Using bentonite to seal a slow leak in a pond

[TimSullivan]

I have a small pond that is about a quarter acre. I have a small leak about halfway down the dike. Never have used bentonite to seal a leak and would like any information available. I have a source for sodium bentonite locally but what is the preferred application method.

[Pat]

The best situation is with the pond drained and dry you mix the bentonite with good clay and pack in a good layer over the entire area near the leak.

OK, you have water in yours... So, you try to sprinkle the bentonite relatively widely in the vicinity of the leak. Leaks are not always simply a straight shot from one side of the dam to another. So, you need to shotgun the general area and not assume the origin of the leak is exactly across from the exit point of the leak.

If you have trees on or near the dam you can look forward to more leaks later on. The roots make channels for the water to flow along. Like a drain pipe without an anti-erosion collar. If a root or heaven forbid, the tree dies the roots will rot away and leave behind "pipe(s)" to effectively drain the pond.

Be prepared to use a significant quantity of bentonite to get results since the application method of sprinkling it around the general area thought to be leaking is not efficient. I know people who had to make many applications before they got beneficial results.

Best of luck to you.

You don't want to hear this but the most sure fire way to "FIX" it is to knock a hole in the dam and let it dry enough to get in with equipment and spread good clay and bentonite over the area containing the leak. Then repair the dam properly with a trenched keyway.

Lets hope you get lucky.

Pat

[TimSullivan]

Thank you Pat.

We brought the pond level down slowly until the leak stopped then dropped the level another six inches. Then did as you suggested laying a mixture of clay and bentonite twenty feet on either side of a straight line from the leak and from the high water level to as far below the lowered level as we could pack the mixture.

Then everything just sat there as we had no rain and the stream that fills the pond was almost dry. Well our rain gage tells us that we have had almost three inches of rain in the last two days and the pond is filling nicely. The level is now well above the level of the leak and NO leaking. We should be at full pond by midnight tonight.

Thanks again,

Tim

[Pat]

I just love it when a plan comes together!

Pat