I don't have a backyard, but if it turned out to be the most effective and safe solution to, let's say, dig a deep borehole under my hypothetical lawn, drop the waste down there and seal it back up, why not?

From what I know of deep geological storage, I wouldn't mind living in a house on top of one of these sites. Since they're usually in the middle of nowhere, it would probably be even safer than living in a polluted city.