Some of our local towns around here have these also. They are a "day or weekend" selected that the town might supply the dumpsters (or not) but the residents are allowed to "spring clean" their yards and garages and throw out anything and everything without penalty. It looks like an endless stream of scrapper trucks driving around picking up the "goodies" and when it's all done the remainder goes in the big dumpster. It's a way to get rid of large amounts without costing a fortune in disposal costs. Or the county trash trucks come around to pick up leftovers, whichever the case.