Opening Remarks
 

1:05 - 1:25 p.m.

Achieving Sustainable Remediation End States at Uranium Legacy Sites in Tajikistan: From Strategy to Implementation

Bakhtiyor Barotov, Scientific and Technical Support Organization to Chemical, Biological, Radiological and Nuclear Safety and Security Agency

Tajikistan has taken decisive steps toward mitigating the long-term environmental and health risks posed by uranium production legacy sites (UPLS). This presentation outlines the country’s progress in transforming its national remediation vision into tangible results, highlighting the regulatory, technical, and collaborative frameworks that underpin success. Key case studies include the Degmay and Taboshar (Istiklol) sites, where phased remediation—ranging from site characterization and feasibility studies to surface covering and post-remediation monitoring—has led to significant reductions in ambient radiation levels and improved safety for local populations.

Underpinned by robust national legislation and guided by international best practices, Tajikistan's remediation activities have been bolstered by partnerships with the IAEA, ISTC, Rosatom, the EU, and EBRD. The Strategic Master Plan, bilateral cooperation, and targeted regional projects have allowed the country to establish inspection protocols, build regulatory capacity, and enhance public engagement. The initiative also emphasizes the role of the newly established Regional CBRN Safety, Security, and Safeguards Center as a regional hub for analysis, training, and stakeholder coordination.

As Tajikistan transitions into its 2025–2029 strategy, the need for sustained donor involvement, comprehensive post-remediation monitoring, and continuous capacity building will be essential. This session will share lessons learned and demonstrate how focused governance, scientific expertise, and regional collaboration can turn the vision of remediation into a long-term reality.

Coauthors: Ilhom Mirsaidzoda (Chemical, Biological, Radiological and Nuclear Safety and Security Agency)

1:25 - 1:45 p.m.

Mixed Anion Exchange Resin Bed Configuration for Multi-Contaminant Groundwater Treatment at Complex Remediation Sites

Sarah Saslow, Pacific Northwest National Laboratory

Ion exchange (IX) resins are commonly used for groundwater remediation at pump-and-treat (P&T) facilities. Traditionally, the resins used are highly selective for individual contaminants of interest, featuring functionalized groups tailored to remove specific anions/cations via IX processes. For Example, the U.S. Department of Energy’s Hanford Site operates six P&T facilities that use different IX resins to remove contaminants of concern from groundwater extracted from the contaminated subsurface. At the 200 West (200W) Area P&T facility Purolite A532E IX resin is used to remove technetium-99 (Tc) and Dowex 21K IX resin is used to remove uranium (U, as uranyl carbonates), while the SIR-700-HP IX resin is used to remove hexavalent chromium (Cr(VI)) in the 100 Area P&T facilities. Expansion of 200W P&T operations to include more extraction wells is anticipated to introduce variable groundwater chemistries that may require additional treatment of Tc, U, and Cr(VI). Rather than investing in additional columns for Cr(VI) (as chromate) and other emerging contaminants, an alternative solution explored in this study is leveraging anion mixed resin bed configurations that enhance the facility's ability to adapt to changes in influent groundwater chemistry. Specifically, this study explored different combinations of the IX resins currently used at the Hanford Site to treat Tc, U, and Cr(VI) simultaneously. Lab-scale column tests were used to measure the performance of two mixed resin bed configurations, either two resins homogeneously blended or two resins in series (separated by sand) in the column, using Hanford groundwater simulant. These columns aimed to optimize the resin ratio used based on historical water chemistry and contaminant concentration profiles to reach contaminant breakthrough at approximately the same time. Contaminant breakthrough curves of the mixed resin bed columns are compared to control columns containing a single IX resin to determine the impact a mixed resin bed may have on contaminant removal. The findings of these studies and their potential to streamline remediation processes at 200W P&T without substantial facility expansion will be discussed.

Coauthors: Rachel Anguish, Aidan Henson, Miguel Valdes, Jacqueline Hager, Alex Kugler, Kelly Rue, Mariah Doughman, Elsa Cordova, Carolyn Pearce, and Tatiana Levitskaia (PNNL); Mark Carlson (Oregon State University); Matthew Schinnell (Central Plateau Cleanup Company); Rob Mackley (PNNL)

1:45 - 2:05 p.m.

