Digging dirt, mining Elemental Stones, building shabby structures for the Dark World denizens to reside in. These three are the main duties being given to the expandables that were sent here.
All in all, the Noxians were being treated as a slave. However, that was only limited to those not part of an Aristocratic Family. If someone is affiliated to it, they're given the same treatment as the Mortal Ranks from the Dark World. Even after surrendering to the enemy, their people were even degraded to something like that.
Not my problem though. Surely, even to those who defected back to us, the hierarchy was still the same. But that's for their race to sort out. Sooner or later someone will rise up and correct those mistakes.
"You. Mining. And you. Mining as well. Get your pickaxes at whoever's at the mine. They will also give you your daily quota. Finish that and you will be able to go home."