Where is the exit?

Hint 1 of 6:

The exit is atop the roof of the lounge building, above the flood zone.

Hint 2 of 6:

It's close to where you found the blue card.

Hint 3 of 6:

Use the red card to enter into the area.

Hint 4 of 6:

Explore a bit, until you find the sewer.

Hint 5 of 6:

Eventually, you'll find a big hole in the sewer.

Hint 6 of 6:

Don't worry, the drop won't kill you.  The water will soften the fall.