I would happily shoot the son of a bitch who buried this thing in my back yard.
I have no idea what it may have been for, but it seems to have a capacity of two or three hundred gallons. It's buried along with all sorts of caliche, concrete and mortar rubble, many pieces of which have to be dug out individually, even if they're small enough for a shovel, because the shovel can't penetrate.
This is what it looks like on the inside.
Kind of pretty, don't you think?
Oh, well... Good thing I don't have to do this kind of work for a living, or I might be the one burying stuff like this.