A mishna on Meila 11a talks about money that a nazarite set aside for his offerings; if he died before completing the term and had set money aside specifically for the sin-offering, those coins are dropped into the Dead Sea. (I know that this is a specific case of a more-general rule.) This led me to wonder how that was done: were the coins dropped in individually, for each person as the case came up, or collected and dumped en masse (after some amount of time perhaps, or when there are "enough" to be worth the effort, like when we collect papers for burial)? I then found two possibly-contradictory ideas: on the one hand, some speculate that a large collection found by archaeologists was from this kind of disposal, but on the other hand, I'm told that Rashi on Pesachim 28a says there was a concern that people would collect them. (According to the latter view, the Dead Sea was chosen because ships didn't go there, not necessarily for its corrosive properties.)
If there is a concern that people will go diving for them, it would make sense to dump them individually, as the cases come up, not in large volumes, to reduce the profitability of that. On the other hand, that's more of a hassle to manage, and raises the risk of the money being used instead of destroyed.
How was this done? Was each payment dumped individually, or was money collected until there was "enough"?