Pond Boss Forums INTRO Questions & Observations New ponds leaking

I had two new ponds build in Sept 04. The small one is approx 1/2 acre and 16 ft. deep and the large one about 1 1/2 acre and 20 ft. deep. I was there for most of the constuction and feel like the contractor did a good job with the dams, keyholes and packing them with a dozer and bobcat. The soil looks like good clay but it also contained lots of small rocks. In the bottom of the ponds we started hitting some large bolders and in the big pond there are some rock cliff formations in the bottom.

The ponds have not filled up but have not dried up either. They have about 3-6' of water in them most of the time. After a big rain, they gain about a foot for each inch of rain we get after ground saturation. However, they then leak at a rate of approx 1" per day until they get down to the 3-6' mark. They both seem to leak at the same rate so I don't think they are leaking thru the dams.

I am determined to fix the problem. It seems like my options are to try bentonite or line the ponds. My question is whether to even bother with the bentonite or just go straight to a liner. Any suggestions?

I've included some pictures taken not long after construction here:

http://home.insightbb.com/~sldeen/tands/pondphoto.htm

Tom

From the picture of the larger pond, I'd guess it may be leaking through the exposed rock strata. The same rock is likely, I think, to preclude using a liner OR bentonite to seal that pond. I suspect the dirt experts will recommend sealing off the exposed rock with clay.

Smaller pond looks to me like bentonite or a liner would be possible fixes (unless there are boulders under the water line, in which case see the above comments on the big pond). Let's see what the leak repair experts say (Bob Lusk has been posting a lot lately and he can have the last word in ANY thread here, IMO).

Are you in Indiana's limestone country?

Hi Tom and "welcome"R-PI is correct to remove the rock and or cover them, We work with alot of soils (ponds)that are near limestone quarrys and packing clay with a sheeps foot 6-12 inches at a time is the only way I see them hold.Then add the rock (boulders) back in for structure. Appears that the dam would be difficult to run a sheepsfoot on however.You would need to remove the rock for the liner regardless so is a great place to start. Were any test borings done to let you know what type of clay you are dealing with and what the water holding ability might be.

I concur with the leak theory. At the same time, have you seen water from your pond manifest itself anywhere downstream? Not knowing your geography really well, my common sense suggests dry soils may be absorbing some of your water via wicking. But, common sense also suggests the rock outcroppings can't be solid, therefore will be a source of water escape.

Thanks for the quick feedback. My ponds are located in Southern Indiana just north of Louisville, KY and yes this is limestone country. Many of the large rocks we removed look like they were under water many moons ago. They are obviously limestone and filled with petrified shells and tiny sea creatures. The rock strata in the large pond are made of the same material.

We didn’t do any soil testing before starting but everyone agreed that the clay looked good to hold water. No one would give me any guarantees that the ponds would hold water – no matter what. My neighbor has a pond not 500 feet away from the small pond that has held water for years, but he said that initially he had to compact the bottom to get it to hold.

I cannot find any seepage below the ponds but might not see it because a natural spring runs in the valley below both dams. I've actually considered pumping water from the spring up into the ponds since it has a good flow rate. Is this crazy?

At the current water level, the dams are very thick and I think constructed correctly so I don't think there is any leak in the dams themselves. The leaking rock theory makes sense except that both ponds seems to leak at about the same rate and the small pond doesn't have any uncovered rock structures in the bottom.

I went over to the property yesterday to consider how to cover the rock strata in the big pond with clay. Doing that will fill in the pond significantly. I'm not sure how to pack clay around those vertical structures except to add enough clay to slope up to the top of the structure.

It's too bad the rock structures cannot remain since they would make great fish cover. By the way, many of the large rocks you see on the sides of the large pond were added after it was dug - again for fish cover.

So it sounds like I need to wait until the dry season around here (late summer), drain the ponds (unfortunately killing my fish), and get some equipment in there again. I'd like to do this one time and therefore would like to find a real pond expert to do the work. Besides contacting the SWCD folks and asking them, do you have any suggestions on how to find a good contractor to do the work?

Thanks again,
Tom

Tom,If you can get a trash pump to pump in from the spring I would try to get as much water in as possible to raise the water level as high as possible.This will satisfy the "wicking" process that Bob mentioned and let you know how fast the water leaks out and to what level.Is it not practical to remove all the rock ??(could be put back in for structure)As far as a pond builder usually the road building companies (sub divisions etc) have the toys and the knowledge of local soils. You might start there.I have had little luck with liners as deer,herons and craw dads seem to puncture them in the shallows. Your situation may be different. We had one float a few years ago by getting water behind it. Touch base with "The Pond Guy"as technology changes fast and there may be something on the market that will work. We like to see soild "packed" soils with a sheepsfoot or vibra rollers as the preferred method. Great article on page 32 by pond construction expert Mike Otto in the latest PondBoss Mag Jan/Feb so be sure to read "Sealing Leaky Ponds" Ted

Nice looking ponds. Looks like your contractor
did a good job. I really like the subtle
sloping on the backsides of the dams - looks
like a 4 : 1 slope. I'm curious about the overflow pipe. It appears quite high on the
dam, giving maybe only a foot of freeboard. Hope
you have good emergency overflow areas on the
dam ends to handle large rains.

I subscribed to the magazine yesterday so hopefully I'll get the Jan/Feb issue in the next few days. I had the dams built with a gentle slope so I could mow them without killing myself and also wide enough to drive a truck across. The small pond has a 10" overflow and the large one a 12" plus emergency overflows on the sides. I wish I had enough water to see if they work right.

The rock shelves in the big pond are too big to remove without dynamite. As you can see in the photos, we pushed some of the big rocks we initially removed with a dozer back in after we were done.

I'll need to dig out the spring some more before pumping. I'm encouraged that the more I dig the better the flow rate seems to get. I’ll get a backhoe in there when it’s dry enough.

I took some more pictures of the rocks and spring today after we got about 1" of rain last night. I added them to the web page in my original post. I’m still hoping on some advice about a pond expert in my area.

Is there a rule of thumb for locating the overflow? I'll measure it next time I'm over there, but I'd guess it's about 3' below the top of the dam.

That's an interesting approach that I haven't seen around here. Right now, the pipe outlet simply runs along the entire backside of the dam (underground) and empties into the valley below.

Tom....welcome to the show. I'm a rookie here with a project in the works. Nice work on the ponds...love the surrounding area...beautiful!

The combination of normal pool, principal spillway size, emergency, and freeboard is an important engineering application. I'm kinda glad that this side-bar has come up. The way I have been taught is as follows...I invite the experts to "tune me up"...I'm gettin' ready to push dirt this summer, too.
Based on your 12" dia principal spillway and using normal pool as "ground point zero" (water just touching the bottom of the principal), the emergency spillway low point should be at 24" above normal pool. The top of the dam should be another 24" above that. In other words, the top of dam should be at least 48" above normal pool. A minimum freeboard is v important, particularly on larger ponds, because of windy wave action that creates lapping at the dam. This lapping action danger multiplies exponentially when the principal is full and the emergency is taking on water, leaving very little freeboard exposed over the balance of the most important stop feature...the dam.

Tom, You can download a free copy of the Jan/Feb "2005" issue and check out Bobs article on page 28 followed by a soils article by Mike Otto.Go to the PB homepage for the link, These articles will give you some things to "ponder"Your now on the right track Ted