DOE recognized the significance of LTS, beginning in the 1990’s. Key events in the history of LTS at Hanford, as well as key events complex-wide, including the following:

• 1990’s: In general, LTS was first recognized as significant work scope in the early 1990’s. Several DOE reports, beginning with the 1995 and 1996 Baseline Environmental Management Reports, indicated that cleanup to pristine conditions was not feasible, and residual hazards would be left upon completion of the cleanup at DOE sites. The program evolved through a series of reports and studies that continued to assist DOE in defining the program and ultimately cumulated in the formation of the Office of Legacy Management (LM) in 2003.
   
• 1999: At Hanford, the Final Hanford Comprehensive Land-Use Plan, Environmental Impact Statement and the Hanford Comprehensive Land-Use Plan Environmental Impact Statement Supplement Analysis, issued later in 2008, called for the development of a Long-Term Stewardship plan.
   
• 2001-2004: The Department of Energy, Richland Operations Office (DOE-RL) developed the first LTS-related documents including the Hanford Sitewide Institutional Controls Plan for Hanford CERCLA Response Actions (Hanford Sitewide IC Plan) and the Hanford Long-Term Stewardship Program and Transition: Preparing for Environmental Management Cleanup Completion (Hanford LTS Transition Plan), holding public workshops in their development, including soliciting public comments for the Hanford Sitewide IC Plan. Also, during this time, the CERCLA USDOE Hanford Site First Five Year Review Report was completed.
   
• In 2003, DOE established Office of Legacy Management (LM) to…”effectively manage remaining legacy responsibilities and to fulfill commitments to our former contractor work force.” This includes responsibilities for managing Environmental Management (EM) sites where cleanup has been completed (e.g., Rocky Flats, Fernald), as well as sites remediated by the U.S. Army Corps of Engineers and remediated uranium processing sites. Although LM will not take land management responsibility of the Hanford Site until cleanup of the entire Hanford Site is complete, the Hanford LTS Program is managed consistent with current LM policies and procedures.
   
• 2005-2008: The Second CERCLA Five-Year Review Report for the Hanford Site was completed in 2006.
   
• 2009: The DOE-RL developed the Hanford Site Cleanup Completion Framework document that provides an overview of the Hanford cleanup scope, defines the main components of cleanup and the overarching goals. DOE recognizes that this cleanup framework will evolve as cleanup progress occurs and as input from interested parties is received.
   
• 2010: DOE-RL developed the Hanford Long-Term Stewardship Program Plan, with input from Tribes and the Hanford Advisory Board, establishing the Hanford LTS Program.
   
• 2011: Segment 1 transitioned into the LTS Program. Information on each of the segments transitioned to LTS is available here. The third CERCLA 5 Year Review document was completed.
   
• 2012: Segment 2 and Segment 3 were transitioned into the LTS Program and an administrative update was made to the Hanford LTS Program Plan. Key events through 2012 are summarized in the figure below.

CERCLA =    Comprehensive Environmental Response, Compensation and Liability Act.
HAB  =    Hanford Advisory Board.
ICP      =    Institutional Controls Plan (DOE/RL-2001-41, Sitewide Institutional Controls Plan for Hanford CERCLA Response Actions).
LM    =    U.S. DOE Office of Legacy Management.
LTS    =    long-term stewardship.
NDAA    =    National Defense Authorization Act.
ROD  =    record of decision.

DOE Complex-Wide and Hanford Long-term Stewardship Key Events Through 2012.

• 2013: Segment 5 and the first reactor area (100-F) which included the cocooned reactor building were transitioned into the LTS Program. LTS worked with regulators to align all 5-year reactor inspections into a single fiscal year (FY2015).
   
• 2014: LTS completed the transition of five cocooned reactor facilities including 105-C; 105-D; 105-DR; 105-H and 105-N/109-N. LTS also completed the Tri-Party Agreement-required interior inspection of the 105-F reactor in October 2014. (Click here to view F Reactor re-entry short video.)
   
• 2015: LTS completed the required 5-year inspections of the 105-C, 105-D, 105-H and 105-N/109-N cocooned reactor facilities. Additionally, 100-IU-2/Segment 4A and portions of the 100-K Area were transitioned from the closure contractor to LTS.
   
• 2016: LTS completed an inspection of the 105-DR cocooned reactor and supported a Tri-Party Agreement change to extend the interior inspection period on all six LTS cocooned reactors (105-C; 105-D; 105-DR; 105-H, 105-N/109-N, and 105-F) from 5 years to 10 years. The next interior inspection will be in 2025.  Additionally, the 100-B/C and 100-D/H Areas were transitioned into the LTS Program.
   
• 2017: 100-IU-6/Segment 4B, 100-N, and 300 Areas transitioned into the LTS Program.  The Hanford Site Fourth CERCLA Five-Year Review Report was completed.
   
• 2018: 618-10 Burial Ground Complex (which is in Segment 5) transitioned into the LTS Program. LTS also assumed responsibility for the WIDS sites within the Hanford Reach National Monument.
   
• 2021: The Hanford Site Fifth CERCLA Five-Year Review Report was completed.
   
• 2022: The transition of the cocooned 105-KE Reactor into the LTS Program was initiated.