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!

Pouring bentonite on the surface is a waste of time. Any wind or wave action causes it to wash to the banks and settle there. If there are springs at the bottom, I expect the head pressure from the pond is causing them to flow backwards into the aquifer.

The only thing I have heard about ESS-13 is the price. Pretty rough. I would contact them and talk though.

Mario,

If they know exactly where the springs were, and they are not too widespread, it may be worth a try to pour a few sacks of bentonite directly on the problem area.

Mario, I agree with Bob. Cecil Baird is the only guy I know of who ever made this work. However, he found his leak and poured the bentonite down a pipe that he placed directly over the leak. That might mean using a diver to identify the leak source(s). If you do this, it would probably be advantageous to use pellet sized bentonite instead of the dust stuff used in the oilfield drilling. Or dust followed by pellets.

Could you you simply lay the bags of bentonite over the leaky spot and alow the bags to swell and open? Seems like this would work even if you had the dust, since the solution is getting the clay on the leak. Has anyone tried this method?

Donnie

Donnie, applying bentonite to a leak is seldom successful. To work correctly, it needs to be tilled into the soil and allowed to expand. I've tried it 4 times and it has only worked once. However, I have no reason to believe that I applied enough or did it correctly on the failures.

Thanks for the leads guys!
I must say that the client said he knows the whereabouts of their spring, because their concern was to seal the pond and not seal the spring...

They probably dont realize that the spring needs to be sealed.
Sure would be less expensive to seal the spring with bentonite and reduce flow of water from well.
Targeting the spring with a pipe application sounds feasible.
If it wont work, I'll suggest ESS-13...
In the end it seems to me that the only garanteed leak free pond would have to have a liner in this situation. I'll try to post some pictures when I visit Saturday. I'll keep you posted.

So here is the pond in question, notice that the owner are not pumping water anymore and water has stabilized, but now that spring is around the corner, water table is dropping and so is the pond at a rate of 2 inches per day


This picture shows that their deep well is right beside the pond. Although sealed with bentonite, the owner noticed that when the well is used to fill the pond, the pond drops as much if not more rapidly... looks like the well is too close and somehow connected in the bedrock.


This picture shows the clay liner that was added a year after the original excavation. I sampled it and it was our regular sticky blue clay we find around here. The contractor did a nice job, but he is not sure if the spring was covered at the bottom. Sure thing is no clay is behind those rocks, so there is seepage in the sides as well.


This picture shows the general setting; obviously the pond's level is higher than the general surrounding. Owner has seen the sides being wet when the pond is kept full. The problem is obviously two fold, the spring leaks and the sides as well.


So i suggested he drains the pond, seals the spring and bedrock bottom with bentonite, cover the bentonite with that clay they have. Fill the pond and see if there is still that 11500 gal. per day seepage. Next step is to get approval from Seepage Control to see if ESS-13 can be used to further seal the pond. If all fails, he will need to re-excavate and rebuild with a liner... an exercise in patience!

Have you looked at the bentonite mats? This may be the most cost effective solution since you are draining the pond. No bigger than the pond is it would be pretty easy to create a liner with the mats.
If you go with the bentonite powder you need a minimum of 5 lbs. per square foot. You then till it in about 6 inches deep and compact.

Bentonite will not work on a active spring. Dig out the spring for example 8 foot down antwice the area and use virin clay dug from a clay pot and cover with road fabric and more clay on top. thsi way if it does back drain you can see where it took out the water.

If you go with bentonite the sides are to steep and you should use 30 mesh mixed with sand wash from your local quarry and tilled in 10inches

If you walk out onto the pond bottom is the clay pumping

ever use thick poly liner? been using the same liner for five yrs for the back yard hockey rink you would surpise how durable itis and CHEAP