Abandoned slate quarry

How to explain this sound ?! It's quite complicate. We are in an underground slate quarry. It's a dead end tunnel. In aim to extract the bad rocks, miners drill into the stone. They make a long drilling, diameter 3 cm, lenght 4 meters. At the end of the drilling, they put some explosive. Here, it's a drilling. As it was the end of the quarry (bankruptcy), they didn't explode the rocks. So, the long drilling remains, as this, since a century. Inside the stone, there's a spring. Water is following a strange way inside the fracking. This is the sound of the water inside the drilling.