Pond Boss Forums POND CONSTRUCTION Soil questions Easy way to fix some types of leaks

I may have stumbled on a way to fix some types of leaks.

I have a small pond, which was dug in early September. It is only 20 by 20 feet and about 5 feet deep. It is built into a slope and has a dam. As soon as it was dug the water gradually came up about 2 1/2 feet from 2 very small springs. One was above where the water level reached before it stopped coming up. Then we got about 6 inches of rain and it came up a foot. It has been unusually dry here and over the next week with no rain it lost about 6 inches, and then stayed the same level for a couple days.

I was worried about this as the back slope of the pond is visibly seeping water and dripping into the pond so between that and springs it seemed a lot of water was going somewhere.

When the pond was excavated the clay in the dam was not compacted as well as it could have been as it was on the wet side, and difficult to work.

When the water stopped going down and found a level it was maintaining, I went out with a wooden baseball bat and worked my way along the inner sides of the pond, beating it down with the bat as I went. I found if I dipped it in the water I could get a couple good thwacks with the bat before clay began to stick to the bat and I had to dip it again. Every time I hit, the clay would indent a couple or four inches and I just kept working it, thwack, thwack, thwack, dip, thwack, thwack, thwack, dip, until it was at a degree of compaction that the bat only made one inch indentations and the clay began to feel solid and plastic. I did this right down to the water line and even an inch or two beneath. Then I used a shovel in the same way, smoothing out the furrows left by the bat, dip, thwack, thwack, dip, thwack, thwack, all along the sides.

The water immediately started rising and in the two rainless days that followed the pond came up 2 inches. We have had some rain now and it's come up more but it doesn't seem to be loosing what it gains.

I'm not sure if this could make the problem worse in some situations, but it seems to have worked for me. If someone has a leaky pond this might be something to try as the simplest solution.

I'm not surprised. When clay is "puddled", or compacted, it's a different animal. Back in the old days before sheepsfoot rollers, people used to drive their sheep or catle over moist clay to make it hold water.

ahhhh, the old thwack, thwack, thwack, dip method

that's great littlestfish, a very humurous and rewarding story. i hope it works on the long term for you.

Well OK ... Truth is, it wasn't quite as easy as I first thought, but I've been continuing to do battle with my leaky pond using nothing but a baseball bat and my pond is 3 inches from full and the water is still rising. I'm still crossing my fingers, but it looks like I may have the problem solved.

Here is what I learned in the process.

After the first beating with the bat reported above, the water came up about 6 inches from it's previous level, but then even as the heavy winter rains began, it would gain water and then loose it at an inch a day, back to about the level it came up to after the first beating.

There is a small seasonal creek on a hill above the pond so now it is running it is easy to fill the pond with a hose.

After it was filled it would loose about 4 inches the first day and about an inch a day after that, leveling out at about 3 feet deep with 3 feet of ugly waterless embankment. In a 6 foot deep pond, this is a real eyesore. As there is water visibly trickling in from the back slope above, I could see I was loosing a lot of water somewhere, and at this time of year, when everything is full of water from winter rains, this is not good news.

After filling it and watching it loose water a few times, on the theory that the leak was close to the water line where the water leveled off, when the water was close to leveling off, I began going along the embankment at that level looking for anything that might be a leak. I developed a technique involving a thin piece of clear plastic tubing and a mouthful of canned milk which I would squirt from my mouth into the tube releasing just a few drops to the side of any small hole or crack I saw on the embankment just below the water line. To my delight I found a couple small holes the size of my little finger where there was a visible current flowing into them .

It seems like knowing where you have a leak is 90% of the battle.

One thing I noticed once I located these leaks, is the dam in that location was slightly softer underfoot than in other places where it has really firmed up over the winter. So that can be one clue if you are trying to locate a leak.

In one of the leaks I tried to stick my finger in it and found that part of the dam was frighteningly soft and squishy compared to other spots and I could easily continue to push my hand and and lower arm into the soft clay.

So I drained the pond as completely as I could and I let it sit and dry out a bit for about 10 days. As I waited I got a hold of 5 50 pound bags of sodium bentonite.

