The pond was down 15 inches from full this morning. I hand dug three test holes at the toe of the dam. The first 16 inches or so was silty clay "topsoil" full of small roots. After that, I hit hard, solid clay that was barely diggable and very sticky and pliable. The water leak is going along the top of this clay layer and saturating the silty clay in the top layer above it. It appears that the old part of the dam either has no core or is penetrated by many roots.

Could a core trench a few feet up from the toe of the dam be cut with a mini excavator? There is enough clay in the dam there to tie in and make the trench impervious.

Last edited by John Fitzgerald; 03/16/18 12:30 PM.