Big hole in the side of mountain in a desert, stick the waste in, full it with rubble and concrete, job done. If some primatives in a hundred thousand years stumble across it and dig it out, fuck em, who cares.
The pyramids have chambers that were unopened for over four thousand years, bone dry inside. Pick an area with very little rainfall, surround it with rock and the problem will stop existing on human timescales.
Dig a hole, anywhere, there's a chance it'll fill with water. Especially with climate change. We're seeing moisture getting dropped in areas at greater frequencies that didn't happen decades ago. There's no guarantee you can dig a hole anywhere on earth that wouldn't become apart of our aquifers as the water travels back to the ocean.
It isn't really minimal since the water cycle on earth is all connected.
Water in the ocean evaporates. It's carries inland by Hadley cells that deposit the moisture inland. It gets dumped on the highest points which all run back the ocean and creating all our aquifers along the way. Those aquifers feed our great lakes and wells.
But you're suggesting we bury toxic material that remains toxic for hundreds or thousands of years somewhere remote that would just be high up in that water cycle. In places where private companies would be out of the eyes of watchdog groups
The hole would be 0.5m wide and >1000m deep, backfilled with bentonite clay and concrete. At the bottom, the path curves back upward, so waste is not stored at the bottom.
Even if geology doesn't collapse the hole, it's hard to imagine material climbing up through 1000m of clogged pipe.