My plan was to drive the baseball bat like a giant peg into where the leaks were, fill them with bentonite, stick a clay cap in there and hopefully no more leak.

It wasn't quite so easy. In the place I previously shoved my hand, there was about 3 square feet where the dam was very soft so I ended up repeatedly making 2 foot deep holes with the bat and filling these with bentonite granules . The benonite helped absorb the water in the sloppy clay an made it stiff enough I could then beat this area firm with the bat.

I did this same thing in the other area where there was a leak, though the mushy clay are here was only about 1 square foot.

I thought I had my problem licked, and with great hopes I refilled my pond, only to see it once again loose 4 inches of water in the first day.

What a crappy feeling that was. I felt completely defeated. I had no idea where it was leaking or what I could ever hope to do about it.

Yesterday afternoon I wandered out there, feeling resigned to living with an ugly ½ full pond on my tiny piece of land. The water was only down 4 inches from full but I knew it was still leaking at the same rate as before. Just for something to do I began wandering along the pond edge looking for anything that might be a leak up at the level the water was at. It only lost an inch a day after the first 4 inches so I figured there might be some leak up higher too. I found a small hole the size of my little finger, under about an inch of water, and by making little clouds of clay with my fingers beside it I noticed it seemed to have quite a suck. I still had 2 bags of bentonite left so I dropped a couple granuals in the hole and saw they seemed to go into it with more speed than just floating to the bottom.

Seemed to be a substantial leak. I wondered if it might be part of the problem. I wasn't expecting anything so close to the high water level.

So I got a 4 foot long and two inch wide stick and pushed it into the hole to see how deep it would go till I hit firmer clay. I easily pushed it down 3 feet and as I did so I saw a few air bubbles come up from about 3 feet under the water suggesting this leak had a few connections further down the dam and far below the present water line.

When I pulled the stick out of the hole, the water began really pouring into it, with enough force a pine needle over the hole began spinning round and round, like a sink when it's draining. So I got my trusty baseball bat and pounded it almost it's full length into the hole and when I pulled it out there was still a strong current running in there so I began pouring in benonite .

I would pour in a whole small bucket and then pound the bat in again to force it deep into the hole, The bentonite tends to ball up once it hits the water and can make it look like the hole is plugged when it is just plugged at the top. .

After pouring about 4 small buckets down this hole, and using the bat or stick to force this deep into the hole and seeing it disappear, and the water still pouring down in there, I began to wonder what was going on. It seemed maybe the bentonite was going into such a big underground stream it was just getting washed away. I thought maybe there needed to be something more solid so I broke some chucks of firm clay into pieces resembling a bite size piece of chocolate and once I had ½ a bucket of that, I mixed in granular bentonite as the other 1/2.

I slowly poured and shoved another 3 or 4 buckets of that into the hole pushing it down with the stick, it all still seem to be disappearing though it was beginning to slow down and only the smaller stick would go all the way into the hole. . Then I threw in a few two inch long by 1/8 inch wide strips of landscape fabric. I was thinking, what plugs up my sink ?

A couple more buckets of bite size bits of firm clay, bentonite and the stick packing it in, and the hole began getting solid and I was able to fill it.

Then I went a few inches beside it, where I had noticed some air bubbles when i was poking around on the first hole, and I found another soft spot so I repeated the whole process there.

As a grand finale I repeatedly jumped up and down on the dam over where I had made the repair and it did sink an inch or two.

I wasn't very hopeful I had really stopped the leak, but today my pond not only hasn't lost any water, it is an inch higher, and is 3 inches from being completely full. It may be a bit soon to start gloating but OH JOY !!!

I may still need to do the same further down the dam, but I feel pretty sure I found my problem and can fix it. And I still have a bag of bentonite left.

I hope this might help someone else with no tractor or way of getting big equipment into a small site, have a full pond.

I think you hit the nail on the head littlestfish. 90% of the battle is knowing where the leak is. I've spent the last couple of years trying to develop a reliable way to locate a leak using electronic methods and it is really tough to do. I've thought that if I could just narrow down the area I could treat it with a method similar to yours.