Field-Scale Remediation Works at Chromium Contaminated Site in Rania Village, Kanpur Dehat, India: A Perfect Example of Turning Vision into Reality

Pankaj Kumar Gupta, Indian Institute of Technology Delhi/Centre for Rural Development and Technology (CRDT)

Engineered microBiome Project” has been employed to undertake the field-scale remediation works at a Chromium (Cr) contaminated site in Rania village, Kanpur Dehat, India. The soil and groundwater of Rania and neighboring villages are heavily contaminated with Cr-concentrations of up to 30g/kg in soil and 45mg/L in groundwater, respectively. Hydrological, hydrogeological, and ecological investigations carried out since the launch of the project were utilized in the field-scale remediation efforts at the COPR dump site covering an area of 1.4 acres, leading to a first-of-its-kind initiative that successfully addressed the soil and groundwater contamination in India. A synergistic approach to phytoremediation was implemented using 6 different grasses (Cyanodon dactylon, Chrysopogon zizanioides, Cyperus sp., Eclipta prostrata, Alternanthera sessilis, and Prosopis juliflora) and bioremediation using Bacillus halotolerans, along with adsorptive/reactive materials was applied to treat the soil and groundwater systems. We found that these grasses sequester Cr in the range of 10mg/Kg to 114mg/Kg of dry biomass weight from soils and help Bacillus halotolerans to completely remove Cr from groundwater within 6-8 months of implementation of remediation works. A total of 2.5 tonnes of roots from C. zizanioides and Cyperus sp. were harvested and used for the production of ~2.56 litres of oil using the steam distillation process. The oil was Cr-free, while the sequestered Cr was adsorbed in the residual biomass, which was used to produce biochar using pyrolysis. Residual Cr from biochar was recovered using a bioleaching process. In this way, the soil and groundwater at this site became free of Cr-contamination. As a part of the capacity-building program, the community was also guided to implement this technology to address similar contamination scenarios.

Coauthors: Anushree Malik (Centre for Rural Development and Technology, Indian Institute of Technology Delhi), K. K. Pant (Department of Chemical Engineering, Indian Institute of Technology Delhi)

2:05 - 2:25 p.m.

KW & KE Groundwater Remediation: KW Soil Flushing History & Rebound Test Results and KE Soil Flushing Operations for Hanford Site Hexavalent Chromium Removal

Ellwood Glossbrenner, U.S. Department of Energy, Hanford Field Office

The U.S. Department of Energy (DOE) contractor Central Plateau Cleanup Company is making significant progress remediating hexavalent chromium [Cr(VI)] contamination in groundwater near the Columbia River through the operation of pump and treat facilities and source removal activities.

Between 2010 and 2016, operation of the K West pump and treat (P&T) system, located near the former 105K West plutonium production reactor, reduced concentrations below the groundwater remediation target of 20 µg/L for Cr(VI). A rebound study was performed in 2016 to evaluate the effectiveness of the P&T remedy and assess the potential for residual Cr(VI) sources contributing to groundwater contamination. The rebound study revealed a source of continued groundwater contamination in the periodically rewetted zone (PRZ)/deep vadose zone. To address this condition, a soil flushing treatability test was approved by the DOE and the U.S. Environmental Protection Agency. The 2019 to 2021 soil flushing treatability test performed at the 183.1KW Headhouse demonstrated that soil flushing as an enhancement to P&T operations expedited the removal of Cr(VI) contamination from the deep vadose zone (VZ) where P&T is less effective on its own.  P&T extraction draws down the water table with all the pumping and leaves the lower VZ untouched, except at high-river stage.  The lower VZ sources remain persistent and provide a slow mass flux and impact to groundwater - P&T actually works against source treatment and continuous sources just keep leaching over an extended period of time.  Soil flushing breaks the paradigm and allows you to get the continuing source moving out of the lower VZ and into the groundwater where it can then be hydraulically captured.

