I know I have not been here in a while, but I need some SERIOUS Help here.
As you may or may not know, I built about a 9.5 acre lake about 2 and a half year ago. Ok also, I have had a BUNCH of trouble getting it to fill up to the top with water. The lake is abouyt 30 feet deep in the deepest part. Recently, about 4 months back I deverted anothe stream to this pond to try to help fill it up. There has been water flowing in it for about a month now and this is very littel change in the water height.

Today I did a little bit more investigation and I have notice about 50 or so feet behind the dam in the original creek channel there is a good stream of water through there. I have come to the STRONG conclusion that I have a major LEAK!!! There is no way that there should be that amount of water flowing through there!! I am CERTAIN this is the reason why the lake will not fill up.

Now I have spent 3 years on this thing along with alot of time and effort to get my lake done.
What do I do about this leak? How do I go about fixing it?
If I have to drain the lake, thats no big deal at all. Should I try to fix this from the front or the back? Like I said draining it and loosing the fish is NOTHING at this point. If draining it at this point fixes my problem I will be glad to do it.
I was with the contractor two years ago when he cut the core and it seemed to me that he went deep enough. But for some reason the lake is not holding water. In fact it has NEVER filled to the top.

PLEASE HELP!!!!

Big Pond :

Get the contractor to come and look to see what he says. Take some pics and post them here. You need to be sure what the problem is and its extent before you take action.

Yeah I know... I have already thrown Thousands at this problem already. Actually to devert the stream I had to build yet another 2 acre pond on about 140 acres of water shed, and have it run into the big pond that is not filling up. The only thing I know to do if I can't do anything is to yet come away and sale this tract of land for the 3rd time in my career at this....I mean this is REALLY dis heartning here, I mean DEPRESSING!!!

Guys!! I really need yall on this one!!
Greg are you out there?? Give me a call man when you get a chance..

bp, Did you give Greg a PM?

No, I did not, at least not yet...

If we hear from Greg every couple of weeks in the warm months (busy season) we're lucky.

big_pond,

Sorry to read about the leak. It has to be frustrating. The first thing I would do is get the original contractor out to look over the situation and make a recommendation. Depending on what he says would determine the next step.

It's only a guess but from your description, proper construction, core dam, I would first suspect the leak to be in the pond bottom itself. What is the bottom like, especially in the near vicinity of the old creek bed? It is very common around here for old creeks to go underground for portions at a time.

To fix a leak like that properly will require draining and repairing. Do you have good clay available at the site? If so, draining, packing a couple of feet over the leaking area(s) should put you back in the game.

Well I thought and I "DO EMPHISISE THOUGHT" the creek bottom was made of clay, but I could have been wrong. I thought the whole bottom was clay. I had the soil maps on the place and it calls the dirt to be Ceicel clay, what ever that is.

I talked with the NRCS and they were talking that some people tend to recore the back of the dam area where the will dig about 1/3 of the back of the dam and re-core it back there. Has anyone heard of this before??

BigPond, hello old friend. I see you have finally made the discovery of why your pond is not filling up. I hate to hear it, for sure, and assumed by your prior posts, that there was so much clay you wouldn't have to worry about it.

The good news, is just that, you do have lots of clay to work with. If you can not determine where the water is going through, and the only way I can think of, if it is not just obvious, is by witching the void, then you will need to treat the entire floor above the water line with a clay blanket, to be sure, or lesser measures of disking and compacting and or hogs sealing your clay.

Good luck, and though I'm not around as much these days, I have noted your absence.

One last thought, be sure to look at all of your photos during lake construction. A problem I have personally had, is from stump holes that I had forgotten about creating, upon removal of various trees.

One last thought, you don't mention the gallons per minute of your diverted stream. It takes an unbelievable amount of water to make a dent in a 9.5 acre pond. Are you sure you have the volume of water?

Lack of volume would still not explain the lack water getting back in the stream.

Goodness. Sheesh. Tough one.


Upon further reading, it appears that she's going right under the dam, or possibly around it. Sounds like the core wasn't deep enough. However, who knows how deep is deep enough? You may have run into major costs, had it been taken deeper, and tons and tons of ponds are never keyed and work fine, especially in areas of good dirt. A clay liner of the whole pond may seal it, keeping it from ever going below.

Keep your head up, and look at the bright side. You have a two acre pond and a 5 acre pond. I know it is not what you want, but many of us here would be jealous.

