We have a site in Denver, CO USA like that now: the Rocky Flats National Wildlife Reserve. It’s one of many such sites in the US. The US manufactured triggers

We have a site in Denver, CO USA like that now: the Rocky Flats National Wildlife Reserve. It’s one of many such sites in the US. The US manufactured triggers for nuclear weapons there, leaving portions contaminated for millennia. They did a major cleanup in the 90’s and built a nice park, but the contaminated core DoE “Legacy Site” has to be maintained and secured in perpetuity. One of the site’s responsibilities is to maintain a very elaborate groundwater contamination remediation system so that runoff doesn’t poison millions. Also, the hazardous waste from the cleanup has to be stored on site as it was legally/practically impossible to transport it out of the state or to any other location in the state. All of this works for now, but it requires the United States government and all of its successor states maintain this remediation infrastructure for the next few thousand years.