Based on the results of the soil flushing treatability test at the 183.1KW Headhouse, an explanation of significant difference (ESD) was developed and approved in September 2021 to address a similar continuing source of Cr(VI) contamination suspected to be beneath the former 183.1KE Headhouse in the deep vadose zone. Adding soil flushing as an enhancement to the current P&T interim action remedy in this area will shorten the overall time for groundwater to meet cleanup levels.

This presentation will review the status of the 183.1KW Headhouse soil flushing test, as well as more details about the following:

•    The design and installation of the soil flushing technology at the 183.1KE Headhouse 
•    The progress of the soil flushing at the 183.1KE Headhouse
•    The results of the sampling data and interpretation
•    Discussion of implementation in other locations at the Hanford Site

Innovative solutions for cleanup, such as soil flushing technology in conjunction with P&T, enhance the removal of groundwater COCs at the Hanford Site, potentially shortening the timeframe required to meet cleanup goals and results in cost savings.

Coauthors: Aaron Marshall (TradeWind Services)

Open Discussion
 

BREAK
 

3:15 - 3:35 p.m.

Leaked Tritium Reveals Cesium Pathways and Informs Efficient Site Remediation Strategies at the Fukushima Daiichi Nuclear Power Plant

Yuichi Onda, University of Tsukuba

Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, a seawall was constructed to reduce direct releases of cesium-137 (¹³⁷Cs)-contaminated groundwater into the ocean. However, seasonal fluctuations in ¹³⁷Cs discharge persisted. Between 2013 and 2014, tritium (³H) from leaked treated water was detected in downstream groundwater, prompting a tracer-based study from 2015 to 2021 to investigate the origins and seasonal dynamics of ¹³⁷Cs discharge via the K drainage channel. By analyzing ³H and correlating it with ¹³⁷Cs concentrations and discharge rates, we estimated the contributions of surface and base flow and identified flow paths through contaminated building zones as the primary ¹³⁷Cs source. Effective rainfall analysis showed that surface flow dominated during wet periods, while base flow ¹³⁷Cs concentrations varied with temperature. These insights demonstrate that ³H serves as a valuable hydrological tracer for identifying contamination pathways and seasonal discharge mechanisms. The findings provide a scientific basis for optimizing monitoring and implementing more targeted, cost-effective site remediation strategies during nuclear facility decommissioning.

Coauthors: Hikaru Sato (Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba, Ibaraki, Japan), Daisuke Tsumune (Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba, Ibaraki, Japan), Katsuhiko Kohata (Tokyo Electric Power Company Holdings, Tokyo, Japan), Tomomi Okamura (Tokyo Electric Power Company Holdings, Tokyo, Japan)

3:35 - 3:55 p.m.

No Longer in Flux: Why Volumetric and Mass Flux Are Your Secret Weapons for Achieving Remediation End States

Prashanth Khambhammettu, Arcadis, Inc.

Successful restoration has always resulted from a judicious balance of three steps: (1) site investigation; (2) system design; and (3) operation and maintenance (O&M). Too much emphasis placed on any of these often results in reduced efficiency, escalated life cycle costs, and, even remedy failure. When the balance is right, though, it leads to more effective outcomes. Over the last 10 years we have seen a shift towards weighing these three phases against the constraints of the natural system within a mass flux framework, pursuing a remedial strategy focusing on the “mass that moves” or a flux-informed approach. We have also seen new technologies lead to improved site characterization which, have increased our understanding of flow, transport, and storage of contaminants. This knowledge allows practitioners to develop more effective remedial strategies. These advancements lead to an approach that converges on systematic remedy optimization. In practice, however, O&M/remedy optimization is largely driven by personal knowledge/experience with decision making leveraged by professional judgement rather than objective site-specific metrics. We need to evolve with the demands of our industry to critically examine how we have been interpreting conditions and solving problems. This presentation introduces a remedy framework focusing on volumetric and mass flux metrics to achieve better outcomes.

A key element of the remedy framework begins with a better CSM, moving beyond ideas like equivalent porous media to develop a realistic framework of remedial response. A hydrostratigraphic-based representation, interpreted using the three-compartment model, provides a realistic framework for possibilities, dividing the aquifer into fast, slow, and static groundwater. A new optimization approach developed around this CSM was used to develop a flux-informed objective function to find the global optimum and “near-optimal” approaches. Results presented demonstrate the practical relevance and the untapped potential that could be realized through further development, testing, and application.

