Our waters come in at room temp, right after collection and are set up then. If they come in on the evening shift they may sit refrigerated overnight. I'm not sure why your people transport them so cold, as it would take much longer for the cultures to grow from what viable organisms remained if they were frozen ( one article suggested up to 29 days vs a week). I'm supposing the time elapsed is long enough that they want to make sure they stay refrigerated, but not frozen?