One thing I noticed that might be helpful is when a stick is forced into a leak that is under the water line, and the stick is substantially thicker than hole, it makes air bubbles come up from other leaks that are connected in a seam. Maybe this could be experimented with, and improved on, like figuring out a way to force pressurized air into a known leak to see if bubbles come up elsewhere, as this can reveal if there is other inlets into a leaking seam.

My pond gained another inch since yesterday and is 2 inches from being full and beginning to trickle out the outlet pipe.

Congratulations Littlestfish! Quite a story in perseverance.

Great story. The same process is used on a larger scale. If the water is leaking in a specific spot and it can be found then it is easy to fix. As you proved.

The methods I have reported so far seem to have worked.

But I had one more problem develop over the winter, which I wanted to tell about, as the way I seem to have fixed it is different than the things I did before.

In the fall my pond filled up and for about a month seemed to stay full to overflowing. ( I now have turned off the outlet pipe as now I have a good grass cover, the overflow is gentle enough it isn't creating any possible erosion problem.) But then I noticed it would fill up after a heavy rain and drop about 1/2 an inch a day, to about 6 inches under being totally full, and it was doing this even when water is trickling in at the back. I am quite sure that this pond would stay full to overflowing for close to 10 months out of the year, if it wasn't leaking. I know 6 inches isn't a big deal, but as I want to enjoy the beauty of a full pond, use this water for irrigation, and in the summer I also want to send all the water off the roof of my house into the pond, to be used as irrigation, these last few inches of capacity are important.

I was disappointed, as over the previous summer I had put a lot of energy into further compacting the sides above the water line with hand tools. I also used up almost 2 50 lb. bags of bentonite which I made into a bentonite soup and once a week I poured this soupy mixture into all the cracks which opened up in the clay dam over the summer, until they would hold no more. It didn't seem there was much more I could do except to rip out the dam and start again.

But then I remembered last fall when the pond first filled up, there was one spot on the side which is in undisturbed natural clay topsoil, where I saw a lot of air bubbles come up when my feet created a bit of pressure on the bank, so I went there with my eyedropper full of canned milk and in the area of the bubbles I found a hole the size of my little finger with a strong current flowing into it.

I had not compacted this area with hand tools last summer as there is a lot of small rocks which get in the way.

So I was glad to find the problem was in an area I had not previously worked on.

I poured a bit of bentonite into the hole and whacked down the bank with the back of a heavy axe, and was rewarded with the water rising about 2 inches a day to the point of overflowing.

But the solution had seemed a bit too easy, and I wasn't surprised a couple weeks later when I woke up to see I had lost 6 inches of water overnight.

This time the leak was similar to water going down the bathroom sink. It seemed the hole I had previously found had opened up even more.

I recently had to deal with a plugged drain in my house, and it was kind of funny having one hole I wanted to plug, and another that plugs when I don't want it to.

Which got me thinking...

I got some acrylic wool which seems to last forever if it ends up underground, and I chopped it into 1 inch pieces and then I pulled these apart into the tiny threads, so I had fluffy bits of acrylic, and one by one I fed these into the hole. It took about an hour, but after a while the bits of acrylic fluff began getting sucked in slower and slower. I tried to encourage things by pushing them in , but after a while there wasn't much flow and I began shoving in dry bentonite and then a couple oval balls of clay. It has stopped leaking, and if it was my kitchen sink, it would be hopelessly plugged.

If it opens again, I think I might try taking a long string of acrylic wool and tie some fluffed up shorter pieces along the length. I could then slowly feed this into the hole followed by dry bentonite. The bentonite does stop the water flow, but it needs something to anchor it in there, which is how the wool works.

I don't know if the problem is permanently solved, but it seems like it may be.

First good work.

Where was the hole that you filled? In the back or in front?

Otto

Now, that's neat.

Littlestfish, you have waxed eloquent regarding a very common problem which tears at men's hearts. Very detailed, vivid explanation. I plan on doing similar on a larger scale. I have bought a 10" X 10" tamper and intend on using it on one side of my pond which is sandy. I will put down bentonite and ruin myself tamping. You have given me great ideas on how to discover sources of leaks.
What brand of baseball bat do you use, eh; also the weight and length.

