Mercury Remediation Technology Development for Lower East Fort Poplar Creek - FY2018 Update

Mercury (Hg) remediation is a high priority for the US Department of Energy (DOE) Oak Ridge Office of Environmental Management (OREM). Mercury contamination in the environment can be found at all three DOE facilities in Oak Ridge, but probably the greatest environmental risk concern relative to Hg on the Oak Ridge Reservation is associated with historical Hg losses at and near the Y-12 National Security Complex (Y-12). Water and fish from East Fork Poplar Creek (EFPC) downstream of Y-12 exceed regulatory thresholds. Because of the complexities of Hg transport and fate in the aquatic environment, conventional remedial options for EFPC are highly uncertain. DOE is using a phased, adaptive management approach to Hg remediation at Y-12, with a focus in the next few years on construction of the Mercury Treatment Facility (MTF) to treat the most contaminated Y-12 outfall entering EFPC (DOE 2017a; DOE 2017b). Once operational, the MTF will provide additional protection against inadvertent releases of Hg into the stream from decontamination and decommissioning of Y-12 Hg-use buildings. Although it is anticipated that the MTF will substantially decrease Hg water concentrations and flux in the upper part of EFPC, research and technology development is needed to develop appropriate and longer-term remedial solutions for the downstream environment. Since late 2014, OREM and UCOR/RSI (URS | CH2M Oak Ridge LLC/Restoration Services, Inc.) have supported Oak Ridge National Laboratory (ORNL) Environmental Sciences Division staff in conducting field and laboratory studies to develop Hg remedial technology solutions for lower EFPC (LEFPC). A technology development strategy for lower EFPC was developed in 2014 that was consistent with the adaptive management paradigm and DOE’s Technology Readiness Level (TRL) guidelines (Peterson et al. 2015). Initially, a thorough review of the literature and site-specific information was conducted to develop a broad number of potential technologies that might be applied in lower EFPC. An adaptive management approach was then used to focus on technologies that might have the most promise and potential remediation benefit. Field and laboratory studies conducted during 2014–2018 have (1) identified the major drivers of Hg flux and bioaccumulation in EFPC and (2) narrowed the list of highmerit technologies that might be of use in remediating the downstream environment.