DIED, marginal pond building area is an overstatement for the central basin of Tennesse. It isn't that good. We have more caves than almost all states.
The post has left out too many details. If it is a little bitty cow pond or something, he might get away with no trench. If it's going to have any real pressure, it's 50/50 chance that it will work no matter what he does.
My thoughts are to do everything just right, from the beginning, by the textbook, and that way if it fails, you know you did the best you could do.
It's what I did.
