Pond Boss Forums POND CONSTRUCTION Building a dam Pond dam is leaking, help....ANOTHER UPDATE!

hello, I rented a excavator and added on about 100 feet to my 1/4 acre pond. Most of it basically a dam. I finished just in time cause we got a good rain for the first time in 2 months. The pond kinda goes on a slant so the enitre pond filled up overnight. I noticed earlier that it lost about 6 inches today and I looked around and their was a wet spot at the bottom of the dam where it meets the ground. I dug around and there are seepage areas for about 5 feet length along the bottom. I went into the pond and tried packing in from the inside, don't know if it will help. I'm just wondering if anyone would be able to tell me what I can do to limit it or stop it. Is it possible it will seal itself since it's so newly dug out? please help!

Hello F1sh,

I'm not one of the experts on this board, but have read enough to maybe impart a little guidance. Earthen dams must be keyed, compacted, and constructed of a correct soil composition. It would be very difficult to sufficiently compact your dam with an excavator alone, most of the pros reccomend a sheeps foot roller. What type of soil used in the dam, need correct mix of clay and dirt.

Many posts refer to "seasoning" of pond. Oftentimes ponds exhibit increased water loss early in their lives, and settle as time passes and the soils compact and saturate.

There art a ton of posts on pond building, check them out, very interesting.

Rgds,
Pedro

F1sh,

I meant there are tons of posts on "dam building". That would narrow the search up a bit.
Good luck.

Hey pedro, and thanks for helping! I have searched this board up and down and have found tons of useful information. What I should said was since it was seeping at the bottom about how much of a clay blanket would be good to line around the bottom inside of the pond? It's a small pond with a small area of leak. The soil is great for ponds it's a mizture of gray/yellow clay some sand and soil, it compact great and it's still only losing about 4 inches today with the leak seeping bad, so I don't think soil will be an issue. Thanks

when i built my lake the contractor told me i needed aleast 12" of clay with 18" being best.i had a leak 1 time just like you did,finished dam and that night got 4 inches of rain.we packed the dam at 11:00 o'clock at night with track hoe.contractor did not think it would hold up but next morning everything was fine.i have found it is best if they fill up slowly over time,this seems to get the dirt to settle better.

f1sh - did you build a keyway into the middle core of the dam's base?. Water has a tremendous ability to find a path of least resistance even around or between layers of a 12" thick packed clay patch. Remember that this area is under hydrolic head pressure from the overlying water. Amount of pressure is dependent of the water's depth.

Bill,I'm not quite sure what your mean about ''keyway'' unless you mean like scraping the top soil to blend with the soil i used to build the dam? I just dug down about 3 foot until I got to a little clay and piled it on. The clay was holding puddles of water before it filled and it kinda like holding water just enough to make it hard mess with without draining but not enough for desired depth which is 3 - 5 foot. I hope I can figure something out. Also I have a spring in the other half of the pond, so it's gonna keep on having water in it, so i'm concerned even if I break the dam and drain it I would be able to get it dry enough to make a good blanket. But your right that water sure did find a way out. I knew something would go wrong. doesn't it always! lol

You need to build a trench like a dovetail joint that is packed with the right material. Dept of that key depends on water pressure caused by water depth at dam.
Packing clay over the base of your dam may help for a little while but not likely to hold in the long term.

f1sh - Tuzz has explained the basic method for building a keyway or core trench for the dam. A trench dug down below the bottom of the dam and packed with good clay ties, connects, or binds the core of the dam to the clay subsoil below the dam. This core or keyway serves as a blockage for horizontal movement of water thru or under the dam's "bottom" layer. As you are experiencing it is very difficult to just build a dam on top of the soil and not get seepage under the bottom or floor of the dam. The dam needs to be "tied" to the subclay layer with a relatively impervious core.

Thanks for all the help everyone!!! After poking around the site and getting all this great information, I drained the pond today and notcied where the ground level met the soil I added on top of it for the dam, I notcied that is where the leak stopped while draining. I also noticed there were roots from small trees on this line. I have decided to do the core from the inside once it has dried out a bit for the enitre dam. How far should I dig under the previous dam before begining my job? Again thanks for all the help!

