Having worked out at Y-12 as a subcontractor on a number of contracts as waste specialist/engineer I have a bit of firsthand knowledge. Every remediation/demolition included mercury in the characterization of waste or soil. Stormwater drains that went to the East fork stream were isolated during work near them. During the remediation of the Alpha Five building next to Alpa Four in some locations we wore respirators for airborne mercury.
Oak Ridge's Mercury Treatment Facility receives new tanks
https://www.ans.org/news/article-6415/oak-ridges-mercury-treatment-facility-receives-new-tanks/
Secret Cold War project results in largest US environmental cleanup
https://archive.knoxnews.com/news/local/secret-cold-war-project-results-in-largest-us-environmental-cleanup-ep-402290682-357323681.html/#:~:text=The%20Y-12%20plant,%20which%20had%20enriched%20uranium%20for%20the%20atomic