Pond Boss Forums INTRO Questions & Observations GA 10 acre pond/hole, 2 years and still notf full? possible dam leak? (new pics)

Well about 2 years ago my grandad and uncle started a 10 acre pond outside my back door (around Valdosta,GA). they moved dirt for months to construct the dam and it looked like it was going to be the perfect pond, with the water level about 20-25ft at the dam. they ran the newly installed well pump for weeks and got the deepest section filled. but then my grandad thought it was leaking and they havent touched it since. he said that it was damp behind the dam and more dirt needed to be moved for the dam. the soil here is all red clay and there is no obvious signs of leakage. anyway ive recently determined this is going to be my permenent home, and as an avid fishermen, ive decided to take the project on myself. im pretty knowledgeable on the basics of pond management but im not really sure how to become an expert on construction. i own "Raising Trophy Bass" by Mr. Lusk and subscribe to Pond Boss, but i would really like some more sources. any advice? good books? contractors in south ga? how will i know if the dam is inadequate?
thanks
brandon
Right side of dam:
Left side of dam:

Behind dam:

Close up of dam:


Side view of pond:

Front view of pond:

View of front of pond/driveway(old 1acre pond on right side):

bhb1034- edit your post again and remove the one space after .jpg

Does the well still work that they tried to fill it with? Did it take a long time to lose water? Does it still have any water? Are you close to any caves or karst areas?

yes the well still works. its a deep well installed for irragating. it actually fills a smaller 1 acre pond that overflows into 10 acre one. if i need to ill get the specifications. but from what i remember it pumped into the lake it just took longer to than expected to fill. i tried to argue that it was possibly just evaporation being that it was the middle of the summer. it was filled to a little more than the point that is in the picture. and the picture in my post was taken today. but about the caves or karst, im not sure. but im willing to find out. im pretty much willing to do anything at this point to get things started.

Was your Grandad thinking that if the pond filled up that the damn would not be strong enough to hold?

As much as I'd love to say let it fill and see what happens, that may not be good advice especially in lieu of more information.

bhb1034- my suggestion at this point is to find out as much information as you can about why they gave up on the pond. Was their a damp area below the dam? If so see if it is still there. Take photos, dig up as much information as possible.

Here is the photo he is trying to post:

To state the obvious, you need to find out where the water is going. The level in the pic, how long has it maintained that level? If this is a typical level for the pond I think I would be looking for places the water could be leaving at & just below the water line.
Are there still wet places below the dam? Try to find also where the water comes out below the dam.
BTW welcome to PB & good job on the PB subscription & books! That's a good start!
Maybe ewest will respond. He always has some good links/sites for info.

Do you guys think it may be something in the drainpipe?

bhb,
There are many unanswered questions related to your query. In my mind, solving this kinda puzzle requires going back to the beginning and documenting the fundamentals. Since it was 2 years ago, hopefully you were exposed to enough to remember what construction steps your Grandad and Uncle followed...?
a) was a core (or keyway) cut for the entire length of the dam? How deep/wide?
b) as mentioned by Turkeyfootnc, was a drain pipe installed? Valve? Anti-seep collars?
c) any input on the soil types? clay content? Do you remember hitting rock, sand, gravel? If yes, how was it mitigated? (edit: just re-read your comment to "all red clay...sounds good. Rock, sand, gravel question still stands)
There are a few "dirt-guys" on this forum that can kick in after some of these questions are answered. It sounds like a magnificent pond waiting to meet potential...I wish you the best and thanks for sharing your story...Welcome!

bhb,

Brettski asks some good questions. With more information, perhaps we can offer some assistance with your situation. You definitely want to insure the sturctural integrity of that dam.

thanks for all the replies. i wasnt expecting to find all the answers right off the bat, i was mainly looking for what questions i should be asking. so you guys have definately given me a start. im going to talk with my grandad and take some more pictures. then ill post them on here.

