Hello All,
Last year I built a 1 1/2 acre pond that began leaking at the base of the dam as soon as it got about 3 ft. of water in it. The leak was a seepage along an area about 50 ft. wide and when it all came together to a ditch it looked like a water hose running on full.
Well I tried the sprinkle Bentonite thing...no good.
Then this summer I drained it. I rented a loader and sheepsfoot, dug out all the rock my pond builder left in the bottom and got a good cover ( at least 2 ft.) of clay on any remaining rock. Then I put on 23 tons of bentonite covered it with about 6 in. of clay and rolled it in. Got an 8 in rain last week and I have the same leak in the same place.
I tend to think that it's just coming right through the dam. I thought before that it was coming through the rock and under the dam but but now I'm not sure. The dam face was the one area I did not cover with Bentonite and pack it in.
This board has been very educational for me and I appreciate all the info I've gathered here. If anyone reading this has any ideas I'd be glad to hear it.
Thanks
Houston

call seepage control at 800-214-9640. they use a system called ess-13. they call add to the water and seal the leaks, really nice folls there, very helpful tp me.see there web page at www.seepcontol.com or search ess-13. the best thing about there deal is they give a gurranty with there work,no leaks when there done.

Sounds like your problem occurred when the dam was built.
It wasn't cored.
A dam sitting on top of natural ground will leak.
A properly constructed dam has topsoil pushed away, then subsoils excavated to least porous dirt, then the excavated site is refilled with compacted clay soils, effectively creating an underground water barrier, called a "core trench."
Get a copy of the Nov/Dec issue of Pond Boss and look at Mike Otto's story about compacting soils, and look at the photos as he built a dam on top of terrible soils, by creating a core trench and backfilling with clay.
Your dam is built like a sandwich, new dirt on top of old dirt.
Your dam needs a core.

budman, i gave someone with some pond leakage problem seepage control info with ess-13. but no where have i ever seen cost estimates. has anyone used them, and want kind of costs are we talking about with them. i am sure it is size dependent but any approximate costs out there that anyone knows about? amrk