I recall ML saying one time that good things come to those who persist. It is true. Take your time, and fix it. You can key the front of the pond floor. What suprises me, is that the weight of the 5 acre pond didn't seal it. The water must be going around the dam at the level it now holds.

It all seem sort of strang to me as well. I talked with the NRCS guy and he thinks its just springs near and around the back of the dam. I am not sure I just think it should be filling up more than it is. Of course we have had a drought this summer as well. He said let this new 2 acre pond with the over flow going in this big lake take effect first and see if it make a difference.
The flow into the big lake is around 20 gallons per minute.

Where it seem it's leaking is near the back of the dam in and around the the creek channel. I can go dwon streem about 20 feet from the bottom of the dam and see water flowing. This what leads me to believe there is a leak. I was told by hime that I could try to RE core the whole back area of the dam. Have any of you herd of this?

20 GPM won't do squat, but keep her capped off.

It may be springs, but spings below the proposed water level ain't good.

Wait and see is not bad, but not fun either.

A feller I know re keyed the back of his one time if I recall. He worked on the front too. Both together worked OK, but nothing like 40 full grown black baldie cows trampling the floor of the pond and dam.

Do you think 20 GPM will at least keep it full?
Iw onder if I can get a bunch of cows like that from. I am thinking I would HATE to drain the pond to try to fix this problem.

If I felt like the pond would stay full once it was filled up then there would be no issue. My fear is that if it EVER filled up it would sooner or later drain back out again.


I thought about drilling a well and letting the well fill up the pond and seeing what happens from there...

BigPond,

We need a little more information on your current situation.

1. What is the approximate volume of your leak? In gallons per minute what would you estimate the outflow to be?
2. Is the water leaving the backside of your structure muddy or clear? Muddy water is a good indicator that your structure is loosing earth fill and probably compromised.
3. How deep did you dig the core trench? What was the material like at the bottom of the core. Sand, silt, clay, rock, tree roots, etc.
4. How deep is the current pool (water level) above natural ground? The probability of a dam leaking goes up exponentially with the dam height. Even tightly compacted clay leaks to some degree; (.04 inches per hour for example). Small “clear leaks” are generally not of much concern on tall structures. Example – Big Mac in Nebraska leaks, they call the resulting leak, Lake Ogalala.
5. I agree with others in that 20 gpm is probably not enough volume in a 9 acre lake to cover evaporation and seepage. In my neck of the woods I like to use 30 gpm as purely pond maintenance. (no net gain or loss).
6. What type of equipment was used to compact the structures fill? Example – Dozer, Dozer scraper combo, scraper, sheepsfoot compactor, etc.
7. Was the earth fill material of proper moisture content? Dry soils regardless of their texture (sand, silt, clay) compact poorly.

Post a few pictures if possible.

Sorry to hear about your pond and I hope we can be of some help.

Good luck,

Ed

Ed, I think this may be another of your classics.

BP,

Sorry to hear about your situation. I know you've spent alot of time on this project to get to this point and now to have a leak is awful.

Following Ed's item #2, is there any way to inject a dye into the lake where you think the leak originates? Just trying to help you determine if the leak is from subsurface flow or lake discharge.

WOW!!! GOOD QUESTIONS!!!
Man this was good STUFF right here.

Ok for number:
1. Man it is tough to say. I look at the "total leakeage about 20 to 30 feet or so from the base of the dam in the creek chanel..Just a quick look, it appears to be maybe 15 gpm give or tak a couple. Like I said I look at it colectivly in the creek channel, and it apears to be this much.

2. is the water in the back muddy or clear
Well it is sort of on the rusty side. I can say that it is NOT muddy. If I may add I have two pipes across the back of my dam about 1/3 of the way up and about 10 feet into the dam. The NRCS called these two drains. They are incased in gravel with a bunch of wholes on the pipe. One goes down the right length of the dam while the other goes down the left and they meet in the center where the water is discharged out.
Now there is some trickle of water coming out of both of these, and it is rust color BUT NOT MUDDY.

Also about 5 feet from the dam just to the right there is a bolder with clear water running over the top of it as well.

But to answer you question, The water apears to be rusty but not muddy.

3.
The core was about 15 to 20 feet deep and was at least as wide as the track hoe bucket. At the bottom it appeared to be a gray silt, a HARD silt, and some of the times we would hit rock. He actually lifted a few bolders out. The core was wide enough in a few places to drive the dozer in it. While he was cutting the core, a dump truck would drop a load right behind where he dug.

