I've got another question for you experts.... the saga continues

Last year, my contractor was "spreading out" the rest of the muck to dry and repack he mentioned that the more he worked an area on the bottom, the wetter it got. His dozer was floating on muck bottom and nearly got stuck. We had a dry so he would stay off and wait for it to crust over and work it again.
It never did fully dry before the rains started.

I spoke with yet another pond consultant yesterday and explained my situation. They mentioned the likely reason is that he was pumping up groundwater through the area that is not stabilized. Thus a likely source of my leak. The recommendation I received is to pack the area with stone to stabilize it before applying any kind of sealer (clay, bentonite etc) otherwise it will continue to leak. How much and how thick is the big question.

The groundwater issue makes sense because my property and region of the state have a large makeup of sand and sandstone. The water table rises and falls quickly because of a fractured subgrade.

Thoughts...?