well i found out some more information on the pond. there never has been a visable leak in the dam. no standing water, just wetter behind the dam than before, which made them think the dam was leaking. the level its filled at now is about as high as its been, it was maybe a foot higher but lowering could have been because of evaporation. i was also told that only clay was used to construct the dam. supposedly one of the dirt movers had to be stopped from putting other types of soil on the dam once, but there wasnt that much "bad" soil added. im guessing there is no keyway or core, my uncle had no idea what that is, so im sure there isnt one. the well used to fill it is a 6" well, so is there any approximate way to estimate how long it would take to fill? and im still not sure about the caves or karst, im not really sure what was meant by that. theres more pictures here if anybody wants to view them:
http://photobucket.com/albums/e281/bhb1034/

bhb,

The expert dirt movers here will tell you that one of the main ingredients of any dam is the keyway http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=002340 . If your uncle had no idea what one was (unless he calls it something else) that would be a red flag to me.

To address the question about karst, hopefully TN Hillbilly will see this post and offer his input.

Considering the amount of water that your pond is losing, I think that you would see a significant amount of standing water behind
the dam if dam seepage was the problem. Will
a post hole dug into your pond bed hold water
overnight ?

bhb1034- If I have read this right no one has checked to see if it is really leaking. Mark your water level and turn that pump on. Try to establish the flow rate of the pump. Calculate as close as possible the area of the water, evaporation rates, how many gallons to fill 1', and see if or how much you are losing. Hold it at 1' and see how much water it takes to maintain. Wait until you are satisfied the amount is about right for evaporation or stop if it a big number and hunt for your leak. Then you can go up another foot and do the same thing until you find your leak or pond is full. Just my 2 cents worth.

I agree with PondsForFun that it sounds like the leak is in the pond basin. If you decide the pond is leaking I'd ask your grandfather how the basin and dam were packed. If they just used a dozer or other crawler type LGP machine I'd drain the pond and hire a self propelled sheepsfoot or if you have a crawler rent a pull-behind sheepsfoot and run it over the entire basin. All clays won't seal themselves well without some help, especially in some areas with limestone bedrock where clays tend to form a clump structure naturally. Pack the face of the dam also. If the dam has sufficient mass and the face is packed water tight then a core trench shouldn't be necessary. Also pay close attention to the moisture content of the soil when doing the compacting. Compaction is the most effective and cheapest method of sealing if you have enough clay in the dirt, which it appears you have plenty. Just $.02 from someone who knows just enough to be dangerous.

Based on the pix that I am looking at, if this is a 20'-25' tall dam without a core, I don't think that I would be camping behind it a whole lot when it fills up. (let alone the old dead tree that seems to be rooted right at the base behind it).

I think the main purpose of a core trench is to prevent water seepage thru other, marginal soils used to construct the balance of an earth dam, other than the core trench. I think it would be unwise to rely on a core trench to provide shear strength to hold back a body of water. I've often heard people say the dam needs to be 'keyed' to the earth for strength, but I don't see how this could be. High clay content dirt provides little shear strength. Large earth dams used to be constructed (and probably still are somewhere) with clay 'puddles' for cores, where the clay was pumped in as a slurry and puddled in the core trench. Now it's easier to move clay with trucks. Earth dams are (should be)designed so that the sheer mass of the earth in the dam is too large to be moved by the water it retains. As long as the base of the dam is cut down to clay subsoil before constucting the dam, and the dam is designed with the proper mass and built entirely out of well compacted clay dirt it should be fine. By proper design I'm assuming 12 ft wide at the top with at least a 2:1 slope on face and back. If water isn't visibly moving thru the dam it should be fine.

Boy!!! you MUST be my long lost twin...10 acre lake in Georgia that want fill up!!! WOW!! boy this is dajavue....wow...and i might add it was built two years ago....like mine .
The differances are yours is in south Georgia mine is in North Georgia. Mine has a live stream feeding it yours does not. Mine has a deep key way yours apparently does not from what you say.
How far is yours from the top? Mine is 6 feet from the top and will be 30 feet at about 2 acres around the dam area.

WOW you have no core or key way trench? This is a recipie for DISATER! This is one of the MUST for build a lake the size you have. and absolute MUST. This IS the first thing you are going to need to correct. What is the yardage of dirt in your dam/ Mine is 21,000 CU yards.

