Going to the Blind Well in the pink/red corridor I think it's next to the guard there is a black hole besides the stairs that you can drop down. Its total black down there but when you drop down and light the room with your gun you can see a open space with stairs going down. Didn't have alot of time as I was then going to bed but I'm going to have another look tonight. There has to be something down there because there are proper stairs been put there.