4.
At the preasent the pool stands at about 23 to 25 feet deep in the deepest parts and has a surface acrage of about 4 acres right now due to the drought we have had.

The machinery used was a 2 trac hoe's, Dozer, and three dump trucks.

Well I hope this helps...I right now don't know what to do....maybe its not a leak...who knows...I sort of HOPE its not. The only way to REALY know (I guess) is to drain the pond and note the change in the water flow conditions in the back area. But I am starting to not like the idea of draining the pond now, I don't know maybe my heart will change about it later.


I tell you we were VERY cautious when we cut this core, I can't see how I could possibly have a leak!

please HELP!!!

Man I thought about useing a dye or something, but man that would be TOUGH!! I mean that is a BIG dam and a Big lake and deep too.


I was reading some where that someone wanted to do a sample of both the lake water, and the "Seepage water" to see if they could be the same thing. Has anyone ever done this?

....hmmmm. Do we have a reason to focus for a moment on these pipes? I guess I'm too green to understand...but...I don't understand. Are these your principal spillways? The gravel and perforations are really throwin' me off.

BP,

When you say rusty water, my thoughts turn to ground water with iron. The rusty color is a result of the iron oxidizing when it reacts with oxygen. Do a search on iron bacteria.

Like Russ, the rusty color makes me suspicious (doubtful) of a dam leak. However, you could have a bottom or side leak that is leaching through a rocky area and exiting behind the dam.

Try catching some of it in a jar and see what settles out. That might tell you whether the "leak" is going through a rocky area.

The drain pipes are put in (under) a dam where there are or could be springs to safely remove that water.
Lessens the prospect that a spring under the dam would hurt the structure through erosion or saturation.
I would doupt it is the structure or core leaking.

The NRCS called these pipes Toe drains. They go about a 1/3 of the way back up the dam then across the entire back of the dam. It is 6 in pipe with a bunch of little 1/8 inch holes in it. One pipe goes to the right one goes to the left. then they are discharged toward the main drain pipe. They are covered in gravel. I would say about a foot or so square in gravel down the entire length.

They are there just incase there is a spring under the dam, the water has a place to go.

It would be NICE to know that it is just springs under the dam...

Here is another thought that makse me suspisous. The second lake we built here 6 months ago, by the same contractor. Does not have this problem. This lake sole purpose in life is to rais its water level high enough to flow over into the big lake and hopefully fill it up. As a result I have this little 2 acre pond, (has no fish in it). But from the same senario, if you go down the creek channel form it, it is BONE dry!! Its like this dam has completely seald off the water. Why has this other creek channel have water in it?

big_pond, do you still have water flowing into the main lake?

I think you had mentioned in the past that the lake had filled to a certain level and never filled up higher than that? Is that true?

Your right, it did fill up to a certain point and then stop. Actually I just measured it on line with terra server. They have the most recent 2005 photos which show my lake and alow me to measure it. The lake back then was about 5.5 acres. It had filled to this point with all the rain we had in the winter of 2005. Now it has dropped about 3 feet since then. Mind you about a 1.5 fot of it was dropped this summer.

This past spring I decided to divert a near by stream into this lake. I esentially built if you would, a 2 acre pond on this near by stream, that filled up durin this drought. Now there IS more water flowing into the big lake. It has been doing this for about a month now.

So is there a level that the pond will not come up above?

If so (and bear in mind that I have zero pond building experience), might the potential leak be related to that elevation.

To rule out that possibility, could you stop any more inflow into the lake? Then see where it levels off at; also take into account evaporation and any rainfall.

So if you're loosing an inch a day due to evaporation (when theres no rainfall), but the pond is not loosing any more water than that, then it's holding water; thus meaning the leak is somewhere above that point????

Big_Pond, have you carefully scanned the banks for sand or gravel strata at the water line? A pond that big has about a half mile of bank, and there is alot of places for it to hide.

No I have not really done that YET...but what I can tell the whole bottom is clay. We had the wole pond rimed out and while we were riming it we never noticed any silt or sand or anything like that. It was mostly all clay..

Have forgot about you Sunil, just don't quit know how to answer that question.

I am SURE its not an obvious leak. It has to do with a combination of a spring under the dam and water working its way into the spring system under the dam from the lake. this would be my guess...

I would guess that if the leak is under the current water level and you removed any water inflow, the pond would continue to loose water until the water level fell below the actual leak.

Again, this is just my logic, without any experience base.

BigPond, price yourself a two foot clay liner. You will fix your pond with this.

