Sandra Phelan is the head of the Youth Transition Center in Pontiac, Illinois.
Sandra is in charge of a Group Home where Claire Novak spends most of her time at, whenever they manage to capture her after she's done something bad or illegal.
When Castiel arrives and poses as "Jimmy Novak" in order to get Claire out of this place, Sandra is not fooled by his acting and rejects Castiel's request. This forces the angel to break Claire out instead.
When Claire manages to run away from Castiel, Sam Winchester comes to speak with Sandra to learn more about Claire. Sandra reveals that Claire took an interest in a former resident of the Group Home, Dustin Tate, whom Sam and Castiel go after in order to find Claire.