Comment by Earw0rm
1 day ago
Right, but there's ground and there's ground.
Geological strata vs shallow landfill sitting above aquifers and subject to near-term erosion.
Disposing of this stuff in deep mines seems like it'd be fine, unfortunately we haven't yet, at a society/economy level, found the discipline to do so. Presumably after a few mya of heat and pressure it'll be indistinguishable from other petrochemicals (which aren't particularly nice to begin with).
I don't think disposing of stuff deep in mines would be a good idea as it would be easy to contaminate the ground water. Modern landfills are generally well engineered and don't contaminate the surroundings too badly.