Nice to see someone having some success and fun at the same time. I hope you got it fixed.

I do seem to be gradually tracking down the problems and getting them fixed, and each time I do I seem to end up with another permanent gain of a few inches of water.

I used the bentonite in 2 ways. In the winter when everything is wet I used sticks or even the baseball bat to make 2 or 3 foot deep holes where the dam was mushy and I poured and rammed bentonite into those holes in the hopes of firming things up. Even though we built the dam in September, it was still too wet to properly compact, so that is the problem I have been having to deal with. As the dam dried out and developed small cracks I discovered some of them went deep enough I could pour in several gallons of bentonite soup, and if I let it dry out for a week I could do it all again. At the end of the summer those same cracks would only have room for a couple cups of the mixture, and I reasoned that the air spaces I was slowly filling up with bentonite residue as the water dried, were the spaces that were transmitting water when the pond was full in the winter.

Bentonite seems to need to be confined by something to hold it in place. If you put a cup of dry granules in a bucket of water it just turns to soft liquid mush. When you pack it into a confined space, its swells and it's own swelling prevents it from absorbing enough liquid to loose the solidity it needs to withstand water. I wonder if putting bentonite into a bunch of gelatin capsules which slowly break down, would be a way to get the bentonite to go deep inside a leak, before it began to swell?

The tamping I did was to compact natural clay, not the bentonite. From what I have seen, I don't think bentonite is really the best material for compacting. I'm not even sure it would compact at all.

My dam is on the south of the down hill side of a slope, and this last leak was on the east side in the natural soil, just above the solid clay subsoil. I was worried that side would always leak, once the water got above the solid clay, but the topsoil has a high clay content and it doesn't seem to loose much through there. It seems the water just found one place that let it through, and gradually created a good sized hole for itself. Because it's in natural topsoil and there is some rocks, it's not so easy to compact it. Because there was an obvious hole with a current, trying to block it up with acrylic wool seemed the best bet.

For compacting I have come to prefer a heavy axe head. But a light weight wooden baseball bat is nice to smooth this out.

It sure does look nice when it's totally full.

This paper was written, given to me by a bentonite salesperson out of Houston. I hope it helps in some way.
Greg

"POND SEALING WITH BENTONITE 2010

Historically, clays have been used to provide earthen seals. Modern technology recognizes that sodium bentonite, a clay having superior qualities, will provide a better barrier to the movement of fresh water through soils.
Sodium bentonite is a unique material. In the presence of fresh water bentonite will swell. Depending on the quality of the bentonite and of the water, the bentonite will increase several dimensions in volume. When exposed to large volumes of fresh water, bentonite will continue to expand forming a “gel” slurry and eventually going into a state of free swell; breaking down into its smallest dimensions, resulting in muddy water. To prevent this from occurring in a “sealing” application the dry bentonite is protected by mixing it with the soil and then compacting into a sealing blanket.
It should be noted that the presence of salt or salt water can have a negative effect on the ability of the bentonite to fully hydrate and develop a satisfactory seal.

SITE PREPARATION:
Remove boulders, tree stumps, roots and foreign objects. Grade and level as necessary & cover exposed sand and gravel or any other area that obviously would leak with a “preliminary base” of the local clay. Sides or banks should have a slope in the range of 3:1.

BENTONITE:
The amount of bentonite required depends on the type of soil to be sealed. A soil engineering report would be helpful however a simple and cost-free analysis is described here.
In the bottom of a 5 gallon pail, drill 20 to 25 holes about an eighth to quarter inch diameter. Gather enough soil from the area to be sealed to fill about 3 inches of the pail. You can either select the most porous soil which is sand, or a mixture of soil taken from several areas of concern in order to present an average soil.
In this soil, mix 1 to 2 pounds of the selected bentonite and tamp down in the bottom of the pail. Into this, pour a gallon or two of water; wait and see if the bentonite as it swells, provides the necessary seal. This should only take a minute or two.
If not, repeat the process and increase the amount of bentonite by half a pound until the water is contained within the pail.
The bottom of the pail represents about one square foot. When you know how many pounds of bentonite it takes to seal the pail, then you know how many pounds per square foot to distribute and roto-till into the pond, dam, or other earthen structure.