Have you priced it? I would like to know how much. You likely could get away with the area above your pool, or maybe drain it a couple feet below.

Good luck.

You know, thats a REALLY good question right there!! One thing that concerns me is I would be covering up springs.....
I also thought about just filling in the deep areas of the pond..In other words just make the lake around 15 to 20 feet deep instead of 30 feet.

without diverted creek, how much land drains into your big pond? big_pond

do you have link to 2005 sat pic?

It is on terraserver.com

http://www.terraserver.com/imagery/image...r_id=380&t=&OL=

Click the left most part of the page and it will pop up right in the middel of your screen.

Big Pond,
If it is leaking my guess is also that water is working into the spring system and it could be at any elevation. I would guess that the elevation the water stays at is how high the water has to go to find an escape in the ridges your dam is tied into.
Then the water flows underground around the dam and core then on down to the low point behind your dam where it surfaces.

Big_Pond

I have been away from the computer for a day or so.

Wow, lots of good comments.
The perforated pipe you describe towards the backside of the dam is in fact a toe drain. These are a very good idea, especially for ponds with proposed higher head pressures like yours. They are very similar to a sewer drain----------only they operate in reverse. Instead of letting water out they collect any water that makes its way through the dam and safely channels it to an opening on the backside of the dam. If this toe drain were not installed and water did make its way through the fill, the result would be a saturated back slope of the dam. NOT GOOD! Once a dams back slope becomes “water logged”, it may begin to slip and erode severely. Remember, most dams fail from the backside. (Some seepage can be expected and not to worry) You might add also animal damage, tree roots and severe storm events to the list of culprits.

A leak of 15 – 20 gpm does not surprise me at all on a structure of this size and height.
I just hope you have the inflow and watershed to overcome the losses?


Toe drain installation in our HSB/YP pond.
Outlet from toe drain pipe is NOT perforated.


Perforated longitudinal toe drain w/ tee.


Ed

Yeah this is about right. It looks just about like this. slightly different configuration but the Idea is the same and they are there for the same purposes of relieving water that might have slipped through.
You are right my REAL fear is that I don't have enough coming in to over come the pond's losses. I am just not quit sure of how to attack this proble if in deed it is a problem. I was hoping to dig a new core accross the back but these toe drains would have to be removed first then reinstalled.

Or I can just drain the wohle thing and fill in the deep areas and make the lake on 20 feet instead of 30 feet.
Just not sure of what to do right now.

Hey big...sorry for all your concerns. Don't get in too big a hurry to do anything just yet. You say you're in a drought condition and have only lost 1.5 feet this summer? We're in (just a bit below, actually) normal conditions and I've lost that much from my little 1.7 acre pond. We've had plenty of rain for crops, but no real runoff this year.

Could that not be the actual problem? 20 gpm inflow? I've done some calculations that show I'd lose (on an average summer day) about 25% of that just in evaporation. You should see quite a bit more from your pond...maybe you just need to see what an average year will do for you...whatever that is. And, if we ever see another one....

Matt I think that is what I am going to do. just see what happens. Besides it look like it could be even MORE harder to build a lake in this state now. I might have to some how make what I have work.

BP sorry to hear your continued trouble. You are gettign some good advice form what I saw. Not my area of expertise that is for sure. If you need some fish, you got my number. thanks

Ed,
Excellent photos depicting the toe drain work...almost looks like we use the same photographer.
Is the toe drain trench filled with gravel, kinda like a reverse septic field (or more accurately, like a french drain)? Also, it looks like your toe drain is located at the base, likely a number of feet behind the centerline (or core, if required)of the dam....correct?
V interesting...new for me. My reaction would have been that if there is enough anticipated seepage to warrant a toe drain, there may be reason to re-consider the construction engineering and integrity of the dam...or the entire project. It seems kinda creepy to think that one would see a constant trickle/flow out of toe drain embedded in an earthen dam holding back a substantial mass of water. How is it's need calculated?...and...how is it's performance predicted?

Brettski,

I should have known there would be some tough questions.

Toe drains are generally located downstream from the dam centerline about 60% of the distance to the downstream toe. Not being an engineer I am not sure why that distance is warranted?
The perforated pipe is enveloped in compacted gravel (47B fine grade to be exact, which reminds me of good concrete gravel). Yep, I said compacted, if its not it will settle and leave a possible void in the structure.

Interesting question; “why consider building a structure when you know it will leak?”

