I have a question about sealing my recently constructed pond with bentonite. I don't really want to dewater the pond (its about 30% full). I have the leaking area isolated and was considering purchasing bagged bentonite and then mixing it with water and basically pumping the bentonite slurry into the leaking area of the pond. It seems like using this method I could avoid issues with sprinkling the bentonite and get an even distribution of the product in the leaking pond area. Has anyone ever tried this method?

That has to beat the sprinkling method. The only thing I know about bentonite is that tossing it out in the vicinity of the leak didn’t work for me.

I think it would be a waste of time and resources. Bentonite works when tilled into the pond bottom, and then strongly compacted while moist, not saturated.

Polymer works in hydrated ponds. Feel free to contact me, I've helped hundreds on the forum seal their leaking ponds, my time and advice is free to the forum. Happy to help however I can.

tj@hudlandmgmt.com
402.730.4897

^^^^^What TJ said right there.^^^^^

I speak from experience...

Bentonite is composed of clay minerals. These minerals can actually incorporate water into their mineral structure.

Some dry bentonites can swell to as much as 8x their original volume when combined with water.

This volume increase works well in leaky soils when you till the bentonite into the dry soil of the lake bottom. The bentonite sits in the small spaces between the soil particles and then swells up to fill the gaps when the pond refills with water.

This process DOES NOT work well if the bentonite is already saturated when trying to fill the gaps in the leaking areas. (Imagine water leaking through your kid's sand box. Putting a few layers of marbles on top of the sand will not stop the leak.)

The linear molecules in the polymer treatments have several advantages over bentonite when used in a water-bearing pond. First, they may expand up to 300x their original volume. Secondly, these are usually a "chain" type of molecule.

I believe the second reason is the most valuable in sealing a flowing leak. Imagine the sink/shower drains in your house once they are partially blocked. At that point, the drain is easily fully clogged by pliable linear items. The hairs, potato peelings, etc. stack up across the hole. As the obstruction cuts the flow rate, the linear items pack in even tighter until they completely clog the drain that had been passing water.

The chain molecules in the polymer treatments act like hairs packing up the tiny flow paths through the soils of the leaky pond.

Most of these treatment types also add a crosslinked polymer. This type of polymer may increase its size and length over a period of several days. Imagine having a hair blockage in your shower drain, and then doubling the volume of each hair. That blockage is not moving!

Hopefully that background will help in the selection of your treatment method. Good luck getting your pond squared away!

I would love some help!!! We bought our house last summer and then found out that the water level goes down significantly without any evidence that is going doneejere specific. I’ve sprinkled entonite around the edges and have not seen any improvement.

I have used bentonite in full but leaking ponds to stop leaks. I am not saying another product might not work better but that was not your question. The clay can act to fill the pores in sand and form a seal. That is why it was developed for the oil drilling business. I have used successfully the method you described.

Ewest can you tell us more about the project you're talking about? Things like how much was the loss per day before treatment, how long was it leaking, how old was the pond, how big and deep was it, how big of area did you treat, how did you determine the area to treat, how deep was the area, how much did you use, how long did it take to work after treatment, how much loss per day after treatment and more about treatment method?

Most say bentonite won't help full ponds but now and then I hear someone say it worked for them and I (and probably many others) would like to hear more about the cases that it did help.

This is similar to what we used. Multiple occasions/ponds.



Several where there was a sand member that was leaking in several feet of water. We used a combination of placing the sacks on the bottom near the sand and cut it open and dumped the contents and also placed some in buckets , added a little water and poured over the area. The flow of the water pulled the mix and slurry to the leaking sand. Amounts vary depending each site. Ponds were from 4 to 10 acres. Average about 20 bags and it took a week or so to stop leaking. Normal type ponds 8-12 ft at the dam with most area 3 ft deep, avg. depth probably 4 ft. Most of the ponds were new < 2 years. Did not try to quantify the water vol. loss.

They now have bentonite drilling mud with polymers in the mix.

Thanks Ewest!