Coauthors: Scott Potter, Michael Kladias, and Marc Killingstad (Arcadis, Inc.)

3:55 - 4:15 p.m.

Hydrologic Characterization Testing to Support Design of a Pump and Treat System at Hanford’s 200-BP-5 and 200-PO-1 Groundwater Operable Units

Darrell Newcomer, Central Plateau Cleanup Company

The U.S. Department of Energy’s remedy to clean up groundwater in the 200-BP-5 and 200-PO-1 groundwater operable units at the Hanford Site consists of a Pump and Treat (P&T) system to remediate technetium-99 and uranium contamination to the drinking water standard. Because groundwater extraction has not been previously implemented in the C Farm and A-AX Farms plume area within these operable units, the response of the aquifer and contaminant concentrations to pumping over time is uncertain. Hydrologic testing was identified as part of a three-phased approach to obtain characterization information to determine the most efficient approach for long-term remediation. Characterization testing information obtained during the three-phased approach is important for improving the conceptual site model and for numerical modeling of contaminant fate and transport and optimization of the P&T system within the C/A-AX Farms plume area. During drilling of two new P&T extraction wells in the C/A-AX Farms plume area, phase 1 depth-discrete hydrologic testing provided information for assessing aquifer hydraulic properties and contaminant concentrations with depth. Phase 2 pre-pumping test activities included small-scale slug tests in the two nearest groundwater monitoring wells to the extraction wells and barometric well response function development. Phase 3 hydrologic testing and groundwater sampling are performed to estimate intermediate- to large-scale hydraulic properties and monitor contaminant concentrations under pumping conditions. Phase 3 characterization tests include modified step-drawdown and extended (~30-day) constant-rate pumping tests performed at the two extraction wells. To provide an indication of the areal drawdown response during P&T system operation, a multi-well pumping test will be performed, which utilizes pumping both extraction wells simultaneously. Information obtained from the three-phased hydrologic testing approach will aid in decision making to remedy groundwater contamination in the 200-BP-5 and 200-PO-1 groundwater operable units.

Coauthors: Eli Moore, Bryce Hatler, and David Rukki (Central Plateau Cleanup Company); Frank Spane, Jr., Marty Doornbos, and Nicole Combs (Freestone Environmental Services, Inc.)

4:15 - 4:35 p.m.

From Waste Chaos to Compliance: A Robotic AI System Achieving Real-World Remediation End States

Halina Harvey, Innovative Physics, Ltd.

Achieving remediation end states in nuclear environments requires a convergence of innovation, adaptability, and measurable results. The Intelligent Robotic Operating System (IROS), developed by Innovative Physics, turns this vision into operational reality by automating the most hazardous and error-prone phase of remediation: nuclear waste sorting and segregation.

IROS is a fully autonomous system that uses AI and robotics to identify, characterize, and classify waste based on material composition and contamination level. Combining real-time sensor data (radiation, LiDAR, photogrammetry) with machine learning and a site-configurable SQL decision engine, the system ensures each item is sorted according to its appropriate Waste Acceptance Criteria (WAC). As a result, downstream storage and processing costs are drastically reduced, and misclassification risks minimized.

Critically, the system adapts to complex, variable waste environments—handling overlapping, irregular items and operating continuously in high-radiation zones without the interruptions of manual processes. Its robust grasping logic, 3D mapping, and aviation-grade safety verification ensure consistent, repeatable success in unstructured environments.

IROS helps organizations meet end-state objectives by reducing radiation exposure, optimizing packing for disposal, and maintaining digital records for each decision made—ensuring complete traceability and regulatory compliance. Furthermore, its modular architecture supports scalability across different remediation sites with minimal customization.

This case study showcases IROS’s deployment potential as a cornerstone in strategic remediation programs. By integrating advanced analytics, automation, and intelligent decision-making, IROS bridges the gap between complex radiological legacies and clean, compliant site end states. It demonstrates how adaptive technology not only improves operational resilience but also accelerates the path to sustainable, verifiable remediation.

Coauthors: Mike Anderson and David Prendergast (Innovative Physics, Ltd.)