Assistant Secretary, Office of Environmental Management
Timothy J. Walsh
Timothy J. Walsh became the Senate confirmed Assistant Secretary for the Department of Energy's Office of Environmental Management on Oct. 23, 2025. He provides leadership for the safe cleanup of the environmental legacy brought about from eight decades of nuclear weapons development and government-sponsored nuclear energy research.
Acting Principal Deputy Assistant Secretary, Office of Environmental Management
Joel B. Bradburne
Joel B. Bradburne serves as the Acting Principle Deputy Assistant Secretary for the Office of Environmental Management (EM). In this role he works to enable the safe and successful execution of the EM mission while providing management and oversite of activities, operations, and program integration across the Department of Energy field sites.
Associate Principal Deputy Assistant Secretary for Field Operations, Office of Environmental Management
Gregory Sosson
Gregory Sosson is the Associate Principal Deputy Assistant Secretary for Field Operations for the Office of Environmental Management (EM). He is responsible for developing strategies, policy, and guidance for the 15 EM field sites in support of the EM mission. He oversees nuclear operations, safeguards and security, and technology development.
Associate Principal Deputy Assistant Secretary for the Office of Regulatory and Policy Affairs, Office of Environmental Management
Jack Zimmerman
Jack Zimmerman began serving as the Acting Associate Principal Deputy Assistant Secretary for the Office of Regulatory and Policy Affairs within the US Department of Energy’s Environmental Management Office in October 2025. His portfolio includes infrastructure disposition, subsurface closure, regulatory compliance, waste and materials management and packaging and transportation.
Associate Principal Deputy Assistant Secretary for the Office of Corporate Services, Office of Environmental Management
Steve Trischman
Steve Trischman serves as the Associate Principal Deputy Assistant Secretary for the Office of Corporate Services, and as the Acting Deputy Assistant Secretary for Resource Management, within the US Department of Energy’s Environmental Management Office. His portfolio includes budget and planning, information systems, workforce management, acquisition and contract management and project management.
Field Managers
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Acting Federal Cleanup Director, Moab Uranium Mill Tailings Remedial Action Project -
Leadership News
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Mark Bollinger is manager of the U.S. Department of Energy Office of Environmental Management’s Carlsbad Field Office, which oversees the Waste Isolation Pilot Plant in southeast New Mexico. November 18, 2025November 18, 2025
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Senior leadership from the U.S. Department of Energy Office of Environmental Management joined executives from Savannah River National Laboratory, Salado Isolation Mining Contractors and West Valley Cleanup Alliance at the 11th Annual National Cleanup Workshop to highlight key successes from the past several months and look ahead to future work. September 30, 2025September 30, 2025
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September 30, 2025 The more than 80 community leaders who took part in the recent Paducah Chamber of Commerce Fly-In discussed environmental cleanup progress, upcoming project milestones and long term planning for reindustrialization of the Paducah Site with members of Kentucky’s congressional delegation and U.S. Department of Energy leaders.September 30, 2025
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As the U.S. Department of Energy Office of Environmental Management addresses the legacy of the past, it has incredible opportunities to be part of what’s been dubbed Manhattan Project 2.0, a strong vision for the future focused on winning the global artificial intelligence race and ushering in a nuclear renaissance to fuel it, acting EM Assistant Secretary Joel Bradburne said in the keynote address at the 2025 National Cleanup Workshop.September 24, 2025
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U.S. Department of Energy officials and Paducah, Kentucky, community members take part in a meeting of the annual Paducah Chamber of Commerce Fly-In. September 23, 2025September 23, 2025
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Shawna Burtenshaw leads a team gearing up to finish the demolition of a submarine reactor prototype plant this year, a project that will reduce the legacy footprint of the Naval Reactors Facility and advance environmental cleanup at the Idaho National Laboratory Site. September 9, 2025September 9, 2025