Having now read this thread properly, here is another bit of information. In Rome there is a place called Monte Testaccio. It is an artificial hill, about 120 feet in height, and it is made up entirely of discarded amphorae numbering in the tens of millions. It was in use from about 150BC to AD 250. It is now a park on the right bank of the Tiber, to the south of the Circus Maximus. Google Earth shows it perfectly.
Yes, but now you're talking industrial refuse. Monte Testaccio was next to Rome's river port, where the ships from Ostia would dock. If some Roman threw a pot out the window of his house it probably wouldn't end up there.