BENTONITE SELECTION:
Sodium bentonite is available in various grind sizes, from a fine powder like drilling mud to 30-Mesh up to ¼ in chips. The two best particle sizes are Benseal an 8 mesh or Casing Seal which is a mixture of particle sizes. Any of these products are available from authorized Baroid IDP retailers.




-2-

APPLICATION:
The required amount of bentonite is uniformly applied over the area of concern. Mix dry bentonite into the top 4 inches of the soil to be sealed. Moisten the working area with a spray of fresh water and compact, taking care not to puncture the sealing layer. In some instances the decision has been made to apply a second layer, consisting of compacted local clay approximately 2 inches thick. This is done to protect the bentonite-sealed area.
The sealed area never becomes hard but remains soft and plastic. Effort should be made to prevent punctures by hoofed animals, people or vehicles.

Experience indicates that in a bentonite-sealing project, the majority of success is dependent upon proper installation. The use of high quality sodium bentonite, adequate coverage and uniform placement are important for successful sealing. Bentonite is not a miracle or a magic material, it is just a tool to help you achieve a desired result and like any tool it must be properly used.

Often the customer wants to “short-cut” the process by dropping the bentonite through standing water. There is no possible way to determine exactly where the bentonite will settle making this a true hit & miss proposition. In addition as mentioned before a situation of free swell will occur that does not contribute to a long term seal.
If the customer insists on this method, it should be noted that while sodium bentonite is not toxic, the powder residues from the package can settle on gill plates of fish and suffocate them.


Phil Polak
Baroid IDP
817-832-5260"

You are an inspiration. As we look from our porch out to our 60-100' half-filled pond with despair, you give me hope!

Hey, DennisRex, welcome to Pond Boss! Post an intro of yourself in the new member intro section of the forum and tell us about yourself and your pond and the issues you're having right now. Maybe some pics so we can see what you've got going on. You're definitely in the right place for help, so post up with your questions and needs and we'll get some opinions and suggestions for you!

I just had to come back to boast about my little piece of heaven!

This year my pond has stayed close to full. It is only about 6 to 8 inches down from overflowing, and I have been watering a large vegetable patch from it once a week. It takes it down a couple inches but over the week it has rebounded. It is slowing down a bit now, but considering the time of year I have no complaints.

But here is the best part...

Although the main body of my pond is only 20 feet by 20 and 5 feet deep in the middle, with a 10 foot circle the center the only part that is free of pond plants, the water is crystal clear. I can climb down a ladder into the steep side and avoid stirring up the mud, and with the help of a child's blow up plastic floaty ring, I can float on my tummy or on my back without making the big swimming motions that don't work so well in such a tiny space. The small blow up ring keeps me afloat but with most of my body under the water, not on top of it.

I'm not sure why the water is so clear. It is full of tree frog tadpoles which quickly ate all the filamentous algae which began to clog up the sides in the spring just before they got born. They are now in various stages between being tadpoles with back legs and perfect teeny tiny frogs, in various shades of green and gold. There is also salamander and newt larva who have eaten anything resembling a mosquito larva, and giant water beetles. I don't have any fish and I don't want any, as the pond is full of life as is.

Anyways... it is very hot here and the land around here is now quite dried out, so being able to have a semi submerged float in such beautiful cool clear water is heavenly.

I never expected the water would still be crystal clear and at all inviting in mid August. That part is beyond my wildest hopes. I feel really lucky I have a spot that had the capacity to do this.

When I started talking about this, I thought I had found an easy way to fix some leaks. It actually turned out to be a fair amount of work, and after I solved one problem there would be another one, but I guess with the right situation, persistence can pay off.

Thanks for all the advice and encouragement.

Thanks for the update. It sounds like the pond turned out perfect for you!

I just uploaded some before and after pictures in the photo gallery section, so people can see the improvement.

The first picture was taken in late January of 2009, at the wettest time of the year, when any small hole in my yard holds water but won't drain. Except my pond... which drained quite well. It is about 2 feet down from over flowing in this picture. This year it overflowed until well into June.



