From 2001-2005, USACE took the following actions at Building 23: conducted a multi-phase remedial investigation (RI) to determine nature and extent of contamination; developed a Feasibility Study (FS) to evaluate cleanup alternatives; issued a Proposed Remedial Action Plan (PRAP) for public comment; and finalized a Record of Decision (ROD) to document the selected remedy for cleanup. These CERCLA phases were conducted to address the residual radioactivity in the southwest quadrant of the building. The remedy identified in the 2005 ROD is “Decontamination with Removal to Industrial Use Levels.” Responses to public comments received on the PRAP are included in the ROD.
From 2009-2013, USACE developed the remedial design and conducted part of the cleanup inside the building, including the removal of equipment and building components with the highest radiological activity. However, based on the persistence of low levels of radioactivity above cleanup goals on certain building surfaces, USACE and W.R. Grace reevaluated the selected remedy.
To support the reevaluation of cleanup alternatives, engineering surveys, geotechnical and hydrologic investigations, and soil sampling were conducted in 2017. Based on these activities, the partial demolition of Building 23 was determined to be technically feasible. The soil sampling showed higher levels of radioactivity deeper underground than previously identified (greater than 16 feet below grade). Because the contaminated soil is close to facility infrastructure including other active parts of Building 23, it was determined that it would not be feasible to remove the soil. Therefore, long-term controls for the management of the soil, if disturbed, will be required.
In consultation with MDE and W.R. Grace, USACE prepared an Amended PRAP in 2019 to summarize the reevaluation of cleanup alternatives and document the new preferred alternative, “Demolition of Southwest Quadrant of Building 23.” A ROD Amendment was finalized in 2020 after a public comment period and is available in the Project Documents section of this website. The selected remedy includes demolition of the southwest quadrant along with land use controls, which will be the long-term controls for the management of contaminated soil. This alternative will minimize risk by removing building components that are contaminated with radioactivity at the site. This alternative is technically feasible and is considered the most protective of human health and the environment when compared to the other alternatives assessed. The remedial design for the demolition of the southwest quadrant is currently in progress. The demolition will be conducted by carefully “deconstructing” the building, with extensive environmental monitoring during work activities, to ensure the safety of workers and the public.
In 2021, as part of CERCLA requirements, USACE completed a Five-Year Review for the remedial action at Building 23. The review process involved an evaluation of the risk posed by residual radioactivity remaining at Building 23. The Five-Year Review concluded that the demolition remedy for Building 23 will be protective of human health and the environment upon completion, and that appropriate site controls are in place in the interim. The Five-Year Review is available in the Project Documents section of this website.
Upon completion of the demolition of the southwest quadrant of Building 23, a Final Status Survey will be conducted using MARSSIM requirements to verify that remedial goals are met for the remaining building components and ensure that the remedial action objective has been achieved. Land use controls will be used to ensure that proper actions are taken any time the soil beneath the southwest quadrant of Building 23 is exposed, and ongoing Five-Year Reviews will be conducted by the Government.