Okay here's the update. It's pretty good so far. I drained the pond and since down south the weather is extremely weird in the summer the pond dried enough for me to get in it and do the core. I dug about 3 feet under the enitre dam and packed it with the good clay from the middle. This clay is pretty good after a puddle sat for 1 week soaked, diggin only 2 foot the clay way dry and fresh ( like modeling clay). So goes the clay, I dont have access to a sheep foot but this thing was jumped,stompt, with 5 people including sheets of plywood lyed along the sides then pounced upon as well. I was fierce. So here comes the rain. Not as much as I would have hoped but enough to fill the pond half ways approx. 2 1/2 feet. It DID not drop at all for 2 days. But, but, but, now it has dropped about 1 inch in 3 days. Now take into mind it was dropping like a half a foot every 4 hours before. There has been no rain 95 degree temps., the pond is not even a acre in size, so my guess is extreme evap. from hot temps and/or ground soakage which I read is normal for new ponds. I sure hope I'm right, please tell me if i'm right, i need all the help i can get even the people that digs ponds i called act like they only know how to dig a deep hole and add lime in it. But so far you guys have been dead on like a broad head on a 10 point. Thanks alot...

If you are in the south, and humidity is less than 40%, temps mid 90's, expect at least an inch of evaporation every three days. If humidity is less, expect an inch every other day.
Also, if your soils were dry, they wick. Sounds better than what you had. Time will tell. Packed soils with plywood and heavy feet, eh?

Bob, trust me brotha, I did everything but a raindance on that clay pack. I know thats not the problem any more. But what I was tryin to say i guess is, do you think it's normal to lose that much it's like i put a stick on the water level and overnight it lost 1 centemeter then i reposistion again and again 1 cenitmeter. I guess the answer i'm look for is, is it fixed?, is this just evap. or could there be another leak? I dont think so but i wanna hear what anyone has to say. The dam was dry and the clay on top of the dam was cracking and turning into rocks. so i added water 3 times a day on the enitre dam to keep the top surface area wet. I busted my chops on this little '' beep'' i hope it works ..thanks man

i vote it's fixed.that's not alot of water to loose.i'm dropping about 1/2" a day on a little over 5 acres per day.i would say at this point you do not want alot of water in pond at one time.let the pond fill up a little at a time,this will help the levee settle and lock in place.

I'm in southern louisiana last i looked the humidity was 60% and the temp was 91 with a heat index of 98%, does 1 1/2 inch after 4days seem normal for a newly dug addition to a pond?

Well i've been a patient man. It sat at the 2 foot depth level and didn't lose nothing for about 5 days. Then the rain came, I was excited thinking I was gonna have me a pond at full pool,boy was I wrong again. It did fill at full level which made it 6 feet deep. Then overnight it dropped 7 inches. Then the next day it dropped 2 inches, then 1, then a 1/2 inch. Now it has stabilzed at a great 1 inch above normal. Yippy! Anyone know whats going on???? It's stopped a inch or 2 higher but it's still puzzling.

fish,

I'm having trouble following:
Full pool is 6ft.
It dropped 7+2+1+1/2= 10 1/2" & stableized at 1" above normal?
It stopped an inch or two higher .. than before adding clay to the bottom?

I think you have made a great effort to first build & then repair your dam. But .. even though you added somewhat of a key to the front of the dam (which I have to add wasn't compacted enough) the rest of the dam directly behind the leak was previously saturated.
Therefore you have simply slowed the leak by adding the clay in front of a pathway for water to pass through your dam.
The leak can be slowed further by adding more clay in front of the dam, or digging down & removing the saturated soil & rebuilding.
Good luck!

Well I was meaning the area of which my sticks are lining the sides of the pond I stuck in their to keep records of water line. So if I went into the middle right now it's a little over 4 foot. So at full pool it was around 6 foot. Then dropped 7, 3, 1, 1/2. The funny thing is the water level is higher by 3 inches than after the first time it filled. I have dug the back bottom 100 feet out looking for srpings , nothing. No signs of leaks. It's not leaking now, but when it fill to the top it drops quick then stabilizes a little above the orignal line. I really dont know if it's a leak, I am hoping it's just saturation from the soil cause the dam is still wet but not dried. The top of the dam is dry and the rest of the dam is dryin more and more and the water level is dropping less and less. Could this just be a situation where the dam will get soak, silted, and lock with time, and keep gaing a inch after a fill. Cause I really dont wanna drain it again cause i've already broke 2 shovels fixing it the last time. Any other thoughts??? I'll prolly kill this thread after this try, cause i can seem to get it no matter what I do. And I know it's not the soil. Thanks

ps I added a good keyway. went 3 feet below the dam and packed with everything in my disposal for 2 days, it was solid. I dug behind that same area when it started leaking again and it was dry as a bone, no leaking at all, thats a none issue now. I guess, even though I dont have the money, I've have to buy a few bags of bentonite if it keeps up, cause i'll have a pond if it's the last thing I do.. I'm young and willing to sling to shovel. Later one i'll tell you why I want one soo bad. Another topic hehe

If it's dry behind the dam then look elsewhere for water leaving your pond. I would be looking at waters edge or just below for pathways underground.