The next picture was taken in August 2010, at what is the driest time of the year, after I had done all of the things described above. The greenery makes it a bit hard to see, but it is about 6 to 8 inches down from over flowing. As I use it to water my large garden this is a big improvement.

Hi Littlestfish,
Enjoyed reading about your experiences overcoming leaks.

I noted in one of your posts you are planning routing roof water to your pond. I did this very thing when we built our house next to our pond. It just seemed like the right thing to do especially as I was concerned I may be short on runoff water.

I did it in two ways: 1) Buried 4 inch drain tile and ran the gutter down spouts into the tile and to the pond.
2) sloped the ground in such a way to catch additional roof runoff and channeled it to the pond.

The first summer I was able to get a good crop of grass growing after completing the drain work. Winter came and being in a midwestern climate we enjoyed using our fireplace and wood stove. Both have roof mounted chimneys.

Well next summer after numerous rains the grass along the drainage channel from roof to pond died. This got me worried I may again have done the wrong thing.

Right now we are in a fast snow melt and water is still draining from my roof to the pond. I have observed brown stained water on the ice in the areas the drains enter - Could this be creosote??

Another potential issue with using roof water direct to the pond is PH. I checked some rain water from our rain gage and the ph was very low (don't remember the values but remember being supprised). If you have any low PH concerns (mine usually is around 6.8 - 7.2 and occasionally 6.2 to a max of 7.4 one time) this may be another issue.

I'm now temporarily rerouting the down spout water.

Is the roofing material made with the anti-moss/anti algae stuff built into the roofing material? I don't know if that would kill the grass or not, just throwing a quick thought out there.

Grass will die if the piping is not buried deep enough. And creosotes usually black I thought.. I've got all my gutters to my pond, I buried them all as deep as possible to avoid freezing and winterkills of grass.

Esshup, I do believe the roofing does have the anti moss stuff. I hadn't thought of that, could be.

BGK, I agree if pipes are too shallow it can kill the grass above but these pipes are plenty deep. The area where the grass died is where the water runs off the roof onto the surface of the grassed area and flows down a lowered shallow grassed channel to the pond.

On the color I was just guessing based on my experience with the glass window on my wood stove. After burning several hours it can get a brownish coating that when cleaned off with fireplace glass cleaner and paper towels leaves the paper towels brown. Also in hindsight now I remember seeing a lot of wood burning chimneys can stain the roof and surrounding areas brown over time.

Thanks for the ideas.

Hey pond people

Well now it is winter, and unseasonably cold here, so no more swimming for me, but I just learned a new trick for finding leaks that I wanted to share.

My pond has maintained the same water level all winter as it did all summer. After a big rain it fills to overflowing but then quickly drops back to the same level. Obviously there was a leak somewhere at about the same level it dropped to.

It is just the last 6 or 8 inches, so it doesn't matter that much, but I still suspect if I could find and seal those last leaks, my pond would probably overflow most or even all of the year.

The problem is, the edges are now grown over with thick grass and clover and marginal water plants, so it would be next to impossible to find small leaks.

We are having a cold snap of minus 6 Celsius at night and highs of 0. This put a skim of ice over my pond, and I got an idea. Moving water tends to stay open, and I knew the leak must be at about the same level the water had gone down to, so I went to see if any areas at the edge were ice free because of the movement in the water caused by the flow going out through the leak.

Withing 2 minutes I found 2 leaks which once I found them could be seen to have a visible current, and this movement of the water had kept the area of the bank around the leak ice free..

Probably if it was really cold, like minus 20, even the moving water would freeze, but for anyone who has a leak that causes the pond to consistently drop to a certain level, mildly freezing weather, which creates a thin skim of ice everywhere the water is still, is a really effective way to find the leak.

On the subject of sending roof water to the pond. I have heard that some roofing material contains elements which can leach into water and be a problem, so probably people should do some research on what might be in their own run off before using it. I have a metal roof, which does not affect the water running off it. My roof water is yellow colored though. I think it is from the leaves and debris in my gutters.