contaminated streambed sediments and/or erode the polluted streambank soil and provide a secondary source of mercury to the creek. In order to investigate the significance of sediment-mercury interactions on the fate and transport of mercury within the UEFPC study domain, simulations were performed for two different cases (i.e., with and without consideration of sediment-mercury interactions). Computed total suspended solids and mercury concentrations at the integration point of the creek are compared with the corresponding historical records in both cases. As confirmed by the numerical simulations, a substantial portion of the mercury detected in the river is likely in the form of sediment particle–bound mercury (i.e., mercury particulates).”