Germany is currently operating the world biggest permanent storage for dangerous waste UTD Herfa-Neurode. Contains at least 690,000 tons of waste containing dioxins and furans, 220,000 tons of waste containing mercury, 127,000 tons of waste containing cyanide, and 83,000 tons of toxic waste containing arsenic. Nuclear waste is currently excluded, but I think it would not make a difference, especially because after about 400 years most dangerous fission products (Caesium-137, Strontium-90, and Iodine-131) decay away and only Plutonium and minor actinides stays. Mercury, arsenic, dioxins and furans stay forever.

https://de.wikipedia.org/wiki/Untertagedeponie_Herfa-Neurode

https://radioactivity.eu.com/articles/radioactive_waste/acti...

We learned quite lot about underground migration of plutonium over millennia because we studied the remnants of the natural nuclear fission reactor which nature run about approximately 1.7 billion years ago in Oklo, Gabon.

https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...

"Plutonium has moved less than ten feet from where it was formed almost two billion years ago contained in the sedimentary rocks that kept them from being dissolved or spread by groundwater."

http://large.stanford.edu/courses/2018/ph241/voigt2/

I mean yeah. Nuclear waste is much safer than fossil fuel waste - deaths caused, radioactivity, etc