Pond Boss Forums POND CONSTRUCTION Soil questions Leaky clay liner

I'm meeting a client next Saturday that built a pond in a rocky and gravel site, they lined the pond with a foot of pure clay to seal it.
Well it never held water. Now it�s all landscaped and the owner wants a solution to stop or reduce leakage without the intrusion of machinery.

I thought of ESS-13 or pouring bentonite on surface. Has anybody had success with ESS-13 if there is a clay liner in place?

My thinking is that all of these methods won�t work because the foundation of the dam is sucking water out of the pond.

They have a well and pump 100,000 gallons per week to keep it full. The bottom is bed rock, a very brittle soft bed rock; they say springs are coming from the bottom. I think the spring may be sucking water out as well if the pressure is high when pond is full.

Any suggestion or specific archives to read out there?
Thanks in advance!