Theory: The Mines aren't real

So I'm up to date on the show and have only just started reading the books (not relevant but i just wanted to add that in) and I've come up with a theory

The idea of the silo having mines makes no sense. Its already been established that entering the bottom of the silo where the giant drill is goes against the pact. So they can't be there. They can't go outwards because there are 50 other silos in each direction and they aren't spaced that far apart. What's stopping two silos from accidentally tunnelling into each other? Unless it goes out a bit and then down, i guess.

My theory is that the "mines" are a lie, and is just a place where Judicial sends criminals who don't want to go out to clean or can't outright kill without sparking an outrage. The only hole in this theory is that Meadows says that people in the mines only last a year or so. So either I'm wrong, or not even Judicial knows the true nature of the mines and thinks the iron ore is being sent up by workers when in reality its probably being sent up by whoever is in charge of the entire silo network.