Actually not every situation or dam building site has the luxury of having optimum building materials (good clays) near the site. A good example would be Merrit Reservoir located near Valentine, Nebraska. This is a Bureau of Rec structure built many years ago from almost pure beach sand. Does it leak? YES. Is it a controlled leak? YES. Is it a safe structure? Very Safe. Why was it built? Same reason most structures are built…. irrigation, elec. power, flood abatement, sediment retention, recreation, fish and wildlife, etc.

Sooooooo why build a dam from less than ideal material? Because you want a pond!
If you want it bad enough---go for it. Just follow the rules, specifications, safety, design; and remember that if it has a controlled leak that exceeds the inflow, you don’t have a pond--------- you have expensive pasture!

To answer your question as to when a toe drain is needed? Again, good question for an engineer. Rule of thumb in Wyobraska, if you have a perennial stream and a permanent pool (pond) that exceeds 10 ft. in depth, you may want to consider a safety valve (toe drain). Hope I didn’t muddy the water too much.

Ed

I was mindlessly watching the tube the other day, and the show was discussing the Hoover Damn.

One of the site personnel was being interviewed, and he said that he believed that the very center of the damn's concrete was still probably not even cured and hardened yet, and that it was probably still soft. He added that such a situation probably helped with the damn's integrity allowing it some flexibility.

They also showed how the damn springs leaks down in the tunnels. When that happens, they create/drill conduits to efficiently drain the water as opposed to trying to "patch" the leak.

Ed,
Thanks for the tune-up on Toe Drain -101. We likely encroached on the advanced course; my advantage.
Now, back to big_pond....
Would these engineering decisions and construction practice provide any clues to what may be going on with his dam? The decision to install the toe drain might indicate fore-knowledge of potential compromise, whether it be in the dam soils or active springs within the damsite. Are they a clue, or is focus an over-reaction? Big_pond noted the toe drain activity: What is the guesstimated volume? History and frequency of flow? Is this a clue to hydrolic activity within the dam mass (and perhaps the entire site)?

Hmmm--- Any clues as to what is going on in Big_Ponds dam?

Guessing and speculation on my part.

1. Equipment used in construction included; Track hoe, dozer and two dump trucks.
Was adequate soil compaction achieved using this combination of equipment?
Again I am guessing but was dirt brought to the site with dump trucks and spread and compacted using the dozer? There has been a lot of discussion on this site regarding the use of a dozer for compaction. I believe adequate compaction can be achieved by using a dozer if lifts are kept less than 6 inches, adequate soil moisture is maintained and the dam is a low head structure. (20 - 30 ft. is not a low head structure IMHO.)
If you can take a shovel and push it into the dam fill------you do NOT have adequate compaction. Digging a hole 8 inches deep with a shovel in a properly compacted dam fill, should be very difficult.
Mother Nature generally deposits our soils at 70 – 80% compaction in a natural environment. A 627 Cat scraper fully loaded weighs in at about 120,000 lbs. That’s a lot of weight distributed on 4 tires. At proper soil moisture content and 9 inch maximum lifts a 95% compaction can be achieved with one pass.

2. Was quality assurance employed throughout the entire work process?
In other words, did the landowner and contractor assure that proper moisture and compaction were employed each day? At the beginning of each day soils can dry out on the dam fill. So was there a good contact from previous days work to the next days work. (No dry seams.)

3. Core trench?
Core trench was probably plenty deep on this project (10 ft. I think)
Was water present in the core and pumped out?
Were side slopes of the core trench sloped at least 1:1. Vertical slopes are not stable and will not accept compaction when core is re-filled. This is a very important step and should not be short changed.

4. Situations beyond landowners control?
Perfect soils for dam construction are not always available throughout the entire process.
Water seeping through the existing upstream banks and exiting downstream.
Un-foreseen gravel and sand layers just under the excavated area.

A personal note on possible over-reaction? If this structure at 25 ft. of pool height is only loosing 20 gpm from seepage……I would be tickled!

Hope I didn’t step on any toes.

Ed

My experience is somewhat limited, but every pond leak I have seen, every single one, has that same rust colored residue present. Further, I have never seen a natural spring or any other source of ground water produce that same signature. This knowledge is how I distinguish between a pond leak and a natural non-pond source of water. In a pond leak, the water filters down through the dam and/or material...in a natural source of water, it is pushed up from below. Thus the difference...or at least my theory on the difference.

I don't claim this applies to anyone but myself and the area I am familiar with. I offer the comment only in hopes it adds to the discussion.