I've been thinking about that, the water will find away into and around anything. It moves with capillary action, one molecule linked to the next. It will be pretty hard to stop that kind of seepage. I guess if I don�t get a bonding of the material to the ledge rock it will find away out.
Back to scratching my head for a better solution.
SF,
If the water is escaping horizontally, you still have a chance to stop it by adding weight to the banks.
If the water is leaking downward, that's another problem. It may require digging out and replacing porous material with clay.
If you're losing a lot of water, it's probably a leak, not just capillary action. Capillary action is a very slow process, and it takes a very wide area to lose significant water. Weight is also the antidote for capillary action.
