This is a dump is on a home site, thats for sure, but there had to have been kids there because I dug a toy train there too! Pretty cool. But it was a nicer home so I imagine it was a richer family that didn't need the deposit as well, you are definitely onto something there.Nice find. What do you think is the nature of the dump--just a family, a farm, resort or community?
A family that hat a lot of kids and didn't care about recovering the deposit could certainly discard the quantity you are recovering.
(Don't worry; I'm out on the west coast and not trying to home in on your site--just curious due to the number of milk bottles.)