Ken-
Decades ago, I lived on 3+ acres of land and had a well put in. I was told by the well diggers that I needed a foot valve. Of course, they could have been lying to me. I think that this is one of those situations where the better part of valor would be to put in a foot valve.
This report is anecdotal. If you get an answer from a well digger, go with that.
Oh! And how deep is a frog's pond.
Knee-deep! Knee-deep! Knee-deep!
That was one of the funniest clean jokes that I have ever heard.
BOL
JayR