How long do we have to store it on site? Does it take any maintenance? Is there any reason to be worried about people stumbling upon it and opening it up in the distant future where nobody can read or understand English anymore?

If its half life is so long that you're afraid people won't be speaking English anymore it means it's not that dangerous.

If it's half life is so long that you're afraid people won't be speaking English anymore that means it's not that dangerous.

I'm completely serious. It was done extensively during the 20th century and never became an environmental issue. Nuclear waste is a social problem, not a technical problem.