Black Rock Quarry Hidden Location. On the side of the corridor leading to the Black rock Quarry. In the Black Rock Quarry Entrance where the Astral monster is is a door in an above alcove you can enter.
Where is Black Rock Processing in Control. You can also look here for some answers. In the room just past the Black Quarry Entrance Control Point the one where all the monsters and Hiss attack you is a doorway located above everything to the left.
Use Levitate to climb the platforms and then follow the sewers until you find a door that leads you back to the Furnace Chamber.
Find the Black Rock Quarry in Control. Before you leave Dr. It is an abandoned quarry. On the table next to the TV you will find access card 5.