The setting is great. Loved the dripping water, too. Some nice shots - looking up the shaft, receding shadows, and the soft focus wing in the foreground. I liked the vests and hard hats, especially the hat falling on the ground.
I have mixed feelings about the bird. I would have rather you didn't use something as common as that. A little more mystery could have taken that further. The character interaction was weak. We don't get much of a feel for them. It might have been better to have the girl being hesitant about going into a dark place, and the guy really needing to convince her to go in. Their voices could have been more clear, but not too bad.
This has a lot of potential to be expanded into something bigger. Good job.