My well is 528 feet deep, and freshly drilled - this pollutant was in the first water test set and in every test set since for 15+ years, and there has been zero spills and good maintenance ever since.

I agree that in this situation it seems very difficult and it is surprising that the pollutant would travel not only that far laterally but also that far down. Yet, there it is.

"Water flowing underground ...." - it moves a lot more than we think!