Ken! So sorry for the lag in response. I read this, sat it on the shelf thinking that I needed to respond, and just ran back across it -- with an inch of dust on it still sitting on the same shelf. Sorry, man!

The water would likely be from both sources; vadose water as well as runoff. It's not uncommon for a quarry to fill up; quickly in some cases depending on the overall geology, underlying rock members, surface soil types, etc.

Any other questions, please feel free to ask!! :) Good to hear from you, bud!

-Brad-

Hello Rockpick - Kenny Haymaker here. You may not remember me, we met at Troyer's a few years back. I live only a few miles from his shop. I have a question for your other area of expertise. Regarding abandoned rock quarries which are filled with water. Is the water from underground or do they fill from rain/runoff etc?