Pond Boss Forums POND CONSTRUCTION Soil questions Central KY - New Pond Leaking

I would choose Sodium Bentonite, if it were my pond, for a proved, permanent solution.

You may want to contact your original builder and the local NRCS Agent to consider all the best options on how to proceed. Re-building the core may be the best soultion, but is going to be very expensive or not even be the problem at all.