Excavator key

[Magus]

Spoiler below!

After your encounter with the spiders you arrive at the storage area. The hallway in front of you (I think it's that one) will lead you to a small room with several shelves full of 'junk.' But what you are looking for should be on the wall. It's a big green cabinet with a symbol of a key on it. Just move the from panel to the side as your looking at it from an angle and you should be able to spot the key. The point is to look for a big green cabinet (similar to the medical cabinets) mounted on the wall.