Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Small Pond Leak

I have a pond leak that is almost identical to the one described by Katana. About six years ago my wife and I purchased some property that had an existing pond. From what I've been told the pond has been on the property for quite a while (the size of trees behind the grade, which may have weakened the integrity of the dam attest to this fact). In an effort to cheaply increase the size and surface area of the pond I installed a culvert at a higher elevation than the previous run-off. The spring-fed pond slowly filled to this new level and I was happy. For a little while at least. The pond soon began quickly draining to well below the original level. Eventually I was able to see and hear where the pond was losing water. It appeared to be in an area that was less muddy and more sandy than the rest of the pond (I'm assuming that it is close to an area with more sandstone). Using thick pond liner and bentonite I patched the hole. The pond filled and then quickly drained again revealing a new hole close to the original. This same scenario of a patch sealing the pond, the pond rising, and then a subsequent draining to a new hole (each time the hole has been about four inches in diameter) has been repeated several times. All of the subsequent holes are in the same general area. I believe that the pressure of the pond rising eventually causes a new area in the pond to open up and find a new access to the one "drain". I believe that overall the pond is in good shape. If I could find some way to fill in the length of the drain instead of merely patching the access to it I think my problem would be solved (but what do I know?). Is there some way to fill in more of the leak so that the pressure caused by the pond filling doesn't result in the forming of a new hole?

I see that several commented to a post submitted by Katana (who describes a leak similar to mine) and suggested that concrete should be used. What's the best way to do this? Is there a particular kind of concrete that should be used? With previous patches I've used powdered Bentonite. Without using a liner in conjunction with the Bentonite the pond pressure eventually eats through the 'patch'. Would a pelletized type of Bentonite that would be carried far into the depths of the drain (between the hole and the back of the dam) work better? Any help/advice is GREATLY appreciated!

Hello thebar [is that the bar, as in the stick, or Thebar?],

Forum activity falls off sometimes on the WE...if you don't get much activity we'll bump you for the experts on Monday.

Do the leaking areas appear to be part of the dam? Can you see where the water is draining out? Do you have any native rocky areas integrated into the pond?

Where in TN?

'Bar' as in the 'stick.'

No, the leaking is not part of the dam, it's on the side of the pond (25+ feet from the dam). Yes, when the dam lowers I can hear and see where it's going out. It's about a 4" diameter hole. I was going to embed a couple miniaturized pictures but I'm not sure how to do it. Is there any way to attach a small pic to my post?

No, there aren't any native rocky areas (at least that I know of) that are integrated into the pond (though the soil on that side of the pond does appear to be more sandy).

I appreciate the bump!

Mornin',Bar.

Since the leak seems localized and locatable, it sounds like it might very well be repaired. Pics would help, check the FAQ tab for instructions, and there is a thread devoted posting pics, which hopefully one of the moderators will include in this post, because I can't find it.

I'm not very skilled with infernal machines [AKA computers] or I'd save you all the trouble of looking this up and just give you the instructions myself.

Can you see where the water ends up, or is it just draining down a hole to destinations unknown?

The water drains out of the pond back behind the pond grade. The draw behind the pond certainly runs while the pond is going down and it appears like the water starts close to the base of the back side of the dam. It's difficult to tell since it's more of just a marshy area than a simple stream.

A few pictures:

Upper circled area is a previously patched hole. I dug out a rectangular area, plugged with bentonite powder, covered with thick pond liner and then held down with large rocks. The lower circled area marks the new 4" diameter hole.


4" diameter drain hole.


Culvert (left arrow) marks the pond 'high point.' You can see how far down the water level is. You can also see how far away the current hole is from the grade.

what if you bought or rented a trash pump and pumped the lake down enough to get some type material in there and let it have time to cure. i am clueless as to what bentonite is? a trash pump moves a lot of water fast.

Bentonite is basically a type of clay that swells greatly when wet.

I've actually thought about lowering the pond level as you suggest (although I'd like to be able to do it simply by starting a siphon if possible). I'm not sure, however, how to go about patching the hole once everything is dry. How big of an area do I dig out? How do I plug the area? Do I merely use concrete?

Given that I've had problems with new holes forming that appear to lead to the same underground channel it seems like I'd do better if I could plug the channel instead of merely plugging the hole to it. I'm not sure if this is possible. I've thought that maybe if I got some pelletized bentonite maybe I could use the water that is funneling into the existing hole to carry the pelletized bentonite into the channel a ways before it would start to swell and plug the leak. The bentoninte powder that I've used in the past does a pretty good job of plugging the hole but if a new hole forms to take its place it sounds like I'll never get the pond permanently fixed this way. Of course, I may be wrong in all of this. Anybody out there have any ideas/hints?

I'm still struggling to patch this hole. The pond filled completely after we received a bunch of rain this spring (so patching it was out of the question at that time). However, now that summer's here and we've had less rain the pond is once again at its lowest level. Anyone out there have any advice regarding how I could patch this hole??

Thanks in advance!

When the pond was full could you see the water exiting on the back side? That would give you an idea of how deep the problem is. If it's less than say 6ft I would drop the water level & dig down with equipment & fix it.
You're idea of pouring bentonite in may have merit if you have the patience. I would imagine it will be a very slow process.
I agree just plugging the hole is probably futile as the water will most likely find another route to the real problem.

Yes, even now with the water trickling out the hole the water is leaving the pond at the back of the dam (there's no real definable place where it exits but it's definitely at the bottom of the dam on the back side). I'm wondering if the pelletized bentonite would do a better job of plugging more of the leak but I'm not sure.

Like you, I'm thinking it may be better to just build a new grade farther down the draw and have a bigger pond/lake. Anyone know of any good pond contractors in the southeast TN area?

Check with Greg Grimes on this site. Greg is very trustworthy, works that area & can steer you in the right direction.

Here's Gregs link: http://www.lakework.com/

Thanks for the link--I'll definitely contact him (even though I'm not sure he would work on my pond since it looks like a bit of a drive north of his location).

Underwater Grout would work to seal the existing leak, you can also look into Soilcrete....

go here

look at the soil stabilizer, you need a hydrophobic polyureathane soil stabilization product..

Thanks for the link. Do you have any experience with their product?

heavies

thanks for the info--do not have time to look it all over right now -but will sometime today.

Where exactly in TN are you?

About half-way between Chattanooga and Dunlap.