Brettski - What you say is understandable. My next question is then how confident are "we" or is anyone that the ENTIRE pond basin has a completely adequate subsoil of clay? If the intended basin has one or a few HIDDEN subsoil zones that contain small or medium sized areas or pockets of loose materials then expect these pockets to be the main seepage spots. In cases where ponds are built in this manner - It becomes a gamble. It is no wonder that many ponds including dug out holes for ponds have various degrees of leakage.
