Pond Boss Forums POND CONSTRUCTION Building a dam The Saga Continues

Hi all. It's been a while since I've posted on Pond Boss, so I can't remember the threads I contributed here when I last posted. Still, maybe I can fill you in and some of you will remember my plight.

I've been fighting a lake that leaks for years. We've tried all sorts of things. I've drained it, dug another core ditch in front of, and deeper, than the original one. We've plated some suspicious looking areas in the lake bed, and around the shore when the water is down, with good clay dirt, and reinforced the levee, which it probably three times the size it needs to be.

And in spite of it all, it still leaks. I've had several threads here about it. Some of you may remember it. We've slowed the leak down a lot, but eventually it still leaks down the same elevation and stays there.

I had a back hoe dig a little behind the levee recently and he hit some junky soil that was once the natural dirt. It has a thin band where the old grass was. A little deeper it's a band of that old blue gumbo kind of mud, and water is trickling all through there. Obviously there is water moving there. whether it is seeping down through a soft or sandy spot in the lake bed, or coming from natural seepage. Either way, water is moving about 6 feet deep from the back side of the dam, right up next to it. It's trickling steadily from the direction of the lake.

So we've now identified a new place where water is moving. Our next proposed move has been to dig a core ditch in the back. They think the core ditch on the levee, and the second core ditch in front of the levee, didn't get down deep enough. I watched both of them being dug, and I thought surely it was deep enough. I'm guessing they went down 15 feet, and they were in ideal clay soil. It was as solid as it could be, and no sign of moving water.

But now I think the guys doing the work currently may be right. They are totally convinced that "this" is "the" leak.

The fish have been stocked for several years and the lake has some nice fish, and I don't want to drain it. Even if we did, I don't think we could get the deep elevation on the front side like we could on the back side. We'd have to drain it completely and just plate the whole lakebed with clay dirt.

What they want to do is dig another core ditch just off the back of the levee, and go down about 20 feet. We are now going about 12 deep with a backhoe, and get below the blue mud to dry, hard, clay ground. We want to go even deeper than that.

We want to line the new core ditch with plastic, such as draping a thick piece of black visqueen on one wall and then back filling with clay dirt. We're not going to be able to dig a simple core ditch, because too much water is trickling in that one narrow layer, and would put water in the bottom of the ditch. We can't go very wide, since we are already so low, that any rain would fill it up. About the only thing we can do is dig a 4-8 foot wide core ditch, line the visqueen as we go, and cover it as we go. Thankfully, the distance is not too long before it rises rapidly to the hills on both sides, and the hard clay dirt. Due to the water tricking in, and no way to drain it, there is no way to get equipment into this proposed new core ditch to haul in and pack clay dirt. Thus, the idea for the visqueen.

We've tried everything else we know to try for years. I've gotten a world of suggestions here at Pond Boss. But, so far, this lake has baffled everyone.

I tried to give you plenty of detailed back ground info here. So, the question now is, have any of you had to resort to a new core ditch on the back side of a levee? And if so, how well do they work? What are your general ideas, thoughts, and suggestions on what I have outlined here? We are to the point now of either doing this, or just accepting the low elevation and enjoy it the best I can, or drain the whole thing and plate the entire lake bed.

I'm interested in any thoughts and experience on putting a core ditch on the back side, in order to get deeper than the core ditch at the bottom of the levee, and the one in front of the levee. I'm guessing water is seeping down in a sandy spot, and running under the existing core ditches. I'm hoping if we can get down deeper than all of that, that it will finally be like putting a stopper in a tub, and once the water back fills all the sandy and junky strata under the lake, that it will then fill normally and hold water.

OK guys...give it your best shot, because I'm running out of options.

Thanks!

Bill Lake

Sounds like an plan. I would use some EPDM material rather than the visqueen. Visqueen breaks down. EPDM lasts forever underground. You can buy 6 foot wide rolls at many big boxes stores that is used for roofing.

How big is this lake? I am guessing that you dammed off a valley and your thoughts of the leak is passing through your dam?

Here in Ontario I have seen some very very odd things with ground water. The rule of thumb here is it will follow the lay of the land. Most really good wells are on top of hills. Long story long if you didn't strip all the top soil from the lake bed and see any wet spots the dam most likely is the problem. These soft spots will transpire water up hill away from the pond area. It is the strangest thing and I for one would never believe it until I seen it.

