The Floor Is Water

Jack goes ahead, walking across to the staircase tower. He reaches the first platform.
Clear.
Michelle follows him as he starts walking downstairs. She reaches the platform.
Clear.
James follows them and also says clear as he reaches the platform. Annie hesitates.
Jack looks up to her from the next platform down and says: Come on Annie, you got this, it's gonna hold.
I'm scared.
James turns around and stomps on the walkway. It makes a dull ringing sound and rust and debris rain down into the depths.
He says: Nah this thing's fiiiine. You can come over.
He goes back to the top of the tower and Annie cautiously walks across.
Jack continues downwards and the others follow, making sure to never be on the same staircase with each other and passing warnings back:
Careful, missing steps here.
James, missing steps.
Annie, missing steps.
Okay.

The staircase tower stands on top of a large, slightly elevated concrete platform roughly taking up a third of the ravine's width. One side is connected to the rock face, the other side ends in a vertical edge that goes down to where the outflow of the power plant flows past. A very rusty railing begrenzt that side, though it looks like it might fall apart if you look at it wrong. The entire platform is flooded by water rushing out of a broken door in the rock face. It spreads out over the platform, and flows off the edge.
Michelle says to Jack: I don't think we'll get in this way.
Got another idea?
They walk down the last staircase and onto the platform.
No, but you're gonna get swept away.
We just need to get past the door, the water inside will be moving a lot slower.
Michelle and Annie decide to stay back, Jack and James approach the door from the side. The two pick up a large rock and throw it right in front of the door. It starts rolling immediately and, within seconds, tumbles off the edge.
Jack calls out to the girls: You were right.

this is in the middle of the chapter after they went downstairs and tried to explore the turbine hall, back up in the tunnel

Jack turns the key and the gate starts to move up, scrathcing and squeeking as it does, revealing a bunch of crates. About half-way up, it gets stuck, making a buzzing noise. He lets go of the key and the buzzing stops. They duck under the gate and find themselves in a warehouse much larger than the gate and windows in the tunnel would lead to assume.
Jack says: Now that, ladies and gentlemen, is what I call an adequate stockpile of spare parts.
He walks up to a huge crate and wipes the dust off the label: Turbine C, replacement 2.

exploring the warehouse, they find a forklift and a railroad in the back