We are digging out a once started lake. Today we dug a test hole and at about 18 feet deep water started to bubble out and the next few buckets was coarse gray sand with small pieces of coal mixed in it. The hole started to fill up slowly with water. Everything previous up until this point is excellent clay.
18 feet was roughly the depth we planned to dig the pond. The big question is do we dig down to the sand and water level or should we stay up at least 2 feet from the sand and water and call it good enough?
We drained some excess surface water down into the test hole and filled the entire hole up to see how much it will drain down in a few days. If it doesnt drain down much would that be a good enough test to see if it will hold water?

EDIT: Here is a link to a video showing the pond.
http://www.youtube.com/watch?v=B0Qd7UGa_WE

Last edited by bummer; 09/10/09 11:24 PM.