My thoughts are that if the lake is big enough like 10+ acres I would be just happy I have water that stays.

Cheers Don.

Bill, I've gone back over all of your posts and find that you have tried just about everything. You've thrown a lot of sweat and cash at it.

One thing stands out. It wasn't leaking until you raised the levee/dam. And all of your work seems to be at or behind the dam. My suspicion is that the higher level found a sand or rock pocket on the sides.

But that's a very uneducated guess.

After I finished this, I did a search on the interenet, and interestingly found a previous thread I had posted here. It has a lot of background info from me, and a lot of thoughts, ideas, and suggestions on core ditches.

The name of the thread is:

"Need Opinions On Secondary Core Ditch."

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=233874

Thanks!

Bill Lake

We've gone around the edges the last couple of times and hauled in good clay dirt with a dirt [pan and tracked it in with a bulldozer. We also dug a core ditch on each side in the areas we thought might be leaking.

I was really surprised to see the water tricking out just behind the dam, and to see the layer of blue mud where it came from.

The one thing that stands out now is that the lowest point behind the dam....where the old creek ran....has always been soggy. I never saw water moving, and since it was in the old creek bed I thought it was naturally soggy like that. But now I'm beginning to think that somehow water is seeping down in the lake bed and getting to the old creek bed and running under the dam.

Does adding a core ditch to the backside usually work, and is that a procedure that is used on lakes that have a history of leaking, and especially when the base of the back side ofhte dam is always soggy?

Bill I can't tell you what usually works. My best guess would be that it doesn't usually work.

Having said that, the back side of our old farm pond that I can remember back 50+ years (I'm 60) always had a "soft" spot. Had it before dad had it cleaned out with a dozer when I was in grade school and had it after. Always had to remember during wet times to not drive a tractor below the dam or would get stuck and even in dry times it would be soft there. Never thought much about it. Grew up with it.

When I cleaned that old pond out myself in 2013 I found that spot as we were refurbishing the dam. Not wanting to take the whole old dam out, I just dug down as deep as I could go with the dozer. Almost got stuck and barely backed out. Shoved a bunch of clay in and packed best I could with the dozer. Then as I got it solid enough for our rubber tracked tractor and rubber tired pan scraper to go over loaded, packed it down and added several more feet of clay. Basically built another dam on the back side of the old dam and sloped it so we could mow it. The old dam was narrow and steep on the back side.

We no longer have a wet spot there. Did I stop the leak? Maybe, maybe not. I may have just pushed the water lower. There is a seasonal creek right behind the dam and the water may just flow to it now directly rather than surfacing. But at least there is no wet spot and we can mow it. The pond seems to hold water at least as well as other ponds and strip pits in the area as far as how far it drops in dry spells. So while I would not claim it to be jug tight and it may very well leak, it does not leak to a degree I am worried about.

Just my one off experience with trying to stop a leak behind a dam.

Thanks SNRUB. That sounds similar to my situation. And it sounds like it fixed your problem. Your experience with this is encouraging. Thanks!

Bill

One thing I haven't asked....if you use heavy visqueen on the wall of a core ditch...will any moving water from the lake hit that and just seep down the visqueen to the bottom of the visqueen?

The other obvious question is....is visqueen any better in the finished project than just good ole quality clay dirt?

The visqueen idea came along when we thought we realized how difficult it would be to get a core ditch wide enough to safely get equipment in and out of, and working in. I'm still not sure how we can do that. With water seeping in the core ditch as fast as we dig it, I'm not sure how we're going to be able to get good soil in there, and packed properly.

Any thoughts and ideas will be appreciated.

Thanks again.

Bill

Well it fixed the wet spot. I would not guarantee it fixed the leak. But the leak was small enough it was never much of a problem as far as the pond holding water. Keep in mind we are in an area that gets about 42" average rainfall per year usually with some pretty large (multiple inches at a time) rain events. So a small leak in a pond likely would only be a problem in the driest of years.

Our local NRCS guy told me when he was designing our pond that a lot of the local cattle watering ponds had minor leaks or seeps in the dams. But most of these ponds are built with only bulldozers and are nothing more than the top soil scuffed off where the dam will be, then dirt pushed up out of a ravine into the dam with the dozer doing a little compacting. Not at all the way a pond should be built but there are hundreds if not thousands built that way in this part of the country including the initial build of my old pond (I can remember the first time this old pond was cleaned out, but not when it was built because that was likely before I was born. D7 17A Cat cable operated dozer and I must have been 10 or 12 years old). We did at least compact the dam with a rubber tired scraper when we rebuilt it. I'm talking about half acre ponds to water cattle with little initial thought of fishing or recreation, which is what my old pond originally was.