I have a plane "B" if you would, for filling up my lake. I have a pretty good size live stream not far from this lake and I plan on combining these two water sheds to fill up my lake now. I will need to raise the water about 18 feet in this creek channel there in makeing about a 2 acre pond. When the pond has reached full pool of around 18 feet then the over flow will run down to the big pond that does not have enough water.

What other solutions are you looking at?

big_pond,

Why do you think lack of a core trench is a recipe for disaster when the entire dam is built from good clay dirt? What do you think would happen?

Hillbilly,

Disclaimer: I'm not an engineer and neither of my two ponds have dams (both are excavated). From the information learned here, I agree with your prior statement that a core trench is a mechanism to limit seepage. However, would it be incorrect to say that, depending on the size, a keyway would offer some shear strength to the dam?

So how much non-clay soil would it take to lessen its ability to stop leaks? like i said not much other than clay was added, but id like to get an idea of how much would be harmful. also, the pond or dam was never really packed. i plan to move a little more dirt but havent decided if im going to drain it completely yet. the dam was made into a small road and its pretty steep on the water side. would the side have to be packed or just the top portion of the dam?
i read the posts about the keyway. so im guessing on those needs to be dug on the dam. will the dam have to be completely redone or can it just be added to it the way it is?
thanks

bhb,
Sorry if I didn't pick it up already in your posts, but please advise some of the spe'cs of the project: total acre/feet of containment at normal pool, drainage area size, avg annual precip (probably pretty high in GA?), you said the dam is 20-25 ft tall (that's a big dam, dude), principal spillway & emergency spillway spec's (or what is planned?)...also, how many trees are within 25 ft of the dam at any point?

edit: the slope on the water side of the dam should not be any steeper than 3:1, the backside 2;1 if it is VERY good compacted clay throughout...otherwise 3:1 min

Russ,

I'm not sure how packing lifts on top of each other in a core trench can have more shear strength than packing lifts on top of virgin ground. In fact, I'd say that a core trench packed with a tracked crawler alone is weaker as far as shear than a dam just lifted without a core and packed properly with a compactor. You always have to go down to clay dirt under the dam, keyway or not. So what is the advantage of digging a key and packing it with dirt that isn't as compact as it was when it was dug? No dozer in the world can put dirt back in firmer than it was when it was dug. You only need a key when you have permeable soils under the dam. If the entire dam is clay and the basin of the pond is clay then the entire dam is a 'core' so to speak.

This is beginning to remind me of one of those board games like clue where you must use deduction to win. We have a dam made mostly of clay. This tells me that someone knew what material was needed to build a pond. I doubt that BHB's Grandpa just said build me a dam and the contractors went forth and built it without someone putting a pencil to it. Bhb did not say the dam was 25' tall. I suspect it is dug down 10' or so and 15'- 20' high. The entire dam is semi-circular shaped. This was the old way to build dams when you have a fairly flat property. When the dam was built the grandpa turned on the pump and let her rip. I imagine the dam was unseasoned and the whole pond soaked up a lot of moisture while it was filling. The grandfather noticed some extra moisture below the dam and had been pumping for a long time trying to fill the pond. He panicked and killed the pump. Since that time the pond has maintained about the same level a foot or less than the highest mark. BHB never mentions the pump being used to add water to the pond. How is the pond maintaining the current level? Does the pond have natural runoff? I say it is doing very well and the dam is now well seasoned.

TN H...
In my simple little mind, I think of when the concrete walls are poured for the foundation of a basement. First, a flat footing is poured...with a keyway (usually a 2x3 or 2x4) laid into the top to create a 2x3 or 2x4 continuous channel (or keyway...or core) right in the middle. Remove the 2x3 or 2x4. Then, the wall is poured directly into and onto this keyway. It's purpose is to create a mechanical bond that will minimize the chance of water permeation where the 2 masses meet and to keep the bottom of the walls from kicking in when the grade is back-filled from the outside.