There is usually a lot more planning, thought and process done in larger ponds with recreation and fishing thought about in the initial planning stages.

I'm a farmer with a dozer. Not a contractor nor professional pond builder. If I do something and it does not work there is no one to blame but myself. So I might do things no self respecting contractor would do. And if it does not work the dozer is there so I dig it out and do something different. On a small pond with lots of extra material to work with a patch on the back side of the dam might work. And it might not. I built almost an entire extra dam on top of and behind the old dam and this one appears to be holding.

At this point we are pretty sure that some of the water is going under the levee and under the core ditch. When we get right agaisnt the back side of the dam where it toes out to natural dirt, and dig down about 4-6 feet we hit a strata of blue mud. Construction people tell me that means a lot of water has been moving there for a long time.

We wonder if there may be an old stump hole out in the lake that allows the water to seep down. Or, is it finding an old ditch that and following it under the core ditch. All we know is that water is moving at the back side of the dam.

My eyeballs always say the lake is around 8-10 acres, but the surveys show it to be less. With it down like this, I'd say it's less than five acres.

It's a nice little lake like it is, but it is a beautiful little jewel when it's full -- one of the prettiest ones I've seen.

This year I will begin (continue) using it as it is, and enjoying it. My plan is to stop the movement of water out of the lake wherever I find it. As late as it is, it might be best if I wait till next summer to do any major dirt work.

Thanks for the suggestions.

Bill

We're going to need something much wider than that...such as 20 feet.

Our concern now is....will the water hit the plastic and, with any amount of pressure, be forced down the plastic to the bottom where it can continue seeping, just only deeper.

Has anyone got any experience or thoughts on that? What happens when underground water hits a plastic liner?

Thanks again.

"Bill"

Bill my thought is that the water will travel down the liner (like a crack in a rock) as there is no bonding between the liner and the soil.

BTW I had to double core with a second core once on a pond and learned a lesson. In my case the second core was not as high as the water level of the pond. The water made a soft / leaky area between the 2 cores. I went back and increased the second core height to the 1st cores height. Has a dam big enough for a 2 lane road when finished. LOL

Bill:

Like Cecil said, visqueen won't last long term, if you go that route, you'd be better off using a pond liner type material, EPDM. IIRC they make it up to 40 mil thick.

I haven't done business with this company, but I'm posting the link so you can get an idea of the sizes of liners available.
http://www.justliners.com/epdm.htm

The NRCS office 2 counties over do something like you are describing with ponds that are in sandy soil that leak. They dig down as far as they can, all around the pond, and drop a curtain of plastic down, sealing the seams. They say that it won't seal the pond completely, but it sure slows down the leak. Here, you can dig down 40+' and still be in sand, so yes, the water will hit the liner, go down and go under the liner.

From what you are describing, I think when your pond hits a higher level the water hits the old creek bed/sandy soil and seeps thru the soil and goes under the core trench in the dam.

I'm not 100% sure that the new core trench/liner sheet will stop the leak. If it doesn't go all the way down to watertight soil, I think the water could leak out around the ends or beneath the liner material.

What about trying the polymer sealants? If you know about where the leak is, it sure wouldn't hurt to try, and would certainly cost less.

Two sources:
http://aquaben.com/ditch-pond-sealing/
http://www.polymerinnovations.com.au/solutions/dam-pond-sealants/
I have not found a bad review of either of these products.

Bill, use the search function and look for member Captwho. He is using a sealer that appears to be inexpensive.

I noted that when you dug your initial core trench you only went down 15 feet to the "ideal clay" soil. I am having a 5 acre lake built now and they dug down past the clay and hammered rock all the way down to the bedrock (about 3-4 feet of rock). They then brought clay back in the core and packed with a sheepfoot packer from the bedrock all the way up. They are still working on bringing dirt to the backside of damn and the lake is filling up and holding water almost too quickly.

If water is seeping down in your lake bottom through the soil/clay to the rock it could easily run under the core clay trench you have dug...

Maybe?

Good luck